Cell Transport and Immunity (SR)

Question 1

What can Cell Membranes act as?

Answer 1

Act as Barriers

Can Control what enters and exits cells and organelles

Question 2

What is the Cell Membrane composed of?

Answer 2

Phospholipids
Proteins
Glycoproteins
Glycolipids
Cholesterol

Question 3

What properties does Cholesterol have? What purpose does this have?

Answer 3

1) A Hydrophilic End and a Hydrophobic End
2) Regulates membrane fluidity
By intercalating b/w the Phospholipids

Question 4

What does Passive Transport involve?

Answer 4

Exchange of substances without requiring metabolic energy from the cell

Question 5

What is Diffusion?

Answer 5

Net movement of particles from an area of high conc. to an area of low conc. (down conc. gradient)

Question 6

What is Facilitated Diffusion?

Answer 6

1) Net movement of particles down conc. gradient
2) Across Partially permeable cell membrane
3) Via Carrier or Channel Proteins

Question 7

What is Water Potential?

Answer 7

Measure of tendency of water molecules to move from one area to another and,
Describes pressure created by these water molecules
More dilute the solution, the higher the water potential (ψ)

Question 8

What is Osmosis?

Answer 8

1) Net movement of Water
2) From an are of High Water Potential to an area of Low Water Potential
3) Across Partially Permeable Membrane

Question 9

How can the rate of Diffusion be increased?

Answer 9

1) By increasing # of channel & carrier proteins
2) Increasing Surface Area of Cell Membrane
3) Reducing Diffusion Distance
4) Creating Steeper Conc. Gradient

Question 10

What is Active Transport?

Answer 10

Movement of particles from an area of low conc. to an area of high conc. (against conc. gradient)
Across a cell membrane, using ATP and carrier proteins

Question 11

What is Co-Transport?

Answer 11

Occurs when transport of one substance is linked to another substance across a membrane
e.g. Glucose and Sodium in the Ileum

Question 12

What are Antigens?

Answer 12

Any part of an organism/substance
Which is recognised as foreign by the Immune System &
Triggers an Immune Response

Question 13

What is the function of Phagocytes (Macrophages and Neutrophils)? (IS1/IS3)

Answer 13

Engulfs and digests pathogens by fusion of the phagosome with lysosomes
(Phagocytosis/Endocytosis)

Question 14

What is the function of T Cells (T-Helper Cells, Cytotoxic T Cells and T memory Cells)? (IS2/IS3)

Answer 14

1) T-helpers stimulate B cells to divide and secrete antibodies
2) Cytotoxic T cells kill abnormal and infected body cells via Perforin
3) T memory cells remain in the blood for yrs and provide long term protection

Question 15

What is the function of B Cells (Plasma cell and B Memory Cell)? (IS3/IS3)

Answer 15

1) Plasma Cells secrete Antibodies

2) B memory cells remain in blood for yrs and provide long term protection

Question 16

What are Antibodies?

Answer 16

Proteins produced by Lymphocytes

In Response to presence of corresponding antigen

Question 17

How do Antibodies Agglutinate/cause Agglutination?

Answer 17

Antibodies Agglutinate pathogens
By forming antigen-antibody complexes
Leading to phagocytosis and neutralise toxins

Question 18

What is Cell-Mediated Immunity?

Answer 18

1) Antigen from pathogen displayed on cell surface of body cells or phagocytes after phagocytosis
2) T Cells with correct specific receptor binds with antigen and activated
3) T Cells divide by mitosis (Clonal Expansion) and differentiate into T Helper, Cytotoxic and memory cells

Question 19

What is Humoral Immunity best at fighting?

Answer 19

Best at fighting pathogens which are free in bodily fluids

Question 20

What happens in Humoral Immunity?

Answer 20

1) Free antigen binds to complementary B cell receptor, activating the B cell (Clonal Selection)
2) Pathogen is endocytose, and antigen presented on plasma membrane
3) T Helper Cell binds to presented antigen and stimulates B Cell to divide by Mitosis (Clonal Expansion)
4) B Cell differentiates into Plasma and Memory Cells

Question 21

What is the Primary Immune Response?

Answer 21

When a pathogen infects the body for the 1st time

Initial Immune Response is slow

Question 22

What is the Secondary Immune Response?

Answer 22

More rapid and vigorous caused by a second or subsequent infection by same pathogens
Due to presence of Memory Cells

Question 23

What is Vaccination?

Answer 23

The Introduction into the body of a vaccine containing disease antigens, by injection or mouth, in order to induce Artificial Immunity

Question 24

How do Vaccines Work?

Answer 24

Work by Injecting Weakened/Dead pathogens into body
To stimulate an Immune Response, to form memory cells against specific antigen, which destroy pathogen quickly upon infection

Question 25

What is Herd Immunity?

Answer 25

When a significant proportion of a population (approx. 93-95%) is vaccinated Protecting those who aren't or cannot be vaccinated, e.g. Cancer Patients

Question 26

What is a problem with Immunisations/Vaccines?

Answer 26

Pathogen may mutate so that its antigens change suddenly (Antigenic Variability) Vaccine is now ineffective to the new Antigens

Question 27

What are the Ethical Considerations of Vaccinations?

Answer 27

``` Side Effects Financial Cost Right to Choose Animal Testing of Vaccines Human Trials ```

Question 28

What is Active Immunity?

Answer 28

Immunity that occurs when specific antibodies are produced by the Individual's own Immune System

Question 29

What is Passive Immunity?

Answer 29

Immunity that occurs when specific antibodies are introduced to the individual from an outside source

Question 30

Name an Example of Natural Active Immunity (Im1/Im4)

Answer 30

Direct Contact with Pathogen

Question 31

Name an Example of Natural Passive Immunity (Im2/Im4)

Answer 31

Antibodies through Breastmilk

Question 32

Name an Example of Artificial Active Immunity (Im3/Im4)

Answer 32

Vaccination

Question 33

Name an Example of Artificial Passive Immunity (Im4/Im4)

Answer 33

Injection of Antibodies

Question 34

What does HIV stand for?

Answer 34

Human Immunodeficiency Virus | A Retrovirus

Question 35

Where does HIV Replicate?

Answer 35

Replicates in T Helper Cells

Question 36

How does HIV Replicate?

Answer 36

1) Viral Glycoprotein binds to CD4 receptor on T helper cell 2) Protein Capsid containing Viral RNA and Reverse Transcriptase enters cell 3) Reverse Transcriptase converts Viral RNA into DNA and this joins host cells DNA in Nucleus using DNA/Retroviral Integrase 4) Host Cell Transcribes DNA and Produces more HIV RNA that move into the Cytoplasm and take part of Plasma Membrane for Lipid Envelope

Question 37

What are Physical Barriers to Infection?

Answer 37

1) Skin - tough physical barrier made of Keritin 2) Stomach Acid (Hydrochloric Acid) - kills bacteria 3) Gut and Skin Flora - Natural bacteria flora that competes with invading pathogens for food and space

Question 38

What are Non-Specific Immune Responses?

Answer 38

1) Inflammation 2) Lysozyme Action 3) Interferon 4) Phagocytosis

Question 39

How does Inflammation act as a Non-Specific Immune Response?

Answer 39

Histamines released by damaged white tissues Cause Vasodilation increasing blood flow to infected area Also increases permeability of blood vessels As a result, antibodies, WBCs and Plasma leak out into infected tissue and destroy pathogen

Question 40

How does Lysozyme Action act as a Non-Specific Immune Response?

Answer 40

Lysozyme are enzymes found in secretions such as tears and mucus Which kill bacterial cells by damaging their cell wall

Question 41

How do Interferons act as a Non-Specific Immune Response?

Answer 41

Interferons prevent Viruses spreading to uninfected cells | By stopping Protein Synthesis in Viruses

Question 42

How does Phagocytosis act as a Non-Specific Immune Response?

Answer 42

White Blood Cells (WBCs) engulf pathogens Destroying them Done by fusing to a pathogen and enclosing around them In a phagocytic vacuole with a Lysosome

Question 43

What can Monoclonal Antibodies be used for?

Answer 43

1) To attach drugs in order to ensure delivery to specific type of cell, e.g. Cytotoxic Drug (Chemo/Immuno) to a cancer cell 2) Disease Diagnosis can be tested for the presence of specific pathogen antibodies in the blood 3) Can be used for Pregnancy Testing 4) ELISA Test

Question 44

How does ELISA (Enzyme Linked Immunosorbent Assay) test for HIV using Monoclonal Antibodies?

Answer 44

1) Monoclonal Antibodies bound to surface of a well 2) Attach to antigen present in a sample 3) Allowing attachment of a detection Antibody 4) An enzyme attached to detection antibody digests a substrate, which is added, causing a colour change 5) Colour Intensity corresponds with amount of Antigen present in the sample

Question 45

What are the Ethical Considerations/Implications of Monoclonal Antibodies?

Answer 45

Treatment may cause Death (risky) Use of Animals for Production may cause harm Human Trials