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U0 Biology 115 > 2 lecture 6 > Flashcards

2 lecture 6 Flashcards

1
Q

recall the structure of DNA

A

Double-stranded

Each nucleotide composed of deoxyribose, phosphate, and nitrogenous base

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2
Q

what are the bases of DNA

A

4 bases: adenine, thymine, guanine, cytosine

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3
Q

what is the structure of RNA

A

Single-stranded

Nucleotides comprised of ribose, phosphate, and nitrogenous base

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4
Q

What are the bases of RNA

A

4 bases: A, C, G, and U (uracil)

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5
Q

what do genes do

A

encode proteins

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6
Q

what is a gene

A

is a sequence of DNA that contains information to make a protein

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7
Q

what does DNA do

A

the DNA stores information required to make every protein in the cell

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8
Q

what does a messenger RNA (mRNA) do

A

a messenger RNA (mRNA) extracts this information (from the DNA) and delivers it to a ribosome

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9
Q

What does the ribosome do

A

the ribosome “translates” the mRNA code into a sequence of amino acids

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10
Q

what is the process to encode proteins

A

the DNA stores information required to make every protein in the cell
a messenger RNA (mRNA) extracts this information and delivers it to a ribosome
the ribosome “translates” the mRNA code into a sequence of amino acids

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11
Q

what is The flow of genetic information

A

DNA → RNA → protein

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12
Q

how does the flow of genetic information occur

A

in 2 steps

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13
Q

what are the steps of The flow of genetic information

A

Transcription

Translation

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14
Q

what is transcription

A

(DNA → RNA)

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15
Q

what is translation

A

(RNA → Protein)

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16
Q

what is coded information is used for

A

coded information is used for protein synthesis

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17
Q

what is always true about the coding strand of DNA

A

coding strand is always 5 prime, 3 prime

an the opposite complimentary strand is 3 prime, to 5 prime

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18
Q

what is the start code for gene structure

A

ATG

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19
Q

what is the stop code for gene structure

A

TAA

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20
Q

whites the mRNA start code for genes structure

A

AUG

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21
Q

what is the mRNA stop code for gene structure

A

UAA

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22
Q

does transcription occur n bacteria?

A

yes

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23
Q

does it occur in the nucleus?

A

No— bacteria do not have a nucleus

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24
Q

where does Transcription occur

A

in the nucleus

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25
Q

is there an exception to where Transcription occurs

A

yes, it is only in the nucleus in eukaryotic cells

26
Q

how does the RNA polymerase know where to to start

A

the promoter region–

thats how it knows where to start, then it zips down the DNA between the start and end code
matches the complimentary DNA to the RNA
it knows the difference between different edna sequences
it will open up the hydrogen bonds so it can read off of a single coding strand instead of 2

27
Q

how does RNA polymerase work

A

RNA polymerase binds to the promoter region of the gene RNA polymerase zips down the length of gene, matching RNA nucleotides with complementary DNA nucleotides this forms messenger RNA (mRNA

28
Q

where does translation occur

A

translation occurs in the cytoplasm

29
Q

what does translation require

A

translation requires:
mRNA (made during transcription),
amino acids (20 different types)
transfer RNAs (tRNAs, for each amino acid)
energy (ATP) to bond an amino acid to a tRNA
ribosomes

30
Q

what is The ribosome is composed of

A

The ribosome is composed of ribosomal RNA (rRNA

has a small and a large subunit that must work together to build a polypeptide

31
Q

how does the Transfer RNA work

A

Transfer RNA: tRNA carries amino acids and matches its anticodon with codons on mRNA

32
Q

how long are codons

A

Codons are 3 nucleotides long

33
Q

how is a protein put together

A

A protein is put together one amino acid at a time

34
Q

how does translation work

A

A protein is put together one amino acid at a time
the ribosome attaches to the mRNA at the promoter region (before AUG)
the ribosome facilitates the docking of tRNA anticodons to mRNA codons.
when two tRNAs are adjacent, a peptidyl bond is formed between the amino acids.
and a chain of amino acids is formed (polypeptide)

35
Q

how does the genetic code work

A

is based in codons

no ambiguity: this means the sequence of codons can be used to predict the sequence of amino acids in a polypeptide..

36
Q

each codon is paired with what

A

each codon to specifies an amino acid

37
Q

a codon is comprised of what

A

a codon is comprised of three nucleotides = 64 possible combinations (43 combinations)

38
Q

how many codons are there

A

61 codons for amino acids

39
Q

what about the remaining 3 codons?

A

3 others are stop codons (UAG, UAA, UGA) which end protein synthesis

40
Q

the genetic code is redundant

true or false

A

true

41
Q

why is the genetic code redundant

A 
multiple codons = one amino acid
e.g. 
CUU
CUC
CUA
CUG
all of these are leu still, the only difference int he last letter but it doesn't make a big difference at all
42
Q

what is the exception to the “genetic code is redundant”

A

AUG

43
Q

can the sequence of amino acids in a polypeptide be used to predict the DNA sequence

A

apart from Met, the sequence of amino acids in a polypeptide CAN NOT be used to predict the DNA sequence

44
Q

why is the code redundant

A

when these 2 molecules come together, it is very hard for them (energetically) to come together perfectly— because the process has to be fast and accurate, this third codon has been found to be dispensable for binding but very important to remain bound

45
Q

is the genetic code generally universal

A

yes

46
Q

what does it mean by the genetic code generally universal

A

this means similar DNA sequences = similar proteins

across many different organisms

47
Q

what are mutations

A

Changes in genetic sequence = mutations

48
Q

Changes in genetic sequence might do what

A

Changes in genetic sequence might affect the order of amino acids in a protein

49
Q

what is Protein function dependant on

A

Protein function is dependent on the precise order of amino acids

50
Q

what are the Possible outcomes of mutation

A

1 - no change in protein
2 - non-functional protein
3 - different protein

51
Q

what is a Neutral mutation

A

mutation does not change the sequence of the protein, new codon = the same amino acid

example: the 3rd base in codon can vary for the same amino acid

52
Q

what is a Base-substitution mutation

A

Substitution of one base for another can change codon; polypeptide sequence; and protein function

53
Q

what is a frameshift mutation

A

Addition or deletion of a base, which changes the reading frame (sequence of codons)
incomplete or different protein

54
Q

which cells in the human body have the same dna

A

each cell in your body (except sperm and egg cells) has the same DNA

but each cell only expresses a small percentage of all its genes

example: nerve and muscle cells perform very different functions, thus they use different genes

55
Q

what is regulating gene expression

A

turning a gene or a set of genes on or off = regulating gene expression

56
Q

how do cells “hit the off switch”

A

cells use repressors to regulate gene expression

repressors bind to the promoter and prevent the RNA polymerase from binding

57
Q

how do cells “hit the on switch”

A

cells use activators to regulate gene expression

activators help the RNA polymerase bind to the promoter

58
Q

how does Regulation by chromosome condensation occur

A

Folding up of the chromosomes prevents transcription

59
Q

how does Regulation by mRNA degradation

occur

A

Nucleases cut mRNA

60
Q

how does Regulation of Translation

occur

A

Slowing of binding of the mRNA to the ribosome

61
Q

how does Regulation of Protein Degradation

occur

A

Proteases degrade proteins

U0 Biology 115 (23 decks)

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