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Topic 6- Section 1

Terms in this set (25)

identify 8 parts of a prokaryotic cell
1) nucleoid- circular ștrand of DNA (no histones)
2) flagellum- for cell movement
3) 70s ribosomes
4) peptidoglycan cell wall
5) capsule
6) mesosome- infolding of cell surface membrane
7) plasmids- small circles of DNA
8) pilli- protein tubes that allow bacteria to attach to surfaces and are involved in cell-to-cell attachment
what organelle does/ doesn't a virus have?
DOES:

- nucleic acid (DNA or RNA)
- protein coat

DOESN'T:

- no cell membrane unless stolen
-no histone
-no cytoplasm
-no organelles
give the type and structure of the nucleic acid in viruses
- DNA- single or double
or
-RNA- single (RNA makes it a retrovirus e.g. HIV)
what are the 2 pathogen barriers of the respiratory tract? how do they work?
- cilia, removes pathogens from lungs by wafting mucus to the top of the trachea
-mucus, traps pathogens, produced by the goblet cells
what are the 2 pathogen barriers of the skin? how do they work?
- sebum, oil on skin with antimicrobial properties
- keratin, tough (strong) protein which is impermeable to pathogens
what do the gut and skin flora do?
harmless bacteria which outcompete pathogens for space and nutrients
how do the eyes, nose and mouth (saliva) provide a non-specific response against pathogens?
- produce and secrete lysozyme enzyme, which hydrolyses peptidoglycan cell walls destroying bacteria
what is a non-specific response? give the 4 non-specific responses?
- work against any pathogens
- the 4 non-specific responses: lysozyme, interferon, inflammation and phagocytosis
How does interferon work?
chemicals released by infected cells, interfere and prevent viral replication (is specific to viruses)
how does inflammation act as a non-specific response?
-damaged wbc's release histamines
- histamines cause area to go red due to vasodilation of arterioles, increases blood flow to area
- increases # of wbc and antibodies in area of damage
histamines cause capillaries to become more permeable, creating more tissue fluid (localised oedema)
- allows more wbc and antibodies to leave the blood and attack any infections
what is an antigen, pathogen and macrophage?
- antigen = a non-self molecule, can be found on surface of pathogens, dust , splinters + transplanted organs

- pathogen = disease causing micro-organism

- macrophage = the largest wbc/ phagocyte
what is the difference between phagocytes and lymphocytes? give examples
phagocytes (e.g. neutrophil or monocyte) are used in the non-specific response, lymphocytes are involved in specific immunity (e.g. in the humoral or cell mediated response)
describe how a B cell is activated (3)
1. {antigen / bacteria / virus / pathogen} {binds / eq} to B cell ;
2. {antigen / bacteria / virus / pathogen} {binds / eq} to MHC (antigen) ;
3. T helper {lymphocytes / cells} {bind / eq} (to B cell) ;
4. reference to cytokines (from T helper cells) ;
name the type of cell division that occurs when B cells are cloned (1)
- mitosis
Suggest how a microscope slide could be prepared to observe cell division in B cells from the lymph nodes (3)
- sample of B cells from lymph nodes
- using toluidine blue
- heat/ fix the stain
- look for the stages of mitosis/ mitotic features
true or false:

1) B and T cells are formed in the bone marrow
2) B cells stimulate T cells to produce clones of memory cells
3) T helper cells produce chemicals that destroy pathogens
4) B and T cells are able to form clones by mitosis
1) true
2) false
3) false
4) true
suggest 2 reasons why bacteria causing an infection may not be visible in a photograph of the cells (2)
- the bacteria may be too small
- they may not be stained
- bacteria already removed/ destroyed by phagocytosis
- idea that bacteria aren't present in the blood e.g. only a small region/ sample shown ref. to local infection
explain how bacterial molecules could trigger a specific immune response (4)
- invading pathogen is engulfed into a macrophage
- macrophage becomes an APC
- T helper cells then bind to the antigens (using the CD4 receptors)
- cytokine released causes cloning of B cells/ formation of B effector cells
- plasma cells release/ produce antibodies
What do cytokines do?
trigger cell differentiation
in patients suffering from severe combined immune-deficiency the T helper cells don't produce cytokines. why are SCID patients vulnerable to both viral and bacterial infections?
cytokines are responsible for the cell differentiation stages for both the B cells in the humeral response and the T cells in the cell mediated response. therefore for both viral and bacterial infections without cytokines cells do not differentiate past the APC macrophage phase
what is the role of macrophages in the specific immune response?
macrophages are specialised cells involved in detection, phagocytosis and destruction of pathogens. their role is to become an APC for the T-helper cells
what are the 4 types of immunity?
active natural, active artificial, passive natural, passive artificial
what is active immunity? what is passive immunity?
active- body actively produces antibodies

passive- you receive antibodies, body doesn't make them
what is natural immunity? what is artificial immunity?
natural- natural process

artificial- administered, by injection or inhalation
which type of immunity are the following?:

1) antibodies in mothers milk
2) injection of tetanus antibodies
3) catching a disease and producing antibodies
4) vaccination
1) natural passive
2) artificial passive
3) natural active
4) active artificial
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