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Cell Structure Flashcards

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1
Q

what is the definition of magnification?

A

how much bigger the image is than the specimen

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2
Q

how do you calculate magnification?

A

magnification = image size ÷ object size

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3
Q

how do you convert between units?

A

millimeter (mm) – x1000 –> micrometer (um) – x1000 –> nanometer (nm) – x1000 –> picometer (pm)

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4
Q

what is the definition of resolution?

A

how well a microscope can distinguish between two points that are close together
it refers to how much detail can be seen in the image

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5
Q

label this microscope

A
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6
Q

what is the eye piece graticule?

A

the scale fitted onto the eyepiece of a microscope
it has numbers but no units

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7
Q

what is the scale micrometer?

A

a microscope slide with an accurate scale and units

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8
Q

what is the scale micrometer used for?

A

to work out the value of divisions on the eye piece graticule at a particular magnitude

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9
Q

what are the 4 types of microscope?

A
  • light microscope
  • laser scanning confocal microscope
  • transmission electron microscope (TEM)
  • scanning electron microscope (SEM)
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10
Q

how does a light microscope work?

A
  • light passes from the condenser lens, through the specimen, where certain wavelengths are filtered to produce an image
  • the light then passes through the objective lens, which focuses it and can be changed in order to alter the magnification
  • finally, the light passes through the eyepiece lens into the eye, which can also be changed to alter the magnification
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11
Q

how do you use a light microscope?

A
  1. clip the slide onto the stage
  2. select the lowest powered objective lens (the one that produces the lowest magnification)
  3. use the coarse adjustment knob to move the objective lens to just above the slide
  4. look down the eyepiece and adjust the focus with the fine adjustment knob until the image is clear
  5. swap to a higher powered (magnified) objective lens if needed and refocus
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12
Q

what is the maximum resolution of a light microscope?

A

0.2um

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13
Q

what is the maximum magnification of a light microscope?

A

x1500

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14
Q

what are the properties of the image seen through a light microscope?

A
  • 2D
  • colorless
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15
Q

how does a laser scanning confocal microscope work?

A
  • a laser beam is focused through a lens which is aimed at a beam splitter
  • this splits the beam and some of the light is directed towards the specimen
  • when the laser hits the dyes, it causes them to give off fluorescent light, which is focused through a pinhole onto a detector (meaning any out-of-focus light is blocked)
  • the detector is hooked up to a computer which generates an image
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16
Q

what is a laser scanning confocal microscope used for?

A

to look at different objects at different lengths in thick specimens

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17
Q

what are the properties of the image seen through a laser scanning confocal microscope?

A
  • 2D
  • can be 3D if multiple images are combined together
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18
Q

how does a transmission electron microscope work?

A
  • a beam of electrons is transmitted through the specimen via a vacuum focused by electromagnets
  • denser parts of the specimen absorb more electrons which makes them appear darker on the image
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19
Q

what is the maximum resolution of a transmission electron microscope?

A

0.0002um

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20
Q

what is the maximum magnification of a transmission electron microscope?

A

x1000000 plus

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21
Q

what are transmission electron microscopes used to look at?

A
  • very small organelles (as they provide very high resolution images)
  • internal structures of organelles in detail
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22
Q

what are the properties of the image seen through a transmission electron microscope?

A
  • 2D
  • black and white
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23
Q

what are the disadvantages of a transmission electron microscope?

A
  • the specimen used must be quite thinly sliced which may be hard to source
  • the angle you cut the specimen can affect how they appear
  • cant be done on a living specimen (only dead)
  • doesn’t produce colored images
  • a lot of preparation is needed to prepare the specimen
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24
Q

how does a scanning electron microscope work?

A
  • a beam of electrons is beamed across the specimen
  • this knocks off electrons from the specimen, which are gathered in a cathode ray tube to form an image
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25
Q

what is the maximum resolution of a scanning electron microscope?

A

0.002um

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26
Q

what is the maximum magnification of a scanning electron microscope?

A

x500000

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27
Q

what are scanning electron microscopes used to look at?

A

the surface of the specimen

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28
Q

what are the properties of the image seen through a scanning electron microscope?

A
  • 3D
  • black and white
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29
Q

what are the disadvantages of a scanning electron microscope?

A
  • gives lower resolution images that the transmission electron microscopes
  • cant be done on a living specimen (only dead)
  • doesn’t produce colored images
  • a lot of preparation is needed to prepare the specimen
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30
Q

why are electron microscopes better than light microscopes?

A
  • they have a higher resolution so give more detailed images
  • this is due to electrons having a much smaller wavelength than light waves
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31
Q

how do you mount a dry specimen?

A
  1. cut a thin slice of specimen so that light can pass through
  2. using tweezers, pick it up and place it in the center of a clean slide
  3. place a cover slip on top
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32
Q

what 4 examples that dry mounts used on?

A
  • hairs
  • pollen
  • parts of insects
  • parts of flowers
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33
Q

how do you mount a wet specimen?

A
  1. pipette a small drop of liquid onto the slide
  2. use tweezers to place the specimen on top
  3. place the cover slip at a 45 degree angle to the slide and lower onto it (to prevent air bubbles)
  4. add a stain by placing a drop next to one edge of the cover slip and a piece of paper towel next to the opposite edge, to draw the stain across the specimen
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34
Q

what are 3 examples that wet mounts are used on?

A
  • blood samples
  • living specimens (e.g. tiny aquatic organisms)
  • specimens that are in a liquid (usually water)
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35
Q

why might you need to stain a specimen?

A
  • in order to view it clearly under a microscope (especially if its transparent)
  • to allow different components of a cell to be seen clearly under a microscope
  • to highlight metabolic processes
  • to differentiate between living and dead cells
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36
Q

how does cellular staining work?

A

different parts of the cell take up more stain than others, allowing different parts of the cell to be seen

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37
Q

why may you need to use different stains?

A

you can use more than 1 stain as different stains are used to make different parts of the cell show up

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38
Q

name 3 examples of stains

A
  • methylene blue
  • cormine
  • eosin
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39
Q

what color does methylene blue turn what?

A

turns cells/nuclei blue

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40
Q

what color does cormine turn what?

A

turns glycogen red

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41
Q

what color does eosin turn what?

A

turns cytoplasm pink

42
Q

what is the plasma membrane?

A

a cell surface membrane

43
Q

where is the plasma membrane found?

A
  • on the surface of animal cells
  • just inside the cell wall of plant and prokaryotic cells
44
Q

what is the plasma membrane made of?

A

mainly lipids and protein

45
Q

what is the function of the plasma membrane?

A
  • it regulates the movement of substances into and out of the cell
  • it has receptor molecules on it which allow it to respond to chemicals like hormones
46
Q

what is the structure of the cell wall?

A

a rigid structure that surrounds plant cells

47
Q

what is the cell wall made of?

A

mainly the carbohydrate cellulose

48
Q

what is the function of the cell wall?

A

it supports plant cells

49
Q

what is the structure of the nucleus?

A
  • a large organelle surrounded by a nuclear envelope (double membrane)
  • the nuclear envelope contains many pores
  • the nucleus contains chromatin and often a nucleolus
50
Q

what is chromatin made from?

A

DNA and proteins

51
Q

what is the function of the nucleus?

A
  • controls the cells activities (by controlling the transcription of DNA)
  • it contains instructions to make proteins
  • its pores allow substances (e.g. RNA) to move between the nucleus and cytoplasm
52
Q

what is the function of the nucleolus?

A

to make ribosomes

53
Q

what is the structure of the lysosome?

A
  • a round organelle surrounded by a membrane
  • it has no clear internal structure
  • it contains digestive enzymes which are kept separate from the cytoplasm by the surrounding membrane
54
Q

what is the function of the lysosome?

A
  • to digest invading cells
  • to breakdown worn out components of the cell
55
Q

what is the structure of the ribosome?

A
  • a very small organelle that either floats free in the cytoplasm or is attached to the rough endoplasmic reticulum
  • it is not surrounded by a membrane
56
Q

what is the ribosome made up of?

A

proteins and RNA

57
Q

what is the function of the ribosome?

A

it is the site where proteins are made

58
Q

what is the structure of the rough endoplasmic reticulum (RER)?

A
  • a system of membranes enclosing a fluid filled space
  • the surface is covered with ribosome’s
59
Q

what is the function of the rough endoplasmic reticulum (RER)?

A

it folds and process is proteins that have been made at the ribosomes

60
Q

what is the structure of the smooth endoplasmic reticulum (SER)?

A
  • a system of membranes enclosing a fluid filled space
  • it has no ribosome’s
61
Q

what is the function of the smooth endoplasmic reticulum (SER)?

A

it synthesizes and process is lipids

62
Q

what is the structure of the vesicle?

A
  • a small fluid filled sac in the cytoplasm
  • it is surrounded by a membrane
63
Q

what is the function of the vesicle?

A

it transports substances in and out of the cell via the plasma membrane and between organelles

64
Q

where are vesicles formed?

A
  • some are formed by the golgi apparatus or the endoplasmic reticulum
  • others are formed at the cell surface
65
Q

what is the structure of the golgi apparatus?

A
  • a group of fluid filled, membrane bound, flattened sacs
  • vesicles are often seen at the edges of the sacs
66
Q

what is the function of the golgi apparatus?

A
  • it processes and packages new lipids and proteins
  • it makes lysozymes
67
Q

what is the structure of the mitochondria?

A
  • usually oval shaped
  • it has a double membrane (the inner one is folded to form structures called cristae)
  • it has a matrix inside which contains enzymes involved in respiration
68
Q

what is the function of the mitochondria?

A

it is the site of aerobic respiration (where ATP is produced)

69
Q

where are mitochondria found?

A
  • in cells that are very active and require a lot of energy
  • they are found in large numbers
70
Q

what is the structure of the chloroplast?

A
  • small, flattened structure found in plant cells
  • it is surrounded by a double membrane
  • it has membranes inside called thylakoid membranes
  • thylakoid membranes are stacked up in some parts of the chloroplast to form grana
  • grana are linked together by lamellae
71
Q

what are lamellae?

A

thin, flat pieces of thylakoid membrane

72
Q

what is the function of the chloroplast?

A

the site of photosynthesis (some parts happen in the grana and other parts happen in the stroma)

73
Q

what is the stroma?

A

a thick fluid found in chloroplasts

74
Q

what is the structure of the centriole?

A

small, hollow cylinders

75
Q

what are centrioles made of?

A

microtubules (tiny protein cylinders)

76
Q

where are centrioles found?

A
  • in animal cells
  • in only some plant cells
77
Q

what is the function of the centriole?

A

it is involved with the separation of chromosomes during cell division

78
Q

what is the structure of the cilia?

A
  • small, hairlike structures
  • in cross section, they have an outer membrane and a ring of nine pairs of protein microtubules inside, with a single pair of microtubules the middle
79
Q

what is the function of the microtubules?

A

they allow the cilia to move

80
Q

what is the function of the cilia?

A

the movement from the microtubules is used by the cell to move substances along the cell surface

81
Q

where are the cilia found?

A

on the surface membrane of some animal cells

82
Q

what is the structure of the flagellum?

A
  • they have a similar structure to cilia but are longer
  • they stick out from the cell surface
  • they are surrounded by the plasma membrane
83
Q

what is the function of the flagellum?

A
  • their microtubules contract to make the flagellum move
  • flagella are used like outboard motors to propel the cells forward (e.g. when a sperm cell swims)
84
Q

what are prokaryotic cells?

A

small and simple cells

85
Q

what are eukaryotic cells?

A
  • complex cells (including all plan and animal cells)
  • usually have more organelles than prokaryotic cells
86
Q

draw and label an animal cell

A

p30

87
Q

draw and label a plant cell

A

p31

88
Q

what additional organelles do plants have, that animals do not?

A
  • a cell wall with plasmodesmata (channels for exchanging substances between adjacent cells)
  • a vacuole (containing cell sap)
  • chloroplasts (for photosynthesis)
89
Q

what are the differences between prokaryotic and eukaryotic cells?

A

Prokaryotic cells
- extremely small (<2um diameter)
- circular DNA free in cytoplasm
- no nucleus
- cell wall made of polysaccharide
- few organelles and no membrane-bound organelles
- flagella (when present) made of the protein flagellin, arranged in a helix
- small ribosomes (≤20nm)
- e.g. E.coli bacterium, salmonella bacterium

Eukaryotic cells
- larger (10-100um diameter)
- linear DNA in nucleus
- nucleus present
- cell wall made of cellulose (plants) or chitin (fungi) or not present (animals)
- many organelles and membrane-bound organelles present (mitochondria)
- flagella (when present) made of microtubules, arranged in a 9+2 formation
- larger ribosomes (>20nm)
- e.g. human liver cell, yeast, amoeba

90
Q

draw and label a bacteria cell (under an electron microscope)

A

p38

91
Q

where are proteins made

A

proteins are made at ribosomes:
- the ribosomes on the rough endoplasmic reticulum (RER) make proteins that are excreted or attached to the cell membrane
- the free ribosomes in the cytoplasm make proteins that stay in the cytoplasm

92
Q

describe the process of protein production

A
  • new proteins produced at the RER are folded and processed (e.g. new sugar chains are added) in the RER
  • then, they are transported from the RER to the golgi apparatus in vesicles
  • at the golgi apparatus, the proteins may undergo further processing (e.g. sugar chains are trimmed or more added)
  • then, the proteins enter more vesicles to be transported around the cell (e.g. glycoproteins - found in mucus - move to the cell surface and secreted)
93
Q

draw and label a diagram of protein production

A

p36

94
Q

what is the cytoskeleton?

A

a network of protein threads running through the cytoplasm

95
Q

how is the cytoskeleton arranged in eukaryotic cells?

A

the protein threads are arranged as microfilaments and microtubules

96
Q

what are microfilaments?

A

very thin protein strands

97
Q

what are microtubules?

A

tiny protein cylinders

98
Q

what are the cytoskeletons 4 main functions?

A
  • the microtubules and microfilaments support the cells organelles, keeping them in position
  • they help to strengthen the cell and maintain its shape
  • they are also responsible for the transport of organelles and materials within the cell
  • the proteins of the cytoskeleton can cause the cell to move
99
Q

what are 2 examples of how the cytoskeleton can transport organelles and materials within the cell?

A
  • the movement of chromosomes when they separate during cell division depends on contraction of microtubules in the spindle
  • the movement of vesicles around the cell relies on the cytoskeletal proteins
100
Q

name 2 organelles that move due to the cytoskeletal proteins

A
  • cilia
  • flagella
101
Q

what does a diagram of the cytoskeleton in eukaryotic cells look like?

A

p37

Biology (11 decks)

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