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A-Level Biology Paper 1 > Cell biology 3 > Flashcards

Cell biology 3 Flashcards

1
Q

What is osmosis?

A

The net movement of water from a region of less negative water potential to a region of more negative potential through partially permeable membrane

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2
Q

What is water potential?

A

Water potential is a measure of the water, molecules, potential for movement in a solution

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3
Q

How is water potential measured?

A

units of pressure

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4
Q

what does adding solute do to a solutions water potential?

A

It lowers it

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5
Q

What does isotonic mean?

A

A solution that has the same concentration of solutes as a cell

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6
Q

What does hypertonic mean?

A

A solution that has a lower concentration of solutes than a cell

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7
Q

What does hypertonic mean?

A

A solution that has a higher concentration of solutes than a cell

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8
Q

What does active transport require?

A

Energy from ATP

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9
Q

What is active transport?

A

Transport when molecules and ions move against a concentration gradient (move from a lower to higher concentration)

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10
Q

What does the term active mean?

A

Requires energy

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11
Q

what do molecules use to transport by active transport?

A

Are you specific carrier proteins in the cell membrane (not channel proteins).

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12
Q

what does cells involved in active transport have a lot of?

A

Mitochondria, so there is enough energy from ATP.

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13
Q

Why is active transport a very selective process?

A

Because each molecule need its own carrier protein.

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14
Q

What are the events of active transport?

A

molecule or ion binds to receptors carrier protein.
ATP binds to the protein on the other side, which causes it to split by hydrolysis into ADP and PI, releasing energy.
The protein changes shape button opens on the opposite side of the membrane.
The molecule or ion is released on the other side of the membrane.
ATPs, reformed and the protein reverts to its original state.

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15
Q

What are some examples of active transport?

A

The exchange of sodium and potassium ions.
Absorption of mineral ions by the roots of a plant. (root hair cell)

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16
Q

Where is the ATP in active transport?

A

Bound to the carrier protein

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17
Q

What factors affect the rate of active transport?

A

Number of carrier proteins
Rate of respiration (more respiration, more ATP for active transport)
Speed of carrier proteins

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18
Q

what are the two active methods of transport?

A

Endo/exocytosis and active transport

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19
Q

What is exocytosis?

A

Transporting substances out of the cell through the plasma membrane.

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20
Q

What is endocytosis?

A

Transporting substances into the cell through the plasma membrane.

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21
Q

What does co-transport?

A

The transport of one substance coupled with the transport of another substance across the plasma membrane in the same direction through the saying protein carrier

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22
Q

What type of transport is co-transport an example of?

A

Active transport

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23
Q

An example of two substances that are co transported?

A

glucose and sodium ions

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24
Q

explain the process of cotransport in sodium ions and glucose.

A

Sodium irons actively transported from ileum cell to blood
This maintains the difference diffusion gradient for sodium to enter cells from lumen
Glucose moves from the ileum cell into the blood by facilitated diffusion
Sodium irons into cells from the lumen by facilitated diffusion. Glucose is absorbed with sodium irons against a concentration.

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25
Q

What is a pathogen?

A

A bacterium, virus or other micro organism that can cause disease

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26
Q

What are pathogen is covered in?

A

Antigens

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27
Q

What are antigens?

A

proteins that stimulate an immune response

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28
Q

What is non-specific immune response?

A

immune response that doesn’t distinguish between different pathogens, response to all pathogens in the same way. They act immediately and always of a similar magnitude.

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29
Q

What is phagocytosis?

A

Where large particles (e.g. pathogens) can be engulfed by phagocytes.

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30
Q

what is the phagocyte?

A

A type of white blood cell involved in phagocytosis

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31
Q

Where are phagocytes found?

A

Blood

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32
Q

What attracts phagocytes to the site of invasion?

A

The chemical products of the micro organism.

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33
Q

what happens to a phagocyte when it reaches a micro organism?

A

It attaches to it

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34
Q

what is a phagosome?

A

The vacuole into which the micro organism is engulfed in phagocytosis

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35
Q

which organelle fuses with a phagosome in phagocytosis?

A

lysosome

36
Q

what do lysosomes release into phagosomes?

A

digestive enzymes, e.g. Protease and lysozyme

37
Q

what happens to a micro organism after a phagocyte engulfs it?

A

it is engulfed into a phagosome, where there are lysosomes containing digestive enzymes will fuse with it, this digests the micro organism, which is then released from the phagocyte by exocytosis.

38
Q

What does a phagocyte do after at expels the remains of the micro organism?

A

presents it’s antigens on the surface of its membrane

39
Q

Why do phagocytes become antigen presenting cells?

A

to act as a signal to activate other cells in the immune system.

40
Q

what are self-antigens?

A

Self-antigens are part of the cell surface membrane of our body cells.

41
Q

What is specific immune response?

A

immune response where it specifies for particular antigens
Responses less rapid than non-specific
Response varies in magnitude
Memory of antigen provides long-lasting community

42
Q

What are the two kinds of specific immune response?

A

Cell mediated and humoral immune response

43
Q

What are lymphocytes?

A

A type of white blood cell.

44
Q

What are the two types of lymphocytes?

A

T lymphocytes and B lymphocytes

45
Q

what is cell mediated immune response?

A

This describes the response of T cells against the bodies own cells that have been invaded by pathogens (antigen presenting cells).

46
Q

What are some examples of antigen presenting cells?

A

Phagocytes, transplanted cells, cancer cells.

47
Q

What are T lymphocytes?

A

A type of white blood cell made in the bone marrow, but matured in the thymus. They have receptors on the surface capable of finding to specific antigens.

48
Q

What is clonal selection and expansion?

A

The selection of the complimentary receptor to an antigen, and then the cloning of that

49
Q

what are two kinds of T cells?

A

Helper, T cells and cytotoxic T cells

50
Q

What does the helper T cell do?

A

helper T cells, assist other white blood cells in the immune response. Release cytokines, which stimulate B lymphocytes to make antibodies.

51
Q

What are cytotoxic T cells?

A

cytotoxic T cells, destroy virus-infected cells and tumour cells. They release a chemical called perforin, which makes holes in the cell surface membrane. The cells become freely permeable to all substances and die. They also secret chemicals that attract and stimulate phagocytes.

52
Q

What is the process of cell mediated immune response?

A

T cells receptors bind to the presented antigens, and are activated.
the activated T cells divide rapidly by mitosis to form a clone
The cells differentiate into either helper or cytotoxic T cells.

53
Q

Where are B lymphocytes located?

A

freely circulating in the body fluid

54
Q

Why are B lymphocytes different T lymphocytes?

A

They not only are made in the bone marrow, but mature there

55
Q

What is the process of humoral immune response?

A

b-cell, with Ab complimentary to pathogen will bind to it and take it in by endocytosis.
It becomes an APC
The activated T-helper cells with receptor complimentary to antigen will bind to antigens presented by the cell
T-helper cell releases cytokines that stimulate B-cell to divide by mitosis
(Clonal selection and expansion)
B-cell clones will be either plasma or memory B cells
Plasma B cells release antibodies which agglutinate pathogens
Memory B cells stay in the blood and divide rapidly upon reinfection.

56
Q

what do plasma B cells do?

A

Secrete large amounts of Ab, complimentary to antigen.

57
Q

What are antibodies made from?

A

Proteins (therefore they have a specific tertiary structure), they are made of four polypeptide chains. Therefore, they also have a quaternary structure.

58
Q

Which part of the antigen to the antibodies attach to?

A

Antigen binding site

59
Q

what forms when an antigen binding site on an antibody binds with an antigen?

A

Antigen antibody complex

60
Q

What are the two kind of polypeptide chains in an antibody?

A

light chains, these are the two short polypeptide chains
Heavy chains, these are the two long polypeptide chains

61
Q

what is the shape of an antibody?

A

Y shape?

62
Q

What is the variable region of an antibody?

A

The amino acid sequence and therefore tertiary structure of this region differ from one Ab to next. It contains the antigen binding sites.

63
Q

what is the constant region of an antibody?

A

The amino acid sequence and tertiary structure of this region is the same in every Ab

64
Q

What is the misconception about Ab structure?

A

but the antigen binding site is in side the Y however, it is on the two tips of it

65
Q

What can antibodies do?

A

They agglutinate (clump) pathogen is by finding to the antigen is making it easier for the phagocytes to locate any golf them.
They also serve as markers that stimulate phagocytes to engulf the bacterial cells which they are attached.
They also neutralise toxins

66
Q

What are monoclonal antibodies?

A

antibodies produced from clones of a single plasma cell.

67
Q

How do pregnancy tests work?

A

in the reaction zone, HCG binds with three antibodies specific for HCG. Ab contains enzymes participates in colour reaction in other two zones.
In a test zone immobilised anti-HCG antibodies bind with the HCG.
Enzyme-linked antibodies catalyse a colour reaction with die molecules.
Control zone, colour change in zone indicates that test strip is working as immobilised antibodies are complimentary with the free antibodies.

68
Q

give an example of how monoclonal antibodies can help with cancer treatment?

A

some cancer cells have receptor proteins that bind to the hormone, growth factor. Monoclonal antibodies can be used to bind to the Receptor preventing growth factor from binding, this means the cancer cell can no longer divide.

69
Q

What are ELISA tests?

A

they are blood tests that can be used to either test for the presence of an antigen in the body (direct Elisa) or can be used to see if a patient has antibodies to an antigen (indirect Elisa).

70
Q

what are direct Elisa tests?

A

Testing for antigens in the blood. Uses a single antibody determines if an individual is infected with a particular pathogen.

71
Q

what is the process for a direct Elisa?

A

Take a sample of patient’s blood and fix the antigen to a well plate.
add antibodies specific to the antigen with an enzyme attached.
Wash plates to remove unbound antibodies.
Add substrate
The substrate will change colour if the antibody with enzyme is bound to antigen

72
Q

what would be the positive and negative result of a direct ELISA test?

A

A positive result would be a colour change from colourless to blue.
A negative result would be no colour change.

73
Q

what is an indirect ELISA test?

A

Testing for antibodies in the blood. Uses two or more different antibodies under determines if an individual has an immune response to a particular pathogen.

74
Q

what is the process of an indirect ELISA test?

A

antigen from pathogen is fixed to the wall plate.
Add patient’s blood sample. If the patient has immunity antibodies will bind.
Wash the plate to remove any unbound Ab
Add a secondary antibody specific to the human antibodies with enzyme attached. If primary antibodies present, it will bind.
Wash plate and add colourless substrate.
The substrate will change colour if the secondary Ab with enzyme is bound.

75
Q

What is primary immune response?

A

Describes the way our body response to an antigen the first occasion it’s encountered.

76
Q

What are the features of primary immune response?

A

antibody level rises to combat infection, however, it is short lived. There is a lag phase before antibodies increase for clonal selection and expansion. Antibody levels decline afterwards.

77
Q

What is secondary immune response?

A

The bodies reaction at second infection

78
Q

What are the features of secondary immune response?

A

ab concentration rises much more due to an immediate activation of memory cells. These memory cells are cloned, many times meaning there are lots of plasma cells and large quantities of Ab.

79
Q

When does the body develop immunity?

A

After first infection

80
Q

What is active immunity?

A

exposure to non-self-antigens. Such as the Covid vaccine, exposure to flu.

81
Q

What is passive immunity?

A

introducing antibodies from an outside source, such as passing from mother to fetus through the placenta or antivenom antibodies given to treat snakebites

82
Q

what are the differences between active and passive immunity?

A

Memory cells are formed with active immunity, however, are not with passive
Direct contact with pathogen is necessary with active immunity, but not with passive
Immunity is not long-lasting with passive but is with active.
immunity is immediate with passive but takes time to develop with active.

83
Q

What is a vaccination made up of?

A

Dead pathogens as long as the antigen remains intact
Weakened, pathogens as long as antigens are intact, but cannot produce toxins
Antigens, if pathogen is too risky

84
Q

What does vaccination stimulate?

A

Primary immune response

85
Q

What is a vaccination?

A

An introduction (via injection consumption or nasal) of disease, antigens in small amounts.

86
Q

what does HIV do?

A

HIV infect T-helper cells, preventing humoral response. HIV can cause acquired immune deficiency syndrome (aids)

87
Q

What does AIDS do?

A

it becomes more susceptible to other infections and cancers. It is the secondary disease is that cause ill health, and maybe death.

A-Level Biology Paper 1 (8 decks)

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