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*move to decks* > 3. Cell structure > Flashcards

3. Cell structure Flashcards

1
Q

What is the definition of magnification?

A

by how much an image is enlarged under a microscope

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2
Q

what is magnification controlled by?

A

power of the lense

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3
Q

what is the definition of resolution?

A

the minimum distance between two objects at which the microscope can distinguish them as separate entities.

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4
Q

what is the resolution controlled by?

A

the wavelength of the illumination used

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5
Q

what equation can you use to calculate image size?

A

actual size x magnification

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6
Q

what is the matrix?

A

the fluid within the mitochondria.

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7
Q

where is the nuclear envelope located?

A

membrane enclosing the nucleus.

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8
Q

what is the basic role of the nuclear envelope?

A

protein-lined pores allow material to move in and out of the nucleus.

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9
Q

what is chromatin?

A

DNA plus associated proteins

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10
Q

what is the nucleolous?

A

A condensed region where ribosomes are formed.

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11
Q

what is the basic role of the peroxisome?

A

metabolizes waste.

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12
Q

What does the cell wall do?

A

helps maintain cell shape.

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13
Q

what is the central vacuole filled with?

A

cell sap

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14
Q

what function does the central vacuole perform?

A

maintains pressure against the cell wall.

holds materials and waste.

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15
Q

what are chloroplasts the site of?

A

photosynthesis

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16
Q

what is stored in the plastid?

A

pigments

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17
Q

what is contained in the endoplasmic reticulum?

A

Rough and smooth ER

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18
Q

what is the rough ER?

A

found within the endoplasmic reticulum, associated with ribosomes.

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19
Q

what is the basic role of the rough ER?

A

makes secretary and membrane proteins

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20
Q

what is the basic role of the smooth ER?

A

makes cellular products like hormones and lipids

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21
Q

what function do the lysosomes perform?

A

digests food and waste materials

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22
Q

what does the golgi apparatus do?

A

modifies proteins

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23
Q

what function do the mitochondria perform?

A

production of energy

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24
Q

what do the plasmodesmata do?

A

channels allow two plant cells to connect.

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25
Q

what can be found within the cytoskeleton?

A

microtubules
centrosome
intermediate filaments
microfilaments

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26
Q

what function do microtubules have?

A

they form the mitotic spindle and maintain the cell shape

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27
Q

what is the centrosome?

A

microtubule-organizing centre

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28
Q

what are the intermediate filaments?

A

fibrous proteins that hold organelles in place

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29
Q

what are microfilaments?

A

fibrous proteins that form the cellular cortex.

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30
Q

What is a tissue?

A

Many cells of the same type grouped together in a structural unit.

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31
Q

What is a organ?

A

many types of tissue which together form a function

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32
Q

what is an organ system?

A

many organs working together to perform a specific function

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33
Q

define a specialised cell?

A

a cell that has differentiated to form a specific function.

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34
Q

what do specialised cells differ in?

A

function
shape
organelles

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35
Q

What main features would you expect to find in a cell that produces lots of ATP?

A

lots of mitochondria

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36
Q

What main features would you expect to find in a cell that exchanges substances with their environment?

A

large golgi apparatus and a high functioning cell membrane

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37
Q

What main features would you expect to find in a cell that secretes many enzymes?

A

ribosomes

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38
Q

what is a cell?

A

one singular component of an organism.

39
Q

what can we use to measure the size of objects under a microscope?

A

An eyepiece graticule

40
Q

how do you calibrate an eyepiece graticule?

A

we use a microscope slide called a stage micrometer

41
Q

How do you calculate the scale for different objective lenses?

A

divide the differences in magnification

42
Q

what is the typical scale of an eyepiece graticule?

A

10mm long and is divided into 100 sub-sections.

43
Q

What is cell fractionation and centrifugation?

A

The process used to separate cellular components while preserving individual functions of each component.

44
Q

What effect does solution being cold have during cell fractionation and centrifugation?

A

This slows enzyme reactions

45
Q

what effect does the solution being isotonic have during cell fractionation and centrifugation?

A

stops osmosis, so organelles dont burst

46
Q

what effect does the solution being buffered have during cell fractionation and centrifugation?

A

stops PH changes

47
Q

How do we break open the cells during cell fractionation and centrifugation?

A

grind the tissue in a blender

48
Q

Why do we filter the cells after blending during the process of cell fractionation and centrifugation?

A

it removes insoluble tissue

49
Q

After filtering what do we call the filtrate? - cell fractionation and centrifugation

A

a cell-free extract

50
Q

what is the cell-free extract capable of? -cell fractionation and centrifugation

A

carrying out most of the normal and basic reactions

51
Q

What happens when we centrifuge filtrate at a low speed during cell fractionation and centrifugation?

A

this pellets nuclei which can then be resuspended.

52
Q

What happens when we centrifuge the supernatant at medium speed - 10000 x g for 30 min during cell fractionation and centrifugation?

A

pellets mitochondria and chloroplasts.

which can then be resuspended

53
Q

What happens when we centrifuge the supernatant at high speed - 100000 x g for 1 hr during cell fractionation and centrifugation?

A

pellets the ER, golgi and other membrane fragments

which can then be resuspended

54
Q

What happens when we centrifuge the supernatant at very high speed - 300000 x g for 3hr during cell fractionation and centrifugation?

A

pellets ribosomes.

which can then be resuspended

55
Q

Explain the process of cell fractionation and centrifugation?

A

cells are broken up and ordered by size ready for study of the organelles.

56
Q

What does cell fractionation and centrifugation do?

A

takes cells apart and separates the major organelles and other subcellular structures from one another

57
Q

What is stage one of cell fractionation and centrifugation?

A

cells placed in a cold, buffered, isotonic solution

58
Q

What happens during stage 2 of cell fractionation and centrifugation?

A

cells are blended

59
Q

What happens during stage 3 of cell fractionation and centrifugation?

A

filter to produce filtrate

60
Q

What happens during stage 4 of cell fractionation and centrifugation?

A

centrifuge filtrate

61
Q

What is left after the supernatant has been through the entire process of ‘cell fractionation and centrifugation’?

A

organelle-free cytoplasm.

62
Q

what are bacterial and yeast cells an example of?

A

prokaryotic cells

63
Q

List some of the main features of prokaryotic cells.

A

singular celled organism
dna is not in a nucleus but in a plasmid
smaller than eukaryotic cells
lack a membrane bound nucleus or any other membrane bound cells

64
Q

what is the cell wall made of in prokaryotic cells?

A

muerin

65
Q

explain the function of the nucleoid in prokaryotic cells?

A

where the dna is housed
lacks the membrane that is found around the nucleus of eukaryotic cells.
may also contain rna, proteins, and enzymes that can be used for cellular processes

66
Q

explain the function of pili in prokaryotic cells?

A

found on the outside of cell

attach a bacterial cell to specific surfaces or to other cells, can also aid in attachment between bacterial cells

67
Q

explain the function of the mesosome in prokaryotic cells?

A

infoldings in the plasma membrane, these are rich in enzymes that help perform functions like cellular respiration, DNA replication, secretion of glycocalyx and cell division.
increases the surface area of the cell membrane

68
Q

what happens to the nucleus during mitosis

A

the nucleus divided into 2

69
Q

what happens to the nucleus during meiosis

A

the nucleus divides into 4

70
Q

what is cytokenesis

A

the division of the cytoplasm

71
Q

at what stage of the cell cycle is a large majority of the cells time spent, and doing what?

A

interphase, ‘resting phase’

no division takes place as the DNA replicates

72
Q

How do tumours form?

A

there are checkpoints between each stage of the cell cycle, these are regulated by control genes
Mutated control genes can cause cells to divide uncontrollably

73
Q

List and describe the types of tumour.

A

Benign: slow growing, do not spread to other parts of the body, not classed as cancer.
Malignant: fast growing, often spread, classed as cancer

74
Q

How can almost half of all cancers be prevented?

A

change in lifestyle

75
Q

List what treatments can be used in the treatment of cancerous tumours.

A

surgery
radiotherapy
chemotherapy

76
Q

How is surgery used to treat cancer?

A

removal of tumour

77
Q

how is radiotherapy used to treat cancer?

A

radiation damages the DNA of cells in the tumour.

78
Q

how is chemotherapy used to treat cancer?

A
  • blocking enzymes involved in DNA synthesis
  • preventing DNA unwinding
  • inhibiting synthesis of new nucleotides
  • preventing development of the spindle
79
Q

List some examples of chemotherapy that can be used in the treatment of cancer?

A

Adriamycin and Cytoxan inhibit DNA helicase, so stops DNA replication
Methotrexate inhibits nucleotide synthesis, so stops DNA replication
Taxol and Vincristine inhibit the formation of the mitosis spindle, so stop mitosis.

80
Q

why do cells perform mitosis?

A

growth of tissues
replacement of lost cells
repair of damaged tissue
asexual reproduction

81
Q

what type of cells division do eukaryotic cells perform?

A

mitosis, production of identical body cells

82
Q

when given a diagram of a chromosome what 2 parts may you be asked to label and roughly where would they be?

A

chromatids, two sticks either side of a central circle

centromere, central circle joining both chromatids together

83
Q

what is the chromosome made of?

A

chromatin

84
Q

what is a chromatid?

A

the two identical arms of an x-shaped chromosome

85
Q

what is a centromere?

A

point at which chromatids are joined

86
Q

what is a chromosome, in simple terms?

A

compact x or I shaped form of chromatin formed during cell division

87
Q

what are the 6 stages of mitosis?

A 
interphase
prophase
metaphase
anaphase
telophase
cytokenesis
88
Q

what happens during interphase?

A

the cell grows and the dna replicates itself
the chromosomes are not visible
not strictly part of mitosis

89
Q

what happens during prophase?

A

chromosomes condense and become visible
centrioles move to opposite ends/poles of the cell
spindle apparatus forms from spindle fibres at the centriole

90
Q

what happens during metaphase?

A

the nuclear envelope breaks down completely

chromosomes align along the equator/centre of the cell pulled by spindle aparatus

91
Q

what happens during anaphase?

A

centromeres split, allowing chromatids to separate.

chromatids move towards poles, pulled by spindle fibres

92
Q

what happens during telophase?

A

spindle fibres disperse
nuclear envelopes reform
chromosomes decondense

93
Q

what happens during cytokenesis?

A

a ring of protein filaments form around the equator of the cell and then the cells splits into two.

94
Q

calculation for mitotic index?

A

number of cells in mitosis / total number of cells.

multiplied by 100

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