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A Level Biology > Cells > Flashcards

Cells Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

magnification equation

A

magnification = image size/ actual size

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2
Q

name 4 types of microscopes

A

optical, laser scanning confocal, scanning electron microscope, transmission electron microscope

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3
Q

how can specimens be made more visible under a TEM?

A

stain the specimen with metal salts

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4
Q

definition of an artefact

A

objects under a microscope that look like real structures but are the result of preserving and staining

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5
Q

which microscope(s) create a 3D image

A

laser confocal microscopes & SEM

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6
Q

which microscope(s) create a 2D image

A

optical & TEM

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7
Q

optical magnification

A

x1500-2000

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8
Q

laser scanning confocal magnification

A

x2000

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9
Q

SEM magnification

A

x2,000,000

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10
Q

TEM magnification

A

x2,000,000

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11
Q

optical resolution

A

50-200nm

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12
Q

laser scanning confocal res.

A

high (varies)

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13
Q

SEM res.

A

3-10nm

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14
Q

TEM res.

A

0.05-10nm

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15
Q

where an how are mitochondria produced

A

they are self-replicating

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16
Q

name 4 organelles that aren’t membrane-bound

A

centriole, ribosomes, nucleolus (technically not a organelle), cytoskeleton, cellulose cell wall

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17
Q

what is the a-level replacement word for cell membrane

A

cell SURFACE membrane

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18
Q

what are SER & RER made of

A

cisternae

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19
Q

describe the structure of ER

A

fluid-filled cavities connected to the nuclear membrane (with/without ribosomes attached)

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20
Q

how many subunits are ribosomes made of

A

2

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21
Q

n

A

b

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22
Q

describe the nucleolus structure

A

concentrated genetic material within the nucleas without a membrane

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23
Q

briefly outline how ribosomes are made

A

2 subunits exit the nuclear envelope through pores and combine in the cytoplasm to form ribosome

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24
Q

what is the purpose of the Golgi apparatus

A

recieevs proteins from RER/ribosomes (1), modifies & packages proteins into vesicles (2) e.g lysosomes., (3) or for replenish plasma membrane

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25
Q

what is the purpose of the rough endoplasmic reticulum?

A

to transport proteins (to golgi apparatus) made from attached ribosomes. proteins pass through membrane into cisternae

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26
Q

what is the purpose of smooth endoplasmic reticulum

A

catalyze lipid metabolic reactions e.g synthesise lipids

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27
Q

name 3 examples of lipid metabolic reactions

A

e.g absorption, transport, synthesis

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28
Q

describe the formation of chromosomes in the nucleus

A

histone protein binds with DNA to form a complex called chromatin, just before cell division the chromatin coils & condenses to form chromosomes

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29
Q

where can chloroplasts be mainly found in the cross-section of a leaf

A

in the palisade mesophyll layer or the spongy mesophyll layer

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30
Q

what other ‘things’ do chloroplasts contain

A

ribosomes, DNA strands, starch grains

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31
Q

what are ribosomes made out of

A

rRNA & protein

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32
Q

why are cells stained before being viewed under a light microscope?

A

most cells have a low contrast when light is shone through them, staining increases contrast, hence increases visibility

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33
Q

differential staining definition

A

using 2 or more stains to color different structures (organelles or cells) to increase visibility

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34
Q

what is the purpose of stains

A

to increase contrast between organelles to increase visibility

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35
Q

name 2 positively charged stains

A

methylene blue, crystal violet

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36
Q

name 2 negatively charged stains

A

congo red, nigrosin

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37
Q

what is negative stain technique

A

staining the background rather than the structures, which then appear white

38
Q

how does negative stain technique work?

A

negative stains are repelled by the cell’s cytosol, coloring the background & not entering the cell

39
Q

why is the incompressible property of water important in nature (2)

A

provides turgidity to plants

provides a hydrostatic skeleton for small animals e.g earthworm

40
Q

why is high surface tension important for organisms (3)

A

slows down rate of transpiration (& water loss)
some insects can skim across its surface
provides capillary action (helpful in roots)

41
Q

what is the bacteria equivalent of organelles which do metabolic reactions e.g mitochondria

A

the mesosome with enzymes attached

42
Q

what size are ribosomes in bacteria cells

A

70S

43
Q

what is bacteria cell wall made out of (2 words)

A

murein & peptidoglycan

44
Q

what is fungi cell wall made out of

A

chitin

45
Q

describe flagella structure

A

whip like projection

46
Q

cilia function

A

moves back and forth rhythmically to move substances/ to be moved

47
Q

What is the nucleas-without-a-membrane equivalent in a bacteria?

A

nucleoid (concentrated area of DNA strands

48
Q

pili’s structure

A

hair like projections

49
Q

pili’s function

A

can adhere to other cells (hosts/bacteria) and form a passage for plasmid DNA to exchange between cells

50
Q

What happens at the ribosomes during protein synthesis? Step 1

A

rRNA attaches to ribosome, where 3 bases/codon codes for 1 amino acid

51
Q

What happens at the ribosomes during protein synthesis? Step 2

A

the ribosome moved to the next 3 bases, attaching amino acids, until the end of the rRNA, when the polypeptide detaches

52
Q

Where are DNA loops located in prokaryotes

A

Nucleoid region

53
Q

What is the cell wall in a prokarotic cell made of

A

Peptidoglycon/ murein

54
Q

Mesosome definition

A

Folded region of plasma membrane (1) containing all the membrane bound proteins (2) for cellular metabolic reactions

55
Q

Why do electron microscopes have a better magnification than light microscopes

A

Electrons have a smaller wavelength than light (1) hence has a higher resolution (2) allowing for a higher magnification

56
Q

what is the object under a microscope called

A

object/specimen

57
Q

Give an overview of cell theory (3points)

A

Both plant and animal tissue is composed of cells (1);
cells are the basic unit of all life (1);
cells only develop from existing cells (1)

58
Q

what is a photo taken through a microscope called

A

photomicrograph

59
Q

magnification definition

A

how much bigger the image is compared to the original object viewed with the naked eye

60
Q

resolution definition

A

the ability to distinguish between two separate entities.

61
Q

cell membrane definition (3 points)

A

a partially permeable barrier between cell contents & environment (1)
sites of chemical reactions(2)
sites of cell communication (3)

62
Q

cytoplasm definiton

A

internal fluid of cells, composed of cytosol (water, salts & organic molecules) organelles & cytoskeleton

63
Q

what is cytosol

A

part of cytoplams; consitst of water, salts & organic molecules

64
Q

what organelles can’t be seen by a light microscope?

A

mitochondria’s internal structures (e.g cristae & matrix)

65
Q

why does optical light microscope & LSC have a limited resolution

A

wavelength of light too long

66
Q

what can you view with light microscope?

A

cell walls, vacuoles, cytoplasm, chloroplasts, nucleus and cell membrane

67
Q

what can’t you view through a light microscope; only an electron microscope?

A

ribosomes, endoplasmic reticulum, lysosomes, centrioles, Golgi bodies, mitochondria’s internal structures (e.g cristae & matrix), nucleolus etc.

68
Q

give an example of differential staining, what is it used for

A

gram stain technique; to distinguish between 2 types of bacteria

69
Q

what does iodine do in … differential staining

A

fixes the dye onto the bacteria sample

70
Q

which 2 dyes are used in …. differential staining and what do they work on?

A

crystal violet dye - gram postitive bacteria

safranin dye - gram negative bacteria

71
Q

what is safranin dye in … differntial staining?

A

a counterstain

72
Q

what type of bacteria does penicillin work on & how?

A

works on gram positive bacteria by inhibiting cell wall formation

73
Q

True or False, endoplamis reticulums have to be connected to the nuclear envelope

A

false

74
Q

which is smaller: ribosomes or lysosomes?

A

ribosomes

75
Q

what is the average diameter of prokaryotes

A

0.5-5 micrometres

76
Q

what is the average diameter of eukaryotes

A

20-40 micrometres

77
Q

what is the technical ter, for vesicle merging with cell membrane during exocytosis

A

vesicle fuses with cell membrane

78
Q

cell theory (3)

A

All living things are composed of cells.
Cells are the basic units of structure and function for living things.
All cells come from pre-existing cells. Also, organisms grow by “adding on more cells” NOT by increasing the size of their cells

79
Q

nucleolus function

A

producing and assembling the cell’s ribosomes

80
Q

what is the role of nuclear pores

A

allow communication between nucleus and cytoplasm
& allows, molecules / named substances, to,
enter / leave (the nucleus)

81
Q

True or False golgi and ER can’t be seen under a light microscope

A

true

82
Q

what is the average diameter of eukaryotes

A

20-40 micrometres

83
Q

what is the average diameter of prokarotes

A

0.5-5 micrometres

84
Q

ribosmes in eukarotes diameter

A

22nm

85
Q

ribosomes in prokaryotes diameter

A

18nm

86
Q

name all eukarotyotes

A

animal, plant, fungi, protists

87
Q

are centrioles present in plants?

A

no, only in animal cells

88
Q

give 3 reasons why cells have to be compartmentalised

A

Incompatible reactions / catabolic and anabolic reactions require different conditions / damage
due to hydrolytic enzymes

89
Q

why are artefacts more likely to appear in electron microscopy and less in light microscropy

A

more sample preparation (in electron microscopy) (1) / (leads to) more damage to specimen

90
Q

why can’t confocal microscopy be used for deep tissue imaging

A

idea of light penetration (of sample) is limited (1)

91
Q

explain the difference between contrast and resolution

A

Contrast is difference in colour/shade between two objects (1) Resolution is the smallest distance
between two objects that can still be seen as separate

92
Q

what does high absorption/low transmission on a colorimeter show?

A

high concentration of pigment in solution

A Level Biology (12 decks)

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