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biology > cell structure > Flashcards

cell structure Flashcards

1
Q

what is magnification

A

how much larger something looks compared to its actual size

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2
Q

what is resolution

A

the ability to distinguish from two points

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3
Q

why should cells be kept cold before homogenisation

A

stop enzymes from reacting and breaking down cell organelles

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4
Q

why should cells be kept in an isotonic solution before homogenisation

A

it contains salts and sugars needed to prevent osmosis in the cells

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5
Q

why should cells be kept in a buffer before homogenisation

A

to prevent enzymes from denaturing due to pH fluctuation

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6
Q

how are cells homogenised

A

mixed in a homogeniser at controlled conditions and then filtered to remove large bits of cell wall / membrane

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7
Q

what is ultracentrifugation

A

cell fragments are placed in a centrifuge and spun at a low speed

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8
Q

what is produced after ultracentrifugation

A

heavier organelles fall to the bottom to from a pellet and the remaining liquid at the top is the supernatant

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9
Q

how to get smaller organelles out of ultracentrifugation

A

repeat the process spinning the supernatant at increasing speeds

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10
Q

why should the homogenate be put evenly each side of the centrifuge

A

because it works with gravity so needs to be balanced

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11
Q

what is the order of cell organelles produced after ultracentrifugation

A

nuclei
- chloroplast
mitochondria
lysosomes
ribosomes

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12
Q

how does a transmission electron microscope work

A

it fires electrons through a thin piece of specimen
the electron beam is focused using an electromagnet and denser parts of the specimen absorbs more electrons so appears darker
an image is produced on photographic paper

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13
Q

why is at TEM better than a light microscope

A

beams of electrons have a shorter wavelength than light
They can magnify an object up to 500,000 times
high resolving power

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14
Q

limitations of a TEM

A

living specimen cannot be used because the whole system is a vacuum
specimen must be very thin
chemically fixing the specimen is time consuming
this can result in artifacts
only 2D images are captured but they ca be built up to make 3D)
expensive

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15
Q

what is an artifact

A

accidentally ruining a sample

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16
Q

how does a scanning electron microscope work

A

electrons are passed across the surface of the specimen
scattered electrons form an image on the screen
depressions appear dark and extensions appear light
3D appearance

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17
Q

good things about SEM

A

3D images
500,000 magnification
less chance of an artifact because prep is less complex
specimen don’t have to be cut so thin

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18
Q

limitations of an SEM

A

resolving power is lower
expensive

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19
Q

what is the structure and function of the cell surface membrane

A

s-phospholipid bi-layer
f-regulates the transport of materials in and out of the cell

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20
Q

what is the structure and function of the nucleus

A

s-it contains a nuclear envelope, nucleolus, and chromosones
f- to hold genetic material for the cell

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21
Q

what is the function of the nucleolus

A

synthesis of ribosomes

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22
Q

what is the structure and function of the nuclear envelope

A

s- porus
f- messenger RNA and ribosomes leave

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23
Q

what is the structure and functions of the chromosomes

A

s - protein bound linear DNA found in a diffuse form
f - copying genetic material accurately during cell division

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24
Q

what is the structure and function of the mitochondria

A

s- cristae is the folded inner membrane , matrix contains proteins, lipids , ribosomes and DNA
f - aerobic respiration and production of ATP

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25
Q

what is the structure and function of chloroplast

A

s- outer membrane, inner membrane and thylakoid membrane which separates the intermembrane space, thylakoid and stroma
f- photosynthesis

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26
Q

what is the structure and function of the golgi body

A

s- a stack of flattened stacks surrounded by membranes
f- packages and modifies proteins, processes enzymes, secretes carbohydrates

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27
Q

what is the structure and function of lysosomes

A

s - small vesicles produced by the golgi body
f- contains digestive enzymes(lysozymes) which hydrolyses old cell organelles or pathogens
fagocytes contain a lot

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28
Q

what is the structure and function of ribosomes

A

s- tiny granuals made from two subunits
that exist in two sizes 80s in eukaryotic cells and 70s in prokaryotic cells
f - protein synthysis

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29
Q

what is the structure and function of the rough endoplasmic reticulum

A

s- membranes enclosed in a network of tubes all cisternae
continuous to the outer layer of the nuclear envelope
f- protein synthesis because ribosomes are attached and it is closer to the MRNA

30
Q

what is the structure and function of the cell wall

A

s- cellulose , fully permeable
f- structural support

31
Q

what is the function of the vacuole

A

f- stores sugar to maintain turgidity of the cell

32
Q

how are proteins and lipids modified

A

vesicle containing proteins from the RER transfer substance to the golgi body
primary lysosomes are formed
membrane forms around the worn out cell organelle
enzymes hydrolyse the particle
soluble products are absorbed into the cytoplasm
insoluble debris is egested

33
Q

examples of specialised cells

A

red blood cells
sperm
egg
nerve cell
muscle cell

34
Q

what is the process of specialisation known as

A

cell differentiation

35
Q

how many chromosomes are in one cell

A

46 identical chromosomes

36
Q

how does cell differentiation occur

A

change in gene expression to determine which gene is needed for it to develop into a specialised cell

37
Q

definition of a cell

A

a membrane bound structure containing nucleic acid , proteins and polysaccharides

38
Q

definition of a tissue

A

a group of specialised cells working together to perform a similar function

39
Q

definition of an organ

A

different tissues working together to carry out a similar function

40
Q

what are some blood vessels organs and other are not

A

capillaries are not organs but veins and arteries are because a capillary is only one tissue whilst veins and arteries have many

41
Q

what is a plasmid and what does it do

A

a small section of DNA which codes for special characteristics

42
Q

what does the cytoplasm do in a prokaryotic cell

A

metabolic reactions

43
Q

what does the slime capsule do in a prokaryotic cell

A

prevents them from drying out and makes them to slippery to be engulfed by white blood cells

44
Q

what does the cell wall do in a prokaryotic cell and what is it made of

A

maintains cell shape
made of murain which is a glycoprotein

45
Q

what does the flagellum do in a prokaryotic cell

A

rotates to propel the cell

46
Q

what does the free flowing DNA in a prokaryotic cell do

A

codes for normal functions

47
Q

what is the matrix in a virus cell

A

a layer of proteins situated under the outer envelope

48
Q

what are attachment proteins in a virus cell

A

proteins used to identify and attach to the host cell

49
Q

what is a capsid in a virus cell

A

protein layer that encapsulates two single strands of RNA and some enzymes

50
Q

what does the genetic material in a virus cell do

A

needed for reproduction

51
Q

what is the lipid envelope in a virus cell

A

allows enveloped viruses to bud out the cell without damaging the cell membrane (not all viruses have them)

52
Q

what is a reverse transcriptase in a virus cell

A

an enzyme that catalyses the production of DNA from RNA

53
Q

what type of reproduction is mitosis and where does it occur

A

a sexual
in sematic cells

54
Q

what is produced after mitosis

A

two new identical daughter cells with the same number of chromosomes as the parent cell

55
Q

why is mitosis important

A

growth of tissues or organisms
replacing damaged or old cells

56
Q

what is the equation for the MI value

A

number of cells with condensed chromosomes/total number of cells x 100

57
Q

what happens to the chromosomes in prophase

A

long threads get shorter and thicker
the centriole is in the poles produce spindle fibres (if its an animal cell)
the nuclear envelope breaks down and chromatids are free in cytoplasm

58
Q

what happens to the chromosomes in metaphase

A

chromatids are joined together at the centromere
the spindle fibres pull chromatids to the equator and bind with the centromere

59
Q

what happens to the chromosomes in anaphase

A

the centromere divides in two and the spindle fibres pull the chromatids to the opposing poles

60
Q

what happens to the chromosomes in telophase

A

chromosomes at the poles become longer and thinner until they disappear leaving a wide spread chromatin. nuclear envelope reforms and cytokinesis occurs

61
Q

how do prokaryotic cells divide

A

by binary fission

62
Q

what happens in G1

A

cell growth before DNA replication

63
Q

what happens in S

A

chromosomes are duplicated

64
Q

what happens in G2

A

after DNA replication and cells prepare to divide

65
Q

what are G1 S G2 all called

A

interphase

66
Q

what causes cancer

A

damage to genes by mutation or environment causing quick and uncontrollable cell division

67
Q

what is a benign tumor

A

a tumor that doesn’t spread to other tissue

68
Q

what is a malignant tumor

A

a tumor that infiltrates other tissue

69
Q

how do cancer cells move around the body

A

through blood and lymth fluid

70
Q

what does metastases mean

A

spread (secondary cancer )

71
Q

what happens in binary fission

A

replication of DNA and plasmids
division of cytoplasm to produce two daughter cells each with a single copy of DNA and variable plasmids

72
Q
A

biology (10 decks)

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