Exam Flashcards
what is the order of the cell cycle
G1, S, G2, M
What happens at each stage of the cell cycle
G1 - growth stage
S -DNA replication
G2 - Cell growth
M - Mitosis
what are the stages of mitosis
prophase - dna condenses into chromosomes composed of two sister chromatids. Microtubules disassemble and spindle fibres assemble.
metaphase - chromosomes line up at the metaphase plate at the equator.
anaphase - dépolarisation occurs causing spindle fibres to separate the sister chromatids to opposite poles.
telophase - operated chromosomes condense forming a nuclear membrane.
cytokinesis - actin and myosin decide the cytoplasm to form two daughter cells.
what results in degenerative disease
an uncontrolled reduction in the rate of the cell cycle.
what results in tumour formation
an uncontrolled increase in the rate of the cell cycle.
what is the role of cyclins
cyclins accumulate and regulate the cell cycle, they combine with cyclin dependant kinases (CDKs) causing the phosphorylation of target proteins which regulate progression through the cycle.
what happens at each cell cycle checkpoint
G1 - cell size monitored. if not reached the cell may such to the G0 phase. this is also where Rb proteins are phosphorylated.
G2 - assesses the success of replication at the end of the G2 stage.
Metaphase - monitors chromosome alignment during the metaphase stage.
what is the cytoskeleton
the cytoskeleton is a network of protein fibres that extends throughout the cytoplasm. it gives mechanical support and shape to the cell.
what are microtubules
microtubules are hallow cylinders. polymers made by alpha and beta tubular proteins. they govern the location and movement of membrane bound organelles and cell contents, they radiate from the centrosome.
what are the 3 roles of microtubules
asters ensure that the cell cycle apparatus is correctly located.
some attach to the kinetochore proteins at centrometers of each chromatid.
some don’t attach to the chromosomes but to the microtubules from the opposite centrosome.
what happens as a result of external death signals
signals bind to a surface receptors protein changing its conformation triggering a protein cascade within the cytoplasm producing cascades.
what happens as a result of internal death signals
p53 proteins activate a caspase cascade through the disruption of the integrity of mitochondria.
what allows a rapid response to death signal to occur
post translational modifications, cleavage.
what is the role of phosphatases
catalysing dephosphorylation
what is the role of kinases
catalysing phosphorylation
what causes revisable conformational cages in proteins
the addition or removal of a phosphate (phosphorylation or dephosphorylation)
describe the features of an integral protein
penetrate the hydrophobic interior of the bilayer.
form strong hydrophobic interactions.
describe the features of periphal proteins
not embedded in the bilayer.
hydrophilic R groups on their surface.
ionic and hydrogen bon interactions.
describe the features of the cell membrane
phospholipid bilayer with proteins. head outside is hydrophilic inside is hydrophobic.
acts as a barrier to ions and most uncharged polar molecules however allows small non polar molecules to pass though.
what causes conformational changes in ligand-gated channels in comparison to voltage-gated channels.
in ligand-gated channels conformational change is caused by the binding of signal molecules whereas in voltage-gated channels conformational change is caused be changed in ion concentration across the membrane.
how does the sodium potassium pump work
there’s high affinity for the Na+ inside the cell so they bind. then ATP is phosphorylase causing conformational change so affinity for Na+ is low and affinity for K+ is high so K+ binds. ATP is then dephosphorylsed for affinity for K+ is low and affinity returns to the start.
how many K+ ions and Na+ are transported by the sodium-potassium pump.
2K+ in, 3Na+ out.
what is the fundamental niche
the fundamental niche is the set of resource the species is capable of using in the absence of any interspecific competition
what is the realised niche
the realised niche is the set of resources that the species uses in response to the presence of interspecific competition.
what is the competitive exclusion principle
the competition exclusive principle states that in cases if interspecific competition where the realised niche of two species are extremely similar one will lose out in more in the competition leading to local extinction.
what is resource partitioning
resource petitioning occurs when two species have significant different realised niches for them to coexist. the two species exploit different components of the resource reducing potential competition.
what is the difference between endoparasites and ectoparasites
endoparasites live within the host whereas ectoparasites live and feed on the surface of the host.
what is the difference between a definite host and an intermediate host
a definite host is the organism in or on of which the parasite reaches sexual maturity whereas the intermediate host is the one in or on of which the development stages happen.
what is the parasitic lifestyle of schistosoma
schistosoma cause the disease schistosomiasis. the intermediate host is a snail where they develop into the larval form and the definite host is human of which skin they penetrate.
what is the parasitic lifestyle of plasmodium
plasmodium cause malaria, they spent time in humans developing into male and female forms then infect the definite host, mosquitoes.
describe the structure of virus
viruses have their genetic information stored in nucleic acid which is packages inside a protective protein coat called caspid.
the outside had proteins called antigen as the cell from the host may not be able to detect them and initiate an immune response.
how are RNA viruses replicated in comparison to RNA retroviruses
RNA viruses genome is replicates directly using an enzyme from the virus and viral DNA is never made whereas RNA retroviruses use the enzyme reverse transcriptase to form a DNA copy of the virus which is inserted to the normal cell cycle so the virus genome is always in host cells.
what is virulence
virulence is the harm to the host species caused by the virus
what factors increase transmission rates of virus
overcrowding and living at high density q
how is virulence increased
surpress immune system
modify size of host make it larger
reduce reproductive rate of host to provide more energy to virus.
what are the first line of defence
this can be physical or chemical for example skin or saliva which breaks down the cell membrane.
what are the second line of defence
inflammatory response = histamine realised causing blood vessels to dilate causing redness and warming and swelling.
Phagocytes antibacterial proteins from the swelling.
natural killer cells which detect abnormal cell surface proteins and induce apoptosis.
what are the third line defences
specific responses involving lymphocytes triggered by virus antigens.
describe lymphocytes and their role
white blood cells found mainly in lymph glands. they each present only one type of antigen receptor protein on their surface.and carry out immune surveillance. they monitor tissues, if they are damaged cytokines are releases increasing blood flow accumulating non specific and specific white blood cells
what are the three ways in which lymphocytes work
colonel election - antigen receptor proteins bind to specific antigen activating lymphocytes making them read lilt active to divide and rapidly produce more clone with the same antigen receptor.
antibodies - bind to antigen forming antigen-antibody complex which is easy for phagocyte to engulf.
other lymphocytes induce apoptosis
what is the red queen hypothesis
states that parasites keep evolving to keep up with host in order to avoid going extinct.
what are the three ways in which parasites avoid going extinct
hiding from immune system.
becoming a moving target.
integrating genome into host genome.
what name is given to the study of outbreak and spread of infections disease
epidemiology
what is the herd immunity threshold
the density of resistant hosts required in a population to prevent an epidemic.
what makes Schistosoma vaccine creation difficult
they are difficult o culture as they need a very narrow range of conditions and specific host.
what makes plamodium vaccine creation difficult
they have rapid antigen change making vaccine design complex as it will have to reflect this.
what else makes vaccine creation difficult
similarities between host and parasite metabolism. so drug compounds only affecting parasite need to be found.
and selection pressure leading to evolved resistant parasite strains.
what are ways to target transmission.
civil engineering projects to improve sanitation.
coordinate vector control strategy (bed nets and insecticide)
what are the benefits of improving parasite control
reduced child morality.
more resources for growth and development.
population wide improvements in child development and intelligence.
what is the proteome
the proteome is the entire set of proteins that can be expressed from a genome
there are lipids synthesised
in the SER
where are proteins synthesised
cytosolic ribosomes
where does post translational modification take place
in the golgi apparatus
what are lysosomes
lysosomes are membrane bound organelles containing a variety of hydrolase enzymes.
what do vesicles do
vesicles transport materials between different membrane compartments
what carries out the synthesis of oils and lipids
steroid hormones by enzymes embedded in the SER
how does the synthesis of transmembrane proetins occur.
- mRNA is translated until signal sequence binds to cytosolic protein.
- particle directs ribosome to dock with a protein pore in the ER forming the rough ER.
- after docking the protein pore removes cytosolic particle and signal sequence so translation continues.
what are the 4 possible fates of vesicles
- fuse with plasma membrane build it and add transmembrane proteins.
- fuse with plasma membrane to allow a protein to be secreted.
- fuse with membranes of mitochondria, chloroplast or nucleus and build then and add transmembrane proteins.
- form a lysosome in the cytosol.
what are examples of secreted proteins
peptide hormones (insulin) digestive enzymes (pepsin)
what are the catagories of amino acids
Basic NH2
polar OH
acidic COOH
hydrophobic hydrocarbon
what kind of reaction occurs between two adjacent amino acids
condensation
what are proteins structures
Primary = sequence of amino acids Secondary = alpha helix, beta sheet and turns. Tertiary = final folded shape with hydrogen bonds, disulphide bridges, LDF etc.. Quaternary = more than 1 polypeptide subunit
what is cooperativity
when binding at one subunit alters the affinity of the remaining
how is affinity for oxygen in haemoglobin lowered
increase in temperature decrease in pH
what do modulators do
modulators regulate the activity of the enzyme when they bind to the allosteric site they alter the affinity of the active site.
