Chapter 14 Flashcards

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1
Q

Discovered DNA

A

Friedrich Miescher

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2
Q

3 main components of DNA

A
  1. Five carbon sugar
  2. Phosphate (PO4) group
  3. A nitrogenous base
    Bases may be :
    Purine- adenine , A, or guanine, G,
    Pyrimidine- thymine ,T, or cytosine, C

RNA - has pyrimidine uracil,U,

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3
Q

Chargaffs rules

A
  1. Proportion of A always equals that of T and the proportion of G always equals that of C. ( A=T ; G=C)
  2. A/T and G/C proportions vary widely in species
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4
Q

The two strands of double helix are referred as the

A

Phosphodiester backbone

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5
Q

What is the complementary strand sequence of TACG

A

ATGC

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6
Q

Native double stranded DNA always has the __________ configuration

A

Antiparallel

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7
Q

Who created the Model of DNA structure

A

Watson Crick

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8
Q

Phosphates are connected to the deoxyribose sugar by

A

Phosphodiester bonds

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9
Q

In a strand of DNA the 3’ C attaches to phosphate group and then attaches to the ______

A

5’-Carbon

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10
Q

The base is always attached to which carbon

A

1’-Carbon

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11
Q

One molecule of DNA when it replicates each new daughter molecule will consist of one new strand and one old strand this makes DNA replication _______

A

Semi conservative

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12
Q

What are the bases in a DNA molecule held together by

A

Hydrogen bonds

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13
Q

How many hydrogen bonds hold A and T together

A

3

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14
Q

How many hydrogen bonds hold G and C bases together

A

2

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15
Q

If one stranded had a 5’ -C beginning and a 3’- C end what would the 2nd strand begin and end with? This makes them ______

A

3’-C and 5’ -C;

Anti parallel

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16
Q

Which characteristics of DNA allows each strand of molecule to act as a template that specifies the exact sequence of nucleotides in the other strand

A

Complementarity of the bases

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17
Q

What is the order of proteins that participate in DNA replication

A
  1. Helicase
  2. Single strand binding proteins
  3. Primase
  4. DNA polymerase III
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18
Q

UV light damages DNA by causing

A

Covalent bonds to form between thymine nucleotides next to each other on the same DNA strand

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19
Q

Thymine dimer weakens_____

A

Hydrogen bonding and leads to mutations

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20
Q

What enzyme is responsible for repairing thymine dimers using the energy of light

A

DNA photolyase

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21
Q

Which protein has a helicase function

A

UvrD

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22
Q

The covalent bonds between the thymine dimers are broken in

A

Light repair

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23
Q

3 items needed for DNA replication

A
  1. Template
  2. Nucleotides
  3. Enzymes
24
Q

These are plugged into the template strand

A

Nucleotides

25
Q

This enzyme attaches nucleotides to the template strand

A

DNA polymerase

26
Q

Which end do the DNA polymerase ALWAYS attach the nucleotides

A

3’ end

27
Q

This is a short RNA molecule that attaches to the DNA template strand

A

Primer

28
Q

What attaches to the strand after the primer

A

DNA polymerase

29
Q

Enzyme that unwinds parent strand to split into 2 strands ( templates)

A

Helicase

30
Q

This enzyme attaches to parent DNA just in front of the replication fork and helps smooth out DNA to prevent supercooling

A

DNA gyrase

31
Q

Enzyme that makes rna primers and attach to the exposed bases on the DNA template strand

A

Primase

32
Q

This strand synthesize continuously; works towards the helicase location

A

Leading strand

33
Q

This strand requires many RNA primers to synthesize and is a discontinuous process creating short sections

A

Lagging strand

34
Q

These are the short sections of new DNA made on the lagging strand

A

Okazaki fragments

35
Q

This enzyme removes RNA primer to replace with DNA bases

A

DNA polymerase 1

36
Q

This enzyme joins the Okazaki fragments together to make a complete new strand

A

DNA ligase

37
Q

This holds the polymerase in place

A

Beta clamp

38
Q

What is Eukaryotes and prokaryotes difference in DNA replication

A

Linear chromosomes

39
Q

Short sequences of nucleotides at the ends of the DNA of a chromosome repeated 1000 of times ; protect the end of chromosomes; and are not a gene

A

Telomeres

40
Q

The base sequence of telomeres in human DNA

A

TTAGGT

41
Q

Where does problem arise when it comes to telomeres ? (Which strand?)

A

Lagging strand

42
Q

What is the problem that occurs with telomeres on the lagging strand

A

It can’t be replicated due to DNA polymerase 1 unable to attach ; so every time the DNA molecule replicates it loses some of the telomere which loses its protection leading to damage and death of cell

43
Q

Which cells can repair the protective cap on DNA

A

Germaine Cells

44
Q

What is the name of the enzyme that attaches to nucleotides to lengthen the telomere

A

Telomerase

45
Q

Where can you find the telomerase enzymes

A
  • cells of embryos
  • cells of growing children
  • cancer cells
46
Q

Name the nitrogenous bases of DNA

A

Adenine
Guanine
Cytosine
Thymine

47
Q

Who developed first techniques for isolating very pure samples of DNA

A

Maurice Wilkins

48
Q

This scientist used X-ray diffraction to discover DNA was a double helix ; width of DNA was 2nm

A

Rosland Franklin

49
Q

Meselson and stahl studied Ecoli using N15 isotope to demonstrate that DNA is

A

Semi conservative

50
Q

In DNA replication a _______ is formed by the old strands of the parent DNA

A

Template

51
Q

These are needed to plug into the template in replication

A

Nucleotides

52
Q

Any change in DNA

A

Mutation

53
Q

Anything that causes mutation of DNA

A

Mutiagen

54
Q

This type of DNA repair targets a single type of mutation repairs only that mutation

A

Specific repair

55
Q

This type of repair can fix several mutation/ mistakes

A

Non- specific

56
Q

Example of a non specific repair in which an enzyme seeks for mistakes and cuts the mistake out which triggers for DNA polymerase I &II

A

Excision

57
Q

Which enzyme is only found in repair

A

DNA polymerase II