Brainscape's Knowledge GenomeTM

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


See full index

BIOLOGY HL > Nucleic Acids > Flashcards

Nucleic Acids Flashcards

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

What are nucleosomes

A

They consist of 8 histones which are wrapped around DNA

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

What is the function of nucleosomes

A

Helps supercoil DNA, which helps regulate transcription + facilitates the movement of chromosomes during cell division

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

What is the difference between the leading and lagging strand

A

lagging = not made continuously, as it is made of Okazaki fragments (away from fork)
leading = made continuously (towards fork)

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

In what direction can DNA Polymerase add nucleotides

A

5’ to 3’

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

In what direction does DNA replication occur

A

5’ to 3’

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

What are the stages of DNA replication pt.1

A
  1. Helicase unwinds the double helix by breaking H bonds
  2. DNA Gyrase relieves the strain of DNA
  3. Single-stranded binding proteins keep the separated strands apart whilst the template is copied
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the stages of DNA replication pt.2

A
  1. DNA primase generates short RNA primers on the template strand, providing a point of initiation for DNA polymerase III to add nucleotides
  2. DNA polymerase III links the nucleotides to their complementary base pairings in a 5’ to 3’ direction
  3. DNA polymerase I removes the RNA primers on the leading and lagging strands and replaces it with DNA nucleotides
  4. DNA ligase joins up the Okazaki fragment through the formation of covalent bonds
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are non-coding genes

A

They don’t make proteins/polypetides

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

List non-coding genes

A

S.T.I.N.G (short tandem repeats, telomers, introns, promoters, tRNA, rRNA, enhancers and silencers)

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

What are silencers

A

DNA sequences that bind to regulatory proteins called repressors that inhibit transcription (non-coding)

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

What are promoters

A

a DNA sequence that initiates transcription (non-coding)

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

What are enhancers

A

DNA sequences that increase the rate of transcription (non-coding)

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

What is the function of telomeres

A

prevents the DNA molecule from degradation during replication (non-coding)

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

How is DNA replication stopped

A

DDNA lacks the hydroxyl group to form a covalent (phosphodiester) bond, which prevents the elongation of the nucleotide chain and stops DNA replication at the point at which it is added

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

In what direction does transcription occur

A

5’ to 3’

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

Where does transcription begin

A

At the promoter region. It is the binding site for RNA polymerase for the initiation of transcription.

17
Q

Explain the stages of transcription

A
  1. Initiation (RNA polymerase once attached to the promoter region, unwinds the DNA)
  2. Elongation (RNA polymerase moves along the anti-sense strand, it adds free RNA nucleotides according to their complementary base pairings in a 5’ to 3’ direction, synthesising a strand of RNA)
  3. Termination (RNA polymerase reaches the termination region and terminates transcription by releasing the mRNA and the RNA polymerase + DNA rewinds)
18
Q

How is gene expression regulated

A

Through regulatory transcription factors
- Activator proteins bind to enhancer sequences and increase the rate of transcription
- Repressor proteins bind to silencer sequences and decrease/block transcription

19
Q

How do nucleosomes help regulate transcription

A

The tails of histones can be chemically modified which can influence whether a gene will be expressed or not (methylation & acetylation)

20
Q

Outline methylation

A

Adding a methyl group will cause the DNA to be more tightly wrapped around the histone. This results in fewer genes being able to be transcribed and thus decreasing the rate of transcription or gene expression

21
Q

Outline acetylation

A

Adding an acetyl group will cause the DNA to be less tightly wrapped around the histones. It allows the gene to be transcribed more often. It increases the rate of transcription/gene expression.

22
Q

Why does post-transcriptional modification of mRNA occur

A

To prevent the degradation of the mRNA because the locations for transcription and translation are separated by the nuclear membrane (unlike prokaryotes)

23
Q

Which are 3 post-transcriptional events must occur to form mature mRNA

A
  • A methylated cap is added to the 5’ end to protect against degradation by exonucleases
  • A poly-A tail is added to the 3’ end for further protection and to help the transcript exit the nucleus
  • Non-coding sequences are removed through mRNA splicing
24
Q

Contrast the function of free ribosomes and RER ribosomes

A

Free: produce proteins for use within the cell and can only move within the cytoplasm
RER: produce proteins to be secreted outside the cell

25
Q

What are the 3 tRNA binding sites

A

A: the mRNA codon joins with the tRNA anticodon)
P: the amino acids attached to the tRNA are joined by peptide bonds
E: the tRNA exits the ribosome

26
Q

Outline initiation (translation)

A
  • Small ribosomal unit binds to the 5’ end of the mRNA
  • AUG = start codon
  • tRNA with the complementary anticodon binds to the codon and occupies the P site on the ribosome
  • The large ribosomal subunit binds to the small subunit
27
Q

Outline Elongation (translation)

A
  • A second tRNA molecule attaches to the mRNA at the A site on the ribosome
  • The amino acid in the P site attaches via a peptide bond to the amino acid in the A site
28
Q

Outline translocation (translation)

A
  • The ribosome moves along the mRNA one codon shifting the tRNA that was attached to methionine to the E site
  • The tRNA is released back into the cytoplasm from the E site allowing it to pick up another amino acid to build another polypeptide
29
Q

Outline termination (translation)

A
  • The process of elongation continues until the ribosome reaches a stop codon (signals for translation to stop)
  • The polypeptide chain and mRNA are released from the ribosome
30
Q

Outline the DNA Structure

A
  • antiparallel
  • A-T (2 H bonds), C-G (3 H bonds)
  • purines (A,G) & pyrimidine (C,T)
  • semi-conservative
  • double helix

BIOLOGY HL (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions