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AS biology > 2.1- cells and microscopes > Flashcards

2.1- cells and microscopes Flashcards

1
Q

eukaryotic cells contain

A

membrane bound organelles

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2
Q

nucleolus

A

site of ribosome production

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3
Q

nucleus

A
  • ALL eukaryotes except rbc
    -contains CHROMATIN
    -chromosomes are made of sections of linear DNA wound around proteins called histones
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4
Q

nuclear envelope

A
  • double membrane surrounding nucleus
  • contains nuclear pores which allow molecules (ribosomes, enzymes etc) to enter and leave the nucleus
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5
Q

prokaryotes contain (6)

A
  • cell wall
  • capsule
  • plasmid
  • flagellum
  • pili
  • ribosomes
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6
Q

preparation of solid slide for light microscope

A
  • cut a thin (so light can pass through) section of tissue (scissors?)
  • place on slide using forceps
  • add a drop of stain
  • add coverslip using MOUNTED NEEDLE at 45 degrees to avoid trapping air bubbles
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7
Q

equation for mag

A

image size = actual size * magnification

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8
Q

magnification

A
  • factor by which the image is larger than the actual specimen
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9
Q

resolution(2)

A
  • ability to distinguish between 2 objects close together
  • level of detail
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10
Q

mag and res of TEM

A

mag : x500,000
res : 0.2 nm

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11
Q

mag and res of light

A

x1500
200nm

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12
Q

ribosomes

A
  • in ALLLL CELLS
    -foubd free in cytoplasm or in rough ER
  • made of PROTEINS and ribosomalRNA
  • large subunit (which joins amino acids)
  • small subunit (with mRNA binding site)
  • translation here
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13
Q

80s ribosomes

A
  • from 60 and 40 subunits
  • eukaryotic cells
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14
Q

70s ribosomes

A
  • prokaryotes, mitochondria, chloroplasts
  • from 50 and 30 subunits
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15
Q

function of mitochondria

A
  • site of aerobic respiration to produce ATP
    -light microscope
  • has cristae-folds to increase SA
  • matrix formed contains enzymes for aerobic respiration andDNA and ribosomes
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16
Q

cristae

A

folds of inner membrane in mitochondria; enable compartmentalisation

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17
Q

chloroplasts

A
  • plant cells
  • LARGER than mitochondria
    -site of photosynthesis to convert solar energy to chemical energy
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18
Q

bacterial cell wall is made of?

A

peptidoglycan

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19
Q

fungal cell wall is made of?

A

chitin

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20
Q

cell wall

A
  • structural support
  • cellulose polysaccharide in plants
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21
Q

plasmodesmata

A
  • threads of cytoplasm
  • connect cytoplasm of neighbouring plant cells
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22
Q

flagellum

A
  • hollow helical tube made of the protein FLAGELLIN
    -made of microtubules
  • rotates to propel organism (usually unicellular)
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23
Q

cilia

A
  • hair like projections made of microtubules
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24
Q

microvilli

A
  • in specialised animal cells
  • cell membrane projections
  • increase SA of plasma membrane to increase rate of exchange if substances
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25
Q

role of cytoskeleton

A
  1. provide support for organelles and shape of cell
  2. intracellular movement; forms tracks where organelles can move
  3. enables cell movement via cilia and flagella
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26
Q

SIMILARITIES euk and prok

A
  • plasma membrane
  • cytoplasm
  • ribosomes
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27
Q

ribosomes eukaryote

A

LARGER : 80S

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28
Q

ribosomes prokaryote

A

SMALLER: 70s

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29
Q

how do prokaryotes reproduce

A

binary fission - ALWAYS asecual

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30
Q

how do eukaryotes reproduce

A

mitosis and meiosis, sexual and or asexual

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31
Q

plasma membrane

A
  • ALL CELLS
    -regulates movement of substances into and out of the cell
  • has receptor molecules which allow it to respond to chemicals eg hormones
  • formed from phospholipid bilayer
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32
Q

plasma membranes are made of ?

A

lipids and proteins- phospholipid bilayer

33
Q

function of lysosome

A
  • contains digestive (hydrolytic) enzymes
  • kept separate from cytoplasm by surrounding membran
  • can be used to digest invading cells or break down worn out components
34
Q

why do light microscopes have limited resolution?

A
  • use light to form an image
  • impossible to resolve 2 objects closer than half the wavelength of light
35
Q

why do electron microscopes have higher resolution

A
  • beam of electrons has a smaller wavelength than light
  • so can resolve 2 objects v close together
36
Q

TEM

A
  • electromagnets to focus a beam of electrons
  • electrons TRANSMITTED THROUGH the specimen
  • denser parts appear darker as they absorb more electrons
37
Q

TEM images adv

A
  • high res
  • can see internal structures
38
Q

TEM disadvantages

A
  • v thin sections
  • dead specimens
  • artefacts can be introduced
  • black and white
39
Q

SEM

A
  • beam of electrons bounce OFF and are detected
  • 3D images of SURFACE
40
Q

advantages sem images

A
  • thick specimens
  • external 3D structure
41
Q

disadvantages of SEM

A
  • lower res
  • dead
  • b and w
42
Q

differential staining

A
  • use multiple dyes
  • as diff stain for diff organelle
43
Q

3 objective lenses

A

x4
x10
x40

44
Q

preparation of liquid slide for light microscope

A
  • use pipette to add a few drops of sample
  • cover with a coverslip and gently press down to remove air bubbles
  • wear gloves to prevent cross contamination of foreign cells
45
Q

starting objective lens

A
  • LOWEST power
  • easier to find in field of view
  • prevents damage if state too high
46
Q

preventing dehydration of tissue?

A
  • thin layers can dry quickly
  • add a drop of water
47
Q

how to calibrate graticule in eyepiece lens

A

use a stage micrometer

48
Q

do chloroplasts need stains?

A

NO- naturally green

49
Q

‘stain’ for TEM

A
  • heavy metals
    -eg gold
  • as they absorb electrons well
50
Q

microtubules

A
  • in all eukaryotes
    -part of cytoskeleton
    -made of alpha and beta tubules combines to form dimers, which join to protofilaments
  • 13 protofilaments = microtubule
51
Q

centriole

A
  • hollow fibres of microtubules
  • make spindle fibres during cell division
  • NOT in flowering plants and fungi
52
Q

vesicle

A

membrane bound sac for transport and storage

53
Q

large permanent vacuole

A
  • in plant cels
  • keep structure and turgor pressure
  • surrounded by tonoplast (selectively permeable membrane)
54
Q

Golgi body

A
  • flattened sacs of membrane (cisternae)
  • modifies proteins and lipids
  • packages them into Golgi vesicles
55
Q

smooth ER

A
  • plant and animal
  • production, processing and storage of LIPIDS (+carbs and steroids)
56
Q

rough ER

A
  • plant and animal
  • surface covered in ribosomes
  • processes proteins made by ribsomoes
  • continuous with nuclear envelope
57
Q

ONLY in animal not plant

A
  • centrioles
  • flagella/cilia
58
Q

protein synthesis

A
  1. transcription in nucleus, mRNA created
  2. mRNA leaves in a nuclear pore and attaches to a ribosome on RER
  3. TRANSLATION by ribosome
  4. protein passes into lumen of RER to be folded and processed
  5. sent in vesicles to Golgi body
  6. GB modifies and processes proteins
  7. proteins leave in vesicles
  8. vesicles fuse with plasma membrane
59
Q

protein fibres in cytoskeleton

A

microtubules and microfilaments

60
Q

microfilaments

A
  • made of actin protein
  • cause movement by moving against each other
61
Q

microtubules

A
  • made of tubular
  • atp drives movement
62
Q

plasmids

A

small loops of DNA
- contain genes that can be passed between proks

63
Q

capsule

A
  • prevents bacteria from drying out
64
Q

hiw to find diaemeter of x using light micrscope

A
  • eyepiece graticule
  • use stage micrometer to calibrate (how many um in 1 epu)
  • masure diamteter in epu
  • use calibrated epu to calc diameter
  • repeat and mean epu
65
Q

TEM resolution

A

0.2nm

66
Q

SEM resolution

A

10 nm

67
Q

light microscope how do u know

A
  • couldnt see plasmodesmata
  • shape of organelle
68
Q

need for stain

A
  • provide contrast
  • highlight and make components visible
  • clearer image obtained
  • organelles more visible as bind to stain
69
Q

importance of differential stain

A
  • see cells
  • see organelles
  • red blood cells always visible anyway
  • CONTRAST
  • can COUNT num of cells
70
Q

thin slices

A

use a MICROTOME
- individual cells visible

71
Q

endosymbiotic theory evidence

A
  • nsmaller ribosomes
  • similar siz to bacteria
  • circular DNA
72
Q

where are pili found

A

surface of prokaryotes

73
Q

role of membrane in rough ER

A
  • controls what enters rough er
  • separates proteins from cytoplasm
  • holds ribosomes in place
74
Q

does yeast have a nucles

A

yes

75
Q

journey of protein from RER

A
  • transport vedicle from RER
  • modification at Golgi
  • packaged intoa SECRETORY vesicle
  • vesicles move along cytoskeleton
  • fuse with cell surface membrane
  • exocytosis
76
Q

translation

A

-mRNA moves out nucleus
- transported to ribosome
- trna brings specific amino acids
- peptide bonsd form between them
- golgi

77
Q

why do the mitochondria look different

A
  • vary in shape
  • just divided
  • cut at different angles
78
Q

how does the cytoskeleton transport

A
  • moves along microfilaments\tubule; provide pathways for movement
  • uses ATP
  • motor protein

AS biology (14 decks)

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