3.2.4.1 - Cell Recognition Flashcards Preview

SHHS - Science - NEW AQA A-Level Biology (Year 1) > 3.2.4.1 - Cell Recognition > Flashcards

Flashcards in 3.2.4.1 - Cell Recognition Deck (22)
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1
Q

Why is a fetus rarely infected by a pathogen?

A

It is protected from the outside world by the mother and the placenta.

2
Q

What is immunity?

A

When the body’s defences are able to kill a pathogen before it can cause harm.

3
Q

Does the body produce specific lymphocytes (white blood cells) in response to non self material?

A

No - there are 10 million different lymphocytes already in the body from birth.

Each one has the potential to bind to a specific antigen.

The lymphocyte with the complementary receptor (clonal selection) undergoes cell division to produce many of the desired lymphocyte.

4
Q

What is an antigen?

A

A protein on the surface of a cell membrane.

That (in the case of a foreign antigen) will trigger an immune response.

5
Q

Describe non-specific defences.

A

General action

Immediate

6
Q

Identify the 2 types of white blood cell.

A
  • T-lymphocytes (helpers (Th) or cytotoxic (Tc)
  • B-Lymphocytes
7
Q

How is the immune response controlled in organ transplant patients to prevent organ rejection?

A

Immunosupressant drugs

Organs donated by family members - for a close tissue match.

8
Q

Why is there a time lag between infection and an immune response?

A

Clonal selection takes time i.e. the correct lymphocyte binding to the non self antigen.

9
Q

Antigens that belong to the body have _____ antigens on their cell membrane.

A

SELF

10
Q

When can the immune system cause problems for medical patients?

A

People who have received organ transplants.

The transplanted organs have non self antigens.

The immune system will destroy the non self material.

11
Q

Foregn antigens are usually found on which 4 materials that can trigger an immune response?

A
  • Pathogens
  • Cells from other or the same species (organ transplants)
  • Toxins from pathogens
  • Cancer cells
12
Q

Why is a fetus not attacked by its own lymphocytes when in the uterus?

A

Any lymphocytes that contain ‘self receptors’ are supressed or die.

The only remaining lymphocytes are those that respond to non-self material.

13
Q

Describe specific defences

A

Less rapid

Long lasting

Highly specific

14
Q

Identify the non-specific defences against infection.

A
  • S.T.E.M.S (Skin, Tears, Earwax, Mucus, Stomach Acid)
  • Pagocytosis
15
Q

Antigens can be which biological molecules?

A

Proteins (glycoproteins)

Lipids (glycolipids)

16
Q

What is it about proteins that makes them useful as antigens?

A

Their specific 3D structure can form a variety of different ‘labels’.

17
Q

Sometimes lymphocytes develop in the bone marrow and have self receptors. Why do they not destroy the persons cells?

A

They are programmed to die before they mature.

18
Q

Antigens that do not belong to the body have _____ antigens on their cell membrane.

A

NON SELF

19
Q

What is a pathogen?

A

A microorganism that causes infectious disease.

20
Q

Who is susceptible to pathogen infection?

A

Very old/young

People with compromised immune systems (AIDs)

21
Q

What is meant by a SELF antigen?

A

A glycoprotein or glycolipid found on a cell surface membrane of a cell that belongs to the organism.

22
Q

What is meant by a NON-SELF antigen?

A

A glycoprotein or glycolipid found on a cell surface membrane of a cell that does not belong to the organism.

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