biology med 103 > topic 5A > Flashcards

topic 5A Flashcards

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1
Q

techniques used for scientific study of cells

A
  1. microscopy
  2. cell fractionation
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2
Q

two types of microscopes

A
  1. light microscopes
  2. electron microscopes
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3
Q

light microscope

A
  • uses visible light to pass through a specimen
  • uses lenses in magnification of cellular structures
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4
Q

electron microscope

A

focuses a beam of electrons through a specimen (TEM) or onto its surface (SEM)

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5
Q

factors that affect image quality

A
  • magnification
  • resolution
  • contrast
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6
Q

what are the different techniques of light microscopes

A
  1. brightfield (unstained)
  2. brightfield (stained)
  3. phase-contrast
  4. differential-inference-contrast
  5. fluorescence
  6. confocal (3D)
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7
Q

brightfield (unstained specimen) microscopy

A

passes light directly though specimen

(has little contrast unless cell is naturally pigmented)

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8
Q

brightfield (stained specimen) microscopy

A

staining with various dyes enhances contrast

(most staining procedures require cells to be fixed)

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9
Q

phase-contrast microscopy

A

enhances contrast in unstained cells by amplifying variations in density within the specimen

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10
Q

differential-interference-contrast microscopy

A

similar to phase-contrast, it uses optical modifications to exaggerate differences in density, making the image appear almost 3D

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11
Q

fluorescence microscopy

A

shows the locations of specific molecules in the cell by tagging the molecules with fluorescent dyes

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12
Q

how do fluorescent dyes work in fluorescence microscopy

A

they absorb UV radiation and emit visible light

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13
Q

confocal microscopy

A
  • uses lasers for “optical sectioning” of fluoroscently-stained specimens
  • only a single plane of focus is illuminated, the rest subtracted
  • a sharp image results
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14
Q

best technique to examine living unpigmented cells (dividing cells)

A

phase-contrast technique

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15
Q

which microscopy technique enables the reconstruction of 3D structures from obtained images

A

confocal microscopy

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16
Q

LMs can magnify samples about ____ the size of the actual specimen

A

1000x

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17
Q

LM resolution

A

200 nm

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18
Q

microscope that can detect viruses, macromolecules, etc

A

electron microscope

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19
Q

microscope that cannot detect subcellular structures (ex: organelles)

A

light microscope

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20
Q

two types of electron microscopes

A
  1. transmission electron microscope
  2. scanning electron microscope
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21
Q

TEM

A

-focus a beam of electrons THROUGH a specimen

  • used mainly to study the internal structure of cells
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22
Q

SEM

A
  • focus a beam of electrons ONTO THE SURFACE of a specimen
  • used to study the surface of the specimen
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23
Q

difference between differential and density gradient centrifugation

A

differential - separation based on size only

density gradient - separation based on density (size and shape)

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24
Q

the first cells that appeared were

A

prokaryotic

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25
all cells have several basic features in common
- bounded by a plasma membrane - contain a cytosol - contain chromosomes - have ribosomes
26
prokaryotic vs eukaryotic cells
- prokaryotes do not contain a nucleus or membrane-bound organelles - eukaryotic cells are bigger - prokaryotes have their DNA in the nucleoid - eukaryotes have organelles that compartmentalize
27
a typical prokaryotic cell contains
- nucleoid - ribosomes - plasma membrane - cell wall - pili - capsule - flagella
28
pili
attachment structures found on the surface of some prokaryotes
29
nucleoid
region where the cell's DNA is located in a prokaryote (not enclosed by a membrane)
30
capsule
jelly-like outer coating of many prokaryotes
31
flagella
locomotion organelles of some bacteria
32
cytoplasm
the region between the plasma membrane and nucleus
33
cytosol
intracellular fluid component of cytoplasm
34
cytoplasm vs cytosol
the cytoplasm includes all subcellular components except the nucleus the cytosol excludes organelles, and contains ribosomes, proteasomes, and cytoskeletal filaments
35
animal vs plant cells
plant cells - chloroplasts, cell walls, plasmodesmata, central vacuoles (instead of lysosomes) animal cells - lysosomes, centrosomes, flagella
36
plasma membrane
a selective barrier that allows sufficient passage of oxygen, nutrients, and waste in and out of the cell
37
each chromosome is made of a complex of proteins and DNA
chromatin
38
chromatin condenses to form
distinct chromosomes
39
_____ and _____ take place in the nucleus
1. DNA replication 2. transcription
40
translation takes place in the
cytoplasm
41
central dogma of transfer of genetic information
1. DNA is transcribed to mRNA in the nucleus 2. mRNA exits the nucleus and moves the the cytoplasm 3. mRNA attached to ribosomes and is translated into proteins
41
nucleolus
where rRNA is synthesized
42
nuclear envelope
- encloses the nucleus, separating its contents from the cytoplasm - has nuclear pores
43
nuclear pores
regulate the entry and exit of molecules from the nucleus
44
ribosomes
- made of rRNA - consist of a small & large subunit - used in protein synthesis
45
2 central locations of ribosomes
1. free ribosomes - in the cytosol (synthesize cytosolic proteins) 2. bound ribosomes - bound to rough ER (synthesize secreted/membrane-bound proteins)
46
the endoplasmic reticulum
- network or membranous sacs - inside space is called the lumen - composed of 2 regions: smooth and rough ER
47
smooth vs rough ER
smooth ER lacks ribosomes while rough ER contains bound ribosomes
48
smooth ER functions
- synthesizes lipids - metabolizes carbohydrates - stores calcium - detoxifies poisons
49
rough ER functions
- protein synthesis - some post-translational modifications - protein targeting (sorting)
50
golgi apparatus
- flatter membranous sacs (cisternae) - receives many of the transport vesicles produced by the rough EE
51
cis face and trans face of the golgi apparatus
cis face - receiving side trans face - shipping side
52
golgi apparatus functions
- protein and macromolecule processing - macromolecule sorting/targeting - manufacture of polysaccharides
53
lysosomes
membranous vesicles containing hydrolytic enzymes
54
lysosomal enzymes function only at the acidic environment of the lysosome of
pH 4
55
lysosomal functions
1. phagocytosis 2. autphagy
56
phagocytosis
- intracellular digestion carried out by lysosomes (fusing with food vacuole) - used by some protists to digest food
57
autophagy
- destruction of damaged organelles - recycling of cell's organic material
58
vacuole
- large membrane-bounded vesicle in plants - plant and fungal cells have one or more vacuoles (instead of lysosomes)
59
vacuole functions
digestion, storage, waste disposal, water balance, cell growth/protection
60
types of vacuoles
1. food vacuole (phagosomes) - formed by phagocytosis 2. contractile vacuole - pump excess water out the cell 3. central vacuole - (in plants) reserves water and organic compounds, stores ions or poisons (for defense)
61
endomembrane system components
- nuclear membrane - endoplasmic reticulum - golgi apparatus - lysosomes/vacuole - plasma membrane
62
organelles not part of the endomembrane system
mitochondria and chloroplasts
63
what makes mitochondria and chloroplasts excluded from the endomembrane system?
- have double membrane - contain their own DNA (circular) - their proteins are made by their own free ribosomes (in mitochondrial matrix and chloroplast stroma)
64
plastids
plant organelles 1. chloroplasts - contain chlorophyll & site for photosynthesis 2. chromoplasts - contain other pigments (carotenoids) 3. amyloplasts - contain starch granules
65
peroxisomes
specialized membrane-bound METABOLIC compartments
66
peroxisome functions
- produce hydrogen peroxide (H2O2) and convert it to H2O - detoxification (ex: liver peroxisomes detoxify alcohol) - fatty acid breakdown
67
proteasomes
giant protein complexes that bind to protein molecules and degrade them
68
short-lived cytosolic proteins and non-functional proteins attach to _____ then targeted to proteasomes for degradation
ubiquitin
biology med 103
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