Diversity Of Life Flashcards
First lines of defence?
Skin- antimicrobial sebum 3-5 pH
Blood clots and scabs if broken
Mucus- in respiratory, digestive and reproductive tracts
Trap pathogens, released by goblet cells and swept by cilia. Contains lysozyme and phagocytes
Ear wax
Nose hairs
Lysozyme in tears (breaks down cross links between peptidoglycan molecules)
Expulsive reflexes- vomit, diarrhoea, cough, sneeze
Stomach- acidic, gut flora compete with pathogens
What are antigens?
On outer surface of cells
Usually proteins or glycoproteins
Foreign antigens cause an immune response
Inflammation and the immune system
1) tissue is damaged
2) mast cells release histamine
3) macrophages release cytokines
4) body temperature rises to reduce the rate of reproducing pathogens
Histamine widens capillaries and increases permeability. This allows plasma and white blood cells to enter the tissue.
Neutrophils digest the pathogen and cell debris.
Phagocytes (neutrophils) and the immune system
1) phagocytes recognises antigens on pathogen as foreign
2) pathogen engulfed by endocytosis
3) a vacuole (phagosome)surrounds the pathogen
4) the phagosome fuses with a lysosome
5) pathogen destroyed and debris released by exocytosis
Interferons and the immune system
Interferons are glycoprotein signalling molecules released by the body cells that have been infected with a virus.
They diffuse to surrounding cells and inhibit viral replication, limiting the spread.
They promote inflammation
They activate macrophages (type of phagocyte)
Macrophages and the immune system
Same as with phagocytes but rather than exocytosis, fragments of bacterial antigens (epitopes) are presented on the cell surface in a complex with MHC II proteins. This signals to the adaptive immune response.
What are white blood cells?
Lymphocytes
B cells and T cells
What are B cells?
Lymphocytes that become activated to secrete antibodies
Made in bone marrow
What are plasma cells?
Type of B cells that produce the majority of antibodies
What are antigen presenting cells?
Cells that present captured antigens to T cells
What are T cells?
Type of lymphocytes that play a central role in the adaptive immune response
What are T helper cells?
Guide cytotoxic T cells to pathogens
Made in the bone marrow but mature in the thymus
What are cytotoxic T cells?
Lymphocytes that destroy pathogens
What are memory T cells?
Lymphocytes that rapidly differentiate into helper and cytotoxic T cells
Differences between humoral and cell-mediated immunity?
B
What is the humoral immune response?
1) macrophage engulfs bacteria and presents its antigens on the surface, becomes APC
2) APC binds to T helper cell by complementary receptors
3) T helper cell divides to form T memory cells and active T cells
4) stimulate other B and T cells
Or
1) pathogen binds to B cells with complementary receptor
2) B cell comes APC
3) an activated T helper cell with complementary receptors binds to APC. Producing cytokines that stimulate the B cell
Linnaean classification order?
Domain Kingdom Phylum Class Order Family Genus Species
Binomial nomenclature rules
Genus- italics with a capital
Species- italics with no capital
Underline if handwritten
Sp- one species
Spp- multiple species
Why use binomial nomenclature?
Unique
Precise
Reflects evolution
Biological species definition?
Organisms that can reproduce to produce fertile offspring
Limitations of biological species definition
Asexual reproduction
Extinct organisms
Geographically isolated
Fertile hybrids
Convergent evolution
Organisms that aren’t closely related independently evolve similar traits because they are adapted to similar environments (same selection pressures)
Limitations of classification by morphology
Convergent evolution
Members of the same species can look different
Animalia kingdom
Eukaryotic Multicellular Heterotrophic (can’t make own food) No chlorophyll No cell walls Motile
Plantae kingdom
Eukaryotic Multicellular Autotrophic Chlorophyll Cells walls made of cellulose
Fungi kingdom
Eukaryotic Multicellular or unicellular Cells walls made of chitin Saprophytic (release enzymes onto dead matter) No chlorophyll Cytoplasm is multinucleate
Eubacteria kingdom
Prokaryotic 70s ribosomes Unicellular Peptidoglycan cell walls Autotrophic or heterotrophic
Protoctista kingdom
Eukaryotic Mostly unicellular Autotrophic or heterotrophic Cell walls present, but not always cellulose Such as seaweed, amoeba
Molecular phylogeny
Molecular phylogeny (evolutionary relationship) is now the standard approach to identify and classify all organisms
Similarities in biological molecules between organisms
Organisms that diverged recently will have the most similar sequences (less time for mutations to alter the sequence)
