2.1 Cell Structure Flashcards

1
Q

what does the nucleus consist of

A

-nucleolus
-chromatin
-nuclear envelope
-nuclear pore

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2
Q

what is chromatin

A

genetic material

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3
Q

what is the structure of the nucleus

A

contains a nucleolus and chromatin and is surrounded by the nuclear envelope which contains nuclear pores

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4
Q

what is the nuclear envelope

A

a double membrane

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5
Q

what is the function of the nuclear envelope

A

separates the contents of the nucleus to the rest of the cells

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6
Q

what is the function of the nuclear pores

A

they enable RNA to leave the nucleus

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7
Q

what is the structure of the nucleolus

A

does not contain membrane around it and contains RNA

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8
Q

what is the function of the nucleolus

A

it creates ribosomes (where they are made)

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9
Q

describe the structure of the rough endoplasmic reticulum

A

system of membranes containing fluid filled cavities that are continuous with the nuclear membrane
- coated in ribosomes

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10
Q

describe the function of the RER

A

-involved in assembling amino acids into proteins
-intracellular transport system

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11
Q

describe the structure of the smooth endoplasmic reticulum

A

-system of membranes containing fluid filled cavities which are continuous with the nuclear membrane
-is not coated in ribosomes

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12
Q

describe the function of the SER

A

-contains enzymes that catalyse reactions involved w lipid metabolism
-involved w absorption, synthesis and transport of lipids

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13
Q

describe the structure of the Golgi apparatus

A

stack of membrane bound flattened sacks

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14
Q

describe the function of the Golgi apparatus

A

it is where proteins are modified and proteins are packaged in vesicles that are pinched off

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15
Q

describe the structure of the mitochondria

A

-can be spherical or rod shaped/branched
-surrounded by 2 membranes with a fluid filled space
-inner part is a fluid filled matrix

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16
Q

describe the function of the mitochondria

A

-site of ATP production during aerobic respiration
-self-replicating so can move easily
-abundant in cell where a lot of metabolic activity takes place

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17
Q

describe the structure of the vacuole

A

-surrounded by membrane (tonoplast)
-contains fluid

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18
Q

describe the function of the vacuole

A

-maintains cell stability
-helps support the plant

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19
Q

describe the structure of lysosomes

A

-small bags formed in the golgi
-surrounded by single membranes
-contain powerful hydrolytic (digestive) enzymes

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20
Q

describe the function of lysosomes

A

-keep digestive enzymes separate from the rest of the cell
-engulf old cell organelles and foreign matter

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21
Q

describe the structure of ribosomes

A

-small spherical organelles
-made of ribosomal RNA
-made in nucleolus
-some attach to the RER and some float free

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22
Q

what is the structure of the nucleolus

A

does not contain membrane around it and contains RNA

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23
Q

describe the function of ribosomes

A

-RER ribosomes synthesise proteins that will export out of the cell

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24
Q

describe the structure of centrioles

A

-2 bundles of microtubules at right angles to eachother
-microtubules arranged to form a cylinder

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25
Q

describe the function of centrioles

A

involved in mitosis

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26
Q

describe the structure of the cellulose cell wall

A

-made of bundles of cellulose fibres
-on outside of plasma membrane

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27
Q

describe the function of the cellulose cell wall

A

-provides strength and support
-maintains cell shape
-allows solutions to pass through

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28
Q

describe the structure of chloroplasts

A

-large organelles
-have an envelope
-inner membrane has stacks of flattened membrane sacs which contain chlorophyll
-contains loops of DNA

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29
Q

describe the function of chloroplasts

A

-site of photosynthesis
-water is split to supply hydrogen ions

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30
Q

describe the structure of cilia and undilipodia

A

-protrusions from the cell
-surrounded by cell surface membrane
-contain microtubules
-formed from centrioles

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31
Q

describe the functions of the cilia and undilipodia

A

-cilia beats and moves mucus
-all cell types have 1 cilium that act as an antenna which contains receptors and allows cells to detect signals about their environment

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32
Q

what does the cytoskeleton contain

A

-microfillaments
-intermediate fillament
-microtubules
-motor proteins

33
Q

what are microfilaments

A

polymers of actin

34
Q

describe the function of microfilaments

A

-give support and mechanical strength
-keep cell shape
-allow cell movement

35
Q

what is the intermediate filament

A

made of a variety of proteins

36
Q

describe the function of the intermediate filament

A

-stabilises tissues
-anchors the nucleus with the cytoplasm

37
Q

what are microtubules

A

made of protein subunits (tubulin)

38
Q

describe the function of microtubules

A

-provide shape and support
-form track for motor proteins
-made up cilia, undilipodia and centrioles

39
Q

what are the motor proteins

A

-myosins
-kinesins
-dyneins

40
Q

describe the functions of motor proteins

A

travel along the track of microtubules

41
Q

where do we have ciliated epithelial cells

A

in our airways

42
Q

what are protrusions in prokaryotes and eukaryotes

A

flagella in P
Cilia and undilipodia in E

43
Q

how are cilia found

A

short in large numbers

44
Q

how are undilipodia found

A

long and in singular structures

45
Q

compare eukaryotes and prokaryotes

A

-E have a nucleus, P don’t
-E are larger cells, P are smaller
-E have centrioles, P don’t
-P have a less developed cytoskeleton, E has a more developed cytoskeleton
-E contain membrane bound organelles, P don’t
- P cell wall is made of peptidolycan, E is made of cellulose
-P have circular naked DNA which floats free in the cytoplasm, E DNA is histone wound and linear

46
Q

What do some prokaryotic cells contain

A

-protective waxy capsule surrounding cell wall
-plasmids (small loops of DNA)
-flagella
-pili

47
Q

how do prokaryotic cells divide

A

binary fission

48
Q

what is the endosymbiont theory

A

that eukaryotic cells arose from prokaryotic cells

49
Q

what does the endosymbiont theory suggest

A

that the mitochondria and chloroplast were created when the invaded prokaryotes’ plasma membrane folded inwards around the invading cell

50
Q

describe how a protein is produced and secreted

A

-The DNA from the nucleus is copied into a molecule of mRNA via a process known as transcription
-The mRNA strand leaves the nucleus through a nuclear pore and attaches to a ribosome on the rough endoplasmic reticulum
-The ribosome ‘reads’ the genetic instructions contained within the mRNA and uses this code to synthesise a protein via a process known as translation
-The processed proteins are then transported to the Golgi apparatus in vesicles, which fuse with the Golgi apparatus, releasing the proteins
-The Golgi apparatus modifies the proteins, preparing them for secretion
-the molecules get packaged into vesicles and are pinched off the Golgi
-the vesicles move towards the cell surface membrane and fuse with it through exocytosis

51
Q

define magnification

A

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

52
Q

define resolution

A

the ability to distinguish between two points. Allows you to see in greater detail

53
Q

how to calculate magnification

A

size of image/size of real object

54
Q

define the 4 types of microscope

A

Light microscope
laser scanning (confocal) microscope
scanning electron microscope (SEM)
transmission electron microscope (TEM)

55
Q

how does a light microscope work

A

it creates a magnified image through the use of a series of glass lenses and a beam of light onto or through an object

56
Q

describe a light microscope

A

magnification - x1500
resolution- 200nm (0.2um)
you can see whole cells and tissues
produces a 2D coloured image

57
Q

describe advantages and disadvantages of light microscopes

A

ADS- cheap, easy to use, portable, can study whole living specimens

DISADS- low resolution and low magnification, specimen may be disfigured during prep and cannot see small structures

58
Q

How does a laser scanning microscope work?

A

They use a laser light to scan an object point by point and assemble the pixel info into one image on a computer

59
Q

describe a laser scanning microscope

A

magnification- x400 to x1000
resolution- 270nm
you can see an object at a certain depth within a cell
image is 3D and black and white

60
Q

describe advantages and disadvantages of laser scanning microscopes

A

ADS- high resolution and high contrast, depth selectivity so it can focus on structures of different depths

DISADS- limited primarily to the limited number of excitation wavelengths available

61
Q

How does a scanning electron microscope work?

A

It passes a beam of fast-travelling electrons over the specimen’s surface.

62
Q

describe a scanning electron microscope

A

magnification -up to x200,000
resolution- 1-20nm
you can see the surface of almost any sample
image is 3D and black and white

63
Q

describe advantages and disadvantages of a SEM

A

ADS-the resolution can be very low so you can see microstructures

DISADS- large and expensive and must be housed in a place free of electric or magnetic interference

64
Q

How does a transmission electron microscope work?

A

It transmits a beam of electrons for an internal view of the specimen. Specimen must be chemically fixed and stained

65
Q

describe a transmission electron microscope

A

magnification- x2,000,000
resolution - less than 1nm
You can see organelles
Image is 2D and black and white

66
Q

describe advantages and disadvantages of a TEM

A

ADS- allows visualisation of internal structures

DISADS- large and expensive, requires special training to operate

67
Q

How to calculate total magnification

A

ocular lens x objective lens

68
Q

why should you stain a specimen

A

provides contrast, allows detail, identifies different organelles

69
Q

what should you be aware of when using a light microscope

A

specimen is 3d but your looking at 2d version some structures may be absent or will appear as different shapes

70
Q

which microscope allows you to view living cells

A

laser scanning microscope

71
Q

what does iodine stain

A

cellulose in plant cell walls yellow, starch granules blue/black

72
Q

what does methylene blue stain

A

cheek cells

73
Q

what does acetic orcein stain

A

Binds to DNA and stains chromosomes dark red

74
Q

What does eosin stain?

A

cytoplasm

75
Q

what does Sudan red stain

A

lipids

76
Q

what is an eye piece graticule

A

A small ruler fitted to a light microscope’s eyepiece

77
Q

What is a stage graticule?

A

A precise measuring device. It is a small scale that is placed on a microscope stage and used to calibrate the value of eyepiece divisions at different magnifications.

78
Q

what is always the magnification of a eyepiece lens

A

x10