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Genes + Cells > RE revise > Flashcards

RE revise Flashcards

1
Q

what is needed before replication can occur

A

initiator protein must bind to the origin of replication

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2
Q

what does DNA topoisomerase do

A

aids unwinding process

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3
Q

what does DNA helicase do

A

breaks hydrogen bonds between bases

form two single strand template strands

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4
Q

where is the RNA primer needed

A

added to 3’ end

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5
Q

what does DNA primase do

A

synthesises short RNA primer (5-10 nucleotide bases)

attaches primer to 3’ end of template

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6
Q

what does DNA polymerase do

A

reads template strand 3’ to 5’
causes nucleotide addition to primer
cataylses the phosphodiester bond forming between 3’ carbon of last nucleotide and 5’ phosphate of incoming nucleotide

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7
Q

what does DNA ligase do

A

joins okazaki fragments to form DNA strand

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8
Q

translocation in eukaryotes

A

scans 5’ UTR
mRNA unwound and more proteins added/bind
mRNA attaches to complex with poly (A) tail at end
tRNA brings methionine, binds to form a large complex

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9
Q

what is rho-dependent

A

rho interacts with elongating RNA transcripts

disrupts interaction causing RNA polymerase to ‘fall off’

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10
Q

what is rho-independent

A

RNA forms hairpin loop due to inverted repeats in DNA
hairpin loop stops RNA polymerase transcribing
followed by uracil poly tail - only weakly bound to poly A sequence so RNA falls off as no strong connection between DNA and RNA

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11
Q

eukaryotes transcription termination

A

AAUAA cleavage signal
signals RNA ending
specific endonuclease cleaves off poly (A) tail added

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12
Q

eukaryotes translation termination

A

termination codons at end of protein-coding sequence
tRNAs don’t have complementary anticodon
release factors bind to ribosome
release mRNA from ribosome-complex falls apart

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13
Q

prokaryote initiation

A

ribosome dissociation
IF2 and GTP complex with formyl methionine tRNA
tRNA brought to mRNA, complementary to AUG codon on mRNA
form 30S initiation complex
IF3 lost
GTP hydrolysed to GDP (+Pi) produces energy
energy displaces IF1 and IF2 so 50S can re-associate

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14
Q

prokaryote elongation

A

EF-Tu binds with GTP to next complementary tRNA in mRNA sequence
tRNA brought to A site, binds = release EF-Tu and GTP
peptide bond forms between amino acid in P site and A site
catalysed by peptidyl transferase
GTP hydrolysed = energy for ribosome to be shifted three nucleotides right till reach stop codon

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15
Q

what is the cell pathway in eukaryotes

A

contractile microfilaments of cytoskeleton - lines of tension in cell
energy transmitted through these lines, lets cell move across

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16
Q

what is the cell pathway in extracellular matrix

A

extracellular matrix has fibronectin fibres
each cell orientated to position of fibronectin fibres
follow fibronectin trails

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17
Q

how do adheren junctions form

A

cadherin proteins cross intracellular space link to catenins
catenins linked to actin filaments
actin filaments anchored to cytoskeleton

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18
Q

how do desmosomes form

A

cadherins cross intracellular, other proteins link cadherins to intermediate filaments
attached to skeletal proteins inside cell
anchored to intermediate filaments of cytoskeleton

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19
Q

how do tight junctions form

A

tightly packed row of protein ridges linking adjacent cells

ensure adjacent cell membranes held together

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20
Q

how is a lateral root formed

A

outer tissue disformation and cell separation
signals outside cells to release cell wall modifying enzymes
allow cells around to stretch move and disengage with each other - can grow through
lateral root contains all same material as primary

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21
Q

what is sclerenchyma and its function

A

provide structure and support to plant tissue

cell walls are thick lignified secondary walls made of cellulose and hemicellulose - often die when age

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22
Q

what is special about phloem cell wall

A

perforated using sieve plates to allow compounds to travel through

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23
Q

what is the sclereid and its function

A

keeps plant together

gives structure and strength without preventing it moving in water

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24
Q

what is the collenchyma and its function

A

elongated cells with thick cell walls
provide structure and support
cellulose and pectin are irregularly thickened at corners

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25
Q

what are hydrophytes

A

important for aquatic plants
stomata only on top of leaf
epidermal layer very little strengthening in stems = not rigid
AERENCHYMA form air channels for gas exchange

26
Q

what is the plasma membrane function

A

coordinates synthesis and assembly of cellulose microfibril
control substances in/out cell via transmembrane protein
relay hormonal and environmental signalling factors

27
Q

what is the function of the perioxisome

A

detoxes cell
help cell survive in toxic environment
hydrogen peroxide is a metabolic waste product, toxic to cell
perioxisome converts it to water

28
Q

golgi body function

A

provides a network of vesicles for secretory purposes
sorts - proteins know where need to go, packages for transport
modifies products from rough ER

29
Q

what is the vacuole function

A

regulate turgidity by regulating water in cell

30
Q

what is a vacuole

A

membrane bound organelle filled with cell sap

often acidic pH, many have toxic/bitter compounds - stop being eaten

31
Q

what is lytic infection

A

host cells destroyed - virus particles released
normally clears in couple days - immunity
some hosts not immune = epidemic

32
Q

what is latent infection

A

lack of gene expression, normally in sensory and autonomic ganglia - immunocompromised
lasts lifetime of host
UV can reactivate - re-enter lytic cycle

33
Q

what is persistant/chronic infection

A

virus does not cause cell death
slow virus release
if not good immunity can last long time

34
Q

what is a germ cell

A

cell containing half the number of chromosomes of a somatic cell and is able to unite with one from the opposite sex to form a new individual - a gamete

35
Q

what is heterogametic

A

X- Y- hemizygous for genes (only has one copy of genes)

36
Q

what is polyploidy

A

condition in which cell/organism has more than two sets of chromosomes

37
Q

what is the paracellular route

A

materials cross through junctions between cells where there is a gap

38
Q

what do motor proteins do

A

change the position of things in the cell

39
Q

what is endocytosis

A

a living cell takes up matter via an invagination in the cell membrane

40
Q

what is exocytosis

A

vacuole contents released to exterior as vacuole membrane fuses to cell membrane

41
Q

what is pinocytosis

A

liquid ingested into cell due to small vesicles budding off cell membrane

42
Q

what is saltatory conduction

A

transmit change by reversing local electric field that passes along nerve axon - active signal. Regenerated along axon

43
Q

intracellular inclusions

A

contain insoluble chemical deposits
used as storage organs
bounded by non-unit membrane

44
Q

what is the effect of a bacterial phospholipid bilayer

A 
hydrophobic core - barrier to most water soluble molecules
protein permeases (membrane transport protein) allow selective transport of molecules in
45
Q

what are the benefits of cytoskeleton on plant cell

A

vesicles from ER and golgi travel along monorails it provides
growth in particular direction
involved in positioning organelles

46
Q

what is a heterotroph

A

relies on carbon from complex compounds

47
Q

what is a phototroph

A

photosynthetic microbes

48
Q

what is binary fission

A

transfer of genetic material before septum formation or will not be viable cells

49
Q

what is a bacterial endospore

A

dormant structure
can permit for long time
dehydrated, no biochemical reactions occur
germination and outgrowth lead to new vegetative cell

50
Q

what were Kochs postulates

A

gene found associated with pathogen
mutation attenuates virulence of pathogen
transfer of gene can give other organisms disease

51
Q

what are exotoxins

A

extracellular diffusible toxins

normally proteins secreted during exponential growth

52
Q

how does an enveloped virus enter/exit cell without destruction

A

envelope pinches off bit of plasma membrane
envelope glycoprotein on outside of capsomere fuses with outside of cell
release nuclear capsid into cytosol

53
Q

what is the capsid function

A

encapsulates nucleic acid - no harm
interact with cell organelles
genome delivery - binds to receptor using spikes

54
Q

what is a transposon

A

small DNA pieces = replicate and move round in genome insert themselves

55
Q

where can clostridium botulinum be found

A

associated with meat or canned foods not reheated before eating
heat sensitive but germinates in cooled food

56
Q

where can bacillus cereus be found

A

spores are heat resistant and germinate in cooled food after cooking
cereals and rice survives in reheated foods

57
Q

where can clostridium perfringens be found

A

natural part of animal gut microflora
spore found in faeces
associated with cooked meat products

58
Q

where can campylobacter be found

A

mainly from poultry or other raw meat

natural habitat is bird intestine

59
Q

where can listeria be found

A

normal habitat is mammal intestine, soil and plants
can grow in refrigeration temperatures
many sources e.g. dairy, salad, cold meat

60
Q

what is post transcriptional gene silencing

A

Gene silencing small interfering RNA cause mRNA degrade, can’t be translated to proteins

61
Q

what must happen for eukaryote transcription initiation to occur

A

several transcription factors bind to core promoter TATA box - must be specific combination of TFs for RNA polymerase to bind

Genes + Cells (23 decks)

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