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Question 1

DNA: where is 5’ to 3’ and opp?

Answer 1

Top:L 5’ to 3’
Bottom: 3’ to 5’

Question 2

composition of a nucleic acid

Answer 2

nucleic acid is composed of many nucleotide (5’ to 3’):
a pentose sugar linked to a N base via glycosidic bond @C1 + PO4 group
each nucleotide is linked tgt via phosphodiester bond

Each nucleotide is linked tgt via PO4 bond

Question 3

purines vs pyrimidies

Answer 3

nitrogenous base can be purines (A G) or pyrimidines ( C T U)
flat surface, hydrophobic, inpt when stacked; has H bond (A T has 2 while GC has 3)

Question 4

what is DNA 2x helix shape comes from?

Answer 4

Chargaff’s rule: in any org, lvl of ATCG will alwyas be consistent (AT > CG)
X-ray diffraction pattern
correct structural (tautomeric) forms of bases: suggested Keto forms

Question 5

DNA 2x helix (B-DNA): ___ antiparallel, ____ stabilised by hydrophobic interactions
is __ n, in diameter, w/ a rise of ___ nm per bp
plane is ___ to ___ while sugar-PO4 ___ wraps around the __ in a __-___ coil

Stabilises through base stacking and base pairing: H bonds

Answer 5

righthanded, double steranded
is 2, 34
perpedincular / axis / backbone / axis / right handed

Question 6

A-T has __ H bonds while G-C has ___

Answer 6

2, 3

Question 7

5 points of comparison btw DNA vs RNA

Answer 7

1. DNA has -H @ C2 while RNA has C2s hydroxyl
2. thymine vs uracil
3. long vs short
4. 2x in double hexlix vs 3 stem loop strucrure
5. few base modifications vs many

Question 8

describe RNA structure

Answer 8

short, 2x helix regions that are antiparallel BT singple stranded
is sequence dependent-> irreguar, creates this complex 3D structure
allows rRNA to interact w/ multiple partners in ribosome

Question 9

Human DNA must be condensed into ____ = DNA plus assoiciated ___ ___
red part is ___ aka tightly packed DNA not ___ )__)_
yellow part is _____ aka one regularly —-

Answer 9

chromatic, pckaging proteins
heterochromatin / regularly / expressed
euchromatin / expresssed

Question 10

describe ribonucleoside

Answer 10

= pentose sguar w. N base (cytidine has cytosine for N base)

Question 11

describe deoxyribonucleotide

Answer 11

in sugar, replace -OH @ C2 w. -H

Question 12

describe ribonucleotide

Answer 12

= pentose sugar + N base + phosphate
has O H- for C2

Question 13

length
%GC (< ___ interactions & ___ bonds)
more/ less complementary
more ___ (neutralize repel __ charges)
organic ____ </> 9affect hydrophobic interactions)
urea/formamide&raquo_space; (___ affect __ bonds)

extreme pH lowers it

Answer 13

factors affecting primer melting temp < when

hydrophobic / H
more
salt / PO4
solvent >
denat / H

Question 14

ROs in bacteria vs eukaryotes

Answer 14

in bacteria you nee d1 w/ circular DNA
in eukaryotes, maybe 30-50k ROs

Question 15

describe initiation of DNA replication

Answer 15

Replication Origin tends tb richer in A-T

@ RO, initiator protein binds to DNA and pulls them apart
helicase splits them apart creating a replication fork and estends the bubble
old DNA used as templates to create new ones = semi conservative

Question 16

priming- DNA replication

Answer 16

need primase (a type of RNA polymerase) = creates a short RNA strand complementary to DNA called primer
bcs top DNA is 5’ to 3’ (L to R), primase creates from 5’ to 3’ (R to L)

Question 17

DNA synthesis (overall_

Answer 17

primase dissociates, leaving behidnt he primer
=> DNA polym picks up from 3’ end, initiates 2nd strand DNA synthesis, adds bases
DNA polym catalyze the addition of dNTP by linking its alpha PO4 to DNA’s chain’s C3 OH
=> pyroPO4 PPi is released

Question 18

how is DNA polym stringent?

Answer 18

DNA polym is stringent– tolerates v lil variation- picky with base it links

select dNATPis dictated by template strand
- if base comes w/ correct geometry, polym-mediated action occurs; if not, no rxn

Question 19

describes proofreading

Answer 19

in case of mismatch / extra base / delete base
use a nuclease = enzyme that degrades nucleic acid (exo from outside, endo from inside)
=> DNA polym has a 2nd activity site w/ exonuclease activity

Question 20

describes ligation

RNA primase must be removed, DNA ____ joines 2 strands @ ___

in prokaryotes/eukaryotes
- ___ ___ (a nuclease) degrades primer, DNA polym ____ fills in gap (nick remains)
- DNA polym III kicks off primer, it __ ___, _____ ___

Answer 20

ligase, nick
Rnase H / IIII
broken down / nick remaisn

Question 21

describes copying mistkae

Answer 21

DNA polym faults every 10^7 nucleotides: mismatch , insertion, deletion
=> if unrepaired, duaghter cell swill cotnains the altered genome, call it a mutation

Question 22

list other DNA damamges

5. can be __ ___ or __ ___: polyaromatic HC
6. suga-____ ___:, mechanical stress

Answer 22

2. depurination
3. demamination
4. pyrimidine dimers: most common dmaage cased by UV radiation
5. base modifications: ionizing radiation or chemical mutagens like charred meats
6. sugar phosphate break: ionization readiation, reactive O species, mechanical stress

Question 23

DNA repari system includes reviewing and mutation repair. T OR F

Answer 23

F. proofreading (DNA synthesis) and mismatch repair

Question 24

describes others of DNA repair ssystems

• nucleotide excision repair: heals __ ___ & dmage that disrupt __ ___
  for eample xeroderma ___ caused by mutation when NER is ineffective
  => SKIN CANCER
  => is _____, tumour

non-___ end __ & homologous ____ reparis 2x stranded break

Answer 24

pyrimidine dimers / 2x helix
pigmentosum
ohotosensitive

homologous joining / recomb

Question 25

describe transcription

Answer 25

first, core promotor sequence must be present RNA polym slides along DNA template and creates complemen. bp -> mRNA -> dissociates - transcription factor binds and recruits RNA polym @ promotor region while regulatory protein binds @ enhancer region

Question 26

combination control

Answer 26

group of protein tht works tgt to control gene expression

Question 27

differential splicing

Answer 27

splice DNA to create similar bt distinct protein, which may have diff function

Question 28

how to process mRNA in eukaryotes

Answer 28

add 5' cap w/ specific protein, done by methylated G 3' polyadenylation tail splicing

Question 29

what is splicing? why slice?

Answer 29

to < coding capacity of gene in eukaryotic cells, coding exons are interrupted by noncoding introns cut out introns to give mature mRNA

Question 30

when does things happen?

Answer 30

transcription happen in nucleus, translation cytoplasm. after mRNA processed, exxits nucleus

Question 31

how does mRNA exit nucleus?

Answer 31

exits nucleus via nuclear pore complex (large protein complex) replace cytosol-specific, RNA-binding protein with nucleus rNA-binding protein

Question 32

silent mutation

Answer 32

DNA sequence change bt not in protein sequence

Question 33

redundancy

Answer 33

more than 1 codon may code for the same am.a bt 1 codon can't code for 2 ama

Question 34

framshift mutation

Answer 34

an insertion or deletion of base

Question 35

missense mutation

Answer 35

if in the exon, a single base change in translated protein

Question 36

nonsense mutation

Answer 36

change a base tht now becomes stop codon-- prematurely terminates protein

Question 37

lose a function - ____ in impt ama residue - ____ or frmashift shoften ____ - lose structual intergrity (can't ___) gain a function: - permanent __ of ____ - toxic to cell

Answer 37

- missense - nonsense / protein - fold - ON// oncogene

Question 38

what is tRNA

Answer 38

adaptor molec have similar structures to fit into the ribosome have distinct features to fit codon and am.a 3' CCA is in all tRNA-- where amino acids attached multiple base pair, H bodn stabilizes

Question 39

features of tRNA

Answer 39

all have a similar structure to fit into ribosome have distinct feature tb truplet & am.a specific 3/ end CCA is concerved in all tRNA- a site for attachmnt of am.a

Question 40

synthesis of all protein chains in prokary + eukary begins with ________

Answer 40

Methionine

Question 41

specifity comes from: - _____tRNA synthetase = enzyme that adds _____ to tRNA correct matching of ____ of ___-______ w/ codon in ___ ___ site

Answer 41

aminoacyl / am.a anticodon aminoacyl tRNA / ribosome

Question 42

features of genetic code

Answer 42

is universal, bt have evolved once non-overlaping every codon codes for something: an ama or stop codon

Question 43

DESCRIBES tRNA

Answer 43

transfer; adapter molec - have similar structure to fit into the ribosome have distinct features to bt codon & ama specific 3' CCA is in all tRNA -- where ama attaches multple bp- H bond stabilizes

Question 44

describes translation

Answer 44

mRNA binds to ribosome from 5' to 3'-> tRNA makes protein from N to C terminus (alpha amino to alpha carboxyl) as mRNA reads a codon @ time, tRNA delivers corresponding ama energy for peptide bond synthesis comes from aa-tRNA ester bond-- indirectly from aTP

Question 45

specifty comes from _____ tRNA ___ = enzyme that adds am.a to ____ correct matching of aminoacyl's ___) to _____'s codon

Answer 45

aminoacyl synthetase / tRNA anticodon / ribosome