Chapter 2 Basic components of living systems Flashcards

Question

Disadvantages of light microscopes

Answer 1

Light microscopes use visible light to create an image -> so resolution is limited to 200nm and magnification to ×2000

Answer 2

- use a high power beam of light to create an image - the laser passes over each single point ij the specimen and CREATES AN IMAGE over time - 3D image - more expensive than light microscopes have a high resolution

Answer 3

- Instead of beam of light like in traditional microscopes, electron microscopes use a beam of electrons to study specimens

Answer 4

Electrons have a higher wavelength and so can be used to create higher resolution images (micrographs)

Answer 5

A micrograph is a digital image taken through a microscope to show a magnified image of an object

Answer 6

- in both types a beam of electrons is focused by a magnet towards a specimen - specimens must also be stained or coated with a metal and placed in a vaccum - this preparation means electron microscopy can only be used to study dead specimens

Answer 7

- The electron beam hits the specimen and is scattered into a detector - this means the microscope image can be 3D because the different orientations where electrons land are scattering in various directions - 3d but low magnification and resolution

Answer 8

The electron beam travels through the specimen to a detector below This allows for a higher resolution and magnification than SEM but a 2D image

Answer 9

Electron beam ✅ 3D 〰️ 2D MAX MAG - 200,000 〰️ 2,000,000 Max resolution- 20nm 〰️ 0.1nm

Answer 10

solid specimens are viewed whole or cut into very thin pieces with a sharp blade - this is called sectioning - the sample is then placed on the centre of the slide, and cover slip placed over

Answer 11

specimens are suspended in a liquid such as water or an immersion oil. A cover slip is placed on from an angle

Answer 12

wet mount 1st prepared, then lense tissue is used to gently press down the cover slip. depending on the material, potential damage to a cover slip may be avoided by squashing the sample between 2 microscope slides - good tech for soft samples

Answer 13

the edge of a slide is used to smear the sample, creating a thin even coating on another slide -e.g used for blood sample

Answer 14

aqueous interior of cells

Answer 15

distinguish between 2 types of organisms that would otherwise be hard to identify

Answer 16

seperate bacteria into 2 groups - Gram-positive and Gramnegative bacteria

Answer 17

to differentiate species of Mycobacterium from other bacteria

Answer 18

1. Fixing 2. Sectioning 3. Staining 4. Mounting

Answer 19

- chemicals like formaldehyde are used to preserve specimens in as near natural state as poss

Answer 20

- specimens are dehydrated with alcohols and then placed in a mould with wax or resin to form a hard block. This can then be sliced thinly with a knife called a MICROTOME

Answer 21

- Specimens are often treated with multiple stains to show difv structures

Answer 22

- the specimens are then secured to a microscope slide and a cover slip placed on top

Answer 23

many of the stains used in the preperation of slides are toxic or irritant. A risk assessment must be carried out before any practical work is started

Answer 24

it's how many times larger the image is than the actual size of the object being viewed

Answer 25

interchangeable objective lenses on a compound light microscope

Answer 26

the ability to see individual objects as seperate entities

Answer 27

is the tendency of light waves to spread as they pass close to physical structures such as those present in the specimens being studied

Answer 28

the structures present in the specimens are very close to each other and the light reflected from individual structures can overlap due to diffraction. - this means the structures are no longer seen as separate entities and detail is lost

Answer 29

using beams of electrons which have a wavelength thousands of times shorter than light. Electron beams are still diffracted but the shorter wavelength means that the individual beams can be much closer before they overlap. so, smaller objects which are closer together can be seen separately without diffraction blurring the image

Answer 30

Image size/ Actual size | note: need to be same units

Answer 31

the true mag of the diff lenses of a microscope can vary slightly from teh stated mag, so every microscope and lesne has to be calibrated individually using eyepiece graticule and a slide micrometer

Answer 32

- very expensive - can only be used inside a carefully controlled environment in a dedicated space - specimens can be damaged by the electron beam and bc the preperation process is very complex, there is a problem with artefacts

Answer 33

to ensure that the electron beams travel in a straight line

Answer 34

electron, light can use both living and dead samples

Answer 35

for light, natural colour of sample is seen (or stains are used), electron black and white images are produced (but can be coloured digitally)

Answer 36

large, need to be installed

Answer 37

distortion, but for electron - sample prep often distorts material

Answer 38

- both light beam - 2D vs 3D - both x1500 - 200nm vs 160 nm - both living

Answer 39

some structures naturally modify light as it passes thru

Answer 40

by collecting around paticular types of molecules

Answer 41

when we want to see individual structures that we wouldnt normally be able to see

Answer 42

1. Proteins are synthesised on the ribsomes bound to the ER 2. they then enter into the cisternae and are packaged into transport vesicles 3. vesicles containing the newly synthesised protiens move towards the Golgi Apparatus, via the transport function of the cytoskeleton 4. The vesicles fuse with the Cis face of the golgi apparatus and the proteins enter. the proteins are structurally modified before leaving the golgi apparatus in vesicles from the trans face 5. secretory vesicles carry the proteins that are to be released from then cell. the vesicles move towards and fuse with the cell surafce membrane releasing their conetnts 6. by exocytois, some vesicles form lysosomes- these contain enzymes for us in the cell

Answer 43

A tube of tubulin protein subunits | diameter: 25nm

Answer 44

- form eukaryotic cilia and flagella (9 + 2 arrangement of microtubules) - form tracks for the movement of vesicles - form spindle fibres which cause the movement of chromosomes in cell divison

Answer 45

helical strands of ACTIN subunits | 7nm diameter

Answer 46

- cause cell movement and changes in cell shape - cytokenisis - lengthen and shorten - TREADMILLING

Answer 47

many different types of protien (e.g. keratin) in a variety of deformable filaments 8-10 nm

Answer 48

form a scaffold inside the cell providing mechanical strength

Answer 49

line representing a distance

Answer 50

image size of scale bar

Answer 51

the basic unit of all living things

Answer 52

single celled organisms with a simple structure of just a simple structure of just a single undivided internal area called cytoplasm

Answer 53

they make up ulticellular organisms like animals, plants, fungi. they have a much more complicated internal structure contaning a membrane bound nucleus (nucleoplasm) and a cytoplasm - which contains many membrane bound cellular components

Answer 54

- production of molecule ATP - site of final stages of cellular respiration - double membrane - inner membrane is highly folded into structures called cristae and fluid interior is called matrix - membranes forming cristae contain enzymes used in resp

Answer 55

- membranous sacs that have storage and transport roles - consist of a single membrane with fluid inside - used to transport materials inside the cell

Answer 56

- specialised forms of vesicles that contain hydrolytic enzymes - responsible for breaking down waste materials, including old orgnelles - break down pathogens ingested by phagocytic cells - role in programmed cell death

Answer 57

- extension that protrudes from some cell types - longer than cilia - used to enable cell motility - in some cells, are used as a sensory organelle detecting chemical changes in the cells environment

Answer 58

- extension that protrudes from some cell types - can be mobile or stationary - stationary cilia are present on the surface of many cells and have an important function in sensory organs - mobile cilia beat in a rhythmic manner, creating a current and cause fluids/ objects adjacent to the cell to move - each cilium contains 2 central microtubules surrounded by 9 pairs of microtubules arranged like a wheel

Answer 59

pairs of parallel microtubules side over each other causing cilia to move in a beating motion

Answer 60

- similar structure to smooth ER - compact structure formed of cisternae and does not contain ribosomes - role in modifying proteins and 'packaging' them into vesicles - these may be secretoty vesicles that are if protiens destined to leave cells, or lysomes which stayb

Answer 61

- component of the cytoskeleton - present in most eukaryotic cells- exception of flowering plants and most fungi - composed of microtubules - 2 centrioles form the centrosome involved in the assembly and organisation of spindle fibres during cell division

Answer 62

- present throughout cytoplasm of ALL eukaryotes - network of fibres necessary for shape and stability of a cell - holds organelles in place and controls cell movement and the movement of organelles within cells - 3 components - microfilaments, microtubules, intermediate fibres

Answer 63

- can be free floating in the cytoplasm or attached to the rough ER - not surrounded by a membrane - constructed of RNA molecules made in the nucleolus - site of protein synthesis

Answer 64

- globular tubulin proteins polymerise to form tubes that re used to form a scaffold like structure that determines the shape of a cell - they also act as tracks for the movement of organelles including vesicles, around the cell - they compose spindle fibres which have a role in the physical segregation of chromosomes

Answer 65

- structures that separate contents of cells from their environment - also separate diff areas within cells from each other and the cytosol - some organelles are divided further by internal membranes - all have same basic structure

Answer 66

- contains coded genetic info in the form of DNA molecules - DNA directs the synthesis of all proteins required by the cell - the DNA controls the metabolic activities of the cell = many of the proteins = enzymes required for metabolism

Answer 67

DNA is too large to leave the nucleus to teh site of protein synthesis in cytoplasm so it is transcribed in smaller RNA molecules which are exported via nuclear pores

Answer 68

- double membrane - contains nucleus to protect it from damage in the cytoplasm - contains nuclear pores that allow molecules that move in and out of the nucleus

Answer 69

- The ER is a network of membranes enclosing a flattened sacs called cisternae. Connected to the outer membrane of nucleus - responsible for lipid and carbohydrate synthesis and storage - Cisternae more tubular then RER

Answer 70

- has ribosomes bound to the surface and is responsible for the synthesis and transport of protiens - secretory cells (release hormones/ enzymes) have more than cells that do not release proteins - closest to nucleus

Answer 71

- contractile fibres formed from the protein acetin | - responsible for cell movement and contraction during cytokinesis

Answer 72

the process in which the cytoplasm of a single eukaryotic cell is divided to form 2 daughter cells

Answer 73

they give mechanical strength to cells and help maintain their integrity

Answer 74

- freely permeable so substances can pass in/out of cell - plant cells are rigid structure- contents of cell press against cell wall making it rigid - also acts as a defense mechanism protecting against pathogens - all plants have

Answer 75

- responsible for photosynthesis - double membrane structure like mitochondria - fluid enclosed in chloroplasts called stroma - also contain DNA and ribosomes so can make own protein - internal membranes provide the large SA needed for the enzymes, proteins, pigment molecules necessary for photosynthesis

Answer 76

- membrane lined sacs in cytoplasm containing cell sap - maintenance of turgor - acts as a temporary store of energy

Answer 77

membrane of a vacuole in a plant cell

Answer 78

component of a cell with a specific function

Answer 79

the cytoplasm inside the nucleus

Answer 80

aqueous solution

Answer 81

are usually found surrounding the nucleus and hold it in place - can also extend outside of the cell - allows cells to stick together and communicate with each other

Answer 82

moving organelles, motor protiens

Answer 83

uptake things into the cell

Answer 84

when substances are released out of the cell

Answer 85

bundles of microtubules that lie perpendicular to each other

Answer 86

cilia and undulipodia

Answer 87

a single long protrusion of microtubules

Answer 88

vesicles filled with digestive enzymes that are formed by the golgi

Answer 89

some cells secrete digestive enzymes from the lysosomes, such as cells in the stomach

Answer 90

CnH2n minus 2 O(^little 2)

Answer 91

breaking down cells to kill them and recycle their contents

Answer 92

fluid filled cavities

Answer 93

smaller ribosomes than tehr est of the cell

Answer 94

starch filled oraganelles (plants)

Chapter 2 Basic components of living systems Flashcards

(121 cards)