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4U BIO > 5.1/5.2 > Flashcards

5.1/5.2 Flashcards

1
Q

Frederick Griffith

A

-experimented with mice to determine the effects of Streptococcus pneumoniae

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2
Q

Avery, MacLeod, McCarty

A
  • published a study that supported the hypothesis that DNA was the hereditary material by removing DNA, proteins, and RNA from extracts and mixed it with live R-strain
  • only one that didn’t cause transformation was the DNA so it had to be the transforming principle
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3
Q

Hershey and Chase

A
  • used bacteriophages which have a protein coat and strand of DNA to see which part was injected into the bacteria that it infected
  • concluded that it was the strand of DNA that was injected which has to carry genetic material which is needed for bacteria to reproduce
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4
Q

Friedrich Miescher

A
  • isolated the nuclei of white blood cells from pus-soiled bandages
  • proved that DNA existed
  • discovered nuclein which is now called nucleic acid
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5
Q

Nucleotide

A

The repeating unit of nucleic acids; composed of a sugar group, a phosphate group, and a nitrogenous base.

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6
Q

Purines

A
  • nitrogenous bases with two fused rings

- adenine and guanine

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7
Q

Pyrimidines

A
  • nitrogenous bases with a single ring

- cytosine, thymine

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8
Q

Uracil

A
  • a nitrogenous base in RNA that replaces thymine

- pyrimidine base

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9
Q

Erwin Chargaff

A
  • found that nucleotides were present in characteristic proportions
  • amount of adenine is approximately equal to amount of thymine
  • amount of guanine is approximately equal to amount of cytosine
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10
Q

Chargaff’s Rule

A

In DNA, the percent composition of adenine is the same as thymine, and the percent composition of cytosine is the same as guanine.

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11
Q

Rosalind Franklin

A
  • determined that DNA had a helical structure using x-ray diffraction
  • found that nitrogenous bases faced inward while phosphate and sugars faced outward
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12
Q

Watson and Crick

A
  • published the model for DNA that showed DNA had a twisted, ladder-like structure (double helix)
  • sugar-phosphate molecules make up the sides of the ladder
  • bases make up the rungs
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13
Q

Complementary Base Pairing

A

In DNA, the interaction of bases of nucleotides on opposite strands through the formation of hydrogen bonds.

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14
Q

Number of Hydrogen Bonds Between A and T?

A

Two

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15
Q

Number of Hydrogen Bonds Between C and G?

A

Three

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16
Q

Antiparallel

A

The directionality of the two strands in a DNA molecule; the strands run in opposite directions, with each end of a DNA molecule containing the 3’ end of one strand and the 5’ end of the other strand.

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17
Q

Orientation of Oxygen in Sugar Groups

A
  • on left side, the oxygen is at the top

- on right side the oxygen is on the bottom

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18
Q

Where does the 5’ and 3’ come from?

A

-the numbering of the carbons on the deoxyribose sugar

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19
Q

Where is the phosphate group located?

A

It is on the 5’ carbon.

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20
Q

Where is the OH group located?

A

It is on the 3’ carbon.

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21
Q

In what direction is the sequence of DNA always written?

A

In the 5’ to 3’ direction.

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22
Q

Genome

A

The complete genetic makeup of an organism; an organisms total DNA sequence.

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23
Q

Gene

A

The basic unit of heredity that determines, in whole or part, a genetic trait; a specific sequence of DNA that encodes for proteins and RNA molecules, and can contain sequences that influence production of these molecules.

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24
Q

Is the majority of DNA coding or non-coding?

A

Non-coding (about 98%)

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25
Q

Form of DNA in Prokaryotes

A

Circular, Double Stranded DNA Molecule

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26
Q

Nucleoid

A

A structure in bacteria that contains the chromosomal DNA.

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27
Q

DNA Supercoiling

A

The formation of additional coils in the structure of DNA due to twisting forces on the molecule. you

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28
Q

Regulatory Sequence

A

A sequence of DNA that regulates the activity of a gene.

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29
Q

Do prokaryotic or eukaryotic cells have more DNA?

A

Eukaryotic

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30
Q

Histone

A

A member of a family of proteins that associate with DNA in eukaryotic cells, which acts to help compact the DNA.

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31
Q

Nucleosome

A

The condensed structure formed when double-stranded DNA wraps around an octamer of histone proteins.

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32
Q

Part A of the Organization of Genetic Material

A
  • DNA molecule winds around histones to form a bead-like structure called a nucleosome
  • each nucleosome is composed of double-stranded DNA (146 base pairs in length), wrapped around a group of eight histone proteins (two copies each of histones H2A, H2B, H3, H4)
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33
Q

Part B of the Organization of Genetic Material

A
  • coiling of the nucleosomes with the aid of H1 histone proteins
  • 30 nm fibre
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34
Q

Part C of the Organization of Genetic Material

A

-the 30 nm fibres form loops which are attached to a supporting protein scaffold

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35
Q

Part D of the Organization of Genetic Material

A

The scaffold folds further to condense the genetic material into chromosomes, which are duplicated during replication, forming pairs of identical chromosomes joined by a centromere.

36
Q

Euchromatin

A

The 30 nm fibre as looped domains. (Part C of Genetic Material Organization)

37
Q

Heterochromatin

A

A further compact version of euchromatin.

38
Q

Diploid

A

Containing two copies of each gene.

39
Q

Haploid

A

Containing one copy of each gene.

40
Q

Two fundamental features that DNA must have:

A
  • must be able to copy itself

- must have a chemical way of carrying a genetic code

41
Q

DNA Replication

A

The process of producing two identical DNA molecules from an original, parent DNA molecule.

42
Q

What is the importance of DNA replication?

A

An exact copy of DNA so that when cells die, all cells will have a full set of genetic info.

43
Q

During what stage of the cell cycle is DNA replicated?

A

Interphase

44
Q

Conservative Model for DNA

A

Formation of two new daughter strands from the parent templates, with the two new strands joining to create a new double helix. Two original strands would then re-form into the parent molecule.

45
Q

Semi-Conservative Model for DNA

A

Each new molecule of DNA would contain one strand of the original complementary DNA molecule and one new strand.

46
Q

Dispersive Model for DNA

A

Parental DNA molecules are broken into fragments and that both strands of DNA in each of the daughter molecules were made up of an assortment of parental and new DNA.

47
Q

Semi Conservative Replication

A

The mechanism of DNA replication in which each newly synthesized DNA molecule is composed of one strand from the original DNA molecule and one new strand.

48
Q

What is the new strand of DNA referred to as?

A

Daughter DNA

49
Q

Three Phases of DNA Replication

A

1) Initiation
2) Elongation
3) Termination

50
Q

Initiation

A

A portion of the DNA double helix is unwound to expose the bases for new base pairing.

51
Q

Elongation

A

Two new strands of DNA are assembled using the parent DNA as a template. The new DNA molecules–each composed of one strand of parent DNA and one strand of daughter DNA–re-form into double helices.

52
Q

Termination

A

The replication process is completed and the two new DNA molecules separate from each other. At that point, the replication machine is dismantled.

53
Q

Origin of Replication

A

The DNA sequence where replication begins.

54
Q

Helicase

A

A group of enzymes that aid in the unwinding of DNA by cleaving hydrogen bonds that link base pairs.

55
Q

Single Strand Binding Proteins (SSBP)

A

Stabilize the newly unwound single strands.

56
Q

Topoisomerase II Enzyme

A

Helps to relieve the strain on the double-helix sections ahead of the replication forks.

57
Q

Replication Bubble

A

An unwound, oval-shaped area between to single DNA strands.

58
Q

Replication Fork

A

A Y-Shaped region at each end of the unwound area or bubble.

59
Q

Two Rules For DNA Replication

A

1) DNA nucleotides can only latch onto an existing nucleotide to form a chain.
2) DNA and RNA nucleotides can only attach at the 3’ end. (the OH- on the sugar)

60
Q

5’ End of Stand

A

Phosphate Group

61
Q

3’ End of Strand

A

Sugar

62
Q

DNA Polymerase III

A

An enzyme that adds nucleotides to the 3’ end of a growing polynucleotide strand.

63
Q

What is required to start a replication chain of DNA?

A

RNA Primer which synthesizes a short sequence that ends in a 3’ end

64
Q

How many RNA primers are needed on a leading strand?

A

One

65
Q

How many RNA primers are needed on a lagging strand?

A

Many (one for each okazaki fragment)

66
Q

What is different about the lagging strand?

A

The daughter strand must be synthesized in the opposite direction. From the 5’ to 3’ end of the parent DNA. In this case the new strand is synthesized in the 3’ to 5’ end and there is no open 3’ during synthesis.

67
Q

Okazaki Fragments

A

Short DNA fragments that are generated during the synthesis of the lagging strand in DNA replication.

68
Q

Leading Strand

A

-has free 3’ end allowing for DNA replication to proceed continuously

69
Q

Lagging Strand

A
  • has no free 3’ end requiring DNA to be replicated discontinuously
  • replicated away from the replication fork in short okazaki fragments
70
Q

Primer

A

In DNA replication, a short segment of RNA that is complementary to a part of the 3’ to 5’ DNA template strand and serves as a starting point for addition of nucleotides.

71
Q

What are the RNA primers synthesized by?

A

Primase

72
Q

What happens after the RNA primer is put down?

A

The DNA polymerase extends the strand by adding new nucleotides to the 3’ hydroxyl end of the primer.

73
Q

DNA Polymerase I

A

An enzyme that removes RNA primer and fills gaps between okazaki fragments on the lagging strand with DNA nucleotides.

74
Q

DNA Polymerase II

A

Proofreads newly synthesized DNA.

75
Q

DNA Ligase

A

An enzyme that catalyses the joining of Okazaki fragments.

76
Q

What happens after the newly formed strands are complete?

A

They rewind automatically into their chemically stable double-helical structure.

77
Q

Replication Machine

A

The protein-DNA complex at each replication fork that carries out replication.

78
Q

What happens to the replication machine during termination?

A

It is dismantled.

79
Q

Error #1 During DNA Replication

A

Mispairing Between a New Nucleotide and a Nucleotide on the template strand.

80
Q

Error #2 During DNA Replication

A

Strand Slippage Causing Addition or Omissions of Nucleotides

  • Addition: Newly Synthesized Strand Loops Out
  • Omission: Template Strand Loops Out
81
Q

What two enzymes work together to fix errors during DNA replication?

A

DNA Polymerase I and II

82
Q

Mismatch Repair

A

A mechanism for repairing errors made during DNA replication, whereby a group of proteins recognize a mispaired nucleotide on the newly synthesized strand and replace it with a correctly paired nucleotide.

83
Q

Similarities Between DNA Replication in Prokaryotes and Eukaryotes

A
  • require origin of replication
  • have elongation occur in 5’ to 3’ direction
  • have both continuous (Leading) and discontinuous (lagging) synthesis
  • require RNA primer
  • use DNA polymerases
84
Q

Differences Between DNA Replication in Prokaryotes and Eukaryotes

A
  • rate of replication is faster in prokayrotes
  • DNA polymerase enzymes in eukaryotes differ from those in prokaryotes (5 in Pro., 13 in Euk.)
  • Prokaryotes have single origin of replication, eukaryotes may contain thousands.
85
Q

Telomeres

A

A repetitive section of DNA near each end of a chromosome; the presence of this sequence helps to protect from loss of important genetic information during replication of the linear DNA in eukaryotic cells.

86
Q

Telomerase

A

Synthesizes telomeric regions and can replace a sequence that has been lost.

87
Q

Telomerase Activity

A
  • childhood: activity is high

- as people age: telomerase activity slows

4U BIO (11 decks)

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