Unit 2: Lecture 2 Flashcards

1
Q

In a set of 23 pairs of chromosomes, each chromosome has 2 chromatids. How many DNA double helices are there?

A

92

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

How many chromatids does a chromosome have?

A

each chromosome has 2 chromatids before the cell divides

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

How many pairs of homologous chromosomes do we have?

A

23

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

Where does each chromosome in a pair of chromosomes come from?

A

one chromosome from mother, one from father

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

What are the monomers of nucleic acids? What is its directionality?

A

nucleotides with 3’ and 5’ directionality based on numbering of ribose sugar

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

Whta is a nucleotide?

A

nucleoside + phosphate groups

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

What is a nucleoside?

A

ribose (in RNA) or deoxyribose (in DNA) sugar + base

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

What is the nucleoside of adenine?

A

adenosine

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

What is the nucleoside of guanine?

A

guanosine

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

What is the nucleoside of uracil?

A

uridine

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

What is the nucleoside of cytosine?

A

cytidine

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

What is the nucleoside of thymine?

A

thymidine

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

What is the nucleoside in ATP?

A

adenosine

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

What are nucleotides important carriers of?

A

chemical energy (ie. ATP)

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

What are nucleotides in DNA and RNA linked by?

A

phosphodiester bonds

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

Which carbon would a nucleoside triphosphate be added to a growing nucleic acid?

17
Q

What are the levels of structure of DNA?

A

primary (sequence)
secondary (double-helix)
tertiary (chromatin)

18
Q

What is the double-stranded DNA structure due to?

A

non-covalent interactions:

  • H-bonds between bases
  • stacking hydrophobic reactions
19
Q

What features of Watson and Crick’s double helix model of DNA are energetically favoured due to increased entropy of
water?

A

the base pair cluster inside the double helix

20
Q

What do stacking interactions in a double helix do?

A

help stabilize the strands and support the H-bonds between the bases

21
Q

Describe base stacking interactions.

A

purine and pyrimidine bases are essentially hydrophobic

22
Q

Why is DNA a double helix?

A
  • sugar phosphate backbone (negatively charged) is hydrophilic, so
    they face the solution
  • bases project towards the center, stacked one on top of the other, form a hydrophobic core, away from aqueous solution
  • bases can H-bond with each other.
23
Q

What are Chargoff’s rules of DNA base pairing?

A

purines are based with pyrimidines

  • AT base pairs form 2 H-bonds
  • GC base pairs form 3 H-bonds
24
Q

Which DNA sequences would denature at the lowest temperature?

A

AT has fewer H-bonds therefore, the sequences with more As and Ts will denature at the lowest temperature

25
What do mutations lead bases to?
mismatch, disturbed geometry
26
Why are purines and purines not paired?
not enough space
27
Why are pyrimidines and pyrimidines not paired?
too much space
28
Describe the uniform structure of the general geometry of Chargaff's base pairs.
purine-pyrimidine pair - same distance between bases on the two strands - same, regular hydrogen bonding pattern - same stacking interactions between bases above and below
29
What are the structural differences between RNA and DNA?
- RNA: 2' hydroxyl (OH) group DNA: 2' H, lacks an O --> "deoxy"ribose - RNA: AUGC DNA: ATGC
30
What does the hydroxyl group of RNA do?
the additional OH (reactive functional group) makes RNA less stable than deoxyribose
31
What is DNA replication?
copying DNA for cell division hereditary information is transmitted from generation to generation
32
What is transcription and translation?
genes provide the information to synthesize RNA or proteins for the cell transcription: gene expression, DNA template transcribed to RNA translation: protein synthesis, mRNA codons translated into protein primary structure