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Biology 12 > Molecular Genetics Test > Flashcards

Molecular Genetics Test Flashcards

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1
Q

What did Gregor Mendel do?

A
  • Pea plant experiment, 3 principles of genetic inheritance
  • Recessive genes
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2
Q

What did Friedrich Miescher do?

A
  • Was eventually credited for the first time DNA was “discovered”
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3
Q

What did Erwin Chargraff do?

A
  • Chargraff’s rules
  • Discovered the amounts of A & T and C & G are relatively identical in DNA
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4
Q

What did Linus Pauling do?

A
  • Proposed (incorrect) triple helical shape for DNA
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5
Q

What did Maurice Wilkins do?

A
  • Worked on X-ray diffraction and isolating single strands of DNA
  • Worked with Rosalind Franklin
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6
Q

What did Rosalind Franklin do?

A
  • X-ray diffraction work led to Photograph 51 showing double helical shape
  • A and B form of DNA
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7
Q

What did Watson and Crick do?

A
  • Are credited for the discovery of the structure of DNA
  • Used Rosalind Franklin’s Photograph 51
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8
Q

Where is DNA located?

A

Exclusively in the nucleus.

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9
Q

Why is DNA located in the nucleus?

A

It must stay in the nucleus because of how important it is. If it left the nucleus and got damaged or mutated, then it wouldn’t function properly and that would be dangerous.

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10
Q

What are histones?

A

Histones are proteins that DNA wrap around to form nucleosomes. These proteins help with the packaging of chromosomes (in eukaryotic cells).

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11
Q

What are chromosomes?

A

Chromatin becomes chromosomes at the time of reproduction.

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12
Q

What is chromatin?

A

Nucleosomes packed into coiled fibres to fit all of the DNA in the nucleus.

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13
Q

What are nucleosomes?

A

DNA wrapped around a set of 8 histones twice. Nucleosomes help to allow the DNA to fit inside the nucleus.

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14
Q

What are nucleotides?

A

The building block of DNA. It consists of a phosphate group, a 5 carbon sugar, and a nitrogen base.

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15
Q

How many strands does DNA have?

A

2 strands, double helix shape.

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16
Q

What is the backbone of DNA made up of?

A

Alternating phosphates and deoxyribose sugars.

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17
Q

What are the rungs between the two sides of the backbones?

A

Nitrogen bases.

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18
Q

What is the distance between each pair of bases?

A

0.34nm, making a full twist every 3.4nm or 10 base pairs.

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19
Q

How far apart are the two sides of DNA?

A

2nm

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20
Q

What are the four base pairs in DNA?

A

Adenine, Thymine, Cytosine, Guanine.

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21
Q

What is on deoxyribose sugar’s first, second, and fifth

A
  • 1st carbon has the nitrogen base
  • 2nd carbon has the H
  • 5th carbon has the phosphate group
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22
Q

What is a pyrimidine?

A

The nitrogen base made up of a single ring. (C & T)

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23
Q

What is purine?

A

Double nitrogen rings (G & A)

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24
Q

What is a polymer?

A

Made up of repeating units
DNA is a polymer of nucleotides

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25
Q

Which side is the sugar?

A

3’

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26
Q

Which side is the phosphate?

A

5’

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27
Q

Since DNA has two strands going in opposite directions, it is said to be what?

A

Antiparallel

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28
Q

DNA replication is semi-conservative. What does that mean?

A

The process results in two strands each with one half of the DNA strand being “old” and half is “new”

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29
Q

What does gyrase do?

A

Relieves tension

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30
Q

What does helicase do?

A

Unwinds the DNA

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31
Q

What does primase do?

A

Places the RNA primers

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32
Q

What does DNA polymerase III do?

A

Synthesizes nucleotides in the 5’ to 3’ direction.

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33
Q

What does DNA polymerase I do?

A

Removes the primers and replaces them with DNA nucleotides.

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34
Q

What does ligase do?

A

Joins any gaps in the phosphate sugar backbone

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35
Q

What does uracil replace in RNA?

A

Thymine

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36
Q

Once DNA is split and opened up, what is the area called?

A

Replication bubble

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37
Q

What do the SSBP do?

A

The single stranded binding proteins prevent the hydrogen bonds from reforming between the nitrogen bases. They attach to the backbone of each DNA parent strand to keep them seperate.

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38
Q

What is the leading strand?

A

The side of the DNA synthesized continuously.

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39
Q

What is the lagging strand?

A

The side of the DNA synthesized discontinuously, through short segments called Okazaki fragments.

40
Q

What is mRNA? Where is it located?

A

mRNA (Messenger RNA)’s role is to leave the nucleus and move to the ribosome where the proteins are produced. It is located in the nucleus.W

41
Q

What is tRNA? Where is it located?

A

tRNA (Transfer RNA) is needed to transfer the amino acids needed to make the protein. It is located in the cytoplasm

42
Q

What is rRNA? Where is it located?

A

rRNA is needed to bring the two subunits of the ribsome together form protein synthesis. It is also located in the cytoplasm.

43
Q

How long does a protein take to make?

A

Less than a minute.

44
Q

Are the shapes of proteins unique?

A

Yes, each protein has a unique shape and function.

45
Q

How are there so many different proteins with so few amino acids?

A

Different numbers and sequences of amino acids

46
Q

How long does the average protein survive?

A

Only two days.

47
Q

How many different amino acids exist?

A

20

48
Q

What type of bonds hold amino acids together?

A

Peptide bonds

49
Q

What are proteins sometimes referred to as?

A

Polypeptides

50
Q

Why are 8 of the amino acids referred to as essential?

A

Because they cannot be synthesized by the body, they must be obtained from the food we eat.

51
Q

What is a codon?

A

A codon is a sequence of 3 bases in DNA or mRNA that codes a specific amino acid.

52
Q

What is the initiator/start codon?

A

It provides signal for RNA polymerase to start transcription. Also known as the TATA box.

53
Q

What is the terminator/stop codon?

A

It provides signal for RNA polymerase to stop transcription.

54
Q

What is an anticodon?

A

A sequence of 3 tRNA bases which bind to the complementary mRNA codon.

55
Q

What is the primary structure of a protein?

A

A sequence of amino acids linked together to form a peptide chain. Linked by peptide bonds.

56
Q

What is the secondary structure of a protein?

A
  • A coiled or pleated structure that form within a polypeptide due to interactions between atoms of the backbone.
  • Both forms caused by hydrogen bonds.
  • The amine group bonds with the other’s carboxyl group
    -“R” group sticks out
57
Q

What is the tertiary structure of a protein?

A
  • The 3D shape comes from the interaction of the R side chains
  • These interactions can be just about any type of chemical bonds
58
Q

What is the quaternary structure of a protein?

A

When multiple polypeptide chains, subunits, come together in closely packed arrangement in a protein.

59
Q

What are some possible uses for biotechnological tools?

A
  • Investigating Genetic Disorders
  • Identifying family linkages
  • Altering the genetic makeup of an organism so that it can be used in the synthesis of other organisms
  • Analyzing DNA evidence in criminal investigations
  • Creating new drug and therapy treatments
60
Q

What is recombinant DNA?

A

Sequences of DNA can be manipulated and moved from one organism to another forming recombinant DNA. This is DNA with sequences from at least two sources.

61
Q

What are restriction enzymes?

A

Molecular scissors that can cut double stranded DNA at a specific base pair sequence.

62
Q

What is the recognition site?

A

The specific nucleotide sequence that the enzyme identifies and then makes the cut.

63
Q

What are sticky ends?

A

The resulting fragment end of the DNA has nucleotides that are no longer matched with their complementary base pair leaving a short sequence of nucleotides that overhang. These are more useful since they will attach more easily.

64
Q

What are blunt ends?

A

The resulting fragment end is fully paired with complementary base pairs.

65
Q

How do restriction enzymes serve as a defence mechanism for bacteria?

A

By slicing the injected DNA of an attacking bacteriophage up into pieces by searching for its recognition sites. This renders the viral DNA unable to be replicated, transcribed or translated.

66
Q

What are mutations?

A

Errors made in the DNA sequence.

67
Q

Are most mutations positive or negative? What are some examples of conditions caused by DNA mutations?

A

Harmful, cystic fibrosis

68
Q

How can mutations be positive?

A
  • It is possible that a mutation may be beneficial, making the organism better equipped for
    survival.
  • Ex. larger brain of humans,
  • Variation and diversity result from mutations.
69
Q

What are mutagens?

A

External factors that cause mutations.

70
Q

What are some examples of mutagens?

A
  • Toxic chemicals
  • UV rays
  • Radiation
  • Some pathogens (like viruses)
71
Q

What are silent mutations?

A

Mutations which have no effect on the functioning of the cell.

72
Q

What are missense mutations?

A

The error results in a codon that codes for a different amino acid.

73
Q

What are nonsense mutations?

A

The error results in an amino acid becoming a stop codon.

74
Q

What are frameshift mutations?

A

Insertion and deletion. Shifts the frame being read.

75
Q

How do mutations affect transcription?

A

Mutated DNA will produce faulty mRNA leading to the production of a bad protein.

76
Q

What are point mutations?

A
  • The error occurs at just one point along the DNA sequence
  • Deletion, insertion and substitution are all examples of point mutation
77
Q

What are translocation mutations?

A
  • Involve groups of bases
  • Usually occur between chromosomes
  • Two fragments of the chromosomes switch places and interrupt the order of the genes
78
Q

What is a gene codon?

A

The region of DNA that codes for a specific protein.

79
Q

Why is transcription necessary?

A

It is necessary to produce mRNA because DNA cannot leave the nucleus.

80
Q

Where does translation take place?

A

In the cytoplasm/ribosome

81
Q

What is transcription?

A

The ability of DNA to make a copy of its code to RNA. It takes place in the nucleus, at the promoter site at the start codon.

82
Q

What are the steps of transcription?

A

Initiation, elongation, and termination

83
Q

What is initiation (in transcription)?

A

RNA polymerase attaches to and opens up a region on the DNA known as the promoter (aks TATA box). This is a highly concentrated region of adenine and thymine which lies “upstream” of the initiation point and the coding sequence. The promoter acts as a binding site for RNA polymerase.

84
Q

What is elongation (in transcription)?

A

RNA polymerase adds RNA nucleotides to the parent DNA template beginning with the start codon (TAC). The strand continues to grow as RNA polymerase adds free RNA nucleotides and the phosphodiester bond forms between the ribose sugar and the phosphate group between nucleotides.

85
Q

What is termination (in transcription)?

A

The process continues until RNA polymerase reaches a terminating codon forming an mRNA primary transcript which breaks away from the DNA chain and leaves the nucleus. Hydrogen bonds reform between the base pairs rejoining the 2 strands of DNA.

86
Q

What is translation?

A

The second step of protein synthesis.

87
Q

What is initiation (in translation)?

A

Initiation of translation occurs when the mRNA reaches the two ribosomal subunits. When inactive, these two units are kept seperate. The arrival of the mRNA however, triggers the two subunits to surround the mRNA strand and become active.

88
Q

What is elongation (in translation)?

A

The rRNA begins reading the mRNA sequence in triplets. These groups of three nitrogen bases are referred to as codons. Each codon matches with a specific amino acid that will be brought to the rRNA by another form of RNA, tRNA. The tRNA molecule has a corresponding anti-codon sewuence that allows proper matching with the attached amino acids.

Each tRNA brings a specific amino acid to an acceptor site on the rRNA structure. As new amino acids are brought the rRNA, the amino acids slide along to a peptide site where peptide bonds are formed linking the amino acids together. The amino acids are added one after another producing an elongated poly peptide chain.

89
Q

What is termination (in translation)?

A

Eventually, a stop codon is reached and the resulting pause signals the end of the translation phase. A release factor protein dismantles the rRNA subunits, releasing the mRNA strand and the newly formed protein.

90
Q

What is added to the 5’ end for protection?

A

a 5’ cap, that works like a helmet for the mRNA molecule.

91
Q

What is added to the 3’ end for protection?

A

a long string of adenine ribonucleotides, forming a long tail.

92
Q

What is an amino acid composed of?

A

A center carbon, an amine group to the left, a carboxyl group to the right, a hydrogen on top, and an R group side chain.

93
Q

What is a somatic mutation?

A

Mutations which occur in body cells.

94
Q

What is a germ mutation?

A

Mutations which only occur in reproductive cells.

95
Q

What are introns?

A

Non-coding regions which are removed before leaving the nucleus.

96
Q

What are exons?

A

Coding regions which remain after processing of mRNA.

Biology 12 (7 decks)

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