MCAT > Biochem Chapter 6 > Flashcards

Biochem Chapter 6 Flashcards

(125 cards)

Study These Flashcards
1
Q

Nucleosides are composed of how many carbon sugars

A

5 , Pentose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

When you connect sugar to what, how does it become nucleoside

A

If you connect it to nitrogenous base

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Nucleotide is what and what connected

A

Nucleoside and one more more phosphate groups attached to

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

DNA basic building blocks is called

A

Nucleotides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How can we tell difference between DNA and RNA

A

Both contain 5 carbon sugar

But difference is that

sugar is ribose in RNA, it has a hydroxyl group attached Carbon 2

Sugar is deoxycarbose, it doesn’t have oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Is RNA or DNA more stable

A

DNA is more stable because it doesn’t have hydroxyl group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

At which carbon would you find OH for RNA and DNA differentiation

A

Carbon 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Nucleoside suffix name

A

-sine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

DNA backbone is based of which 2 things

A

Sugar and phosphate groups

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

DNA is read from what prime to what prime end

A

5’ to 3’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Nucleotides are joined by what bonds

A

Phosphodiester bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Do dna and rna strands have a a positive neutral or negative charge

A

Negative because phosphates carry a negative charge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

DNA and rna
Generally double or single stranded

A

DNA double
RNA single

There are exceptions though

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the 2 purines

A

Guanine
Adenine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the 3 pyramidines

A

Cytosine
Uracil
Thymine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are purines how many rings do they have

A

2 rings

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How many rings do pyramidines have

A

1 ring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Are all purines ofund in DNA and RNA

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Are all pyramidines found in DNA and RNA

A

Uracil only rna

Thymine only dna

Cytosine both

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Purines and pyramidines are what types of heterocycles

A

Aromatic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What makes purines and pyramidines aromatic

A

Cyclic

Planar

Conjugated (alternating single and double bonds)

Follows huckle’s rule 4n+2pi to find number of pi electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Why are purines or pyramidines heeterocycles what makes it that

A

Ring structure that has at least two different elements in its ring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How did we figure out what DNA looked like what model to find out about its double helix

A

Watson and crick

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Two strands of DNA are

A

Anti parallel

One strand has polarity 5 to 3’ down the page

And the other strand has polarity 5’ to 3’ up the page

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Sugar phosphate backbone Nitrogenous base Are these located on the outside or inside of the helix
Nitrogenous base - inside Sugar phosphate backbone : outside
26
Adenine always base pairs with
Thymine
27
Adenine and thymine bond with how many H bond
2
28
Guanine always bonds to
Cytosine
29
Guanine and cytosine bond with how many hydrogens
3
30
Are AT or GC bonds stronger :
GC stronger cuz 3 H bonds
31
Are total purine equal to total pyramidines What is this rule called
Yes Chargaff rules
32
If there a sample of DNA with 10% G, what is percent of T?
G is 10, so C is 10 100-20=80 A and T = 80 So T is 40%
33
Hydrogen bonding and what stabilizes the helix
Base stacking - vanderwaals interactions between aromatic bases and when they stack on top of each other
34
Most common form of DNA found is
B-DNA
35
What is BDNA How often does it turn, within how many nm and bases
It is a right handed helix Turns every 3.4nm and 10 bases within span
36
What is the left. Handed helix called
ZDNA
37
How quickly do ZDNA turn in nm and in bases
Turns every 4.6nm 12 bases per span turn
38
When doles ZDNA show up more , 2 reasons
High GC content Unusual super coiling
39
Denaturation of DNA strands meaning - what bonds break - what are ways to make this happen - what is result
Happens when hydrogen bonds between base pairs break Using chemical , high heat Produces single stranded DNA
40
When denaturing conditions are removed and strands pair again, what is that process called
Reannealing
41
Denaturation and reannealing happens most in which lab process
PCR
42
DNA contains coding regions called
Genes
43
DNA is divided into how many chromosomes in humans
46
44
What are positively charged molecules that help wind DNA wrap tightly
His tones
45
What his tone complexes form nucleoside
H2A, H2B, H3 and H4 make the core and dna base pairs wrapper around to form this
46
Which histone promotes further packaging into smaller compact chromatin packages
H1
47
Example of nucelotportein
Histone
48
What is heterochromatin - in terms of how it looks - transcriptionally active or silent
Dark, dense and solid Silent
49
What is euchromatin - in terms of how it looks - transcriptional active or silent
Less dense, Active DNA
50
What are telomeres - where they located on chromosome, - high in which nucleotide pair content -prevents what - disadvantage
Ends of chromosomes High GC content Prevent unravelling of DNA Each time slowly shortened after replication
51
Telomeres can be reversed with
Telomerase
52
What is centromeres for - where are they - what is use, and until when - high in which nucleotide pair content
High in GC content Found in middle Hold sister chromatisds together after DNA replication until they are separated during anaphase in mitosis
53
What are telomeres and centromeres main functioning in summary
Protecting integrity of DNA during replication
54
Unwinding of prokaryotic cell and eukaryotic cells is done by
Helicase
55
Steps of replication (4)
Finding the origin of replication Unwinding double helix Stabilization of unwound template strand Synthesis of RNA primers
56
How many origins of replication in prokaryotic cells and eukaryotic cells
1 per chromosome in prokaryotes Multiple per chromosome in eukaryotes
57
Synthesis of RNA primers in prokaryotes and eukaryotes is by
Primase
58
Origin of replication number for prokaryotic and eukaryotic cells
Prokaryotes 1 per chromosome Eukaryotes multiple per chromosome
59
Unwinding of DNA double helix is done by what
Helicase
60
Stabilization of unwound template strand in DNA replication is done by what always
Single stranded DNA binding protein
61
Synthesis of RNA primers in DNA replication is always by
Primase
62
What is replication seen as semiconservative
Because one parental strand is retained in each of hte two resulting identical double stranded DNA molecules
63
DNA polymerase reads form what to what direction
3 to 5
64
Which way does rna translation and tracnscription occur ( 5 to 3, or 3 to 5)
5 to 3
65
Synthesis of DNA in prokaryotic cells is done by
DNA plmyerase III
66
Synthesis of DNA in eukaryotes is done by which 3
DNA polymerase Alpha, delta, epsolum
67
What removes RNA primers in prokaryotes
DNA polymerase I , 5’ to 3’ exonuclease
68
What removes RNA primers in eukaryotes
RNase H (5’ to 3’ exonucelase )
69
Replacement of rna with dna in prokaryotes in by
DNA polymerase I
70
Replacement of RNA with DNA is done by what in eukaryotes
DNA polymerase delta
71
Joining of Ozaki fragments is always done by
DNA ligase
72
What bonds does DNA ligase make
Phosphodiester bond s
73
Removal of positive supercoils ahead of advancing replication forks is done by
DNA topoisomerase
74
Leading strands what is it Which side is it read which side is it synthesized
Leading strand is the one that is copied 3’ to 5’ for reading Synthesized oppositely
75
What is lagging strand
The strand that is copied in a direction oppposite the direction of replication fork
76
What is released during DNA replication
Phosphates
77
What is the sliding clamp for in DNA replication
Strengthen interaction between DNA polymerases and template strand
78
What is the complex that helps DNA polymerases
Replisome Replication complex
79
What does topoisomerase do
Prevents supercoiling ahead , temporary cuts in DNA and allowing it to relax
80
What does single stranded dna binding protein do
Prevents reannealing of DNA double helix during replication
81
Primase functionn
Places RNA primer to start DNA replication
82
What is the purpose of dna polymerase II and alpha
Add nucleotides to daughter strand
83
What does DNA polymerases I do
Fills in the gaps left behind after RNA primer excision
84
What does RNase H do
Cuts out RNA primer
85
DNA ligase purpose
Joins the strands together between ozakazi fragments
86
Oncogenes what they do
Mutated genes promote unchecked cell division
87
How d tumor suppressor genes work Name one
P53 Protect cancer by halting cell cycle or repairing DNA
88
Is the leading strand or lagging strand more prone to mutations
Lagging because it constantly has to start and stop the process of DNA replication Has more primers , so more have to be fully remove to fill with DNA
89
In DNA repair, there is replication error and damaged bases What is meaning
Replication error is correcting the errors after DNA synthesis Damaged bases is fixing chemical or environmental damage anytime during cell cycle , not relating to replication
90
What are the 2 ways for replication error dna repair
Proofreading Mismatch repair
91
How does proofreading work in dna repair
DNA polymerase detects unstable base pair and excises and replaces it
92
What processs is used in proofreading
Methylation
93
At which part of celll cycle doles mismatch repair occur
G2
94
What is mismatch repair
Detecting and removing errors that happens in replication that were missed in the S phase
95
What are the two genes in mismatch repair that help with detecting and removing errors in S phase of cell cycle What are the homologous of these n prokaryotes
MsH2 and MLH1 MutS and MutL
96
What are hte two forms of fixing damaged bases in DNA repair
Nucleotide excision repair Base excision repair
97
What is nucleotide excision repair What cuts it, what fills the gap, what seals it
Excision endocnuelase cuts both sides of the lesion to repair bulky lesion DNA polymerase fills gap Ligase seals it
98
What is a type of base excision repair
Using thermal energy It can be absorbed by DNA, and the cytosine will turn into uracil And because uracil can;t be found in DNA, it is easily detected as an error
99
How doles base excision repair work - what does it work on What removes base What site is created What cuts after What fills gap What seals it
Repairs small non bulky damage Glycosylase removes base AP site is created AP endonuclease cuts back-bone DNA polymerase fills gap Ligase seals it
100
How does DNA polymerase know which stand is template strand once daughter strand is synthesized
Methylation Parent strand is heavily methylated and daughter strand not so much
101
Which phases do these repair mechanisms work in cell cycle Proofreading Mismatch repair Nucleotide excision repair Base excision repair
S G2 G1/G2 G1/G2
102
What does recombinant. DNA let us do
Allow us to use dna fragments from any sourced to either be multiple by gene cloning or polymerase chain reaction
103
DNA cloning uses what enzymes to do what Where do they insert them into
Restriction enzymes to cut DNA and insert into vectors like plasmids, this makes recombinant DNA
104
What does it mean when we say tht restriction enzymes in recombinant DNA technology are palindronic
It means the 5’ to 3’ sequence of one strand is identical to the 5’ to 3’ strand of the antiparallel strand
105
Why is it good for restriction enzymes to create sticky ends
For easy insertion into vectors
106
What are dna libraries
Collection of cloned dna sequences
107
What are the two types of dna libraries
Genomic library CDNA libraries
108
What is inside genomic libraries
Entire genomes with exons and introns They are not ideal for identifying expressed genes
109
Exon and intron Which one is coding and non coding
Exon is coding and intron is noncoding
110
What can be found in cDNA libraries - how does it come about - what genes it contain
Comes from reverse transcribed mRNA Only contains genes that were actively expressed ( no introns )
111
What is hybridization - does it happen between DNA and. DNA - does it happen between DNA and RNA
Joining complementary base pair sequences Both
112
What are the two ways of hybridization in gene biotech
Polymerase chain reaction Southern blotting
113
What does polymerase chain reaction (PCR) do
Produces millions of copies of a dna sequence without amplifying dna in bacteria
114
What are the 5 things needed for a PCR to work
DNA sample Free nucleotides Taq polymerase Primers Buffer
115
Does PCR need heat to work
Yes to cause the double helix to melt apart and denature
116
What are the steps of PCR (3)
DNA strands dentuare and separate Primers bind to the template and annealing occurs New strands are synthesized and sequence is extended
117
How does gel electrophoresis work with DNA
DNA is negatively charged so these strands will migrate to anode end The longer the strand of DNA the slower it will migrate in the gel
118
What does a southern blot do
To detect presence and quantity of various DNA strands in a sample
119
What does DNA sequencing do
Helps us figure out exact order of DNA nucleotides to study genes and genetic variation
120
DNA sequences uses what modified base
Dideoxyribonucleotides (ddATP, ddCTP etc)
121
Why does adding dideooxyribonucleotide terminate the DNA chain
They lack a 3’ OH group So these can be separated by gel electrophoresis and sequence can be read from gel
122
What is gene therapy for
Introducing a functional copy of gene with a viral vector to help cure genetic deficiency
123
What are transgenic mice How are they created
Mice is inserted with a cloned gene (transgene) into their embryonic stage to learn about a disease.
124
What are knockout mice for?
A specific gene is deleted to see loss-of -function diseases
125
The resulting offspring of transgenic mice is called
Chimera
MCAT
flashcards
Decks in class (48)
# Cards
Brainscape helps you reach your goals faster, through stronger study habits.
© 2026 Bold Learning Solutions. Terms and Conditions