Infection and disease

Module 4 - Disease. Mostly long form questions to explain key ideas and processes, a few one mark style questions

List the stages of phagocytosis

1. Pathogen releases chemicals that attract phagocyte

2. Phagocyte binds to non specific receptors on pathogen recognising it as non-self

3. Pathogen engulfed by phagocyte, encased in vesicle forming phagosome

4. Lysosomes fuse with phagosome forming phagolysosome

5. Lysosome releases lysozymes which hydrolyse pathogen

6. Soluble parts adsorb in cytoplasm, remainder is expelled from phagocyte

what do cytokines do

released by phagocyte once pathogen is engulfed, attracts more phagocytes

what do opsonins do

bind to pathogen preventing them from repelling phagocytes

name a human disease caused by bacteria

tuberculosis

name the disease caused by bacteria that kills potatoes and tomatoes

ring rot

name two human diseases caused by viruses

AIDS, flu

what type of pathogen causes black sigatoka in banana plants

fungi

how do plants stop the spread of infection

produce callose or detach infected part via abscission

Explain how the site of a wound becomes inflamed

blood vessels around the wound dilate, increasing their permeability, which allows fluid to enter the tissue. This leads to swelling and allows the entry of WBC to kill pathogens

how do Naïve B Cells differentiate

1. Cells receptors bind to complementary antigens on pathogen, internalising the pathogen and presenting the antigens on its surface.

2. The processed antigens bind to receptors on T helper cell which release interleukins Outlstimulating B cell to clone.

3. Differentiate into plasma cells or memory cells

Outline three functions of antibodies

1. Agglutinins - Bind to antigens causing them to clump together making it easier for phagocytes to locate and destroy

2. Opsonins - Prevent pathogen from repelling phagocytes

3. Anti-toxins - bind to toxins preventing them from functioning

Antibodies released by cloned B cells are called

monoclonal antibodies

describe how antibodies act as agglutinins

antibodies bind to complementary antigens on the surface of the pathogen, forming antibody-antigen complex. Causes pathogens to clump together

how does a killer T cell work

bind to virus infected body cell release protein perforin, which creates holes in the cell surface membrane leading to cell death

describe the cell mediated immune response

Naïve helper T cell bind to antigen on antigen presenting cell, T helper clones itself

Cloned T helper stimulates B cells to clone, phagocytes to undergo phagocytosis, and killer T cells to target virus cells, also develop memory T cells which divide into killer T cells.