Cell Structure Flashcards

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1
Q

what kind of nucleus does a eukaryotic cell contain

A

membrane- bound nucleus

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2
Q

what is the definition of a tissue

A

a group of cells working together to perform a particular function

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3
Q

define a system

A

a group of specialised organs working together to perform a specific function

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4
Q

define an organ

A

a group of tissues which work together to carry out a particular function

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5
Q

what type of cells are eukaryotic

A

animal and plant

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6
Q

draw and label the organelles of an animal cell

A
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7
Q

draw and label the organelles in a plant cell

A
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8
Q

what is the function of the nucleus

A

it contains the genetic material in the form of chromatin which is made of DNA and histone proteins

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9
Q

describe the structure of the nucleus

A
  • it has a double membrane with pores that allow substances to move between the nucleus and the cytoplasm
  • the nucleus makes ribosomes
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10
Q

what is the function of ribosomes

A

to carry out proteinsynthesis

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11
Q

describe the structure of ribosomes

A
  • made of proteins and rRNA
  • they have a small subunit and large subunit
  • float free in the cytoplasm or attached to rough endoplasmic reticulum
    -eukaryotes contain 80s ribosomes
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12
Q

what is the function of the rough endoplasmic reticulum

A
  • contains ribosomes on its outer surface which synthesise proteins
  • transport proteins through the cell
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13
Q

describe the structure of both the smooth and rough endoplasmic reticulum

A
  • made of flattened membrane sacs called cisternae
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14
Q

what is the function of the smooth endoplasmic reticulum

A

synthesises and transports lipids

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15
Q

what is the function of the golgi apparatus

A
  • modifies and packages proteins from the RER into vesicles for secretion
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16
Q

what is the function of lysosomes

A
  • vesicles containing lysozymes which cause hydrolysis for example of invading pathogens and worn out organelles
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17
Q

what is the function of the mitochondria

A

carry out aerobic respiration
produce ATP

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18
Q

describe the structure of mitochondria

A
  • they have a double membrane
  • the inner membrane is folded to form cristae
  • they have their own DNA and ribosomes
  • the matrix contains enzymes for aerobic respiration, DNA and ribosomes
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19
Q

what is the function of the cell membrane

A
  • controls the movement of substances in and out of the cell
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20
Q

what us the function of chloroplasts

A
  • site of photosynthesis
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21
Q

describe the structure of chloroplasts

A
  • they have a double membrane
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22
Q

what is the function of the cell wall

A
  • give cells and organisms support
  • prevents cells from bursting
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23
Q

describe the structure of the cell wall

A
  • made of cellulose in plants and algae
  • made of chitin in fungi
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24
Q

what is the function of the cell vacuole

A
  • helps maintain pressure inside the cell
  • keeps the cell rigid
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25
Q

describe the function of the cell vacuole

A
  • contains cell sap ( a weak solution of sugar and salts)
  • has a surrounding membrane called the tonoplast
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26
Q

draw and label the structure of a chloroplast

A
27
Q

what is the job of the granum

A

its a stack of thylakoid membranes which increase surface area for absorption of light

28
Q

what is a thylakoid membrane

A

contains chlorophyll for photosynthesis and increases surface area for absorption of light

29
Q

what is the job of the stroma

A

fluid filled matrix contains enzymes for some of the photosynthetic reactions

30
Q

what is the use of starch grains

A

storage molecule in plants. its a polysaccharide and does not effect the water potential of the cell

31
Q

what is the job of DNA and ribosomes in a chloroplast

A

chloroplasts have their own DNA and ribosomes to make enzymes for photosynthesis

32
Q

describe what happens in the golgi vesicles

A
  • proteinsynthesis occurs at ribosome
  • rough endoplasmic reticulum transports protein from ribosome to gogli body
  • golgi body modifies and packages into vesicles
  • vesicles transport protein to cell-surface membrane ad fuse with cell-surface membrane
33
Q

draw and label a prokaryotic cell and its organelles

A
34
Q

how is prokaryotic DNA different from eukaryotic DNA

A
  • prokaryotic DAN is shorter so has fewer genes, eukaryotic DNA is larger so has more genes
  • prokaryotic DNA does not contain introns, eukaryotic DNA contains introns
  • prokaryotic DNA floats free in the cytoplasm, eukaryotic DNA is enclosed in a membrane-bound nucleus
  • prokaryotic DNA is circular, eukaryotic DNA is linear
  • prokaryotic DNA is not associated with histone proteins, eukaryotic DNA is associated with histone proteins
  • prokaryotic DNA is only one molecule of DNA, eukaryotic DNA has multiple molecules of DNA
35
Q

Describe how mitochondria and chloroplasts evolved from prokaryotic cells

A
  • mitochondria and chloroplasts have 70s ribosomes which are smaller than the 80s ribosomes found in eukaryotic cells
  • ## mitochondria and chloroplasts have shorter DNA which is circular and not associated with histone proteins
36
Q

draw and label a typical virus

A

envelope = capsid
attatchment proteins are ridges outside

37
Q

describe a virus

A
  • viruses are acellular
  • they contain genetic material surrounded by a capsid with attachment proteins sticking out
  • these are used to attach to host cells so the virus can enter the cell and use the cell to replicate
  • viruses are smaller than prokaryotic cells
38
Q

describe how an epithelial cell is adapted for the synthesis of proteins

A
  • the ribosomes on the endoplasmic reticulum carry out proteinsynthesis and transport proteins throughout the cell
  • mitochondria provide energy by aerobic respiration through ATP hydrolysis
39
Q

what is cell fractionation

A

cells are broken open open and the organelles can be separated out and studied in detail

40
Q

why do organelles need to be separated from the cell in order to be studied

A

so they can be studied individually without other organelles affecting their function

41
Q

describe how cell fractionation happens

A
  1. the tissue is placed in an ice-cold, isotonic, buffered solution.
    - it’s ice cold to reduce enzyme activity to prevent damage to organelles
    - it’s isotonic to prevent osmosis so organelles don’t burst or shrink
    - it’s buffered to prevent a change in pH so proteins in organelles don’t denature
  2. the tissue is homogonised to break open the cells and release the organelles
  3. the mixture is then filtered to remove cell debris and unbroken cells
  4. the solution is centrifuged at a slow speed to pellet the most dense organelles (nucleus)
  5. the supernatant is removed and placed in a new tube and centrifuged at a faster speed to pellet less dense organelles
  6. this is called differential centrifugation
42
Q

define magnification

A

how much bigger the image appears than the real object

43
Q

define resolution

A

the ability to see 2 objects close together as separate objects

44
Q

how is the image gained by an optical microscope

A

light

45
Q

how is the image focused on an optical microscope

A

glass lenses

46
Q

what is the resolution on an optical microscope

A

low resolution (200nm)

47
Q

is the specimen alive or dead when using a light microscope

A

living or dead

48
Q

what colour image is produced with a light microscope

A

coloured image

49
Q

does a light microscope produce a 2D or 3D image

A

2D

50
Q

what does the image of a light microscope show

A

large organelles

51
Q

how thick is the sample needed for a light microscope

A

thin

52
Q

how easy is the prep for a light microscope

A

easy

53
Q

how is the image formed with both TEM and SEM

A

beam of electrons is fired at the specimen

54
Q

how is the image focused on TEM and SEMs

A

electromagnets

55
Q

Which microscope has the highest resolution

A

TEM (0.1 nm)

56
Q

is the specimen dead or alive for TEM and SEMs

A

dead as it has to be placed in a vacuum

57
Q

what colour images do TEM and SEMs make

A

black and white

58
Q

what thickness of samples do TEM and SEMs

A

extremely thin

59
Q

how easy is the preparation of the sample

A

complex and time consuming staining procedure

60
Q

why do electron microscopes have a higher resolution than an optical microscope

A

electrons have a much shorter wavelength then light so have a higher resolution

61
Q

describe how to use an optical microscope

A
  • use the lowest magnification lens to start and lower the stage
  • place the slide on the stage with the specimen under the objective lense
  • look down the microscope and focus first with the course focus wheel and then with the fine focus
  • keep increasing the magnification lense and refocus witht he fine focus
62
Q

describe how to prep a slide for a specimen

A
  • add a drop of water to the slide
  • prepare a thin slice of tissue and place on top of the water
  • stain the cells with methyl blue if plant, or iodine if animal specimen to visualise the components
  • low cover slip onto the cell using a mounted needle
63
Q

why does the tissue for an optical microscope need to be thin

A

to produce a thin layer of cells that the light can pass through

64
Q

how do you calculate the area of the field of view

A
  • place the stage micrometer onto the stage and focus up to x400 magnification
  • work out number of graticule units per 0.1 mm
  • work out the size of one graticule unit in mm