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A-level biology > 2.1.1 - cell structure > Flashcards

2.1.1 - cell structure Flashcards

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1
Q

formula of magnification

A

mag=image size/object size

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2
Q

structure of the nucleus

A

contains gentic info in the form of chromosomes
contains the nucleolus
surrounded by the nuclear envolope that contains pores

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3
Q

functions of the nucleus

A

controls cells activities (DNA has instructions to produce proteins)
synthesis of ribosomes - nucleolus makes ribosomal RNA
Substance can enter or leave the nucleus and cytoplasm via the nuclear pores

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4
Q

structure of the cell membrane

A

mainly made of lipids and proteins

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5
Q

functions of the cell membrane

A

controls movement of substances in and out of the cell
cell signalling - receptors can detect signals from other cells

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6
Q

structure of the mitochondria

A

contains an enzyme rich liquid called the matrix
contain the own DNA (mtDNA) and ribosomes

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7
Q

function of mitochondria

A

site of aerobis respiration and produces ATP

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8
Q

where are ribosomes found

A

free floating in the cytoplasm or attached to the rer

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9
Q

how many ribosomes does a eukaryotic cell contain

A

80S

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10
Q

structue of the ribosome

A

made of proteins and rRNA
consist of a large and small subunit
not surrounded by a membrane

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11
Q

funtion of ribosomes

A

site of protein synthesis and involved in the process of translation

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12
Q

structure of the golgi

A

contains fluid filles membrane bound sacs called cisternae
contains smaller vesicles

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13
Q

functions of the golgi

A

process and package lipids and proteins - carries out by the cisternae
store and transport lipids and proteins - done by vesicles
synthesise lysosomes

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14
Q

structure of the rer

A

contains cisternae that is covered with ribosomes

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15
Q

what happens at the RER

A

processing and folding of proteins

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16
Q

what happens at the SER

A

making and processing of lipids

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17
Q

what is the nucleolus

A

a very darkly stained area in the nucleus

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18
Q

what does the nucleolus do

A

contains DNA to make ribosomes

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19
Q

what is the cytosol

A

the soluble part left over when you remove the organelles form the cytoplasm

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20
Q

what does the cytosol consist of

A

mainly of water with dissolved substances such as amino acids

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21
Q

where are chloroplasts found

A

in some plant cells

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22
Q

how are the reactions in the chloroplast isolated from the rest of the cell

A

it is bound by 2 membranes - an envelope

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23
Q

do chloroplasts contain their own dna

A

yes

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24
Q

how many ribosomes do chloroplasts have

A

70S

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25
Q

why do chloroplasts contain chloropyll

A

for the light dependant reactions during photosynthesis

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26
Q

what is the granum

A

stacks of thylakoid inside the chloroplast joined together by intergranal lamellae

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27
Q

what is a lysosome

A

a spherical sac bound by a single membrane (0.5um diam) containing around 40-50 digestive (hydrolytic) enzymes

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28
Q

where are lysosomes made

A

golgi

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29
Q

what do lysosomes look like under an electron microscope

A

darkly stained with no clear features

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30
Q

what do lysosomes do

A

take in and digest material from the outside and inside and are involved in the self destruction of cells in the developmental process

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31
Q

what are cilia and flagella

A

long thin extensions from the surface of the cell that produce movement

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32
Q

where are cilia and flagella found

A

in some animal cells but rarely in plant cells

33
Q

what is the difference between cilia and flagella

A

cilia are relatively short but found in large numbers but flagella are relatively long and occur in smaller numbers

34
Q

cilia and flagella both contain microtubules arranged in what arrangement

A

9+2

35
Q

how is movement produced by the cilia and the flagella

A

the microtubules slide against each other causing them to bend and straighten

36
Q

where are centrioles found

A

only in animal cells

37
Q

what is the structure of a centriole

A

consists of 2 microtubule bundles at right angles to each other

38
Q

what are microtubules made of

A

tubulin protein subunits and they are arranged to form a cylinder

39
Q

what is the function of centrioles

A

before a cell divides, centrioles replicate and move to the poles of the cell and form the spindle apparatus

40
Q

what is the spindle apparatus made of

A

threads of tubulin (microtubules) which extend s from the poles of the cells

41
Q

where is the cell wall found

A

only in plant cells

42
Q

what is the cell wall made of

A

cellulose

43
Q

what does the cell wall do

A

provides mechanical support and protection of the cell and prevents osmotic bursting of the cells

44
Q

where is the vacuole found

A

it is absent or small in animal cells but large in plant cells

45
Q

what is the enclosing membrane of the vacuole called

A

the tonoplast

46
Q

why does the vacuole contain hydrolytic enzymes

A

to act as lysosomes during life and cause autolysis after death

47
Q

what is magnification

A

The number of times larger an image appears compared to the size of an object

48
Q

what is resolution

A

the level of clarity in an image

49
Q

how does a light microscope work

A

the specimen is clipped onto the stage and the nosepiece is rotated to set a specific objective lens. The coarse and fine focusing knob are adjusted to get a clear image

50
Q

where are light microscopes used

A

schools, colleges and research labs hospitals

51
Q

advantages of light microscopes

A

relatively cheap
easy to use
portable
can be used to study whole living specimens

52
Q

disadvantages of light microscopes

A

has a low mag and res
cant see some subcellular structures in detail

53
Q

what is another name for laser scanning microscopes

A

conofocal microscope

54
Q

how does a laser scanning microscope work

A

uses a laser light to scan an object point by point and assemble by computer to form one image

55
Q

what is the laser scanning microscope used for

A

medicine and branches of biological research

56
Q

advantages of laser scanning microscopes

A

can collect clear images
high resolution and contrast
can focus on different depths within the specimen
can be used to clearly observe whole living specimens as well as cells

57
Q

disadvantages of laser scanning microscopes

A

need to be highly trained in order to use

58
Q

how does a TEM microscopes work

A

specimen has to be dehydrated and stained. Beam of electrons passes through the specimen and form a 2D black and white image (electron micrograph)

59
Q

advantages of a tem

A
  • have a very high magnification and resolution
  • high quality images
60
Q

disadvantages of tem

A
  • the image is not in colour and is in 2D
  • large and very expensive
  • need to be trained a lot to use
61
Q

how does a sem work

A

electrons don’t pass through the specimen but cause secondary electrons to bounce off the specimens surface and be focused onto a screen giving a 3D image

62
Q

advantages of a SEM

A
  • gives a 3D colour image
  • very high magnification and resolution
63
Q

disadvantages of sem

A
  • image is black and white but computer programmes can add false colour
  • large and very expensive
  • need to be trained a lot to use
64
Q

what are stains

A

coloured chemicals that bind to molecules in or on the specimen to make it easier to see

65
Q

what is differential staining

A

when some stains bind to specific structures

66
Q

Methylene blue

A

an all purpose stain

67
Q

acetic Orecin

A

binds to DNA + stains chromosomes dark red

68
Q

Eosin

A

stains the cytoplasm

69
Q

Sudan Red

A

stains lipids

70
Q

Iodine in potassium iodide solution

A

stains cellulose in plant cell walls yellow and starch granules blue/black

71
Q

functions of the cytoskeleton

A
  • Maintaining the shape of the cell
  • securing some organelles in specific positions
  • allowing cytoplasm and vesicles to move within the cell
  • enabling cells withing multicellular organisms to move
72
Q

what are the 3 types of fibres within the cytoskeleton

A

microfilaments
intermediate filaments
microtubules

73
Q

diameter of a microfilament

A

7nm

74
Q

diameter of intermediate filaments

A

8-10nm

75
Q

diameter of microtubules

A

25nm

76
Q

what do microfilaments do

A

thicken the cortex around the inner edge of a cell and resist tension

77
Q

which of the 3 fibres in the cytoskeleton can disassemble and reform quickly to allow the cell to change shape

A

microfilaments
microtubules

78
Q

what do intermediate filaments do

A

hold organelles in place

79
Q
A

A-level biology (25 decks)

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