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Biology KS5 Booklet - Recall Questions > Cell Immunity And Recognition > Flashcards

Cell Immunity And Recognition Flashcards

(58 cards)

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1
Q

What is a capsid

A

Protein coat around the core

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2
Q

What are the attachment proteins on a virus

A

Attachment proteins stick out from the edge of the capsid of envelope, let the virus cling on to a suitable host cell

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3
Q

What is the envelope on a virus?

A

Extra outer layer stolen from the cell membrane of a previous host cell

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4
Q

Describe the basic structure of a virus

A

A strand of nucleic acid (DNA or RNA) enclosed within a protein coat

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5
Q

What is an antigen

A

A molecule (usually protein) which triggers an immune response.

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6
Q

How does the human body distinguish between self & non-self cells?

A

Marker molecules (proteins) are present on the membrane of cells, enabling the body to recognise these as ‘self’ cells.

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7
Q

How does the body prevent attack by own immune system?

A

some of the membrane proteins on the surface of our cells mark the body cell as ‘self’. they allow us to distinguish between our cells and invaders

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8
Q

Why must patients who receive organ donations, take anti-rejection medicines?

A

The organ has non-self antigens- which will trigger an immune response. The anti-rejection medicines prevent this response.

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9
Q

Briefly, what is phagocytosis?

A

When foreign cells are engulfed by phagocytes, digested by lysozymes released by lysosomes in the cell.

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10
Q

How does a phagocyte use chemotaxis?

A

Phagocytes are attracted to pathogens by chemicals released by the pathogen( phagocytes move down conc.gradient)

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11
Q

Outline what phagocytosis is

A

Phagocyte recognises the antigens on a pathogen. endocytosis. pathogen is contained in a phagocytic vacuole. lysosomes, containing digestive enzymes fuse with the vacuole, enzymes are released and they destroy the pathogen. phagocyte presents antigen on its surface

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12
Q

What is lysozyme?

A
  • digestive enzymes which hydrolyses and kills bacteria by damaging their cells walls making them burst open.
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13
Q

What does the cellular immune response consist of?

A

T cells- phagocytes, cell signals etc.

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14
Q

Describe the role of T-helper cells.

A

Recruit & signal to phagocytes AND activate B cells

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15
Q

Describe the role of T-cytotoxic cells.

A

Kill abnormal & foreign cells (produces proteins to do this e.g. perforin)

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16
Q

What do the receptors on T cells do?

A

bind to antigens displayed by antigen presenting cells

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17
Q

How are T cells activated?

A

When their receptors bind to complementary antigens on the surface of antigen presenting cells.

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18
Q

What do T helper cells do?

A

Binds to an antigen-presenting B cell and produces cytokines that stimulate B cell to divide and become capable of producing antibodies. they also enhance the activity of phagocytes

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19
Q

What are B cells?

A

lymphocytes that secrete antibodies in response to antigens. antibodies bind to the antigens on the cell surface membrane to form an antigen antibody complex.
each b cell has a different shaped antibody which binds to only one specific antigen. they allow phagocytes to recognise and destroy the cell.

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20
Q

What is a B plasma cell?

A

A type of B cell which secrete LOTS of monoclonal antibodies (all complementary to a specific antigen)

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21
Q

What is B cell division also known as

A

Clonal selection

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22
Q

What is a memory cell?

A

Remain for years in the body, enabling an individual to respond more quickly to the same antigen in the future

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23
Q

What are B memory cells?

A

Record the specific antibodies needed to bind to the antigen. they remain or months or years in the body, enabling the individual to respond more quickly to the same antigen in the future

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24
Q

What does the humoral immune response consist of?

Study These Flashcards
A

B-cells, antibodies, clonal selection

25
Why is the primary response slow?
there aren't many B cells that can make the antibody needed to bind to the antigen
26
Explain why the secondary response is quicker than the primary immune response.
B- memory cells are activated and divide into plasma cells, producing antibodies. T-memory cells are activated and produce T-cells to kill the pathogen.
27
What is the primary immune response?
Immune response the first time the body is exposed to a particular foreign antigen. B cells take 10 to 17 days to produce sufficient antibody producing cells. the person is likely to suffer symptoms of the infection during this time
28
What is the secondary response?
if the same pathogen enters the body again the immune system will produce a quicker stronger immune response. the b memory cells produced in the primary response can differentiate immediately to produce plasma cells and release antibodies
29
What is an antibody?
Bind to antigens to form an antigen-antibody complex
30
Describe the structure of an antibody
Four polypeptide chains, 2 heavy and 2 light. each chain has a variable region and a constant region
31
State the variable region on the antibody and describe importance of this region.
- Form the antigen binding site. The shape is complementary to a particular antigen, its shape varies between antibodies - Has a unique protein structure, which provides specificity to one type of antigen.
32
What is the constant region
Allow binding to receptors on immune system cells. It is the same in all antibodies.
33
How do antibodies help clear up an infection?
Agglutinating pathogens, neutralising toxins, preventing the pathogen binding to human cells
34
What is active natural immunity
When a person is immune, after naturally contracting an infection.
35
What is passive immunity
When a person is immune, by being given antibodies rather than making them. e.g. natural from breastfeeding
36
Give 2 differences between passive & active immunity.
Active- lasts longer, memory cells are produced, response takes longer to happen, needs antigen to trigger response.
37
What is a vaccine
A low dose of an inactive/dead pathogen are injected- contain antigens to trigger immune response, creating protective memory cells.
38
What is herd immunity
If more members of a population have had a vaccine, more people are then protected as a disease can spread less rapidly, even if they haven't had the vaccine themselves.
39
What is natural active immunity
When your immune system makes its own antibodies after being stimulated by an antigen (after catching a disease)
40
What is passive natural immunity
When a baby receives antibodies from its mother through the placenta and in breast milk
41
What does active immunity give you
Long term protection but it develops after a time lag
42
What does passive immunity give you
Short term but immediate protection
43
How is HIV spread
Through infected bodily fluids. via sex, sharing needles, direct blood to blood transfer and maternal transmission from mother to unborn child
44
How does the HIV virus replicate?
- Attaches to receptor molecule on host cell membrane. - capsid is released into cell and it uncoats and releases nucleic acid. - reverse transcriptase is used to make a complementary strand of DNA from the viral RNA template. - double stranded DNA is made and inserted into the human DNA (using integrase). - host cell enzymes are used to make viral proteins from the viral DNA within the human DNA. the viral proteins are assembled into new viruses and releases from the cell via cell lysis
45
How does HIV invade T helper cells?
glycoprotein molecules on the virus surface bind to CD4 receptors on the surface of t helper cells this allows the envelope surrounding the virus to fuse with the T helper cell membrane, enabling the viral RNA to enter the cell
46
What are opportunistic infections?
Infections that occur when the body's defenses are weakened
47
What are the initial symptoms of AIDS?
Minor infections of mucosal membranes and recurring respiratory infections caused by a lower than normal number of T helper cells
48
When are people with HIV classed as having AIDS?
When symptoms of failing immune system start to appear or their T helper cell count drops below a certain level
49
What is AIDs?
When the immune system deteriorates and eventually falls
50
Which part of the immune system does HIV initially affect?
T-helper cells
51
Describe how HIV uses reverse transcriptase to replicate in host cells.
- HIV attaches to the host cell, releasing the capsid containing viral RNA. - Reverse transcriptase is then used to generate complementary DNA- inserted into human DNA and uses host enzymes to to create new proteins- new viruses which can affect more host cells.
52
Why should HIV testing not occur on a newborn baby?
Would give inaccurate results- need to wait 18 months before baby can be tested as HIV can pass from the mother into baby's bloodstream.
53
Explain why antibiotics cannot be used on HIV
Antibiotics are specific to bacteria e.g. murein cell walls, so would be ineffective on viral structure.
54
Give a short summary of how HIV weakens immune system
HIV invades T helper cells, preventing the activation of macrophages, B cells and T killer cells, which weakens the immune response
55
What are monoclonal antibodies
Antibodies which are all made from identical B plasma cells- complementary to the same specific antigen.
56
Describe how monoclonal antibodies can be used in anti-cancer drugs
Antibodies are specific to antigens on cancerous cells (tumour markers)- the drug binds& accumulates in specific area (much fewer side effects than conventional cancer treatments).
57
What is an ELISA test
Where antibodies are attached to an enzyme, which produces a coloured substrate- used in diagnosis.
58
What is the main difference between a direct & an indirect ELISA test.
Direct- one type of antibody applied to sample/antigen. Indirect- many antibodies present

Biology KS5 Booklet - Recall Questions (1 decks)

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