Chapter 10+11, Infectious Diseases And Immunity

Question 1

What is an infectious disease

Answer 1

Disease is an illness or disorder of the body or mind that leads to poor health,
And it is infectious
Because it is transmissible from infected to non infected person

Question 2

What is a non infectious disease

Answer 2

Disease not caused by pathogens,
Often because of malnutrition, inherited siroder or mental disease,
Most are to do with gas exchange system and cardiovascular system

Question 3

Name the pathogen that cause cholera and state what type this is

Answer 3

Vibrio cholerae, caused by a bacterium

Question 4

Explain the method of transmission of cholera

Answer 4

Spread through water and food,
Through an infected persons faeces,

When this contaminates water or then food grown by contaminated water
(So occurs because of a lack of sanitation)

Question 5

Explain how cholera is transmitted

Answer 5

Bacteria not killed by stomach acid, so reaches the small intestine,
-secrets a toxin called choleragen, which binds to receptors n the epithelial lining causing it to enter the cell through endocytosis,
-so the cells on the epithelial lining is destroyed, causing chloride and sodium ions to be released into the small intestine via osmosis
-so water potential of small intestine decreases so there is a mass loss of water (fluids and slat form the body) in the form of eg diarohea

Question 6

Explain how to prevent and control cholera

Answer 6

-lack of funds for proper sewage infrastructure in developing countries
-education abt how to treat and prevent cholera limited because difficult to reach remote and rural areas
-civil war and famine can increases outbreaks
-preventive controls not implemented by government, (eg provision of drainage systems)
-antibiotic resistance can occur

(Cost, education, humanitarian, prevention, resistance)

Question 7

State the the pathogens that cause malaria and then state what type of pathogen this is.
Then state the extra part that takes part in malaria

Answer 7

4 species of plasmodium.
-plasmodium falciparium(most common)
-plasmodium malarie
-plasmodium ovale
-plasmodium vivax

Plasmodium is a protoctist.

And the female anopheles mosquito is what acts as a vector, (which is an organism that carries a disease form one person to the other)

Question 8

Explain the methods of transmission of malaria

Answer 8

-through the VECTOR female anopheles mosquito,
-takes a blood meal inorder to obtain the protein needed for their eggs
-but if infected person is infected with PLASMODUIUM, mosquitos takes some of this pathogen w blood meal
-so when the mosquito feeds on the next human they transfer the pathogen form an INFECTED PERSON T AN UNINFECTED PERSON.

-through blood transfusion when unsterile needles are used

-via the placenta from mother to child

Question 9

Explain the mechanism behind how malaria occurs

Answer 9

-plasmodium gametes fuse inside the mosquitos stomach
-they then rapidly reproduce and then the infective stages of the parasite invade the salivary glands o the mosquito
-when mosquito takes a blood meal inroder to obtain protein for it’s eggs, plasmodium enters uninfected persons blood stream and then enters liver cell
-then enters red blood cells and multiplies, causing it to lyse
-then infectes the blood cells and is then picked up by another Mosquito in a blood meal

Question 10

Give methods to treat and prevent malaria

Answer 10

-use preventive dugs,
(Eg drugs that inhibit sexual reproduction of plasmodium gametes or that inhibit protein synthesis to prevent parasite from spreading throughout the body)

-drain marshes or uneccrarsy bodys of water
-spread oil over water bodies
-use fish that feed on mosquito larvae

-sleep under bed nets soaked in insecticide
-use soit-il replant
-avoid going out at dusk when mosquitos are most active

Question 11

Exclaim causes of increased spread of malaria:

Answer 11

(Cost, education, humanitarian, climate, prevention, resistance)

-education difficult, despite to reach remote areas
-warm climates can increases life span of anopheles and rainfall can also increase this
-preventive contours not implemented by governments
-use of drugs can result in drug resistant strains of malria

Question 12

State the pathogens that cause tuberculous and state what type of pathogen these are

Answer 12

Mycobacterium tuberculousis
Mycobacterium Bovis

A bacterium

Question 13

Explain how the diff types of tuberculosis are transmitted

Answer 13

Mycobacterium,

-infected person sneezes,
So bacterium enters tiny droplets of liquid
And so transmitted when uninfected person inhales these droplets

Bovis;

-spreads in un contaminated meat and unpasteurized milk

Question 14

Explain how TB infects the body

Answer 14

-primary infection site is the lungs, and then secondary infection site are the lymph nodes bones and gut

-but most of the time the infection is slow bc the incubation period is slow, and person can be symptomless,

-but can be activated again after many years if immune system is weakened eg by HIV

Question 15

Explain preventive measures for tuberculosis

Answer 15

-for mycobacterium,

-can perform contact tracing
-can isolate patients in ingecftive stages
Can use the BCG vaccine

-For Bovis,

-ensure meat is properly cooked
Pasteurize milk
Regularly test cattle for TB

Question 16

State the pathogen and type of pathogen that causes HIV

Answer 16

HIV, human immunodeficiency virus

A virus.

Which is a retrovirus, because it converts rna to dna using the enzyme reverse transcriptase.

Question 17

Explain how HIV affects the human body

Answer 17

-viral rna form the hiv and the enzyme reverse transcriptase enter t helper lymphocytes(or cells of immune system).
-reverse transcriptase converts the viral rna into dna
-this dna is the converted in the host dna, and this begins to then express viral proteins.
-viral proteins can then be assembled into other virus particles

Question 18

Explain how HIV can lead to aids

Answer 18

Bc hiv is a slow infection hat can remain dormant in body for years and can remain symptomless

But this weakens immune system

So other opportunistic infections such as AIDS can occur bc of this compromised immune system.

Question 19

State the ways in which HIV can be transmitted

Answer 19

Through the exchange of body fluids.

-sexual intercourse
-blood transfusion so through unsterile needles
-from mother to baby, so across the placenta

Question 20

Explain the ways in which HIV can be prevented

Answer 20

By using eg condoms, to create pshycial barrier between fluids and body

By screening blood donations for the virus

HIV mothers treated with drugs eg in combination therapy(that inhibit reverse transcriptase,)or by advising ot not breast feed

Question 21

What type of immune response are phagocytes involved in, and then what kind are lymphocytes involved in

Answer 21

-non specific immune response,
So responds to MANY DIFFERENT non self antigens,
And is a defense that you are born with

-
But lymphocytes, specific immune response
Responds to only CERTAIN non self antigens
And is learned by the body due to previous exposure to pathogens

Question 22

Explain the difference betwwwn neutrophils and macrophages

Answer 22

Neutrophils have a multilobed nucleus, macrophages have a lobed nucleus
Neutrophils are much smaller than macrophages
Neutrophils are short lived(so die after infecting pathogens),but MACROPHAGES are long lived

Both have receptor protiens on their membrane
Both produced in the bonde marrow,
(Once prudced howver, neutrophils patrol the body tissues, but macrophages remain in the blood stream as monocytes and once matured leave the blood and enter other organs)

Question 23

Explain the process of phagocytosis

Answer 23

1)chemicals are released by pathogens which attract neutrophils to the site where pathogens are located, this is called chemotaxis
2)antibodies bind to receptor protiens on neutrophil surface. Antibodies then trigger neutrophils to attack the pathogen
3)receptor binding points on neutrophil then bind to antigens on the pathogen
4)cell surface membrane of neutrophil extends around the pathogen and engulfs it, and traps into a phagocytic vacuole
5)lysosomes are released which fuse with the vacuole to form a phagolysosome.
Lysosomes release digestive enzymes which hydrolyse the pathogen and destroy it
6)soluble products are absorbed and used but then neutrophil dies and so pus is a sign of dead neutrophils.

Question 24

Explain the mode of action of a macrophage

Answer 24

1)chemicals are released by pathogens which attract neutrophils to the site where pathogens are located, this is called chemotaxis
2)antibodies bind to receptor protiens on neutrophil surface. Antibodies then trigger neutrophils to attack the pathogen
3)receptor binding points on neutrophil then bind to antigens on the pathogen
4)cell surface membrane of neutrophil extends around the pathogen and engulfs it, and traps into a phagocytic vacuole
5)lysosomes are released which fuse with the vacuole to form a phagolysosome.
Lysosomes release digestive enzymes which hydrolyse the pathogen and cut it up into its antigens
6)antigens are displayed din the surface of the athogen to form an antigen presenting cell which can then be recognized by lymphocytes

Question 25

Where are immature b lymphocytes found and where are mature b lymphocytes found.
And then where are immature t lymphocytes found and where are mature t lymphocytes found

Answer 25

Immature, in the bone marrow
Mature, in the lymph nodes and the spleen

Immature in boned marrow
Mature in the thymus

Question 26

Explain how b lymphocytes respond to pathogens

Answer 26

Respond to pathogens directly
-only specific b lymphocytes with receptors complimentary to the shape of the antigen are activated to divide by mitosis (clonal selection)
-repeatedly divide by mitosis until large numbers are formed. (Clonal expansion)
-either form plasma cells which produce antibodies, which are either directly secreted into the blood and bind to pathogens, or then are inserted into the plasma membrane of the B cell, serving as receptors for antigens
-or then form memory cells, which can form plasma cells and thus antibodies. Memory cells also enable a faster response during secondary immune response

Question 27

Time difference between plasma cells and memory cells

Answer 27

Plasma cells are shirt lived, (although the antibodies still remain)
Memory cells are long lasting and remain in blood

Question 28

What are two ways in which plasma cells secrete antibodies

Answer 28

-secrete antibodies directly into the blood stream which can bind to antigens on the pathogen
-secrete antibodies which then form part of the plasma cell membrane of the b lymphocyte, to act as glycoprotein receptors for antigens

Question 29

Difference between B cells and plasma cells in terms of mitosis and producing antibodies

Answer 29

B cells can divide by mitosis but can not produce antibodies
Plasma cells can not divide by mitosis but can produce antibodies

Question 30

Explain how t lymphocytes respond to pathogens

Answer 30

-Pathogen invades and an antigen presenting cell is formed.
-only specific t lymphocytes with receptors complimentary to the shape of the antigen will be activated (clonal selection)
-and so will divide repeatedly by mitosis until large numbers of t lymphocytes are produced. (Clona expansion)
-then can either form t helper cells or t killer cells

-t helper cells can either,
=stimulate specific b lymphocyte cells to divide and so produce plasma cells which secret antibodies
(By releasing cytokines)
=stimulate macrophages to increase rates of phagocytosis(by releasing cytokines)
=stimulate t killer cells to divide and produce more toxins

T killer cells;
=attach to antigens and eiether secret toxins or then punch holes into he cell in order to destroy cell body and the pathogen inside it

Question 31

Explain the 2 types of cells that t lymphocytes can form and their functions

Answer 31

T helper cells, 3 types;
-release cytokines (hormone like signals) which can stimulate b lymphocytes to divide and so produce more plasma cells so produce more antibodies
-release cytokines(hormone like signals) to stimulate macrchopages to divide to increase rates of phagocytosis
-stimulate t killer cells to produce toxins or punch holes inside a cell in order to destroy cell body and pathogen inside it

T killer cells
-attach to antigens on infected cells and thr either
Secret toxins or punch holes into the cell
Inorder to dteosry host cell and so therfore the pathogen inside it.

Question 32

What is another word for an antibody and what can they be described as

Answer 32

Immunoglobulin.

Glycoproteins

Question 33

Describe the strutcure of an antibody

Answer 33

Quaternary structure
-2 heavy polypeptide chains
-2 light polypeptide chains
-each chain has a variable region and a constant region

-Hinge regions are located on heavy polypeptide chains which are where disulfide bridges attach

Question 34

What is the antigen binding site on an antibody

Answer 34

Site on the variable region where the epitope of the antigen binds
-it is complimentary and specific to the antigen (so its shape depends on the primary structure)
-forms h bonds and ionic bonds with the antigen
-matches the epitope of the antigen

Question 35

Features of the constant region on an antibody

Answer 35

Constant region is the same within the class of an antobdy but varies between the classes

It is the part that either binds to receptors on phagocytes
Or then that attaches to the cell surface membrane of the B cell to act as a receptor

Question 36

What is the hinge region in an antibody

Answer 36

Region located on the heavy polypeptide chain where the disulfide bridges form.
-function is to give flexibility to the antigen binding site so that it can be placed at different angles when binding to antigens

(Region is not present within all classes of antibodies)

Question 37

Give 6 functions of antibodies

Answer 37

1)act as antitoxins, so bind to toxins produced by pathogens and so neutralize them to make them harmless
2)opsonization, so attach to bacteria so more easily identifiable by pathogens, and then receptors on phagocytes attach to the heavy polypeptides constant region, so phagocytosis can occur
3)agglutinization, cause pathogens to clump together to reduce their spread throughout the body and to make it easier for phagocytes to engulf them
4)block virus and toxins, form entering the host cell
5)punch holes in cell walls of pathogens to cause them to burst via osmosis
6)less active pathogens, so combine w flagella of bacteria, so that less active and easier for phagocytes to engulf

Question 38

Explain how monoclonal antibodies are produced

Answer 38

1)Inject antigens that stimulate the production of plasma cells, to produce antibodies against this antigen into a mouse.
2)isolate plasma cells from mouse spleen and fuse with immortal tumor cells, using a fusion or an electric current, to form a hybridoma cell
3)grow hydbiromda cels in a selective growth medium and screen for the production of the desired monoclonal antibodies
4)culture these hybrid cells to produce large numbers of monoclonal antibodies

Question 39

Give 2 features of monoclonal antibodies

Answer 39

-bind to antigens, the same way that normal antibodies do
-generally only used once

Question 40

Explain how monoclonal antibodies can be used to locate the position of blood clots

Answer 40

-Inject mouse with fibrin, the protien found in blood clots, so that plasma cells can be produced which produce antibodies against this
-isolate plasma cells and then fuse with immortal tumour cells using fusogen or electric current to produce hybridoma cells
-attach a radioactive chemical to the hybdridoma cells so that antibodies produced are radioactively labelled
-attach a gamma ray camera to detect where the radioactively labelled antibodies are, inorder to locate where blood clots are

Question 41

Explain how monoclonal antibodies cna be used to test for HIV

Answer 41

-Antigens are attached o a test plate
-sample of blood is passed over the test plate and so hives antibodies in the blood will bind to the antigen
-hiv antibody and antigen form a combination which act as an antigen for a monoclonal antibody to attach to
-monoclonal antibody has an enzyme attached to it, so when chormagen dye is passed over it, the enzyme catalyses a colour change in thr dye substrate, where the darker the colour, the more hives and the lighter the colour, thr less hives present.

Question 42

Give two problems associated with monoclonal antibodies

Answer 42

-Monoclonal Antibodies can from laboratory animals so can be detected as non self antigens by the body and so can trigger an allergic reaction
-remain in the body for a short period of time only and so need to be continuously administered

Question 43

Give two solutions to tackle problems associated with monoclonal antibodies

Answer 43

-change the type and position of sugar groups attached to the heavy chains to be the same as those on human antibodies (rmeber monoclonal antibodies are glycoproteins)
-alter the genes in the laboroaty animals antibodies in the light and heavy chains, to code for the human antibodies instead.

So main problem is basicllay that they resemble animal antibodies.

Question 44

Explain how monoclonal antibodies can be used for pregnancy tests

Answer 44

-woman urinates on stick and urine contains the hormone HCG which is present if pregnant
-test stick contains mobile monoclonal antibodies which bind to the HCG to form an antibody complex
-monoclonal antobides move up the test strip and reach a window which contains immobilized monoclonal antibodies in a line, HCG antibody complex binds to this new line of antibodies (so the enzyme form the HCG complex binds to substrate on new complex, causing a colour change, if compared line appears means woman is pregnant
—then whether régnant or not, urine moves up to next window which contains a new line of immolized monolconal antibodies which bind ti the HCG antibody complex and a new colourless line appears, which acts as a control to show that the test is working.

Question 45

Where can antibiotics be derived from.
And cna they harm the cells of the infected organism?

Answer 45

For living organs or can be made say ethically in the lab.

No. They only kill or sto the growth of the bacteria

Question 46

explain how thr bacteria cell wall functions

Answer 46

Pencilllin is an antibiotic derived from fungi.

Cell wall of a bacteria cell si made up of peptiodyglycans, long molecules of peptides and sugars.

-peptidoogylcans are held together by cross links between them made by the enzyme peptidase.
-as the bacteria grow, they secrete autolysins which are enzymes that cause small holes in the bacteria cell wall causing it to stretch
-this creates space for more peptidoglycans to form.

Question 47

Explain where pencilin comes from, what it is and how it works

Answer 47

Penicillin is an antibiotic derived form fungi.

-it inhibits the enzyme peptidase in bacteria cell walls, which is responsible for creating cross links
-however autolyisns continue to make holes in the bacteria cell wall
-so bacteria cell wall becomes weaker and eventually unable to withstand turn or pressure
-so water moves in via osmosis and then the bacteria lyses and dies

Question 48

Explain why penicillin only works against bacteria that is still growing

Answer 48

-bc only growing bacteria still has cross links being formed.
In bacteria that is fully grown, cross links have already been formed, and autolysins no longer create holes

Question 49

Which parts of bacteria can antibitoics target

Answer 49

Cell walls,
DNA synthesis
Protein synthesis,

Question 50

Explain why antibiotics such as penicillin can not target viruses

Answer 50

-Bc they do not have cell walls
-bc they do not have cell structure or few organelles to act as sites for the antibiotic to act upon

Question 51

Explain how antibiotic resistance occurs

Answer 51

-first begins when individuals do not complete their course or when sued unnecessarily
-there is variation within a bacteria population due to mutation, where some mutation can cause resistance, (as there is a change to the nucleotide sequence which therfore codes for a different protein not affected by ther antibiotic)
-when treated w antibiotics, non resistance bacteria die but bacteria with resistant mutation do not die,
-resistant bacteria reproduce and so the genes for antibiotic resins the passed on to offspring through vertical transmission
-and vetrime ther entire bacteria population becomes antibiotic resistant

Question 52

Explain what vertical transmission is and what horizontal transmission is

Answer 52

Vertical,
When the chromosomes and the plasmid both replicate
-forming daughter genes wth identical copies

-this type can occur asexually, adn through one bacteria population

Horizontal,
Process of conjugation occurs, so when a thin tube forms between two bacteria and a single dna strand form one plasmid from one donor bacteria is thus transferred to the other recipient bacteria
-the bacteria then synthesis a complimentary strand of the plasmid

-this type can occur within a single bacteria population but also between populations of of different species.

Question 53

4 ways to reduce antibiotic resistance

Answer 53

-tighter control of prescription
-limit use for non serious infections that immune system will clear up/or for viral infections
-less use for animals in agriculture
-ensure that course is finished

Question 54

Explain 4 differences between active and passive immunity

Answer 54

Active immunity triggers an immune response, bc it causes the body to make its own antibodies. (Bc antigens trigger lymphocytes to produce plasma cells to then produce antibodies)
Passive immunity does not trigger an immune response, bc it introduces pre made antibodies.

In active immunity, antigens are introduced
In passive immunity, antigens are not introduced

Active immunity takes longer to occur, so is not immediate
Passive immunity occurs immediately

Active immunity results in the formation of memory cells, so results in long term immunity.
Passive immunity does not form memory cells so protection is short term.

Question 55

What is natural active immunity

Answer 55

-when the body is naturally exposed to a pathogen
(Eg ctahcing an infection like a cold)
-repulses in antibodies being made, so in a Primary immune response and then in a secondary immune response

Question 56

Explain difference between what primary immune response is and what a secondary immune response is

Answer 56

Primary,
when first exposed to an pathogen
-only a few b lymphocytes specific to the antigen are produced
So response is much slower and the person becomes ill

But in secondary,
-Memory cells have been formed, so many more B cells are specific to the antigen
-so more plasma cells formed so more antibodies
-so response is quicker and no symptoms are developed

Question 57

Explain what active artficial immunity is

Answer 57

When person is exposed to the antigen artificially such as through vaccination

Question 58

Explain what passive natural immunity is

Answer 58

When eg maternal antibodies travel from the mother to the infant via the placenta.

Or by giving breast milk, bc it contains the antibody IgA, which prevents the growth of bacteria or virus in the infants stomach.

Question 59

Explain what passive artificial immunity is

Answer 59

When preformed antibodies from another organism are inserted into the body for the same disease,

Eg from an animals blood who had already received the vaccine for the disease.
Eg for the tetanus disease