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BIOL 1090 > Week 5 > Flashcards

Week 5 Flashcards

1
Q

What does DNA stand for

A

Deoxyribonucleic acid

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2
Q

What is DNA

A

=at the heart of genes and genetics

  • a polymer
  • each subunit of polymer is a nucleotide
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3
Q

What are the 3 things nucleotides are comprised of

A
  1. phosphate group
  2. a 5 Carbon sugar ( 2-Deoxyribose)
  3. 1 of 4 cyclic nitrogenous bases
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4
Q

What are the 2 groups of nitrogenous bases?

+ what nitrogenous bases are in each group

A

2 groups: purine and pyrimidine

Purine: Adenine (A) & Guanine (G)
Pyrimidine: Thymine (T) and Cytosine (C)

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5
Q

How are purine and pyrimidine nucleotide chains connected?

A

By phosphodiester bonds

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6
Q

What are phoshodiester bonds

A

= the sugar-phosphate backbone of DNA

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7
Q

True / False : DNA strands are polar

A

True

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8
Q

What is the difference between the 5’end and the 3’end?

A

5’ end has a free phosphate group

3’ end has a free hydroxyl group

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9
Q

True or False: DNA is double-stranded and run parallel

A

False. DNA is double-stranded, but runs anti-parallel

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10
Q

DNA is a double helix that is left/right handed?

A

right-handed, meaning it runs clockwise

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11
Q

FIll in the blank:
Strands are held together by _____ bonds between bases on opposite strands.

Strands are held together by _______ interactions between _________ stacked bases

A

Strands are held together by “hydrogen” bonds between bases on opposite strands.

Strands are held together by “hydrophobic” interactions between “adjacent” stacked bases

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12
Q

Fill in the blank:

Opposing strands are said to be ________.

A

Opposing strands are said to be “complimentary”

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13
Q

How are bases paired and how are they mediated?

A

A = T and G = C

They are mediated by Hydrogen bonds

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14
Q

Define b Dna.

A

= the most common form of DNA

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15
Q

WHat are the 2 grooves of different width?

A
  1. Major grooves

2. Minor grooves

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16
Q

The right-handed helix is. ______ per turn

a) 5 base pairs
b) 10 base pairs
c) 20 base pairs

A

b) 10 bp

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17
Q

What are eukaryotic chromosomes composed of

A
  1. DNA
  2. RNA
  3. proteins
18
Q

Define and describe the 1st level of condensation?

-What metaphor is associated with this?

A

=packing DNA into nucleosomes

  • produces a 10nm fibre
  • DNA wraps around the nucleosome cores of 8 histone proteins (+ ancored by a 9th)
  • The space inbetween the nucleosomes is connected by Linker DNA
  • 146 bp of DNA wrapped 1 3/4 turns around histone

“beads-on-a-string” view of chromatin

19
Q

What are nucleosomes made up of?

A

made up of 8 histone proteins

20
Q

Name the histone proteins that have 2 molecules each

A

H2A, H2B, H3, H4 are in the nucleosomal core

+ 1 molecules of Histone H1 to further stabilize the structure

21
Q

What is H1 and what does it do

A

=the linker histone

-it further stabilizes the structure

22
Q

Define and describe the 2nd level of condensation.

A

= an additional folding / supercoiling of 11nm fibre to produce a 30nm fibre

-driven by nucleosomal interactions
-H1 = involved
2 models that describe the structure : solenoid and the zig-zag models

23
Q

What are the 2 models that describe the structure that occures in the 2nd level of condensation?

A
  1. solenoid

2. zig-zag models

24
Q

Define the 3rd level of condensation

A

= attachment of the 30nm fibre at many positions to a (non-histone) protein scaffold

25
WHat is the 30nm fibre?
= the basic structural unit of the metaphase chromosome | -DNA in its most condensed form
26
GIve a summary of the levels of condensation.
Level 1 : packing DNA into nucleosomes Level 2 : an additional folding / supercoiling of 11nm fibre to produce a 30nm fibre Level 3 : attachment of the 30nm fibre at many positions to a (non-histone) protein scaffold
27
Where else can you also find DNA that exist in circular chromosomes, besdies the nucleus?
Mitochondria and Chloroplasts
28
What is the 4 function of telomeres.
1. they protect the ends of the chromosomes the "aglet" 2. resist degration by DNases (attacking enzymes) 3. prevent fusion of chromosomal ends 4. facilitate replication of the ends of the inear DNA - encode not important information
29
What is the function of the centromere
provide the point of attachment of sister chromatids and of the chromosomes to microtubles in the mitotic spinde
30
What is the 2 step process of the transfer of information from DNA to protein in all organisms
1. Transcription | 2. Translation
31
What happens during Transcription
= information is transferredfrom DNA to an RNA molecule
32
What happens during Translation
Information is transferred from RNA to a protein through a code that specifies the amino acid sequence
33
Define the central dogma of molecular biology
DNA --> RNA --> Protein
34
What is the difference between RNA and DNA
1. RNA uses a ribose sugar ( has another OH) 2. has the pyrimidine uracil (T) instead of thymine - A=U instead of A=T 3. RNA is single stranded
35
RNA is less stable than DNA. Explain why
the 2' hydroxyl group makes RNA more reactive than DNA, therefore RNA is less stable
36
RNA is synthesized in a _' to a _' direction. Is this the same as or different to DNA polymerase. What is the template strand direction that the RNA uses to transcribe
5' to 3' direaction. This is the same as DNA polymerase The template strand the RNA reads off of is 3' to 5'
37
True or false: The initionation of RNA synthesis requires a primer
False. It does not need a primer
38
Are new nucleotides added to the 5' or 3' end of the RNA molecule?
the 3' end
39
The DNA double helix is locally unwound during transcription or translation?
Transcription
40
Define promoter
the region of DNA that is upstream of transcribed region

BIOL 1090 (3 decks)

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