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AQA A Level Biology > ✅3 - Cell Structure > Flashcards

✅3 - Cell Structure Flashcards

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1
Q

Describe the structure of the nucleus:

A

A nucleolus within a nuclear envelope and surrounded by nucleoplasm

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2
Q

Describe the function of the nucleus:

A
  • contains the genetic material

- controls the cell’s activities

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3
Q

Describe the structure of the mitochondria :

A

Rod shaped double membrane bound structures with a folded inner membrane and matrix

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4
Q

Describe the function of the mitochondria:

A
  • sites of aerobic respiration

- production of ATP

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5
Q

Describe the structure of the chloroplasts:

A

A double membrane bound organelle with stacks of thylakoids (grana) all connected by lamellae

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6
Q

Describe the function of the chloroplasts:

A

-to harvest sunlight for photosynthesis

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7
Q

Describe the structure of the Golgi apparatus + vesicles:

A

A stack of membranes that make up flattened stacks, or cisternae

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8
Q

Describe the function of the Golgi apparatus + vesicles:

A
  • add carbohydrates to proteins to form glycoprotiens
  • transport, modify and store lipids
  • produce secretory enzymes
  • secrete carbohydrates
  • make lysosomes
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9
Q

Describe the structure of the lysosomes:

A

Golgi vesicles which contain enzymes such as proteases and lipases

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10
Q

Describe the function of the lysosomes:

A
  • digest worn out organelles (using lysozymes)
  • break down cells completely after they’ve died
  • hydrolyse material ingested by phagocytic cells
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11
Q

Describe the structure of the ribosomes:

A

Small cytoplasmic granules, with ribosomal DNA and protein

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12
Q

Describe the function of the ribosomes:

A

-the site of protein synthesis int he cell

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13
Q

Describe the structure of the RER and SER:

A

RER: Three dimensional sheet like membranes continuous with the outer nuclear membrane, studded with ribosomes
SER: Three dimensional sheet like membranes continuous with the outer nuclear membrane, no ribosmes

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14
Q

Describe the function of the RER and SER:

A

RER: -provides large surface area for synthesis of proteins and glycoprotiens
-provides pathway for transport of materials. especially proteins, throughout the cell

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15
Q

Describe the structure of the cell wall:

A

Microfibrils of cellulose embedded in a matrix

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16
Q

Describe the function of the cell wall:

A

-provides mechanical strength to prevent the cell bursting when water enters by osmosis

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17
Q

Describe the structure of the vacuole:

A

A single membrane bound sac filled with cell sap (sugars and salts)

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18
Q

Describe the function of the vacuole:

A
  • temporary food store

- keeps cells turgid

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19
Q

How do prokaryotic cell differ from eukaryotic cells in terms of size?

A

The are much smaller

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20
Q

How do prokaryotic cell differ from eukaryotic cells in terms of organelles?

A

The have no membrane bound organelles

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21
Q

How do prokaryotic cell differ from eukaryotic cells in terms of nuclei?

A

The don’t have a nucleus, instead a singular circular DNA molecule, free in the cytoplasm and not associated with any proteins.

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22
Q

How do prokaryotic cell differ from eukaryotic cells in terms of cell membrane

A

It contains murein, a glycoprotien

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23
Q

What other features may a prokaryotic cell have?

A
  • one or more plasmids
  • a capsule surrounding the cell
  • one or more flagella
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24
Q

Viruses are…

A

…acellular and non-living

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25
Q

Describe the structure of a virus:

A

They include genetic material, capsid and attachment protein

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26
Q

Describe the principles of an optical microscope:

A

Creates a magnified image of an object specimen with an objective lens and magnifies the image further with an eyepiece.
Light source —-> condenser lens —-> object —-> objective lens —-> intermediate image —-> eyepiece lens—-> eye

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27
Q

Describe the limitations of an optical microscope:

A
  • the resolution is only half the wavelength of visible light
  • magnification is relatively low
  • the surface view is not always very clear
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28
Q

Describe the principles of an transmission electron microscope:

A

Electron gun focuses a beam of electrons onto the specimen using a condenser electromagnet. It passes through a thin section of the specimen.
Electron source —-> magnetic condenser —-> object —-> magnetic objective —-> intermediate image —-> magnetic projector —-> fluorescent screen

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29
Q

Describe the principles of an transmission electron microscope:

A

Electron gun focuses a beam of electrons onto the specimen from below using a condenser electromagnet. It passes through a thin section of the specimen.
Electron source —-> magnetic condenser —-> object —-> magnetic objective —-> intermediate image —-> magnetic projector —-> fluorescent screen

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30
Q

Describe the limitations of a transmission electron microscope:

A
  • The whole system must be in a vacuum so living things can’t be observed
  • Complex staining processes are involved, and the image is still in black and white
  • Specimen must be thin
  • The image may contain artefacts
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31
Q

Describe the principles of a scanning electron microscope:

A

Directs a bean of electrons on to the surface from above rather then below. Beam passed back and forth in a regular pattern, electrons are then scattered

32
Q

Describe the limitations of a scanning electron microscope:

A
  • The whole system must be in a vacuum so living things can’t be observed
  • Complex staining processes are involved, and the image is still in black and white
  • The image may contain artefacts
33
Q

What is magnification?

A

How many times larger the image is than the real life object

34
Q

What is resolution?

A

The smallest distance below which two discrete objects will be seen as one

35
Q

What is the equation for magnification?

A

size of image/size of real object

36
Q

How are cell components separated?

A

Using cell fractionation and ultracentrifugation

37
Q

Do all cells retain the ability to divide?

A

No

38
Q

Where in the cell cycle does DNA replication occur?

A

Interphase

39
Q

What is mitosis?

A

The part of the cell cycle in which a eukaryotic cell divides to produce two daughter cells, each with the identical copies of DNA produced by the parent cell during DNA replication

40
Q

What happens to the chromosomes in prophase?

A

They spiralize

41
Q

What happens to the chromosomes in metaphase?

A

They align with their centromeres on the ‘equator’ and attach to the spindle

42
Q

What happens to the chromosomes in anaphase?

A

Chromatids of each chromosome separate into daughter chromosomes and move to opposite poles

43
Q

What happens to the chromosomes in telophase?

A

Two nuclei reform at the poles

44
Q

What is cytokinesis?

A

The division of the cytoplsam, forming two new cells

45
Q

Mitosis is a…

A

…controlled process

46
Q

What can uncontrolled cell division lead to?

A

The formation of tumours and cancers. Many cancer treatments are directed at controlling the rate of cell division.

47
Q

What doe binary fission in prokaryotic cells involve?

A
  • replication of the circular DNA and of plasmids
  • division of the cytoplasm to produce two daughter cells, each with a single copy of the circular DNA and a variable number of copies of plasmids.
48
Q

Do viruses undergo cell division?

A

No, because they’re not living. Following injection of their nucleic acid, the infected host cell replicates the virus particles.

49
Q

What is a retrovirus?

A

One which rewrites DNA in the host cells and puts genetic instructions in

50
Q

What is adenovirus?

A

The common cause of colds/sore throats

51
Q

What is a bacteriophage?

A

A virus which uses a bacteria cell as a host

52
Q

What are the features of a prokaryotic cell?

A
  • No true nucleus
  • Some DNA in the form of plasmids
  • No membrane bound organelles
  • No chloroplasts, only bacterial chlorophyll in some bacterium
  • ribosomes are smaller (70s)
  • Cell wall made of murein (peptidoglycan)
  • May have a capsule
53
Q

What is the function of the capsule?

A

Protects bacterium form other cells and helps groups of bacteria to stick together for further protection

54
Q

What is the function of circular DNA?

A

Possesses the genetic information for the replication of bacterial cells

55
Q

What is the function of a plasmid?

A

Possesses genes that may aid the survival of bacteria in adverse conditions eg. produces enzymes that break down antibiotics

56
Q

How does a cell differentiate?

A

Every cell contains the genes needed for it to develop into any one of the different cells, but only one is switched on (expressed) in any one cell.

57
Q

What are epithelial tissues?

A

Sheets of cells found in animals, lining the surface of organs and often having a protective secretory function.

58
Q

What is the xylem?

A

Found in plants, made up of a number of similar cell types. Used to transport water and mineral ions throughout the plant and provides mechanical support

59
Q

What are organs in plants made up of?

A
  • palisade mesophyll
  • spongy mesophyll
  • epidermis
  • phloem
  • xylem
60
Q

What is spongy mesophyll adapted for?

A

Gaseous diffusion

61
Q

What does the phloem do?

A

Transports organic materials away from the leaf

62
Q

Describe the digestive system:

A

Digests and processes food. Made up of organs such as the salivary glands, oesophagus, stomach, ileum, liver

63
Q

Describe the respiratory system:

A

Used for breathing and gas exchange,made of organs such as the trachea, bronchi and lungs

64
Q

Describe the circulatory system:

A

Pumps and circulates blood, made up of organs that include the heart, arteries and veins

65
Q

What are the three stages of the cell cycle?

A
  • interphase
  • nuclear division
  • cytokinesis
66
Q

What is a haploid cell?

A

A cell with half the number of chromosomes, GAMETES

67
Q

What is a diploid cell?

A

One which has two sets of chromosomes

68
Q

What is cancer caused by?

A

A growth disorder of cells, the result of damage to the genes that regulate mitosis and the cell cycle

69
Q

Why do most cells divide by mitosis?

A

Either to increase the size of a tissue during developmental growth replace dead or worn out cells.

70
Q

What can the rate of mitosis be affected by?

A

The environment of the cell and by growth factors

71
Q

How do drugs used to treat cancer usually disrupt the cell cycle how?

A
  • preventing DNA from replicating

- inhibiting the metaphase stage of mitosis by interfering with spindle formation

72
Q

What are the problems with cancer drugs?

A

They also disrupt the cell cycle of normal cells

73
Q

What does the cell look like in prophase?

A

The chromosomes become visible and get shorter and thicker

74
Q

What does the cell look like in metaphase?

A

The centromeres attach to the spindles and arrange at the equator

75
Q

What does the cell look like in anaphase?

A

The centromeres divide in two and chromatids are pulled to poles

76
Q

What does the cell look like in telophase?

A

Chromosomes reach poles and become thinner, finally disappearing

77
Q

What is the energy for anaphase provided by?

A

Mitochondria

AQA A Level Biology (22 decks)

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