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Exam 5 Flashcards

1
Q

Griffith’s experiment

A

first experiment suggesting that bacteria are capable of transferring genetic information through a process known as transformation.
used mice

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2
Q

Avery & McCarty experiment

A

that DNA is the substance that causes bacterial transformation

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3
Q

Hershey and Chase experiment

A

helped to confirm that DNA is genetic material, bacteriaphague experiment

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4
Q

Three components of a nucleotide

A 
A sugar (called deoxyribose)
A Phosphate (1 phosphorus atom joined to 4 oxygen atoms)
One of 4 bases (Adenine, Guanine, Cytosine, Thymine)
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5
Q

deoxyribose

A

found in DNA, is a modified sugar, lacking one oxygen atom (hence the name “deoxy”)

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6
Q

ribose

A

found in RNA, is a “normal” sugar, with one oxygen atom attached to each carbon atom

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7
Q

Difference between deoxyribose and ribose

A

difference of one oxygen atom is important for the enzymes that recognize DNA and RNA, because it allows these two molecules to be easily distinguished inside organisms

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8
Q

nitrogen bases found in DNA

A

adenine(A), guanine(G), cytosine(C), thymine(T)

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9
Q

pyrimidine

A

have only a six-membered nitrogen-containing ring (T and C)

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10
Q

purine

A

consist of a six-membered and a five-membered nitrogen-containing ring, fused together (A and G)

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11
Q

Watson and Crick model of DNA

A

double-stranded, helical molecule. It consists of two sugar-phosphate backbones on the outside, held together by hydrogen bonds between pairs of nitrogenous bases on the inside

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12
Q

sugar-phosphate backbone makes

A

the molecule more stable

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13
Q

DNA coils up into a double helix so that it’s

A

more compact, so lots of information is stored in a small place

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14
Q

The sequence of bases allows it to

A

carry coded information for making proteins

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15
Q

It is very long so it stores

A

lots of information

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16
Q

Complementary base pairing allows the molecule to

A

replicate itself accurately

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17
Q

The double helix makes it

A

stable as the base pairs are on the inside and so are less likely to get damaged

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18
Q

The bases are help together by weak hydrogen bonds allowing the molecule to

A

‘unzip’ (separate) easily when it replicates

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19
Q

Chargaff rules

A

states that DNA from any cell of all organisms should have a 1:1 ratio (base Pair Rule) of pyrimidine and purine bases and, more specifically, that the amount of guanine is equal to cytosine and the amount of adenine is equal to thymine

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20
Q

base pairing rule

A

A pairs to T and C pair to G

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21
Q

significance of base pairing in DNA function

A

hydrogen bonds are weak, allowing DNA to ‘unzip’. This lets enzymes replicate the DNA.

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22
Q

chemical bond that holds nucleotides of each strand

A

phosphodiester bond: a covalent bond is formed between the 5’ phosphate group of one nucleotide and the 3’-OH group of another.

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23
Q

type of bond that holds dna strands together

A

linked by hydrogen bonds that also hold the strands together

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24
Q

semiconservative replication

A

would produce two copies that each contained one of the original strands and one new strand

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25
Q

DNA replication

A

biological process of producing two identical replicas of DNA from one original DNA molecule

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26
Q

First step of DNA replication

A

‘unzip’ the double helix structure of the DNA? molecule

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27
Q

unzipping the double helix is done by

A

an enzyme called helicase which breaks the hydrogen bonds holding the complementary bases of DNA together (A with T, C with G)

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28
Q

separation of the two single strands of DNA creates a

A

‘Y’ shape called a replication ‘fork’. The two separated strands will act as templates for making the new strands of DNA

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29
Q

leading strand

A

oriented in the 3’ to 5’ direction (towards the replication fork)

30
Q

lagging strand

A

oriented in the 5’ to 3’ direction (away from the replication fork)

31
Q

leading strand stage 1

A

short piece of RNA called a primer (produced by an enzyme called primase) comes along and binds to the end of the leading strand. The primer acts as the starting point for DNA synthesis

32
Q

leading strand stage 2

A

DNA polymerase binds to the leading strand and then ‘walks’ along it, adding new complementary nucleotide bases (A, C, G and T) to the strand of DNA in the 5’ to 3’ direction

33
Q

lagging strand stage 1

A

Numerous RNA primers are made by the primase enzyme and bind at various points along the lagging strand

34
Q

lagging strand stage 2

A

Chunks of DNA, called Okazaki fragments, are then added to the lagging strand also in the 5’ to 3’ direction.

35
Q

DNA ligase

A

seals up the sequence of DNA into two continuous double strands

36
Q

DNA primase

A

enzyme involved in the replication of DNA and is a type of RNA polymerase. Primase catalyzes the synthesis of a short RNA (or DNA in some organisms) segment called a primer complementary to a ssDNA template

37
Q

single strand binding protein

A

a protein, 178 amino acids long, that binds to single-stranded regions of deoxyribonucleic acid (DNA). Single-stranded DNA is produced during all aspects of DNA metabolism: replication, recombination, and repair

38
Q

antiparallel

A

parallel to each other but with opposite alignments

39
Q

Okazaki fragments

A

short, newly synthesized DNA fragments that are formed on the lagging template strand during DNA replication. They are complementary to the lagging template strand, together forming short double-stranded DNA sections

40
Q

transcription

A

particular segment of DNA is copied into RNA (especially mRNA) by the enzyme RNA polymerase

41
Q

Translation

A

A step in protein biosynthesis wherein the genetic code carried by mRNA is decoded to produce the specific sequence of amino acids in a polypeptide chain. The process follows transcription

42
Q

transcription and translation in prokaryotes

A

in cytoplasm simotaneoulsy

43
Q

transcription and translation in eukaryotes

A

transcription occurs in the nucleus, and translation occurs in the cytoplasm

44
Q

codon

A

sequence of three nucleotides that together form a unit of genetic code in a DNA or RNA molecule

45
Q

explain the relationship between the linear sequence of codons on mRNA and the linear sequence of amino acids in a polypeptide

A

The codon is located on the mRNA and will be translated. The linear codon sequence and the linear amino acid sequence have a 3-nucleotide to 1 amino acid correspondence. That is, for every codon or set of three nucleotides, there will be one amino acid on the polypeptide, except for the stop codon

46
Q

three stop codons

A

UAG (“amber”) UAA (“ochre”) UGA (“opal”)

47
Q

start codon

A

always codes for methionine in eukaryotes and a modified Met (fMet) in prokaryotes. The most common start codon is AUG. The start codon is often preceded by a 5’ untranslated region (5’ UTR).

48
Q

why is the genetic code redundant

A

because a single amino acid may be coded for by more than one codon

49
Q

evolutionary significance of universal genetic code

A

genetic code is a nearly universal “language” that encodes directions for cells. The language uses DNA nucleotides, arranged in “codons” of three, to store the blueprints for amino acid chains

50
Q

three major steps of transcription

A

initiation, elongation, termination

51
Q

mRNA

A

large family of RNA molecules that convey genetic information from DNA to the ribosome, where they specify the amino acid sequence of the protein products of gene expression

52
Q

tRNA

A

a type of RNA molecule that helps decode a messenger RNA (mRNA) sequence into a protein. synthesizes a protein from an mRNA molecule

53
Q

rRNA

A

RNA component of the ribosome, and is essential for protein synthesis in all living organisms

54
Q

structure of tRNA

A

three hairpin loops that form the shape of a three-leafed clover. One of these hairpin loops contains a sequence called the anticodon, which can recognize and decode an mRNA codon. Each tRNA has its corresponding amino acid attached to its end

55
Q

structure of a ribosome

A

two major components: the small ribosomal subunit, which reads the RNA, and the large subunit, which joins amino acids to form a polypeptide chain. .

56
Q

initiation translation

A

mRNA, tRNA, and ribosome come together

57
Q

elongation translation

A

tRNAs bring amino acids to the ribosome for incorporation into the elongating polypeptide

58
Q

termination translation

A

ribosome encounters a stop codon and releases polypeptide

59
Q

DNA strands

A

template and coding

60
Q

DNA template strand

A

strand of DNA double helix used to make RNA

61
Q

DNA coding strand

A

strand of DNA complementary to the template strand

62
Q

RNA polymerase

A

enzyme that synthesizes RNA from the DNA template

63
Q

promoter

A

initial site on DNA to attach RNA polymerase

64
Q

RNA polymerase I

A

transcribes rRNA.

65
Q

RNA polymerase II

A

transcribes mRNA and some snRNA.

66
Q

RNA polymerase III

A

transcribes tRNA and some other small RNAs.

67
Q

anticodon loop contains 3

A

nucleotides complementary to mRNA codons

68
Q

prokaryotic mRNA

A

polygenic in nature, contains many sites for initiation and termination codons

69
Q

eukaryotic mRNA

A

monocistronic in nature, only one site for initiation and also termination of protein synthesis

70
Q

how is eukaryotic mRNA processed before it leaves the nucleus

A

a cap is added to the 5’ end of the mRNA molecule; a poly A tail is added to the 3’ end; introns are removed and exons are spliced together

Biology (8 decks)

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