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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?) using a MICROTOME
  • 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

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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11
Q

80s ribosomes

A
  • from 60 and 40 subunits
  • eukaryotic cells
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12
Q

70s ribosomes

A
  • prokaryotes, mitochondria, chloroplasts
  • from 50 and 30 subunits
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13
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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14
Q

cristae

A

folds of inner membrane in mitochondria; enable compartmentalisation

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15
Q

chloroplasts

A
  • plant cells
  • LARGER than mitochondria
    -site of photosynthesis to convert solar energy to chemical energy
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16
Q

bacterial cell wall is made of?

A

peptidoglycan

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17
Q

fungal cell wall is made of?

A

chitin

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18
Q

cell wall

A
  • structural support
  • cellulose polysaccharide in plants
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19
Q

plasmodesmata

A
  • threads of cytoplasm
  • connect cytoplasm of neighbouring plant cells
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20
Q

flagellum

A
  • hollow helical tube made of the protein FLAGELLIN
    -made of microtubules
  • rotates to propel organism (usually unicellular)
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21
Q

cilia

A
  • hair like projections made of microtubules
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22
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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23
Q

role of cytoskeleton

A
  1. provide MECHANICAL STRENGTH to cells
  2. can change chape
  3. intracellular movement; forms tracks where organelles can move
  4. enables cell movement via cilia and flagella
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24
Q

SIMILARITIES euk and prok

A
  • plasma membrane
  • cytoplasm
  • ribosomes
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25
ribosomes eukaryote
LARGER : 80S
26
ribosomes prokaryote
SMALLER: 70s
27
how do prokaryotes reproduce
binary fission - ALWAYS asecual
28
how do eukaryotes reproduce
mitosis and meiosis, sexual and or asexual
29
plasma membrane
- 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
30
plasma membranes are made of ?
lipids and proteins- phospholipid bilayer
31
function of lysosome
- contains digestive (hydrolytic) enzymes - kept separate from cytoplasm by surrounding membran - can be used to digest invading cells or break down worn out components
32
why do light microscopes have limited resolution?
- use light to form an image - impossible to resolve 2 objects closer than half the wavelength of light
33
why do electron microscopes have higher resolution
- beam of electrons has a smaller wavelength than light - so can resolve 2 objects v close together
34
TEM
- electromagnets to focus a beam of electrons - electrons TRANSMITTED THROUGH the specimen - denser parts appear darker as they absorb more electrons
35
TEM images adv
- high res - can see internal structures
36
TEM disadvantages
- v thin sections - dead specimens - artefacts can be introduced - black and white
37
SEM
- beam of electrons bounce OFF and are detected - 3D images of SURFACE
38
advantages sem images
- thick specimens - external 3D structure
39
disadvantages of SEM
- lower res - dead - b and w
40
differential staining
- use multiple dyes - as diff stain for diff organelle
41
3 objective lenses
x4 x10 x40
42
preparation of liquid slide for light microscope
- 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
43
starting objective lens
- LOWEST power - easier to find in field of view - prevents damage if state too high
44
preventing dehydration of tissue?
- thin layers can dry quickly - add a drop of water
45
how to calibrate graticule in eyepiece lens
use a stage micrometer
46
do chloroplasts need stains?
NO- naturally green
47
'stain' for TEM
- heavy metals -eg gold - as they absorb electrons well
48
microtubules
- in all eukaryotes -part of cytoskeleton -made of alpha and beta tubules combines to form dimers, which join to protofilaments - 13 protofilaments = microtubule
49
centriole
- hollow fibres of microtubules - make spindle fibres during cell division - NOT in flowering plants and fungi
50
vesicle
membrane bound sac for transport and storage
51
large permanent vacuole
- in plant cels - keep structure and turgor pressure - surrounded by tonoplast (selectively permeable membrane)
52
Golgi body
- flattened sacs of membrane (cisternae) - modifies proteins and lipids - packages them into Golgi vesicles
53
smooth ER
- plant and animal - production, processing and storage of LIPIDS (+carbs and steroids)
54
rough ER
- plant and animal - surface covered in ribosomes - processes proteins made by ribsomoes - continuous with nuclear envelope
55
ONLY in animal not plant
- centrioles - flagella/cilia
56
protein synthesis of PROTEINS THAT LEAVE
1. transcription in nucleus, mRNA created 2. mRNA leaves in a nuclear pore and attaches to a ribosome on RER 3. TRANSLATION by ribosome 5. cytoskeleton moves it in transport vesicles to Golgi body 6. GB modifies and packages proteins into secretory vesicle 7. cytoskeleton moves secretory vesicle to PM 8. vesicles fuse with plasma membrane 9. secreted by exocytosis
57
protein fibres in cytoskeleton
microtubules and microfilaments
58
microfilaments
- made of actin protein - cause movement by moving against each other
59
microtubules
- made of tubular - atp drives movement
60
plasmids
small loops of DNA - contain genes that can be passed between proks
61
capsule
- prevents bacteria from drying out
62
hiw to find diaemeter of x using light micrscope
- 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
63
TEM resolution
0.2nm
64
SEM resolution
10 nm
65
light microscope how do u know
- couldnt see plasmodesmata - shape of organelle
66
need for stain
- provide contrast - highlight and make components visible - clearer image obtained - organelles more visible as bind to stain
67
importance of differential stain
- see cells - see organelles - red blood cells always visible anyway - CONTRAST - can COUNT num of cells
68
thin slices
use a MICROTOME - individual cells visible
69
endosymbiotic theory evidence
- nsmaller ribosomes - similar siz to bacteria - circular DNA
70
where are pili found
surface of prokaryotes
71
role of membrane in rough ER
- controls what enters rough er - separates proteins from cytoplasm - holds ribosomes in place
72
does yeast have a nucles
yes
73
why do the mitochondria look different
- vary in shape - just divided - cut at different angles
74
how does the cytoskeleton transport
- moves along microfilaments\tubule; provide pathways for movement - uses ATP - motor protein

bio (31 decks)

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