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bio 2 > quiz 1 - midterm - lectures 5,6 > Flashcards

quiz 1 - midterm - lectures 5,6 Flashcards

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1
Q

what organisms is photosynthesis carried out by

A

plants
cyanobacteria
green algae

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2
Q

where does photosynthesis occur

A

chloroplasts

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3
Q

describe heme

A

red, has iron, mitochondria
hemoglobin - RBC
cytochrome c

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4
Q

describe porphyrin ring

A

resonance structure
conjugated system
absorbs light
has magnesium
green

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5
Q

describe chlorophyll

A

found in chloroplasts
porphyrin ring, phytol- hydrophobic tail
important pigment
absorbs in blue and red region of visible spectrum
cofactor of photosystems i and ii, located in thylakoid membranes

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6
Q

what are photosystems

A

complexes of proteins carrying out light reaction

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7
Q

name 3 things that excite chlorophyll by light

A

fluorescence- not useful for plants
resonance energy transfer
charge separation reaction (decay by successive electron transfers, initiates electron flow in etc)

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8
Q

describe charge separation reaction

A

PEA = primary electron acceptor
electron is transferred from donor to pea via chlorophyll
reaction center initiates electron flow

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9
Q

describe resonance energy transfer

A

excitation energy is transferred from chlorophyll to chlorophyll by antenna
no electron movement

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10
Q

describe photosystems (reaction center)

A

charge separation reaction
electron flow in etc is initiated
P680 - PSII and P700 - PSI = special chlorophyll pairs (best wavelengths of absorption)

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11
Q

describe photosystems (antenna)

A

chlorophyll a and b, bound to proteins
undergo resonance energy transfer to maximize light absorption

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12
Q

what is purpose of photosynthesis

A

fix inorganic CO2 to synthesize carbs using light energy

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13
Q

state overall redox equation for photosynthesis

A

6CO2 + 12H2O —> (light over arrow) C6H12O6 + 6O2 + 6H2O
24 electrons exchanged
without light = endergonic
carbon dioxide to glucose = reduction
water to oxygen = oxidation

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14
Q

name the two parts of photosynthesis

A

A - light dependent: etc and chemiosmosis
B - light independent: carbon fixation reactions of the calvin cycle

both happen in chloroplasts

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15
Q

describe A generally

A

production of atp and reducing power NADPH, O2 bi product
only with light
photo phosphorylation
~ oxidative phosphorylation

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16
Q

describe B generally

A

carbohydrate synthesis from CO2, using atp and nadph produced in light dependant reactions
reductive synthesis

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17
Q

purpose of A

A

require light energy to generate proton gradient across thylakoid membrane
resulting proton gradient drives atp synthesis by chemiosmosis
nadph generated is used for reductive synthesis of glucose
O2 is generated as bi product

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18
Q

redox reaction of A

A

2h2o + 2nadp+ —> (light) o2 + 2nadph + 2 h+

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19
Q

explain route taken by electrons of the photosynthetic electron transport chain

A

Z scheme - non cyclic phosphorylation
h2o —> PSII —> cyt b6/f —> PSI —> FNR —> NADPH
pathway of electrons

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20
Q

name the mobile electron carriers that shuttle electrons between complexes

A

PQ
Fd
Pc

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21
Q

what is responsible for electron flow in A

A

initial light dependant charge separation reaction
from PSII to PSI and from PSI to NADP+

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22
Q

name the 2 photosystems in A

A

1 - create protein gradient for atp synthesis by chemiosmosis - PSII
2 - to generate NADPH (reducing power) for reductive synthesis of glucose - PSI

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23
Q

how is proton gradient generated by z scheme (3 steps)

A

1- release in thylakoid lumen of 4 protons per o2 produced (oxidation or photolysis of 2 water molecules)
2- proton translocation/pumping by cytb6/f and shuttling of protons by pq
3- two protons are used from stroma to reduce 2nadp+ to 2 nadph

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24
Q

describe what oxidative phosphorylation and photo phosphorylation have in common

A

both use
etc to generate proton gradient
chemiosmosis to produce atp

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25
describe oxidative phosphorylation
across IM etc involved oxidation of nadh/fadh2 high energy electron carriers and reduction of oxygen to water (low energy acceptor)
26
describe reactions of oxidative phosphorylation
reduction of oxygen = exergonic proton gradient = endergonic
27
describe photo phosphorylation
across thylakoid etc involves low energy electron from water to nadp+ —> nadph light energy required
28
describe reactions of photo phosphorylation
electron transfer = endergonic and exergonic proton gradient = endergonic
29
describe non cyclic photo phosphorylation
o2 evolution, nadph production, proton gradient, atp synthase by chemiosmosis needs light all components of etc are used h2o —> psii —> cyt —> psi —> pnr —> nadph 18 atp and 12 nadph linear pathway
30
describe cyclic phosphorylation
no o2 and nadph production proton gradient allowing extra atp formation needs light psi <—> cyt 12 atp
31
name components used and not used cyclic phosphorylation
components involved = psi, cyt b6/f, mobile electrons carriers pc and fd comments excluded = psii and nadp+ reductase FNR
32
purpose of B
fix CO2 using ATP and NADPH produced in light dependent reaction to synthesize carbohydrates such as G3P (and eventually glucose) interdependent with light reactions
33
name key features of calvin cycle
cyclic pathway stroma rubisco is required per glucose - 18 atp and 12 nadph are needed to fix 6 co2 in 2 complete cycles
34
describe first step of calvin cycle
carbon fixation - rubisco enzyme co2+rubp (5c)--> 6c intermediate (unstable) --> 2pga (2x3c)
35
describe second step of calvin cycle
reduction phase pga-->g3p 12PGA +3C→12G3P +3C uses 12 atp and 12 nadph
36
describe third step of calvin cycle
rubp regeneration phase 10 G3P +3C→6 RuBP +5C uses 6ATP - back to square 1
37
describe structure of DNA
double helix two sugar phosphate backbones base pairs in middle 2 strands are anti parallel direction 5’—>3’ number of purines = number of pyrimidines G+A=C+T
38
describe spacing and units of dna
distance between 2 adjacent base pairs is 0.34nm 10 base pairs make complete helical turn - 3.4nm width of dna = 2nm spacing respected because of pairing rule
39
purines and pyrimidines (rings)
purines = double rings pyrimidines = single ring
40
describe dna in eukaryotes
stored in nucleus in from of chromatin (dna is coiled around histone proteins - nucleosomes)
41
why are the sides labelled 5’ or 3’
5’ = phosphate linked to 5th sugar 3’ = oh linked to 3rd sugar
42
meselsons and stahls experiment
semi conservative replication each parental strand serves as template for synthesis of new and complementary daughter strand daughter cells are always hybrids with a patently strange and new daughter strand (all identical)
43
describe dna replication (5 statements)
formation of phosphodiesther bonds between nt of a daughter strand, complementary and anti parallel to template strand requires free 3’ oh or else primer is needed bidirectional opposite replication enzymes
44
how is dna replication read
synthesis is always 5’ to 3’ template is read 3’ to 5’
45
describe replication fork
y shaped structure where synthesis of 2 complementary daughter strands happens 5’—>3’ synthesis, primer needed to initiate rna primer (provides initial 3’ oh, needed for dna replication)
46
describe replication towards replication fork
leading strand continuous synthesis
47
describe replication away from replication fork
lagging strand discontinuous synthesis many short dna segments called okasaki fragments (1000-2000nt) these fragments form lagging strand
48
how many steps to dna replication
6
49
describe step 1 of dna replication
recognition of origin of replication unzipping of dna by dna helicase topoisomerase reduced strain produced by unwinding initial bubble grows bi directionally
50
describe step 2 of dna replication
single stranded dna binding proteins keep the parental strands apart and prevent their reannealing
51
describe step 3 of dna replication
primase produces a short rna primer complementary to sequence of the template strands has free 3’ oh group
52
describe step 4 of dna replication
dna is synthesized by dna polymerase III in 5’ to 3’ direction sliding clamp pushes dna polymerase III along template strand proof reading minimizes mutations
53
describe step 5 of dna replication
rna primers are degraded and replaced by dna catalyzed by dna polymerase I
54
describe step 6 of dna replication
okasaki fragments of the lagging strand are joined by dna ligase
55
describe dna replication of eukaryotes (when, replication origins, problems)
when = s phase replication origins = multiple origins per linear chromosome, speeds up replication problems = replication of ends of linear chromosomes
56
describe dna replication of prokaryotes (when, replication origins, problems)
when = ongoing and uncoupled from cytoplasmic division replication origins = single circular chromosome, single origin problem = improper segregation of replicated chromosomes
57
describe dna repair (mismatch repair)
during dna replication other enzymes double proof the replication by dna polymerase
58
describe dna repair (excision repair)
repairs damage due to chemicals, radioactivity, x-rays occurs after dna replication (g1 ex)
59
describe telomeres
sequences at both ends of linear chromosomes non coding hexanucleotide repeats added to chromosomes of zygote by telomerase most somatic cells lose ability to maintain telomere length (absence of telomerase)
60
describe role of telomeres
protect coding region of chromosomes shortening is associated with aging cells
61
describe telomerase
precursor cells, stem cells, embryonic cells telomerase enzyme is present to maintain telomere length germ line (ovary and testes) express telomerase
62
describe function of telomerase
ribonucleoprotein and contains rna molecule that serves as template to elongate telomeres has reverse transcriptase activity to make dna from rna template
63
describe telomeres and cancer
cancer cells have high levels of telomerase activity and do not exhibit shortening of normal differentiated cells (immortal cells)
64
describe what chargaff found
equal amounts of T and A equal amounts of G and C equal amounts of purines and pyrimidines A+G=T+C
65
describe griffith experiment
2 bacterial strains - IIR (avirulent no capsule) and IIIS (virulent with capsule) infect mice experimental condition = heat killed IIIS virulent and live IIR avirulent - combo kills (transforms into IIIS)
66
conclusions of griffith experiment
genetic material is heat resistant genetic material contains info for making capsule avirulent IIR can be transformed into virulent IIIS in presence of this transforming principle
67
describe avery, mcleod and mccarty experiment
structure of dna rna and macromolecules not known uses transformation principle
68
4 possibilities of avery, mcleod and mccarty experiment
transform IIR with IIIS boiled extract treated with dnase rnase and protease boiled IIIS alone and with rnase or protease= transformation occurs IIR TO IIIS boiled IIIS with dnase = no transformation
69
conclusions of avery, mcleod and mccarty experiment
genetic material in bacteria is dna dna alone transforms IIR avirulent to IIIS virulent (rna and proteins cannot transform IIR to IIIS)
70
describe hershey and chase experiment
phage = bacterial virus, requires host to reproduce 2 populations of phages = 35s labelled protein and 32p labelled dna question = is it dna or protein that infects bacteria to replicate phages?
71
conclusions of hershey and chase experiment
32p labeled phage dna enters bacteria and 32s labeled phage protein doesn’t genetic material of viruses is dna (directs replication of phage peptides) dna is universal genetic material
72
what does dnase rnase and protease do
dnase destroys dna rnase destroys rna protease destroys proteins
73
result of conservative replication
no hybrids
74
result of dispersive replication
conservative and crossing over
75
sequence of repair steps of excision repair
1 nuclease - removes lesion, leaves exposed bases 2 dna polymerase - fills in gap left by exposed bases 3 dna ligase - seals

bio 2 (6 decks)

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