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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
DNA replication
biological process of producing two identical replicas of DNA from one original DNA molecule
26
First step of DNA replication
‘unzip’ the double helix structure of the DNA? molecule
27
unzipping the double helix is done by
an enzyme called helicase which breaks the hydrogen bonds holding the complementary bases of DNA together (A with T, C with G)
28
separation of the two single strands of DNA creates a
‘Y’ shape called a replication ‘fork’. The two separated strands will act as templates for making the new strands of DNA
29
leading strand
oriented in the 3’ to 5’ direction (towards the replication fork)
30
lagging strand
oriented in the 5’ to 3’ direction (away from the replication fork)
31
leading strand stage 1
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
leading strand stage 2
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
lagging strand stage 1
Numerous RNA primers are made by the primase enzyme and bind at various points along the lagging strand
34
lagging strand stage 2
Chunks of DNA, called Okazaki fragments, are then added to the lagging strand also in the 5’ to 3’ direction.
35
DNA ligase
seals up the sequence of DNA into two continuous double strands
36
DNA primase
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
single strand binding protein
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
antiparallel
parallel to each other but with opposite alignments
39
Okazaki fragments
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
transcription
particular segment of DNA is copied into RNA (especially mRNA) by the enzyme RNA polymerase
41
Translation
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
transcription and translation in prokaryotes
in cytoplasm simotaneoulsy
43
transcription and translation in eukaryotes
transcription occurs in the nucleus, and translation occurs in the cytoplasm
44
codon
sequence of three nucleotides that together form a unit of genetic code in a DNA or RNA molecule
45
explain the relationship between the linear sequence of codons on mRNA and the linear sequence of amino acids in a polypeptide
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
three stop codons
UAG ("amber") UAA ("ochre") UGA ("opal")
47
start codon
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
why is the genetic code redundant
because a single amino acid may be coded for by more than one codon
49
evolutionary significance of universal genetic code
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
three major steps of transcription
initiation, elongation, termination
51
mRNA
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
tRNA
a type of RNA molecule that helps decode a messenger RNA (mRNA) sequence into a protein. synthesizes a protein from an mRNA molecule
53
rRNA
RNA component of the ribosome, and is essential for protein synthesis in all living organisms
54
structure of tRNA
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
structure of a ribosome
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
initiation translation
mRNA, tRNA, and ribosome come together
57
elongation translation
tRNAs bring amino acids to the ribosome for incorporation into the elongating polypeptide
58
termination translation
ribosome encounters a stop codon and releases polypeptide
59
DNA strands
template and coding
60
DNA template strand
strand of DNA double helix used to make RNA
61
DNA coding strand
strand of DNA complementary to the template strand
62
RNA polymerase
enzyme that synthesizes RNA from the DNA template
63
promoter
initial site on DNA to attach RNA polymerase
64
RNA polymerase I
transcribes rRNA.
65
RNA polymerase II
transcribes mRNA and some snRNA.
66
RNA polymerase III
transcribes tRNA and some other small RNAs.
67
anticodon loop contains 3
nucleotides complementary to mRNA codons
68
prokaryotic mRNA
polygenic in nature, contains many sites for initiation and termination codons
69
eukaryotic mRNA
monocistronic in nature, only one site for initiation and also termination of protein synthesis
70
how is eukaryotic mRNA processed before it leaves the nucleus
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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