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

quiz 1 - midterm - lectures 5,6 Flashcards

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Biology 101 flashcards
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
Q

describe oxidative phosphorylation

A

across IM
etc involved oxidation of nadh/fadh2
high energy electron carriers and reduction of oxygen to water (low energy acceptor)

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26
Q

describe reactions of oxidative phosphorylation

A

reduction of oxygen = exergonic
proton gradient = endergonic

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27
Q

describe photo phosphorylation

A

across thylakoid
etc involves low energy electron from water to nadp+ —> nadph
light energy required

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28
Q

describe reactions of photo phosphorylation

A

electron transfer = endergonic and exergonic
proton gradient = endergonic

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29
Q

describe non cyclic photo phosphorylation

A

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

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30
Q

describe cyclic phosphorylation

A

no o2 and nadph production
proton gradient allowing extra atp formation
needs light
psi <—> cyt
12 atp

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31
Q

name components used and not used cyclic phosphorylation

A

components involved = psi, cyt b6/f, mobile electrons carriers pc and fd
comments excluded = psii and nadp+ reductase FNR

32
Q

purpose of B

A

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
Q

name key features of calvin cycle

A

cyclic pathway
stroma
rubisco is required
per glucose - 18 atp and 12 nadph are needed to fix 6 co2 in 2 complete cycles

34
Q

describe first step of calvin cycle

A

carbon fixation - rubisco enzyme
co2+rubp (5c)–> 6c intermediate (unstable) –> 2pga (2x3c)

35
Q

describe second step of calvin cycle

A

reduction phase
pga–>g3p
12PGA +3C→12G3P +3C uses 12 atp and 12 nadph

36
Q

describe third step of calvin cycle

A

rubp regeneration phase
10 G3P +3C→6 RuBP +5C
uses 6ATP - back to square 1

37
Q

describe structure of DNA

A

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
Q

describe spacing and units of dna

A

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
Q

purines and pyrimidines (rings)

A

purines = double rings
pyrimidines = single ring

40
Q

describe dna in eukaryotes

A

stored in nucleus in from of chromatin (dna is coiled around histone proteins - nucleosomes)

41
Q

why are the sides labelled 5’ or 3’

A

5’ = phosphate linked to 5th sugar
3’ = oh linked to 3rd sugar

42
Q

meselsons and stahls experiment

A

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
Q

describe dna replication (5 statements)

A

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
Q

how is dna replication read

A

synthesis is always 5’ to 3’
template is read 3’ to 5’

45
Q

describe replication fork

A

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
Q

describe replication towards replication fork

A

leading strand
continuous synthesis

47
Q

describe replication away from replication fork

A

lagging strand
discontinuous synthesis
many short dna segments called okasaki fragments (1000-2000nt) these fragments form lagging strand

48
Q

how many steps to dna replication

A

6

49
Q

describe step 1 of dna replication

A

recognition of origin of replication
unzipping of dna by dna helicase
topoisomerase reduced strain produced by unwinding
initial bubble grows bi directionally

50
Q

describe step 2 of dna replication

A

single stranded dna binding proteins keep the parental strands apart and prevent their reannealing

51
Q

describe step 3 of dna replication

A

primase produces a short rna primer complementary to sequence of the template strands
has free 3’ oh group

52
Q

describe step 4 of dna replication

A

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
Q

describe step 5 of dna replication

A

rna primers are degraded and replaced by dna
catalyzed by dna polymerase I

54
Q

describe step 6 of dna replication

A

okasaki fragments of the lagging strand are joined by dna ligase

55
Q

describe dna replication of eukaryotes (when, replication origins, problems)

A

when = s phase
replication origins = multiple origins per linear chromosome, speeds up replication
problems = replication of ends of linear chromosomes

56
Q

describe dna replication of prokaryotes (when, replication origins, problems)

A

when = ongoing and uncoupled from cytoplasmic division
replication origins = single circular chromosome, single origin
problem = improper segregation of replicated chromosomes

57
Q

describe dna repair (mismatch repair)

A

during dna replication other enzymes double
proof the replication by dna polymerase

58
Q

describe dna repair (excision repair)

A

repairs damage due to chemicals, radioactivity, x-rays
occurs after dna replication (g1 ex)

59
Q

describe telomeres

A

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
Q

describe role of telomeres

A

protect coding region of chromosomes
shortening is associated with aging cells

61
Q

describe telomerase

A

precursor cells, stem cells, embryonic cells
telomerase enzyme is present to maintain telomere length
germ line (ovary and testes) express telomerase

62
Q

describe function of telomerase

A

ribonucleoprotein and contains rna molecule that serves as template to elongate telomeres
has reverse transcriptase activity to make dna from rna template

63
Q

describe telomeres and cancer

A

cancer cells have high levels of telomerase activity and do not exhibit shortening of normal differentiated cells
(immortal cells)

64
Q

describe what chargaff found

A

equal amounts of T and A
equal amounts of G and C
equal amounts of purines and pyrimidines
A+G=T+C

65
Q

describe griffith experiment

A

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
Q

conclusions of griffith experiment

A

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
Q

describe avery, mcleod and mccarty experiment

A

structure of dna rna and macromolecules not known
uses transformation principle

68
Q

4 possibilities of avery, mcleod and mccarty experiment

A

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
Q

conclusions of avery, mcleod and mccarty experiment

A

genetic material in bacteria is dna
dna alone transforms IIR avirulent to IIIS virulent (rna and proteins cannot transform IIR to IIIS)

70
Q

describe hershey and chase experiment

A

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
Q

conclusions of hershey and chase experiment

A

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
Q

what does dnase rnase and protease do

A

dnase destroys dna
rnase destroys rna
protease destroys proteins

73
Q

result of conservative replication

A

no hybrids

74
Q

result of dispersive replication

A

conservative and crossing over

75
Q

sequence of repair steps of excision repair

A

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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