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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
Q

WHat is the 30nm fibre?

A

= the basic structural unit of the metaphase chromosome

-DNA in its most condensed form

26
Q

GIve a summary of the levels of condensation.

A

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
Q

Where else can you also find DNA that exist in circular chromosomes, besdies the nucleus?

A

Mitochondria and Chloroplasts

28
Q

What is the 4 function of telomeres.

A
  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
Q

What is the function of the centromere

A

provide the point of attachment of sister chromatids and of the chromosomes to microtubles in the mitotic spinde

30
Q

What is the 2 step process of the transfer of information from DNA to protein in all organisms

A
  1. Transcription

2. Translation

31
Q

What happens during Transcription

A

= information is transferredfrom DNA to an RNA molecule

32
Q

What happens during Translation

A

Information is transferred from RNA to a protein through a code that specifies the amino acid sequence

33
Q

Define the central dogma of molecular biology

A

DNA –> RNA –> Protein

34
Q

What is the difference between RNA and DNA

A
  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
Q

RNA is less stable than DNA. Explain why

A

the 2’ hydroxyl group makes RNA more reactive than DNA, therefore RNA is less stable

36
Q

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

A

5’ to 3’ direaction. This is the same as DNA polymerase

The template strand the RNA reads off of is 3’ to 5’

37
Q

True or false: The initionation of RNA synthesis requires a primer

A

False. It does not need a primer

38
Q

Are new nucleotides added to the 5’ or 3’ end of the RNA molecule?

A

the 3’ end

39
Q

The DNA double helix is locally unwound during transcription or translation?

A

Transcription

40
Q

Define promoter

A

the region of DNA that is upstream of transcribed region

BIOL 1090 (3 decks)

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