Bio 211 > Unit 2: Topic 8 > Flashcards

Unit 2: Topic 8 Flashcards

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1
Q

Components of DNA:

A
  1. Pentose sugar(ribose or deoxyribose).
  2. Nitrogenous base(purine or pyrimides).
  3. Phosphate.
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2
Q

What is the difference between a ribose and deoxyribose sugar?

A

Ribose(C5H10O5)- Used in ribonucleic acids, RNA.
Deoxyribose(C5H10O4)- Used in deoxyribonucleic acids, DNA.

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3
Q

What are the differences between the two types of nitrogenous bases?

A

Purines: Double ring (G,A)
Pyrimides: Single ring (C, T)

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4
Q

RNA uses:
DNA uses:

A

A, C, G, and T
A, C, G, and U

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5
Q

Nucleosides:

A

Pentose sugar and nitrogenous base, the bases are bound to the 1 carbon.

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6
Q

Deoxyribose nucleosides:

A

DNA and nitrogenous base

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7
Q

Nucleotides:

A

Nucleoside and phosphate, phosphates are bound to the 5 carbon at the sugar.

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8
Q

DNA is a ________ of deoxyribonucleotides.

A

Polymer.

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9
Q

Nucleotide ______ polymerize via ___________ bonds.

A

Monomers
Phosphodeister

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10
Q

Where do the covalent bonds occur in DNA?

A

Between the phosphate and the c-3 and c-5 of the two pentase sugars (pentase sugar-phosphate bonds).

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11
Q

Read polynucleotide from ___ end to _____ end.

A

5
3

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12
Q

Polynucleotide has ______ with a _ and _ end.

A

Polarity
5
3

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13
Q

How is the type of nucleic acid determined?

A

Depends on on the sugar (RNA or DNA) in the pentose-phosphate backbone.

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14
Q

DNA molecules have a _______ charge.

A

Negative.

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15
Q

How is the 3D structure of a DNA created?

A

Determines on the 3 chemical components.

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16
Q

DNA is _________ ________.

A

relatively linear.

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17
Q

What is chargaff’s rule:

A

A%=T%
G%=C%

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18
Q

What did the x-ray defraction studies discover?

A

1) DNA is a double helix structure, found out through x shaped defraction pattern.
2) DNA molecules were cylindrical and about 2nm in diameter, with a 0.34nm periodically.

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19
Q

The double helix is formed from:

A

Two strands of the phosphate-pentose backbone sprial about a common axis.

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20
Q

The 2 strands run _____-_________, one strand in the - direction and the other in the -.

A

Anti-parallel
5-3
3-5

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21
Q

Purine on one strand pair with a _________ on the other strand.

A

Pyrimidine.

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22
Q

There are _ hydrogen bonds between A/T and _ hydrogen bonds between C/G.

A

2
3

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23
Q

The backbone exterior is _________.
The interior is _________.

A

Hydrophylic
Hydrophobic

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24
Q

What is nucliec acid hybridization:

A

Annealing of single strands of DNA or RNA by forming hydrogen bonds. Highly specific, temp driven, and concentration dependent.

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25
Parental strands act as _______ for DNA replication of ____ strands.
Templates New
26
How do parent strands unwind?
By breaking the hydrogen bonds between bases.
27
What is semi-conservative replication?
Double helix contains a parental strand and a newly synthesized strand.
28
Eukaryotes have ________, _______, DNA molecules enclosed in the nucleas.
Multiple Linear
29
DNA is organized by being condensed into ______.
Chromatins(Normal state of DNA).
30
Nucleosome:
DNA double helix wrapped twice around a histone protien.
31
10nm chromatin fibre:
Repeating series of nucleosomes.
32
30nm Chromatin fibre(Soleniod):
Further coiling of the DNA by histones.
33
DNA ______ during DNA replication and transcription, and _________ further during meiosis and mitosis.
Unwinds Condenses
34
Histones:
Basic, positively charged protein. That binds linker DNA and two nucleosomes to form 30nm chromatin fibre.
35
The Nucleosome is a histone _______.
Octamer.
36
Euchromatin:
Regions have lower DNA compaction and genes are actively expressed.
37
Heterochromatin:
Are chromosomal regions of high DNA compaction where gene expression is silenced.
38
What are the differences between the two types of heterochromatin?
1) Constitutive heterochromatin: DNA is always highly compacted. 2) Facultative heterochromatin: can switch to euchromatin depending on cell type during development.
39
Origin of replication:
Multiple DNA sequences along the chromosome which initiate DNA replication.
40
Centromere:
DNA sequences required for correct segregation of chromosomes by directing formation of the kinetochore in which the mitoric spindle attaches.
41
Telomere:
DNA sequences located at the ends of the chromosome that prevent degradation and allows proper regulation of the chromosomal ends.
42
Chromosomal ploidy of eukaryotic cells:
Majority of eukaryotic cells are diploid(2A), 2 complete sets of chromosomes one from each parent.
43
Only sexually repdroductive cells like ________, _______, have _______ genomes.
Sperm, eggs Haploid
44
Polyploid:
More than one pair of each chromosome, occurs in some eukaryotic cells such as large protists and flowering plants.
45
DNA in prokaryotes is ________ and found in the ________.
Circular Cytosol
46
Do prokaryotic cells have the same level of compaction as eukaryotic cells? How are they compacted?
No, they do not need as much compaction, Use histone like protiens(HLP'S) also called associated protiens(NAP's).
47
Plasmids:
Additional small circular peices of DNA that hold a few non essentiel genes, called bonus genes that give them an advantage in some environents.
48
In what kind of environments are plasmids useful?
When antibiotic resistence is needed and rare metabolism genes for competition.
49
What were the 3 models of DNA replications?
1)Semi-conservative(correct). 2) Conservative. 3) Dispersive replication.
50
Conservative:
After replication both daughter strands pair up.
51
Dispersive replication:
Daughter strands will have a mixture of new and parental DNA.
52
What test did Meselon and Stahl conduct to prove semi-conservative replication?
Used nitrogen isotopes, N14, 15N(heavy). Grew E.coli in a N15 environment, then in an only N14 medium. DNA then settled in a position depending on its density.
53
What results did Meleson and Stahl find?
In the N14 medium the DNA was heavy, after one replication was a hybrid of N14/N15, after two replications was purely N14(light). Proved sem-conservative theory.
54
DNA polymerization:
The enzyme DNA polymerase adds nucleotides to a growing chain.
55
DNA polymerase can only add a new strand at the _____ end, DNA replication happens in the _-_ direction.
3'-OH 5'-3'
56
What does it mean that DNA polymerase cannot sythesize a new strand de-novo?
It rewuires an RNA primer with a 3'-OH for sythesis.
56
What provides the energy for the formation of new phosphodiester bonds?
The hydrolisis of pyrophasphate.
57
Origins of replication(ori):
Starting point of replication- DNA replication starts at multiple points along the length of each DNA molecule.
58
DNA polymerase has a ____ active site that catalyzes _ different reactions.
single 4(dATP, dCTP, dTP, dTTP).
59
As 2 parental strands seperate a _______ _______ is formed.
Replication bubble
60
How many replication forks does each replication bubble have? What direction do they point?
2, point in opposite directions.
61
What happens to the replication forks as DNA sythnesise continues?
The replication forks grow longer and will evuntually merge together.
62
Helixase:
Enzye that untwists the double helix at each replication for, seperates the old(template) strands.
63
Single-stranded binding proteins:
Protien binds to the DNA and prevents them from re-annealing.
64
Topoisomerase:
Release tension(supercoling) caused by the helixase ahead of the replication fork.
65
Primase:
DNA polymerase cannot add nucleotides to a single stranded template, when DNA replication starts at each replication fork there is no 3'-OH. Primase sythesises short RNA primer .
66
Primase adds __-__ RNA nucleotides base paired with a template strand forming a _________(RNA/DNA hybrid).
10-20 Primer.
67
The leading strand:
Elongated and sythesized continously, leads the other strand.
68
How is the leading strand replicated?
1. DNA polymerase 3 adds dNTP's 2. Strats at the 3'-OH end of the RNA primer. 3. Reads the template DNA in the 3'-5' direction. 4. Adds dNTP's to the new strand in the 5'-3' direction.
69
DNA sliding clamp:
Holds the DNA polyerase, so it does not fall off the template strand.
70
The lagging strand:
Replicated away from the replication fork, elongates discontinously, in short osaki fragments.
71
The template strands are ____-_______.
anti-parallel.
72
When replicating the lagging strand the _____ _____ must advance before the ______ and _____ _______ can start adding nucleotides.
Replication fork primase DNA polyerase 3
73
What does each new double stranded DNA molecule contain?
One parental template strand. One Daughter strand that is a mix of DNA plus RNA primers from the start of each leading strand and throughout each lagging strand.
73
What is DNA polymerase 1's role when replication bubbles collide?
Comes to the lagging strand and removes RNA primers and replace them with nucleotieds.
74
The ____ dNTP added by DNA polymerase _ will be next to the ____ dNTP added by DNA polymerase ___
Last I First III
75
DNA lygase:
Seals together the break in phosphodiester bonds.
76
The end replication probem:
There is additive loss at the chromosome ends for every round of DNA replication. This is becuase DNA polymerase cannot fill in the gaps at the chromosomal ends.
76
What pattern do telomeres repeat?
5-8x T/G
77
Telomerase:
Enzyme that helps telomeres
Bio 211
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