Exam 1 Flashcards
(103 cards)
1
Q
What are the steps of central dogma?
A
DNA synthesis (replication)-. RNA synthesis (transcription)-> protein synth (translation)
2
Q
What is DNA composed of
A
2 strands of nucleotides
3
Q
How are the nucleotide strands held together
A
hydrogen bonding
4
Q
what are the 4 nitrogenous bases
A
A C G T
5
Q
what does anti-parallel mean
A
opposite 5 to 3 and 3 to 5’
6
Q
What are the prymidines
A
cytosine (C), thymine (T, DNA), and Uracil (U, RNA)
7
Q
what are the purines
A
Adenine (A) and Guanine (G)
8
Q
Do G to C have 2 or 3 hydrogen bonds
A
3
9
Q
whats the ratio for nucleotides and amino acids in the genetic code
A
4 nucleotides encode for 20 amino acids of proteins
10
Q
what is a complete set of info of DNA
A
genome
11
Q
How is eukaryotic DNA packaged
A
into discrete chromosomes (23)
12
Q
DNA in combination with organization proteins is
A
chromatin
13
Q
what are homologous chromosomes
A
chromosome pair (maternal and paternal) minus sex chromosome
14
Q
what specialized DNA sequence links duplicate chromosomes during cell division
A
centromere
15
Q
What organisms have larger genome
A
more complex organisms (minus amoeba)
16
Q
what proteins are involved with compaction
A
Histones
17
Q
combination of protein and DNA
A
chromatin
18
Q
how many histones form a protein bead
A
8
19
Q
what is it called when DNA coils around these protein beads
A
nucleosome
20
Q
what is an octamer
A
nucleosomes that have 2 of each histones
21
Q
What does the H1 histone do
A
further compacts the “beads on the string”
22
Q
what uses ATP hydrolysis to slide DNA around a histone
A
chromatin- remodeling
23
Q
How does DNA replicate
A
chromosome is duplicated using itself as a template
24
Q
how is DNA semi-conservative
A
daughter molecule contains one of the parent strands
25
where does DNA replication start
origin of replication
26
How is DNA split during cell replication
with specialized enzymes
27
where are replication origins typically enriched?
A-T because they only share 2 hydrogen bonds
28
what begins splitting the DNA
the replication fork
29
which strand is continous and which is fragmented
leading= continuous
lagging has Okazaki fragments
29
how is the replication fork asymmetrical
there is a leading and lagging strand
30
what unwinds the double strand
DNA helicase
31
what prevents the formation of the double helix
single-stranded binding proteins (SSB)
32
What does primase do
creates short RNA primer so the DNA polymerase can begin
33
What synthesizes new DNA by adding nucleotides to existing strand
DNA polymerase
34
what corrects some errors made by DNA polymerase
exonuclease
35
what does primase make
RNA
36
difference betweenn making DNA and RNA
DNA needs primers
37
What fills in the gaps after the RNA primers are digested
ligase
38
What did Meselson and Stahl discover
that DNA is semiconservative
39
What keeps DNA polymerase attached to DNA
sliding clamp protein
40
what attaches the clamp protein
clamp loader protein
41
what separates RNA primer from DNA strand
nuclease
42
repair polymerase
Replaces RNA with DNA
43
what creates temporary breaks in DNA strand to relieve torsional stress
topoisomerases
44
What is a permanent error in DNA
mutation
45
negative consequences of mutations
leads to diseases
46
positive consequences of mutations
can cause resistant to infections (malaria)
47
what happens in mismatch repair
errors by the replication machine remove the new synthesized DNA and DNA polymerase and ligase fix gap
48
what are the three types of mutations
substitution, insertion, and deletion
49
substitution
changes from one base to another
50
insertion
extra base pairs are inserted into genome
51
deletion
base pairs are removed from genome
52
what happens during a frameshift
insertion and deletion cause the genetic code to read incorrectly during translation and transcription
53
what happens during depurination
loss of A or G, can be repaired or become permanent mutation
54
what happens in deanimation
loss of amino group on C/U
55
steps to DNA repair pathway
1. removal of erroneous nucleotides via nucleases
2. DNA repair polymerase fills gaps using the undamaged strand
3. ligase seals the nick on the repaired strand
56
what causes double strand breaks
radiation, chemicals, errors around replication fork
57
gene expression
transcription converts DNA to RNA and the translation converts RNA to proteins
58
how does RNA differ from DNA
1. RNA contains ribosomes, not deoxyribose
2. RNA contains U instead of T
3. RNA is typically single-stranded
59
what does RNA polymerase do
builds an RNA strand one nucleotide at a time, doesn't require a primer
60
whats mRNA
RNA that will be converted to amino acids (proteins) called messenger RNA
61
rRNA
component of ribosomes (protein machine)
62
tRNA
move amino acids to ribosomes, match them to appropriate codons
63
microRNA
regulate gene expression by base pairing to mRNA silencing them by cutting them apart
64
what is a promoter
a specific sequence within DNA that signals the start of a gene for transcription
65
what is the terminator
where transcription ends the polymerase encounter
66
what does RNA polymerase ll do
trnasribe genes that code for mRNA and miRNA
67
what does RNA polymerase l and lll do
transcribe genes that code for tRNA and rRNA
68
what does RNA polymerase ll require
transcription factors
69
what does transciption factor TFllD do
binds to a promoter region known as a TATAbox (composed mainly of A and T nucleotides
70
what does mRNA need to receive before translation
it needs further processing. must receive a 5' cap and 3' polyA tail --> to stabilize mRNA and for it to be transferred out of the nucleus
71
Eukaryotic RNA need an extra step
needs introns and exons
72
what do introns do
a noncoding sequence that are interspersed in a coding sequence
73
what do exons do
coding region between introns
74
what do spliceosomes do
carry out RNA splicing in the cell and recognize common introns
75
what cuts out the introns
lariat (lasso)
76
alternative splicing do
transcripts several different ways to produce a variety of proteins from a single transcipt
77
where is mRNA exported
from the nucleus to the cytoplasm
78
what degrade mRNA after use
RNAses
79
which mRNA lifespan is shorter bacterial or eukaryotic
bacteria (3 min), eukaryotic last (30 min- 10 hours)
80
what is the genetic code
-set of rules that describe how a nucleotide sequence of a gene encodes a protein through mRNA
81
what is a codon
a set of 3 nucleotides code for a single amino acid
82
t/f the genetic code is redundant
true
83
what does the genetic code being redundant mean
most amino acids have more than one codon that codes for them
84
what are the three stop codons
UAA, UAG, UGA
85
what translates genetic code to proteins
tRNA
86
what links amino acid to tRNA
aminoacyl-tRNA synthetases
87
what are the protein manufacturing machines
ribosomes
88
where does the RNA message decode
ribosomes
89
what is the ribsome made of
a large and small subunit
90
what are the three binding sites for tRNA
E, P, and A site
91
function of E site
discharged tRNA exit at this site
92
function of P site
tRNA at this site carry the growing peptide chain
93
function of A site
accepts incoming charged RNA
94
what do release factors do
bind to stop codons instead of tRNA- waters added abd peptide chain is releases and ribosomal complex falls apart
95
what is needed to start protein synthesis
initiator RNA
96
where is intiator tRNA loaded
P site
97
how is translation started with ribosomes
1. subunit attaches to mRNA until encounters start codon
2. initator factprs fall away and large ribosomal binds
3. begin protein synth woth tRNA added to A site
98
clusters of genes that direct different steps in the same process that are transcribed together in same mRNA
operons
99
what increases the rate of translation for each mRNA
polyribosomes
100
what destroys proteins by breaking peptide bonds between amino acids
protease
101
what do 'stoppers' do
bind to proteins tp be degrade, unfolded, and thread into inner chamber
102
what disrupts prokaryotic protein synth
antibiotics
