Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

B. BIO/BIOCHEM MCAT > DNA > Flashcards

DNA Flashcards

You may prefer our related Brainscape-certified flashcards:
MCAT flashcards Biology 101 flashcards
1
Q

Polymerase chain reaction

A

PCR is a technique to make copies of a sample of DNA in the lab.
Consists of repeated cycles of heating and cooling.

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

Polymerase chain reaction

Taq polymerase

A

Key property is heat stability. DNA polymerase isolated from a bacteria for usage in vitro.

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

Polymerase chain reaction

Primer

A

The primers used in PCR must have high G-C base pair content with a G or C on either end.

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

Polymerase chain reaction

Step 1. Denaturation

A

High temperature is used to denature the template DNA in a tube

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

Polymerase chain reaction

Step 2. Annealing

A

Cool temperature allows for the DNA primers to anneal.
Note that either DNA or RNA primers could be used, although DNA primers are more commonly used

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

Polymerase chain reaction

Step 3. Extension

A

Moderate temperature (e.g. 72°C) allows for activity of Taq polymerase

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

Nucleic Acid Structure

Nucleoside

A

Composed of a 5-carbon sugar and a nitrogenous base.
Unlike nucleotides, they do not have phosphates.

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

Nucleic Acid Structure

Nucleotides

A

The structural unit of DNA and RNA.
Consist of a nucleoside plus phosphate groups.

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

Nucleic Acid Structure

Nucleotide bonds

A

Nucleotides are joined by phosphodiester bonds. The link between the sugar and the base within a nucleotide is a glycosidic bond.

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

Nucleic Acid Structure

Base pairing

A

A pairs with T or U and C pairs with G.
Base pairs are held together by hydrogen bonds.
A-T forms two H bonds. C-G is a stronger interaction that forms three H bonds.

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

DNA repair

Mismatch repair

A

Repairs an erroneous pairing (e.g. G-T).
A segment of the DNA is removed → DNA polymerase replaces it with correct sequence → sealed with DNA ligase

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

DNA repair

Nucleotide excision repair

A

Fixes structural issues, for example thymine dimers caused by UV radiation.
Removes the segment of DNA and replaces it.

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

DNA repair

Base excision repair

A

Fixes base mutations, for example when a cytosine gets deaminated into uracil.
Removes a single nucleotide and replaces it with the correct nucleotide.

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

Bases, structure and mnemonic for nitrogenous bases purines and pyrimidines

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

Oncogene precursors

Proto-oncogene

A

Genes that stimulate growth. If mutated with gain of function, they can become oncogenes and cause cancer.

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

Oncogene precursors

Tumor suppressor genes

A

Genes that suppress growth. If mutated with loss of function, this can cause tumors.

17
Q

DNA structure

Watson-Crick model

A

Describes the 3D structure of DNA as a double-stranded helix with antiparallel strands.

18
Q

DNA structure

Chromosome structure

A

A chromosome consist of two identical sister chromatids, held together by a centromere.

19
Q

DNA structure

Centromeres

A

The middle portion of chromosomes. Function to keep sister chromatids together until separation during anaphase.
Need to maintain a strong bond so have higher proportion of C-G base pairs.

20
Q

DNA structure

Telomeres

A

The end portion of DNA that becomes shorter through rounds of replication.
Repetitive structure with noncoding sequences, that function to protect DNA from breakdown.
Only found in eukaryotes.

21
Q

DNA structure

Restriction sites

A

These are locations in the DNA sequence that can be cut by restriction enzymes.
Each enzyme will cut a specific DNA sequence where the two strands are palindromes.

22
Q

DNA stability

Structural interactions

Two main interactions contribute to stabilizing the double helix structure in DNA:

A
  • Hydrogen bonding between nitrogenous bases in opposite strands
  • Base stacking interactions between aromatic rings of bases
23
Q

DNA stability

Denaturation

A

Under disruptive conditions, the double-strand helix can come apart, called denaturation.
At the melting point (Tm), half of the DNA is denatured and single-stranded, half is double-stranded.

24
Q

DNA stability

Factors in stability

A
  • Higher G-C base pair content results in higher stability
  • Acidic or basic pH can denature DNA
  • High salt concentration will stabilize DNA due to ionic interactions
  • DNA molecules that have greater length take longer to denature
25
Q

DNA replication

Topoisomerase

A

Unwinds the DNA helix by uncoiling it

26
Q

DNA replication

Helicase

A

“Unzips” the DNA helix by separating the strands

27
Q

DNA replication

Single-stranded DNA binding protein (SSB)

A

Prevents re-annealling of the separated single-stranded DNA

28
Q

DNA replication

DNA primase

A

Synthesizes RNA primers that anneal to the single-stranded DNA, starting replication

29
Q

DNA replication

DNA polymerase

A

Synthesizes new nucleotides in a 5’ to 3’ direction, reading the template DNA in a 3’ to 5’ direction.
At the end of replication, removes the RNA primer.

30
Q

DNA replication

DNA ligase

A

The lagging strand is synthesized piecewise, with the pieces called Okazaki fragments.
These pieces are then connected by DNA ligase.

31
Q

DNA versus RNA

A
32
Q

Organization of DNA

Nucleosomes

A

A unit of DNA wrapped around a core of histone proteins.

33
Q

Organization of DNA

Histones

A

Proteins that can affect the expression of DNA. If DNA is more tightly wound around a histone, expression will decrease because their DNA is less accessible.
Histones are positively charged whereas DNA is negatively charged.

34
Q

Organization of DNA

Histone acetylation

A

The process of adding an acetyl group to lysine residues in the histone.

This results in a decrease in the positive charge of the histone, loosening the coupling and increasing DNA expression.

35
Q

Organization of DNA

DNA methylation

A

Methylation of base pairs will increase the coupling between histones and DNA and result in decreased expression.

36
Q

Organization of DNA

Chromatin

A

Composed of a mass of DNA plus histones.
Heterochromatin is dense and inactive while euchromatin is uncondensed and expressed.

B. BIO/BIOCHEM MCAT (29 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions