test 3: nucleic acid Flashcards
1
Q
what are the nitrogenous bases
A
cytosine, thymine, uracil , adenine and guanine
2
Q
what are the pyramidine bases
A
cytosine, thymine, uracil
3
Q
what are the purine bases
A
adenine, guanine
4
Q
what absorbance do all of the bases have
A
260 nm
5
Q
what is a common tautomeric form
A
lactam(keto)
6
Q
what is a rare tautomeric form
A
lacti (enol)
7
Q
what is a nucleoside
A
base+ sugar
8
Q
what is sugar
A
D ribose or 2-deoxy-D ribose
9
Q
what connects nucleosides to the base
A
B-N-glycosidic bond
10
Q
how is a nucleoside numbered
A
1st number goes to where the base is attatched to the sugar and then 5 is HOCH2
11
Q
what is a nucleotide
A
nucleoside + phosphate
- phosphoric acid is extrified with an -OH of the monosacc either the 3’ or the 5’OH
12
Q
what does esterified mean
A
an acid reactions with an alcohol to make an ester
13
Q
what is 3-5 cyclic adenosine monosphosphate (cyclic adenosinde monophosphate, cAMP)
A
- derived from ATP
- used in intracellular signal transduction( signalingn) as a second messenger
14
Q
wht does the 2nd messenger do in signal transduction
A
amplifies the signal
15
Q
wht are the bases for DNA and RNA
A
dna: ATGC
RNA; AUGC
16
Q
what are the nucleoside names based off of the base
A
- adenine= adenosine
- guanine= guanosine
- cytosine= cytidine
- Uracil = uridine
- thymine = deoxythymidine
17
Q
what is an example of a nucleoside/ tide in medicine
A
- antivirals
- zidovudine = nucleoside analog reverse transcriptase inhibitor
18
Q
what does NRTI do
A
used to treat HIv
19
Q
zidovudine is what analog
A
uracil
20
Q
what is emtricitabine
A
- used for the treatment of HIV in adults
21
Q
what analog is emtricitabine
A
cytosine analaog
22
Q
what contains minor bases in RNA
A
tRNA
23
Q
what does a methylated form of a major base mean in DNA
A
- role of regulating and protecting genetic info
24
Q
what are the names of the xanthines
A
hypoxanthine, inosine, xanthine
25
where is inosine found
in tRNA for wobble base pairs
26
what structure is this
hypoxanthine
27
what structure is this
inosine
insoine = Hypoxanthine + ribose
28
what structue is this
xanthine
29
what are polynucleotides
- nucleic acids
- joined by phosphodiester linkage
30
what is the primary structure of dna and rna
- sequence read from 5' to 3' end
- RNA: 5'-AUCG-3' or AUGC
31
what bond is this showing
phosphodiester bond
32
what structure is this
phosphoester
33
what is RNA's problem
stability
34
what is RNA susecptible to
base catalyzed hydrolysis
35
what makes RNA unstable
- 2 OH group
36
who examined base rations from bacteria and plants and founded chargaffs rules
erwin chargaff
37
what was chargaffs rules
A = T
G= C
38
who discovered complementary base paiting
watson and crick
39
who did X ray fiber diffraction
rosalind franklin
40
who knew it was a helix
francis crick
41
what is the central dogma of biology by francis crick
framework that dscribes the flow of genetic information
- dna to rna = trancription
-rna to protein = protein translation
42
what are some characteristics of B DNA structure
- right hand helix
- bases perpen to the helix axis
- wide and deep major; narrow and deep minor
- phosphate backbones on outside
- pitch = 10 bases per turn = 34 angstroms
- helix rise per basepair = 3.4
43
what grooves does B DNA have
- wide and deep major, narrow and deep minor
44
what is the pitch of B DNA
- 10 bases per turn = 34 angstroms
45
what is the helix rise for B DNA
- 3.4 angstroms
46
is B DNA antiparallel
yes
47
what is anti conformation in base
the base is rotated away from the sugar
48
what is syn conformaiton
the base is rotated towards the sugar
49
which one is syn which one is anti
syn is on the left and anti is on the righ
50
what structure is this
a dna
51
what dna is this
b dna
52
What type of groove does Z have
major flat
minor: narrow and deep
53
what tyeo of groove does A have
major groove: narrow and deep
minor: wide and shallow
54
what structure is the one on the far left
Z dna
55
what structure does RNA-RNA/ RNA DNA hybrids assume
A dna like structure
56
which occurs in alternating purine -
z dna
pyramidine tracts and is favored in high salt conc
57
what are telomeres
the end of chromosomes
58
what tyoe of dna does the telomers have
tetraplex or quadruplex dna
59
what does tetraplex or quadruplex dna have a role in
- transcription, telomere maintenence, dna recom
60
what is the structure of rna
- single stranded
- double helical regions that assume tupe A helix
61
what structure is this
rna
62
describe the tertiary structure of tRNA
- cloverleaf secondary structure'- L or banana tertiary structure
63
dna supercoling topology: what are the different super coiling
positive and negative
64
what is positive supercoiling
- dna DH is twisted in the same direction as the natural right handed helical twist
- makes it tightly wound
65
what is negative supercoiling
- dna is twisted in the opposite direction
- easier to seprate strands for transcription and replication
66
what supercpil do most natrual dna in cells use
negative supercoil
67
how does supercoiling occur in linear dna
both strands are anchored
68
what are the enzymes that affect dna superstructures
- topoisomerases
-type 1 and type 2
69
what does topoisomerase do
- relax or make supercoils in dna by causing a transient nick that is resealed
70
what does type 1 do
relax supercoils by breaking 1 strand( ssDNA) break
71
what does type 2 do
relax or make supercoil by breaking two strands
72
where are topoisomerase inhibitors uesed
in anticancer and antibacterial agents like quinolones
73
what is the size of a human dna molecule
3,200,000 Kb
74
describe the dna in prok
- supercoiled circular dna that is bound to basic proteins = bacterial chromosomes in the nucleoid
75
what is a separate small circular molecules that carries genes for their own replicaton adnd code for benefical enzymes like antibiotic degredation
bacterial plasmids
76
euk. package dna as what
chromatin at normal stage of cell cycle; chromosomes when cells are ready to divide
77
what is dna coiled around
histone octamer called a nucleosome
78
what are the types of histones
H2A, H2B, H3, and H4 (2x)
79
how many turns of dna arouund the nucleosome
1.8
80
what amino acids are histones rich in
lysine and argine whose sides chains have a +Ve charge
81
what charge is dna
negative (-ve)
82
what is the last histone
H1
83
what is the role of H1 histone
- linker histone
- stabilizes the chromatin fiber
- regulation of genes and chromatin
84
which structure does not have jistones
mitochondrial (mtDNA) and chloroplast DNA(ct DNA)
85
what is mito and chloroplast dna used for
forensic analysis when nuclear dna is too degraded
86
what can damage dna
UV irridation
thymine dimers(cyclobutyl dimers)
alkylation
HNO2
87
what is alkylation
causes dna mismatch mutations that can lad to cancer
88
what are some alkylating agents
- mustard gas
nitrogen mustard
89
what does HNO2 do
causes dna mismatch mutations
- food cured with NaNO2
90
