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cell bio > Nucleic acid and protein synthesis and regulation > Flashcards

Nucleic acid and protein synthesis and regulation Flashcards

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1
Q

what are the four basic genetic process that help produce and maintain the proteins and nucleic acids of a cell?

A

protein synthesis
DNA replication
DNA repair
genetic recombination

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2
Q

what are some steps involved in the synthesis of protein?

A

DNA transcription
mRNA translation
ribosomal assembly

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3
Q

what is the first step in protein synthesis?

A

transcription

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4
Q

what does transcription do?

A

process takes the genetic information from DNA and transcribes it into form of a messenger RNA

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5
Q

how is immature mRNA modified?

A

RNA splicing to remove introns

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6
Q

describe the process of RNA splicing

A
  • done by enzyme RNA polymerase which recognize promoter sequence in DNA with help of transcription factors
  • RNA polymerase binds to this sequence and then initiates transcription of downstream genes
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7
Q

what happens when RNA polymerase reaches the termination sequence?

A

dissociates from template DNA strand and releases newly synthesized immature mRNA to be modified by splicing

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8
Q

what are some components that can affect whether or not certain genes are transcribed?

A

gene regulatory component
histone acetylation/deacetylation
methylation

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9
Q

what are the three main types of RNA involved in protein synthesis?

A

mRNA
rRNA
tRNA

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10
Q

what is rRNA?

A

ribosomal RNA
- makes up the structure of the ribosome

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11
Q

what do ribosomes catalyze the formation of?

A

peptide bonds (connections between each amino acid in a protein)

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12
Q

what is tRNA?

A

transfer RNA
- RNA that carries specific amino acids based on the genetic code to the ribosome that creates peptides

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13
Q

How does the tRNA know which amino acid it needs to take to the ribosome to make protein?

A

anticodons

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14
Q

what are codons?

A

three-nucleotide sequence that correspond to specific amino acids

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15
Q

what is a group of three nucleotides considered and what does that mean?

A

reading frame
- means that when protein synthesis occurs, DNA code is read by three nucleotides

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16
Q

what is used when a tRNA transfers an amino acid corresponding to the genetic code?

A

anticodon (complimentary to the codon present in DNA)
- tells tRNA which amino acid is next in the polypeptide sequence

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17
Q

in prokaryotes, the 70S ribosome is made of which subunits?

A

30S and 50S

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18
Q

in eukaryotes, 80S ribosomes are made up of which subunits?

A

40S and 60S

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19
Q

what is the A site of the ribsosome?

A

part of the ribosome where tRNA delivers amino acid

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20
Q

what is the P site of the ribosome?

A

where the formation of the peptide bond is catalyzed

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21
Q

what is the E site of the ribosome?

A

where the peptide chain exits the ribosome as it is being synthesized

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22
Q

list the stop codons

A

UAG
UAA
UGA

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23
Q

what is the start codon and which amino acid does it correspond with?

A

AUG
methionine

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24
Q

in prokaryotes, what is the start codon and what is special about it?

A

fMET because it has a formyl group attached to it

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25
Q

how are disease causing mutations found in our cells usually eliminated from the population and only present at low rates?

A

natural selection

26
Q

list types of mutations

A

silent
frameshift
missense
nonsense

27
Q

what is point mutation caused by and which types of mutations are included in this?

A

caused by a single base pair change
- silent, missense, and nonsense

28
Q

describe frameshift mutations and what does it produce?

A
  • result in shift of reading frame
  • causes production of short (truncated) protein or change up protein structure entirely due to addition of wrong amino acid
29
Q

what are the DNA repair mechanisms that are commonly used in cells?

A

base excision repair
double stranded break repair
mismatch repair

30
Q

describe base excision repair

A
  • only the damaged nucleotide is removed and then replaced
  • everything is glued back together using DNA ligase
31
Q

describe mismatch repair

A
  • mis-paired bases removed from DNA strand
    ~ done by proteins that first recognize mismatched area and then cut out that whole patch of DNA
  • DNA polymerase puts the new correct base
  • DNA ligase glues pieces back together
32
Q

describe double stranded break repair

A
  • occurs when DNA has been damaged and a double stranded break has been created
  • occurs when exposed to high-energy radiation
  • repaired via non-homologous end joining (NHEJ) and homologous recombination (HR)
33
Q

describe NHEJ in double-stranded break repair

A
  • cell glues DNA back together at breakage point
  • usually small mutation at the breakage site
34
Q

why is NHEJ not the best way to repair?

A

the cell can lose some DNA at the breakage point or could be addition of new DNA at breakage point which results in small mutation at breakage site

35
Q

describe HR in double-stranded break repair

A

information of damaged chromosome is found in homologous sister chromosome/chromatid, and information is used to repair DNA

36
Q

what must happen in order to replicate DNA?

A

strand must be separated and each single strand is replicated by DNA polymerase

37
Q

what is the purpose of primase?

A

RNA primer to start replication

38
Q

what is the main idea behind DNA replication?

A

base pairing

39
Q

what is base pairing?

A

explains which nitrogenous bases bond together

40
Q

list which nitrogenous bases bond together

A

A (adenine) ——> T (thymine)
G (guanine ——-> C (cytosine)

41
Q

how many hydrogen bonds are between A and T?

A

2

42
Q

how many hydrogen bonds are between G and C?

A

3

43
Q

If the DNA has a higher percentage of G and C base pairs, it will have a ______ melting point compared to DNA that has a ______ percentage of A and T base pairs.

A

higher

44
Q

how does the DNA composition melt?

A

temperature at which it denatures or two strands separate

45
Q

what DNA helicase work?

A

unzips DNA to make a replication fork

46
Q

what is a replication fork?

A

point at which DNA transitions from being one double stranded molecule to two strands

47
Q

the synthesis of the copy of DNA using the single strand as a ______ will begin

A

template

48
Q

DNA polymerase only synthesizes DNA in which direction?

A

5’-3’ direction

49
Q

describe the leading strand

A
  • has normal DNA replication
  • DNA synthesis will occur continuously in the 5’-3’ direction starting at the 3’ end of the template strand
50
Q

describe the lagging strand

A
  • DNA replication occuring in a discontinuous manner
  • synthesis still occurs in 5’-3’ direction
  • DNA polymerase will have to stop and then continue behind the previously synthesized fragment
51
Q

what fills the space in between the okazaki fragments?

A

DNA ligase

52
Q

what is the 3’-5’ exonuclease activity?

A

removes mis-paired/unpaired bases during replication

53
Q

When DNA is unzipped by DNA helicase, sometimes upstream the DNA gets wound up into a ________.

A

supercoil

54
Q

what enzyme removes supercoils that appear downstream of the DNA helicase?

A

DNA topoisomerase

55
Q

how does topoisomerase remove coils?

A

creates a “nick” in the DNA to relieve tension and prevent DNA from breaking
- nick closed immediately because when DNA topoisomerase creates this break, its a reversible reaction

56
Q

DNA topoisomerase I vs II

A

I- makes a single strand break
II- makes a double strand break

57
Q

how do viruses replicate their genetic material?

A

they infect other cells and hijack their replicative machinery in order to replicate themselves
- genetic material can be either DNA or RNA, which can be linear, circular, double stranded, or single stranded

58
Q

what is the result of genetic recombination?

A

increase in diversity of gene combinations in our chromosomes

59
Q

what are the two types of genetic recombination?

A
  • general recombination
  • site-specific recombination
60
Q

describe general recombination

A
  • process involves double strand breakage of a segment of DNA on a chromosome which is then switched with homologous region on the homologous chromosome
  • only occurs between two homologous regions on chromosomes
  • used in homologous recombination
61
Q

what does site-specific recombination require?

A

recombination enzyme that recognizes specific sequences that are present on the recombining DNA molecules which are the ones that are involved in recombination
- commonly occurs in bacteria

62
Q

in prokaryotic and eukaryotic chromosomes, what are the mobile genetic elements that function in the same way as site specific recombination and how does it work?

A

transposable elements
- move around in the host genome using recombination enzyme
- elements can insert themselves in the middle of important genes, causing a disruption which may lead to disease

cell bio (12 decks)

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