Lecture #2 - Cell Structure & Function Flashcards

Question

What is the limit of resolution for light microscope?

Answer 1

about 0.2 μm - MIN distance that 2 objects need to be apart from 1 another, in order for that microscope to show you separate objects - if those 2 objects are less than that distance apart (closer together), the microscope cannot get energy source that it's using b/t them, so you see a blurry image (not separate objects)

Answer 2

If we report a resolving power/limited resolution = to 0.2 μm. That means, this microscope with the energy source it's using can provide light that can only get through spaces that are AT LEAST 0.2 μm - anything BIGGER works too - anything smaller, the light CAN'T fit, therefore can't energize sample or provide a clear image

Answer 3

SMALLER - b/c then those 2 objects can be even closer together & you can still see a clear image (ex: e- microscopes)

Answer 4

* Magnification = ocular x objective * ex. Ocular = 10x, objective = 40x * Magnification = 10 40 = 400x

Answer 5

* The ability of a lens to distinguish small objects that are close together * Ex) resolving power of 0.2μm * Two points can be distinguished if they are at least 0.2 μm apart * Light must pass between two points for them to be viewed as separate objects (providing clarity) * As wavelength decreases resolution improves

Answer 6

INVERSELY PROPORTIONAL

Answer 7

↑ ENERGY ↑ RESOLUTION

Answer 8

↓ ENERGY ↓ RESOLUTION

Answer 9

- gamma rays - x-rays - ultra-violet rays

Answer 10

DANGEROUS b/c energy it carries can be transferred all the way to DNA for ex & can result in damage/mutation that can lead to cancer - ↑ energy radiation is dangerous b/c energy it carries will then be transferred to other objects its in contact with

Answer 11

- infrared rays - microwaves - radio waves

Answer 12

NO - b/c as you magnify, it doesn't mean the resolution maintains clarity - ex: zooming on phone doesn't mean it will still be clear

Answer 13

DOESN'T mean/guarantee resolution will also increase; dependent on microscope you chose

Answer 14

1. CANNOT fit b/t arms, poor resolution 2. Fit b/t arms, resolution improves 3 & 4. As DIAMETER of objects thrown DECREASES, GREATER NUMBERS pass b/t the arms & the RESOLUTION INCREASES (no size limitation - ton of clarity)

Answer 15

a better final image | - STICK OUT BETTER, BETTER CLARITY & you can see better dets of cell

Answer 16

• Dyes are organic compounds (carbon containing CH2-COO-) that bind to specific cellular materials (inside the cell)

Answer 17

methylene blue, safranin, and crystal violet

Answer 18

1. Simple staining | 2. Differential stains

Answer 19

One dye used to color specimen - just shows if something is THERE or NOT - 1 size fits all (1 colour only) think: taking attendance at exam, are you there or not?

Answer 20

colored portion of a dye - colour your cell will appear as a conseq. of that dye adhering to portions of the cell or cellular structures Ex: red chromophore

Answer 21

1. Basic dye | 2. Acidic dye

Answer 22

ALWAYS HAVE A NET (-) CHARGE - if you apply a basic stain it will adhere - if you apply an acidic stain it will repel

Answer 23

positively charged chromophore • Binds to negatively charged molecules on cell surface - (+) at pH=7

Answer 24

negatively charged chromophore • Repelled by cell surface • Used to stain background (cells will stick out) • Negative stain - (-) at pH=7

Answer 25

crystal violet - cells are violet

Answer 26

nigrosin - background is purple ish

Answer 27

1. PREPARING A SMEAR - Spread culture in THIN film over slide 2. a. Dry in air OR b. HEAT FIXING & STAINING - Pass slide through flame to heat fix (think: cleaning pan next day - hard to get off, dehydrating sample so it is stuck on slide, therefore it doesn't get rinsed off in next step) - Flood slide with stain (engaging with cells or background - depending on if basic/acidic) 3. Microscopy - Place drop of oil on slide; examine with 100X objective lens - not gonna get differentiation, just able to see if it's there

Answer 28

be (-)ly charged on their external surface

Answer 29

architecture of their cell wall is different

Answer 30

a differential stain; a staining procedure where you can create differences based on the cell structure, that allow you to identify if the bacterium that you have in your sample is gram + or gram -

Answer 31

1. Narrows the pool of suspects - so you can investigate knowing which it is 2. Gram + or gram - are targeted by certain antibiotics - & some antibiotics target both

Answer 32

the good thing is you leave your gram - bacteria that are good alone - the drug won't harm all of the good bacteria - means better toxicity just to what you want so general state of health can be more or less maintained

Answer 33

- plasma membrane | - THICK peptidoglycan

Answer 34

- plasma membrane - THIN peptidoglycan layer - outer membrane

Answer 35

1. Apply CRYSTAL VIOLET stain purple & basic: Gram + = purple Gram - = purple Human cell = purple 2. Apply IODINE = a mordant - intensifies bound stain Gram + = purple Gram - = purple Human cell = purple 3. Apply ALCOHOL = a decolourizer Gram + = purple (trapped in cage like structure - alc bulked them up so they can't get mordant & crystal violet out) Gram - = colourless Human cell = colourless (b/c no cell wall) 4. Apply SAFRANIN (pink & basic) - sticks to any living cell Gram + = purple (pink will stick but will stay purple b/c it never came off & its darker) Gram - = pink Human cell = pink

Answer 36

- The Gram Stain - Acid fast stain - Endospore stain

Answer 37

- Differential Stains - Gram positive - Gram negative

Answer 38

cells that retain a primary stain | • Purple

Answer 39

cells that lose the primary stain • Take color of counterstain • Red or pink

Answer 40

purple is darker so it will trump

Answer 41

everything will be BLACK - b/c you added (+)ly charged stains, but you added the darker one AFTER the alcohol decolourization so it's gonna stick to gram -'s just like safranin would have, sticks to gram +'s & is gonna trump yellow b/c it's darker

Answer 42

- differential stains - Detects mycolic acid in the cell wall of the genus Mycobacterium - Mycobacterium – retains primary stain • Fuchsia (pink) Anything else on slide – color of counterstain • Blue

Answer 43

* Endospores retain primary * Green - malachite green - sticks to endospores if present * Cells counterstained * Pink - safranin + - stick to all things that contain a - charge * Ex. Bacillus anthracis spores. ONLY produced by SOME bacteria - always be a gram + bacterium

Answer 44

has plasma membrane, gram +, & MYCOLIC ACID (hydrophobic) as the outside of their peptidoglycan

Answer 45

- hydrophobic - outside of their peptidoglycan - unique to members of mycobacterium genus - can engage with things ALSO hydrophobic

Answer 46

undergo a gram stain | - so has to do AFS

Answer 47

No - b/c "like dissolve like" - can engage with things that are also hydrophobic - acidic/basic carry a charge so it's hydrophobic

Answer 48

the stain to remain purple b/c it's trapped, it won't come out (not outer membrane)

Answer 49

retains primary stain | • Fuchsia (pink) - carbol fushin sticks to mycolic acid

Answer 50

Anything else on slide – color of counterstain • Blue - methylene blue (basic & blue) - basic is +, so blue stain will stick to cells (any cell that's not acid fast); so other gram +'s, -'s, human cells that might be in the sample (anything with a net - charge on its outermost surface, methylene blue will try to stick too trying to create a differential output

Answer 51

resilient structures ex: if a bacterium finds themselves in a situation where water/nutrients are limited, they can enter in spore state (metabolically inactive) where he hides out until conditions become more fav. for survival, then he comes out & wakes up & starts metabolism & being normal again ex: rice - when they fuel replication from those conditions, the microbial count goes up! - & if you take it & put it on fridge, it will grow slowly - can destroy with an autoclave- combines temp & pressure for ex

Answer 52

everything would be pink

Answer 53

``` def not - b/c you'll have bugs there that the pink is sticking too but you don't know if its gram + or - (it can be either) - it's only when you know it produces endospores, that you know it must be gram + & therefore will produce a purple stain ```

Answer 54

purple - b/c it's an endospore forming & gram + are the only kind of bug that'll form an endospore & it's not all

Answer 55

mycobacterium is gonna be there - pink will be members of mycobacterium genus - BLUE (hydrophilic stuff) is other cell types - everything else that's there - (+) result

Answer 56

no pink - everything blue (just blue would tell you no mycobacterium, but won't tell you gram +/-)

Answer 57

Phase ring amplifies differences in the refractive index of cell and surroundings • Improves the contrast of a sample without the use of a stain - therefore, doesn't constitute characteristics of viability • Allows for the visualization of LIVE SAMPLES - so you study further or to protect if it's the last one • Resulting image is dark cells on a light background

Answer 58

- inverted like how we saw in the previous • Specimen is illuminated with a hollow cone of light • Only refracted (bent) light enters the objective - everything else will go around so it's not gonna make its way up through the lens & will not be part of the image you get as a result of the eye piece • Specimen appears as a bright object on a dark background * Used to observe bacteria that don’t stain well (meaning it's gonna be hard to visualize) * Ex) Treponema pallidum – the causative agent of syphilis

Answer 59

* Used to visualize specimens that fluoresce * Emit light of one color when illuminated with another color of light absorption wavelength: characteristic of the chemical properties of a fluorescent particle - have to know what this is so it can be absorbed - have to strike this with light of a particular wavelength emission wavelength: what's given off to provide the fluorescents that you see

Answer 60

LARGER wavelength - b/c of the energy that was absorbed, some of it was converted to heat - so not all of it will be there - b/c there is a loss of heat, when this gets absorbed you're gonna have less that'll come out which means that wavelength must be larger b/c larger wavelength is lower energy which counts for amount spent in absorption activity

Answer 61

• Ex. Photosynthetic Cyanobacteria (ORIGIN OF THE EUKARYOTIC CHLOROPHYLL) have chlorophyll - have photosyn. pigments that have the opportunity to absorb light * Absorbs light at 430 nm (blue-violet) * Emits at 670 nm (red)

Answer 62

Ex) DAPI (has affinity for DNA) specifically binds to DNA (allows you to localize it) - anything in fluorescent blue is an indication of DNA

Answer 63

1. Take antibodies (highly specific to 1 antigen) - HIGH SPECIFICITY of binding to a target 2. Couple it to a fluorescent particle on the other end 3. That fluorescent particle has a certain absorption & emission wavelength 4. Take a cell, & apply the antibody, knowing fully well it will go in & bind to a SPECIFIC REGION of the cell 5. TREAT cell with the absorption wavelength, & then leave it alone so it emits & you have a detector to pick up on the emission wavelength Can use a # of antibodies, targeting a # of diff fluorescent particles, in order to allow the opp. to be able to see things inside the cell BENEFIT: more bang for your buck - b/c you're not just staining for 1 thing, but for other things as well!

Answer 64

* Uses a polarizer to create two distinct beams of polarized light * Gives structures such as endospores, vacuoles, and granules a three- dimensional appearance (but still a light microscope - so not amazing but not perfect) * Structures not visible by bright-field microscopy are sometimes visible by DIC - can see curvature & dimensions of nucleus

Answer 65

1. Phase-contrast microscopy 2. Dark field microscopy 3. Fluorescence microscopy

Answer 66

1. Differential interference contrast (DIC) microscopy | 2. Confocal scanning laser microscopy (CSLM)

Answer 67

• Uses a computerized microscope coupled with a laser source to generate a three- dimensional image (will see layers of the cell b/c of where the laser is engaging) - when you get that layer, you take it & put it together with another layer of laser image - stack on top of one another) - building image of the cell * Computer can focus the laser on single layers of the specimen * Different layers can then be compiled for a three-dimensional image (can tell a lot of dets) • Resolution is 0.1 μm for CSLM (μm = light microscope) - not clearest ever

Answer 68

LIGHT microscope

Answer 69

nm ranges of resolution | - smaller than light microscopes

Answer 70

use electrons instead of photons to image cells and structures • Wavelength of electrons is much shorter than light (therefore higher E) --> higher resolution BETTER UPPER LIMIT OF MAGNIFICATION - also even if you HOLD magnification constant the resolution beats a light microscope!

Answer 71

* Transmission electron microscopes (TEM) | * Scanning electron microscopes (SEM)

Answer 72

* Electron beam focused on specimen by a condenser * Magnets used as lenses * Electrons that pass through the specimen are focused by two sets of lenses * Compound microscope (combining 2 things that are happening) • Electrons strike a fluorescent viewing screen (providing the image) - magnet is condenser & inverted same way as light microscope * High magnification and resolution (0.2 nm) (nm = 10^-9m) * Specimen must be very thin (20 – 60 nm) *stained adhered differently based on the characteristics of those structures, which means that now the image that's created as the e-'s are deflected back to the viewing screen is gonna be heavily detailed

Answer 73

- won't be able to see anything - b/c e-'s have poor penetrin • Must be stained with (heavy) metals (means sebitonic particle # is high & so e- # is high, creates e- density that allows you to visualize when e- beam strikes the sample)--> lead or uranium - therefore heavy metal stain is gonna be e- dense - stick to thin section diff. on a ribosome then it would stick to a DNA region/membrane • Bind to cell structures to make them more electron dense • Enables visualization of structures at molecular level - can see inside of cell (not alive not) but lot of work THINK: egg - has to cut to visualize the inside - slice to see diff. dets - BUT cell is 60-80% water - think: cutting water balloon - so must permeate it with a resin - resin is injected as a liquid to polymerize & harden once it goes inside - then all internal materials of that cell are fixed & isolated to 1 particular region - then use a microtome = diamond knife to do thin sectioning - see diff. in texture, see morphology of nucleoid region where chromosome located, see characteristics of mem. cross-section & all fine dets on surface on cell

Answer 74

= diamond knife to do thin sectioning

Answer 75

when you wanna see INSIDE of cell

Answer 76

e- microscope: - way better than light - even when magn. is constant - great solution therefore, even when magn. is set constant, the e- microscope provides such a great clarity b/c resolving power is gonna be much smaller than the light microscope

Answer 77

• Specimen is coated with a thin film of heavy metal - e- dense! (e.g., gold) • An electron beam SCANS the object • Scattered electrons are collected by a detector, and an image is produced • Allows an accurate 3D image of specimen’s SURFACE. - clarity - can see surface dets (round, amount of space, arrangement, contour) - good job at providing external dets

Answer 78

e-'s sprayed on an angle on the surface - thin coat of heavy metal adhering to the side e- beam slowly scans - provides it's blunt at bottom, narrow at top, out like this on side - fine surface dets

Answer 79

when you want to see OUTSIDE of cell (contour)

Answer 80

- bachelor suite (everything happens in the open - no separate compartments, everything within boundaries of plasma membrane) • NO membrane bound nucleus or organelles - genetic material floating • Generally smaller than eukaryotes - pack a lot less * Simple internal structure * Divide by binary fission (EQUIVALENT OT MITOSIS) • Most are unicellular - if they're multi they will not have tissue differentiation (just will be power in #'s)

Answer 81

- such that in the absence of any error during DNA replication, this process produces genetically identical daughter cells, so you don't expect any genetic variation - it's meant solely as a means of increasing cell # - diff. when we do mitosis, we get a total cell # that's higher - but when BF is completed they get a whole new organism b/c they are unicellular

Answer 82

true bacteria • Diverse metabolism - allows them to explore so many of the diff. environments that exist on the face of the earth - means ton of diversity & a vital role in every ecosystem found (creating imp. characteristics - if removed, it'll be impactful) • Live in a broad range of ecosystems • Pathogens (cause disease) and non-pathogens (cannot cause disease) - a lot of change can potentially occur - not consistent all throughout life (genetically plastic)

Answer 83

NOT BACTERIA - only thing they share with bacteria is their prok. cell structure * Diverse metabolism * Live in extreme environments - that allow them opp. to thrive, b/c can live under low pH conditions sometimes & increased salt - but can also live in mild ones (like our gut) * - some can live @ 30% NaCl (& still can maintain water nonetheless), our blood is 0.9% • Non-pathogens - has capacity to change - through picking something up (a weapon) - via a gene set that can be produced into a toxin or capsule that can lend ability to cause disease

Answer 84

- -> shape! - diff. in morphology have nothing to do with intelligential ability, height, weight, interpret lang, etc. - as well as nothing to do with genetics of cell, comparisons & contrasts of other species, just a unique characteristic to fully understand the organism - physical characteristic totally unrelated to almost all other characteristics - shape gives a bit of a push to a direction/hint of the cause based on how it looks to diagnose an infection

Answer 85

- Coccus (pl. cocci) - Bacillus (pl. bacilli) - Spirillum (pl. spirilla) - Cells with unusual shapes - Budding & appendaged bacteria - Filamentous bacteria

Answer 86

• Roughly spherical • Ex) Streptococcus pyogenes - causes strep throat/flesh eating disease (organisms are not the same strain) - like "tall" in name

Answer 87

* Rod shaped (asymmetrical shape) | * Ex) E. coli

Answer 88

* Spiral shaped | * Ex) Spirillum volutans

Answer 89

• Spirochete - LONGER in length, allows them to bend (FLEXIBLE) • Ex) Treponema pallidum - cause disease of syphilis

Answer 90

appendaged - allows opp. to make contact with the surface (attachment is imp.) - appendage to allow opp. to bind to a particular structure - stick to surface to not get flushed away - we are flushing clean (vomit, urinate, defectate, etc.), these so we need to have an organism that can grab on if it has capacity to stick when it gets deposited to inside of body, otherwise all these self-cleaning mech's are gonna eject organism from where it came from Ex) Caulobacter crescentus

Answer 91

Ex) Streptomyces griseus - produces imp. antibiotics - increase SA for things like absoprtion - b/c long & thin - better opp. to take nutrients in

Answer 92

Morphology typically does not predict physiology, ecology, phylogeny, etc. of a prokaryotic cell

Answer 93

selective forces involved in setting the morphology

Answer 94

• Optimization for nutrient uptake (small cells and those with high surface-to- volume ratio) - SA:V will do better - b/c they have better/more membrane to interact with their environ., allowing the opp. for the cell to protect itself against environ. changes - nutrients come in, get distributed & cell is benefiting from that • Swimming motility in viscous environments or near surfaces (helical or spiral-shaped cells) - if a cell has a particular shape its able to cut a lot of that material so its able to disseminate & relocate to other locations • Gliding motility (filamentous bacteria) - filamentous structures have opp. to glid over the surface (move from A --> B in order to max. contact with environ., use physical support as a means of locomotion) - use physical support as a means of locomotion rather than free-living movement

Answer 95

cooci - individual cell structures - can choose to arrange themselves in more complex patterns * -if they choose to get together in a more high level organization, they are still individualized cells that live autonomously - still indiv. cells that are free living but chose to get together - diplococcus (diplococci) - diplobaccillus (diplobacilli) - streptococcus (streptococci) - staphylococcus (staphylocci)

Answer 96

doesn't have anything to do with the name but ppl chose to include morphological dets & arrangements within the name/genus name (strepto)

Answer 97

strept throat - whereas if you didn't see that or if you saw a baccilis, autonomically you'd be realizing its something else

Answer 98

manifests almost same as strept throat, doctors confuse/misdiagnose - virus WOULDN'T grow freely b/c it's not a free living cell, so you wouldn't see anything if you took a throat swab to try to identify - therefore, wouldn't see infection agent b/c virus' can't be cultured that way (would just see normal flora)

Answer 99

a lot easier to kill one | - then they will start transcribing/translating a toxin or something

Answer 100

- Average • E.coli (asymmetrical) ~ 1.0x3.0μm • Staphylococcus aureus ~ 1.0 μm diameter - Very small • Mycoplasma (as genus more have cell wall) genitalium ~ 0.3 μm - exception - respon. for sexually transmitted infection (STI) - anomaly b/c it does NOT have a cell wall --> outermost component = plasma membrane (sounds like an ANIMAL cell b/c no cell wall) - also small b/c they've come to rely on the host for many things - extremely efficient - pack lighter - pathogenic & really tiny so when they enter body they can enter tight tissue - Very large • Epulopiscium fishelsonii ~ 80 x 600 μm.

Answer 101

- very small - exception (as genus none have cell wall) - respon. for sexually transmitted infection (STI) - anomaly b/c it does NOT have a cell wall --> outermost component = plasma membrane (sounds like an ANIMAL cell b/c no cell wall) - also small b/c they've come to rely on the host for many things - extremely efficient - pack lighter - pathogenic & really tiny so when they enter body they can enter tight tissue

Answer 102

No Appear pink - look like a Euk - b/c alc would destain their membrane & then go on & stain pink by the end - doesn't mean gram - either, but just the way all organisms without a cell wall will appear - so gram staining not effective for identifying this b/c it will look like any gram - cell

Answer 103

Surface-to-volume ratios, growth rates, and evolution • Advantages to being small • Small cells have more surface area relative to cell volume than large cells (i.e., higher S/V) • Support greater nutrient exchange per unit cell volume - distributes nutrients & have less to make everytime you have to make a new cell (b/c small & don't have to make organelles) • Tend to grow faster than larger cells - v. efficient - turn over cell a lot faster

Answer 104

``` Large cell V = 1 - membrane you're able to interact with your envir. with to bring nutrients in etc. SA:V ↓↓↓: 1 ex) 2 ``` ``` Individual (small) cells V = 1 - small, therefore tons of opp. to bring nutrients in & share those nutrients with entire volume on inside of cell SA:V ↑↑↑:1 ex) 10 5x greater ```

Answer 105

- you wanna be small & pack light but you can only get so light before you can't bring your essentials with you • Cellular organisms <0.15 μm in diameter are unlikely (b/c can't fit dets req. for survival (ribosomes ex) - anything smaller they can't fit key dets * Open oceans tend to contain small cells (0.2–0.4 μm in diameter) * Many pathogenic bacteria are also small (missing many genes whose functions are supplied to them by host) - rips out pages of recipe book they don't use anymore b/c they grow it in garden - able to whizzle way in tissue (has to be small)

Answer 106

• THIN structure that surrounds the cell - thinner it is, the easier it will be for nutrients to be able to transit into cell & wastes to exit cell * Vital BARRIER that SEPARATES cytoplasm from environment * Highly SELECTIVE PERMEABLE BARRIER (can chose what goes in/out (control); enables concentration of specific metabolites and excretion of waste products - metabolites - necessary for metabolism & fuel generation (ex: ability to let glucose in) - waste products - imp. b/c can be toxic if accumulated

Answer 107

``` CYTOPLASMIC MEMBRANE (cell or plasma membrane) is the key defining characteristic of a LIVING cell - prok, euks ``` BUT except viruses - b/c no plasma membrane, therefore no living features to be able to move things in/out & control things imp. for life

Answer 108

* General structure is PHOSPHOLIPID BILAYER * Contain both HYDROPHOBIC (fatty acid) and HYDROPHILIC (glycerol-phosphate) components * Can exist in many different chemical forms as a result of variation in the groups attached to the GLYCEROL BACKBONE * Fatty acids point INWARD to form hydrophobic environment; hydrophilic portions remain EXPOSED to external environment or the cytoplasm

Answer 109

phospholipid bilayer is this b/c it has a head group that prefers interactions with water (hydrophilic) & tails that prefer interaction away from water (hydrophobic)

Answer 110

has a head group that DETERMINES IDENTITY & also TAIL LENGTH & UNSATURATION that can also determine characteristics/behav. of the structure ex: longer tails --> more sturdy unsat. creates more fluidity

Answer 111

phospholipids naturally come together in water in order to promote fav. interaction & circularize (won't be living in water) - therefore, won't be exposed b/c their touching water which is undesired but they become an uniform structure

Answer 112

Will stick head groups to inside so they have fav. int with each other & tails pointing out getting fav. int. with oil ("hydrophobic like hydrophobic") - think: inverse micelle

Answer 113

* 2 Fatty acids * Phosphate * Side chain (optional)

Answer 114

``` CH2-C=0 | O | C ``` carbonyl group attached - impacts heat stability & beh.

Answer 115

has both polar and non-polar characteristics | - arranged to meet demands of both ends of molecule

Answer 116

molecule carries full or partial charge | • Hydrophillic

Answer 117

molecule is uncharged (CH2 - no charge - therefore non-polar) • Hydrophobic

Answer 118

e-'s held closer to N b/c polar covalent bond | - therefore, partial +

Answer 119

* 8–10 nm wide * Embedded proteins * Stabilized by HYDROGEN BONDS and HYDROPHOBIC interactions * Mg2+ and Ca2+ help STABILIZE membrane by forming ionic bonds with negative charges on the phospholipids * SOMEWHAT fluid

Answer 120

LENGTH OF FA CHAINS - will determine how far apart head groups will be from 1 another - if you adjusted the FA tail length (bigger or smaller), the protein wouldn't have portions that are hydrophobic contacting tails properly & portions that are hydrophilic contacting the tails properly - critical to have tail length how it should be otherwise like & like won't be interacting as it should!

Answer 121

``` DIVALENT CATIONS (Mg2+ & Ca2+) - bring (+)ity to bond & alleviate repulsion - stabilizes (-)ity so membrane don't have strong forces (repel) forcing it apart ```

Answer 122

WdW's - weak int. b/t non-polar group - still take heat to break

Answer 123

H BONDS & IONIC BONDS | - respons. for creating a higher level structure in these regions

Answer 124

VdWs require heat to break - monounsat tails allows VdW's int. that req. heat to break - since tail is far apart - you are not forming VdW's there so it creates a FLUIDITY - imp. to be somewhat fluid for optimal function

Answer 125

• Outer surface of cytoplasmic membrane faces the environment • In gram-negative bacteria, interacts with a variety of proteins (periplasmic proteins) that bind substrates or process large molecules for transport - meaning diff. proteins floating in periplasmic space & outer surface will interact with those proteins * Inner surface of cytoplasmic membrane interacts with proteins involved in ENERGY-YIELDING REACTIONS and other important cellular functions * Integral membrane proteins * Peripheral membrane proteins

Answer 126

Firmly embedded in the membrane | can be transmembrane integral or just integral

Answer 127

One portion anchored in the membrane - usually attached to EC face of mem. or IC face attached to hydrophilic regions, usually H+ bonds & ionic int. (electrostatic int. b/t (+) & (-)ly charged areas) - to stay fixed

Answer 128

on inner mitochondrial membrane is ETC - the inner surface of cytoplasmic membrane is analogous to inner mitochondrial membrane which will have ETC present within

Answer 129

EXTREME enviromental conditions (therefore, must have cell structure able to tolerate)

Answer 130

ETHER - O holding together * better thermal stability - stronger - able to survive more environmental extremes

Answer 131

ESTER | - carboxylic acid

Answer 132

* Archaeal lipids LACK fatty acids; have isoprenes instead * Major lipids are glycerol diethers and tetraethers * Can exist as lipid monolayers, bilayers, or mixture

Answer 133

in Archaeal membranes C5 tails hydrophobic & come together C5 + C5 = C10 C10 + C5 = C15

Answer 134

- glycerol structure that has a phosphate as part of its head group - 2 hydrophobic tails attached to glycerol by just O (2 ether linkages) bilayer in Archaeal membranes

Answer 135

- 2 glycerols - tails are connecting them * - forms a mono layer - NO gap b/t 2 tail structures - will get more VdWs - which means we have more that we'll have to break to be able to melt - @ higher temps. the membrane will be able to hold its shape better with more VdWs

Answer 136

depending on how many of each you have - it'll determine at a partic. temp if you're solid, semi-fluid or liq - membrane ALWAYS must be semi-fluid - mixture will have lil bit of fluidity & also lil bit of stability

Answer 137

want gaps in b/t - lipid bilayer to prevent solidification

Answer 138

no gaps in b/t - lipid monolayer - a lot of stability to prevent melting

Answer 139

Lipid bilayer: - gap - no VdW's - separated --> less thermal stability Lipid monolayer: - 1 layer - no gaps

Answer 140

extremely heat resistant ↑↑ VdWs

Answer 141

Commonly found in hyperthermophilic Archaea (grow best at temperatures above 80oC) - Archea that perfers extrem. or excessively high temps - increasing # of monolayers, having more VdW's, allows them to be semi-fluid @ those temps

Answer 142

small/non-polar molecules from [high] to [low]

Answer 143

*polar molecules are more controlled/need transporters/channels pores are highly specific, polar material can move

Answer 144

• PERMEABILITY BARRIER - Polar and charged molecules must be transported - Transport proteins accumulate solutes AGAINST the concentration gradient (active transport) (ex: glc transport does this from low to high concen., therefore where it isn't there that part of the mem. is non-permeable to that solute so unable to so you can concen. it against its gradient) PROTEIN ANCHOR • Holds transport proteins in place - to be in the right location for function ENERGY CONSERVATION • Generation of proton motive force

Answer 145

MUST stay in that order (anchored) or else they will lose function of ETC

Answer 146

can move protons to outside of cell thorugh complexes 1,3 & 4 - building a [ ] gradient, where they can flow back in to allow for ATP synthase - producing energy

Answer 147

GRADIENT WOULD DISSIPATE (energy stored within would be lost - not harvested) - protons have to stay there & then flow in - controlled

Answer 148

Makes a membrane leaky to proton. Able to move from high to low concen. (don't need to use ATP syn). Lose ability to harvest that energy & ability to produce ATP & drive Na+/K+/ATPase to keep gradient from neurons firing. Becomes lethal - energy prod. goes to a hault & brain runs out of fas

Answer 149

* Show saturation effect | * Highly specific

Answer 150

molecule is moving directly through the plasma membrane (moving along [ ] gradient) - no transporter/transmembrane protein - inefficient

Answer 151

b/c inside of mem. is not really hospitable to that movement (wait a long time for it to come in) - can use a transporter to help

Answer 152

carrier; physically binding to, & then guiding a molecule into a cell to let it go

Answer 153

polar inside - get dramatic increase in solute entry & then levels off when all binding sites are saturated inside of carrier protein, it can't go any faster in terms of internalization - saturation effect - & is highly specific-bringing in 1 particular molecule

Answer 154

* Simple transport * Group translocation * ABC system

Answer 155

All require energy in some form, usually proton motive force or ATP - ALL ACTIVE!

Answer 156

driven by the energy in the proton motive force *SECONDARY ACTIVE TRANSPORT - energy released from PROTON movement from [high] to [low] funds energy needed to move another SOLUTE from [low] to [high]

Answer 157

chemical modification of the transported substance driven by phosphoenolpyruvate * solute will STOP moving into cell @ equilibrium - wants to EXCEED equil. since they're in an envir. with abundance of nutrients (wants to bring more in past equil.) b/c it's not sure if in a hour or so there won't be any nutrients - by MODIFYING it when they bring more in

Answer 158

by MODIFYING it when they bring more in - modification comes with phosphorylation - once modified, it's not the same molecule again (think: hat on head (changed - not same) - so won't reach an equil. b/t molecule & molecule phosphorylated (diff.) - outcome is that conc. of solute inside the cell, consistently stays low, therefore you can bring in even more (maximizes your intake potential)

Answer 159

periplasmic binding proteins are involved & energy comes from ATP - PRIMARY active transport - ATP binding domain on inside of cell that allows transporter to take ATP & hydrolyze it; releasing energy - energy is then used to pay for solute that moves across the mem. to inside of cell

Answer 160

uniport, symport, and antiport

Answer 161

transport in one direction across the membrane

Answer 162

function as co-transporters

Answer 163

transport a molecule across the membrane while simultaneously transporting another molecule in the opposite direction - cotransport - move 2 solutes with same transporter

Answer 164

Lac permease is bringing H+ into cell (releasing energy b/c high to low) & then the lactose is active (going against - req. energy) - proton is being used to pay for movement of the lactose - nutrients that have been taken up are the lactose

Answer 165

- Lactose is transported into E.coli by the simple transporter lac permease, a same direction - Activity of lac permease is energy-driven (to pay for it) - Transports lactose and a H+ into the cell simultaneously

Answer 166

(takes up glucose) - Sugar is phosphorylated during transport across the membrane - Moves glucose, fructose, and mannose - Phosphoenolpyruvate (PEP) donates a P to a phosphorelay system - P is transferred through a series of carrier proteins and deposited onto the sugar as it is brought into the cell * normally energy release here is used to form ATP by substrate level phosphorylation - but here, you take phosphate group & use energy from that rxn to transfer it through those enzymes & then drops it on glucose that's coming through - PE-P is the most energy rich molecule that exists (breaking it releases energy that is used for substrate level phosphorylation - to produce an ATP molecule) - trying to est. equil., the outcome is it will eventually equalize, putting a stop to glucose uptake by phosphorylating it - becomes Glucose 6-P (no longer glucose - therefore no longer part of glc gradient & so glc can continue to come in)

Answer 167

• Involved in uptake of ORGANIC compounds (e.g., sugars, amino acids), INORGANIC nutrients (e.g., sulfate, phosphate), and trace metals - BRINGING IN VITAL THINGS for cell * Typically display HIGH substrate SPECIFICITY * Gram-NEGATIVES employ periplasmic-binding proteins and ATP-driven transport proteins * Gram-POSITIVES employ substrate-binding lipoproteins (anchored to external surface of cell membrane) and ATP-driven transport proteins

Answer 168

- NEED A LOT, v. imp. nutrient uptake & life - specific - separate one for each molecule - huge part of genome is dedicated to providing instructions to make these diff. ABC transporters b/c you need a separate 1 for each nutrient & protein info in order to assemble the structure originates from genes within the DNA

Answer 169

molecules can pass through, as long as they are polar & have the appro. size characteristics, the molecules are able to pass through - think: fence

Answer 170

specific to nutrient

Answer 171

highly specific

Answer 172

1. PORIN in OUTER mem. that's NON-SPECIFIC as long as you meet size criteria & polarity, you can go through 2. Wandering around as a nutrient in PERIPLASMIC SPACE that's large & endless 3. PERIPLASMIC BINDING PROTEIN (SPECIFIC) for good guys-nutrients to that nutrient & deliver to the ABC transporter (HIGHLY SPECIFIC) which will allow the nutrient to be taken to the inside of the cell

Answer 173

1. Reaching around, swishing around in ECF 2. Finds nutrient for which its specific (substrate binding lipoprotein - specific) 3. Brings to door & guides it through ABC transporter (highly specific) (no outer mem. to create boundary & periplasmic space)

Answer 174

Solute binding protein • Periplasm • Binds specific substrate Integral membrane proteins (transporter) ATP-hydrolyzing proteins • Supply energy for the transport event (costs 2 ATP)

Answer 175

Outside the cell membrane - Rigid --> Helps determine cell shape (regardless of how mem. might appear underneath - will see the outermost strong layer) - NOT a major permeability barrier (as long as the molecule is small enough (unrestricted) it can bypass that layer - Porous to most SMALL molecules (think: jungle gym net - anything that can fit through; provided that it's the right size (small) - will go through that layer - Protects the cell from osmotic changes

Answer 176

imp. for designing antibiotics that go into a cell to target a ribosome & inhibit protein syn., antibiotic must have size characteristics that allow it to go through the cell

Answer 177

plasma membrane

Answer 178

our skin - our guaranteed outermost layer

Answer 179

water will rush in by osmosis [low] to [high] b/c of the hyper/hypo - plasma mem. will swell (bigger) b/c of additional water - & cell wall pushes back exerting a counter pressure but the cell won't burst b/c the cell wall protects from osmotic changes

Answer 180

1. Cell wall won't be able to provide indefinit protection (can only protect so much) - if cell continues to swell b/c of continuous influx of water - outcome is it will rupture 2. Cell wants this added layer of protection b/c anything that happens to this 1 cell could be the end of the organism as a whole --> highly protective 3. ECF & cytoplasm has 0.9% [NaCl] - but bacterium can find itself anywhere so constantly will have alternate external environment - so need to be able to adopt or prevent serious changes to cell structure since it is not constant like ours is

Answer 181

balloon = plasma membrane air - makes bigger until glass exerts counter pressure on that expanded balloon glass = cell wall if you keep adding more air in, the glass is not gonna help & the outcome is the balloon will blow

Answer 182

Penicillin actively interferes with formation of peptidoglycan - peptidoglycan on an organism that's growing doesn't have cross links (not strong) - a bacterium trying to grow in presence of penicillin, will have holes blown in side of its plasma membrane b/c cell burst without a strong cell wall there to protect against osmolarity issues

Answer 183

• Cell wall prevents cell expansion – protects against osmotic lysis • Protects against toxic substances – LARGE hydrophobic molecules (CAN'T fit through pores therefore unable to get through - outcome: cell is protected against chemical threats in this way) Ex) detergents, antibiotics • Pathogenicity (ability to be able to escape immune detection or immune capture - able to get away from immune system & the destruction of its own self) - Helps evade host immune system (imp. for survival) - Helps bacterium stick to surfaces (better chance for bacterium to persist inside the body - since body is trying to constantly flush clean) • Partly (b/c some might also have a cytoskeleton) responsible for cell shape (cocci, bacillum, spirilum). (b/c its a rigid structure - even if mem. has dehydrated away - the cell wall maintains external shape)

Answer 184

Isotonic: no net movement of water Hypotonic: water moves into the cell & may cause the cell to burst if the wall is weak or damaged (osmotic lysis) - not living anymore (internal contents leak out) Hypertonic: water moves out of cell, (b/c water always moves to more hypertonic envir.) causing its cytoplasm to shrink (plasmolysis) - cytoplasm pulls back from cell wall - not dead, just dehydrated - can rehydrate & become metabolically active

Answer 185

- doesn't need to be refrigerated - it's so hypertonic that bacteria in there are dehydrated (therefore, impossible to spoil) - not enough water to metabolize sugar & grow and increase in # - can store at RT b/c maintains semi-fluid viscous material

Answer 186

anything outside of plasma membrane

Lecture #2 - Cell Structure & Function Flashcards

(216 cards)