Cells and the Immune System

Question 1

definitions of
1-antigen
2-pathogen
3-abnormal body cells
4-toxins

Answer 1

1- molecules ( usually proteins)that can generate an immune response
2-organsims that cause disease. (bacteria, virus, fungi) they all have antigens that is identified as foreign and the immune system cells respond to kill.
3-cancerous or pathogen infected cells have abnormal antigens on their surface which triggers an immune response
4- poisons molecules that are antigens

Question 2

what are the 4 stages of an immune response

Answer 2

phagocytosis
t-cells
b-cells
antibody production

Question 3

explain the steps of phagocytosis

Answer 3

phagocyte recognises the foreign antigens , cytoplasm moves to engulf the foreign antigen
the pathogen is then contained in a phagocytic vacuole, a lysosome then fuses with the phagocytic vacuole and breaks down the pathogen, the phagocyte present the pathogens antigens on its surface membrane to activate other immune system cells - this phagocyte acts as an antigen presenting cell

Question 4

what is a T-Cell

Answer 4

T-lymphocyte (white blood cell) that has receptor proteins on its surface that bind to complementary antigens presented to it by phagocytes , which then activates the T-cell

Question 5

what are the different types of T-cells and what do they do

Answer 5

helper T-cells: which release chemical signals that activates and stimulates the phagocytes and cytotoxic T-cells also stimulates B-cells
cytotoxic cells : which kills abnormal and foreign cells

Question 6

what a phagocyte

Answer 6

a type of white blood cells phagocytosis , found in blood and tissues and are the first cells to respond to an immune trigger

Question 7

What is a B-Cell

Answer 7

B-lymphocytes are a type of white blood cell that secretes/covered in antibodies

Question 8

in B-cells when proteins bind to the antigens what is formed

Answer 8

antigen-antibody complex-m each b cell has a different shaped antibody so different ones bind do different shaped antigens

Question 9

describe clonal selection

Answer 9

when an antibody on the surface of a b-cell meets it complementary shaped antigen and binds to it , then together the substance released from the helper T-cells activates the B cells.

Question 10

what are the B-cells that are activated through clonal selection called and function

Answer 10

plasma cells- secrete antibodies

Question 11

what is it called when pathogens become clumped together

Answer 11

agglutination

Question 12

2 types of immune responses and what they mean

Answer 12

Cellular - T-cells and other immune system cells that interacts with phagocytes from the cellular response
Humoral - B-cell, clonal selection and the production of monoclonal antibodies from the humoral response

Question 13

what is active immunity

Answer 13

immune system makes its own antibodies after being stimulated by a pathogen

Question 14

2 types of active immunity and what they mean

Answer 14

Natural- become immune AFTER catching the disease
Artificial- become immune after getting a VACCINATION containing a harmless dose of an antigen

Question 15

what is passive immunity

Answer 15

get from being given antibodies made by a different organism
IMMUNE SYSTEM DOES NOT PRODUCE ITS OWN ANTIBODIES
memory cells are NOT produced and its short-term

Question 16

what are the 2 types of passive immunity and what do they mean

Answer 16

Natural- when a baby becomes immune because of the antibodies it receives from its mother, placenta or breast mild
Artificial- become immune from being Injected with antibodies from someone else. ex; blood transfusions

Question 17

what is herd immunity

Answer 17

when many people are vaccinated so it protects/reduces the amount of non vaccinated people that get infected

Question 18

what do vaccines always contain

Answer 18

antigens

Question 19

what is antigenic variation

Answer 19

when pathogens change their surface antigens

Question 20

what is
Direct ELSA
Indirect ELSA

Answer 20

1- uses a SINGLE antibody that its complementary to the antigen its testing for and using an enzyme/substrate to produce a colour change to indicate a POSITIVE test
2- uses 2 different antibodies

Question 21

steps for testing for HIV

Answer 21

indirect ELSA
1. HIV antigen bound to the bottom of a well
2-plasma is added
3- antibody specific to HIV antigen binds
4- secondary antibody is added
5-bind with attachment enzyme
6-substrate is added , positive -colour change

Question 22

Explain what are viruses

Answer 22

they are not living things, they can only reproduce inside the cells of another organism

Question 23

Explain what is HIV

Answer 23

Human Immunodeficiency virus that affects the human immune system

Question 24

What can HIV eventually lead to ?

Answer 24

acquired immune deficiency syndrome (AIDS)

Question 25

what is AIDS

Answer 25

a condition where the immune system deteriorates and eventually fails. which makes someone with AIDS more vulnerable to other infections

Question 26

How does HIV invade cells

Answer 26

1- HIV infects and kills the T-helper cells , which acts as the host cell for the virus

Question 27

what is the affect of the HIV infecting T-helper cells
(2 parts)

Answer 27

the immune system is unable to produce an effective response to infections because other immune system cells don’t behave as they should

Therefore people with HIV develops AIDS when the T-helper cells reach a critically low level

Question 28

describe the initial infection period

Answer 28

during the initial infection period HIV replicates rapidly and the person may experience flu-like symptoms

Question 29

what is the latency period for HIV

Answer 29

when HIV replication drops to a low level, this period can last for years and the infected host won’t experience any symptoms

Question 30

what are they symptoms/stages of AIDS
( 3 steps/stages)

Answer 30

initial symptoms - minor infections of the mucus membranes (nose, genitals, ears) and recuring respiratory infections

as AIDS progresses the number of immune system cells decreases further, which makes patients more susceptible to more serious infections ( chronic diarrhea, bacterial infections, TB)

During the last stages patients have a low level of immune system cells and can develop a range of serious infections (parasite infection of the brain and fungal infection of the lungs) which can KILL AIDS patients NOT HIV itself

Question 31

what are the 4 main factors that can be accounted for with the survival of AIDS

Answer 31

1- existing infections
2- strain of HIV
3-age
4-access to healthcare

Question 32

describe HIV structure

Answer 32

has a spherical structure with RNA and reverse transcriptase included in its core genetic material
it has an outer coating made up of proteins called a capsid,
an outer layer called an envelope with attachment proteins which allow the HIV to attach to host the T-helper cells

Question 33

how does HIV evade destruction by the immune system

Answer 33

HIV attachment proteins are foreign antigens that can be recognized by the immune system. during replication the virus can change parts of the structure of its attachment proteins which is antigenic variation

Question 34

what does HIV replicate in and why ?

Answer 34

HIV replicates in the T-helper cells of the host
this is because HIV lacks the required organelles such as ribosomes an d enzymes to replicate in its own

Question 35

what is the 6 steps for HIV replication

Answer 35

1- attachment proteins attaches to the receptor molecule of the cell membrane of the T-helper cell for the host.
2- The capsid is released into the cell where it uncoats and releases the genetic material (RNA) into the cell cytoplasm
3-Reverse transcriptase is used to make a complementary strand of DNA from the viral RNA template
4- the double strand stranded DNA is then inserted into human DNA
5-Host cell enzymes are used to make viral proteins from the viral DNA that was founded in the human DNA
6- the viral proteins are assembled into new viruses which then emerge from the cell to go on and infect other cells

Question 36

what happens when HIV particles emerge from the cell

Answer 36

the cell ruptures and dies

Question 37

how does antibiotics kill bacteria

Answer 37

it interferes with the metabolic reactions by targeting the bacterial enzymes used in these reactions

Question 38

why don’t antibiotics kill viruses

Answer 38

Because viruses use human enzymes and ribosomes to replicate an antibiotics don’t target human ribosomes and enzyme’s

Question 39

What do antiviral drugs target

Answer 39

They are designed to target the few virus specific enzymes that exist ( only enzymes the viruses use)