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Biology 1406 > Chapter 16 The Molecular Basis Of Inheritance > Flashcards

Chapter 16 The Molecular Basis Of Inheritance Flashcards

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1
Q

Who introduced an elegant double-helical model for the structure of deoxyribonucleic acid?

A

James Watson and Francis Crick

In 1953

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2
Q

Substance of inheritance?

A

DNA

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3
Q

Morgan’s group showed that genes are located on chromosomes

What become candidates for the possible genetic material?

A

DNA and protein

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4
Q

The role of DNA in heredity was first discovered by studying….

A

Bacteria and the viruses that infect them

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5
Q

The discovery of the genetic role of DNA began with research by ….

A

Fredrick Griffith in 1928

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6
Q

When Griffith mixed heat-killed remains of the pathogenic strain with living cells of the harmless strain….. what happened?

A

Some of the living harmless strains become pathogenic

This is called transformation*

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7
Q

When there is a change in phenotype and genotype due to assimilation of foreign DNA

A

Transformation

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8
Q

Who announced the transforming substance was DNA?

A

Oswald Avery, Maclyn McCarty, and Colin MacLeod

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9
Q

More evidence of DNA as the genetic material came from studies of…..

A

A virus that infects bacteria

These are called bacteriophages or phases

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10
Q

A virus that infects bacteria is called?

A

Bacteriophages or phages

They are widely used in genetics research

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11
Q

Who proved that one of the two components of T2 (DNA or protein) enters an E. coli cell during infection?

A

Alfred Hershey and Martha Chase

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12
Q

What are Charagaff’s rules?

A

Base pairings are different among species

The amount of and ratio of base pairings is equal

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13
Q

Who used X-Ray crystallography to study the molecular structure of DNA?

Who produced the image of the DNA molecule using this technique?

A

Maurice Wilkins and Rosalind Franklin

Franklin

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14
Q

Franklins X-Ray crystallography images of DNA enabled _________ to deduce the width of helix and the spacing of the nitrogenous bases

The width suggested that the DNA molecule was made up of two stands, forming a double helix

A

Watson

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15
Q

What is the backbone of DNA?

A

Sugar phosphate backbone

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16
Q

Bases are on the _____ of DNA?

A

Inside

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17
Q

DNA is stabilized by?

A

Hydrogen bonds

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18
Q

What are the three components of DNA?

A

Nitrogenous base (purines or pyrimidines)

Phosphate group

Pentose sugar (deoxyribose)

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19
Q

In DNA replication, the parent molecule unwinds, and _________ daughter strands are built based on base pairing rules

A

Two new

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20
Q

What were the three alternative models of DNA replication?

A

Semi-conservative (this one is correct)

Conservative

Dispersive

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21
Q

Who’s experiment supported the semi conservative model?

A

Meselson and Stahl

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22
Q

Explain Meselson and Stahls model for replication.

A

Old nucleotides labels with a heavy isotope of nitrogen, while any new nucleotides were labeled with a lighter isotope

First replication produced a band of hybrid DNA, eliminating the conservative model

The second replication produced both light and hybrid DNA, eliminating the dispersive model

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23
Q

Backbone of nucleotides?

A

Nitrogen

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24
Q

Replication begins at special sites called _______________, where the two DNA strands are separated, opening up a replication “bubble”

A

Origins of replication

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25
Q

How many sites of origin may a eukaryotic chromosomes have?

A

Hundreds or even thousands

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26
Q

Replication proceeds in what direction from each origin?

A

Both directions

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27
Q

At the end of each replication bubble is a …..

A

Replication fork, a Y-shaped region where new DNA strands are elongating

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28
Q

Are enzymes that untwist the double helix at the replication forks

Unzips or breaks hydrogen bonds

A

Helicases

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29
Q

Binds to and stabilizes single-stranded DNA until it can be used as a template

This prevents Two stands from coming back together

A

Single-strand binding protein

30
Q

Corrects overwinding ahead of replication fork by breaking, swiveling, and rejoining DNA strands

A

Topoisomerase

31
Q
  • catalyze the elongation of new DNA at a replication fork
  • nucleoside triphosphate added to a growing DNA strand
  • the rate of elongation is about 500 nucleotides per second in bacteria and 50 per second in human cells
A

DNA polymerase

32
Q
  • adds nucleotides
  • always elongates in a 5’ to 3’ direction because of the OH group
  • for the enzyme to work it must be able to bond to OH
A

DNA polymerase

33
Q

DNA polymerases add nucleotides only to the free _____ end of a growing strand; therefore, a new DNA strand can elongate only in a ____ to ____ direction

A

3’

5’, 3’

34
Q

DNA ploymerases cannot initiate synthesis of a ploynucleotide; they can only add nucleotides to the ____ end

A

3’

35
Q

The initial nucleotide strand is a short one called an….

A

RNA or DNA primer

36
Q

An enzyme called ___________can start an RNA chain from scratch

A

Primase

37
Q

How many primers are needed to synthesis the leading strand?

A

Only one

38
Q

Most _____________ require a primer and a DNA template strand

Catalyze the elongation of new DNA at a replication fork

A

DNA polymerase

39
Q

This adds RNA, DNA replication starts this way

Initiated by an RNA primer
5’ ——-> 3’ direction

A

Primase

40
Q

DNA polymerase dose not start DNA replication. What does?

A

Primase

41
Q

Can synthesis a complementary strand continuously, moving away from the replication fork

In a 5’ to 3’ direction

A

DNA polymerase

42
Q

________

A

DNA polymerase 3

43
Q

Synthesized as a series of segments in the lagging strand called ….

A

Okazaki fragments

44
Q
  • removes RNA primer from leading and lagging strand

- replaces primer with DNA

A

DNA polymerase 1

45
Q

Joins okazarki fragments together

A

DNA ligase

46
Q

__________ untwists the double helix and separates the template DNA at the replication fork

A

Helicase

47
Q

Binds to and stabilizes single stranded DNA u til it can be used as a template

A

Single-stranded binding protein

48
Q

Corrects “overwinding” ahead of replication forks by breaking, swiveling and rejoining DNA strands

A

Topoisomerase

49
Q

DNA polymerase removes ______ and replaces it with ______

A

RNA, DNA

50
Q

_________ Synthesizes an RNA primer at the 5’ ends of the leading strand and the Okazaki fragments

A

Primase

51
Q

_________________ continuously synthesizes the leading strand and elongates Okazaki fragments

A

DNA pol 3

52
Q

_________ removes primer from the five prime end of the leading strand and Okazaki fragments, replacing primer with DNA and adding to adjacent three prime end

A

DNA pol 1

53
Q

___________ Joins the three prime end of the DNA that replaces the primer to the rest of the leading strand and also joins the lagging strand fragments

A

DNA ligase

54
Q

When exposed to UV light, T=T can happen. How is it repaired and what is it called?

A

Mismatch repair

Polymerase will remove the damage

55
Q

The DNA replication machine is probably ____________ during the replication process

Recent studies support a model in which DNA polymerase molecules “real in” parental DNA and “extrude” newly made daughter DNA molecules

A

Stationary

56
Q

Enzymes cut out and replace damaged stretches of DNA

A

Nucleotide excision repair

57
Q

_____________ proofreads newly made DNA, replacing any incorrect nucleotides

In mismatch repair of DNA, repair enzymes correct errors in base pairing

A

DNA polymerase

58
Q

The ends of chromosomes are called?

A

Telomeres

59
Q

Limitations of DNA polymerase create problems for the linear DNA of eukaryotic chromosomes

The usual replication machinery provides no way to complete the five prime ends, so repeated rounds of replication produce….

A

Shorter DNA molecules

60
Q

_______________ do not prevent the shortening of DNA molecules, but they do postpone the erosion of genes near the ends of DNA molecules

A

Telomeres

61
Q

An enzyme called _________ catalyzes the lengthening of telomeres in germ cells

A

Telomerase
It extends, and fills in gaps

This reduces as an organism ages

62
Q

99% of all types of human cancers have high levels of _____________

A

Telomerase

63
Q

Discrete unit of genetic material

And It is composed of _______

A

Chromosomes

Chromatin- DNA-protein complex

64
Q

What are the three levels of DNA compaction?

A
  1. DNA wrapping
  2. 30-nm fiber
  3. Radial loop domains
65
Q

DNA wrapped around histones to form _________

A

Nucleosomes

66
Q

DNA wrapping shortest length of DNA molecule _________

A

7-fold

67
Q

Current model suggests asymmetric, 3-D zigzag of nucleosome’s
Shortens length another sevenfold

A

30-nm fiber

68
Q
  • interaction between 30 nm fibers and nuclear matrix
  • each chromosome located in discrete territory
  • levels of compaction of chromosomes not uniform (hetrochromatin, euchromatin)
A

Radial loop domains

69
Q

When cells prepare to divide, chromosomes become….

A

Even more compacted

70
Q

When chromosomes are not as compact (this is when they are being used)

A

Euchromatin

71
Q

When chromosomes are much more compact (off/not being used)

Metaphase chromosomes highly compacted

A

Hetrochromatin

Biology 1406 (20 decks)

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