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Microbiology > 8 - Genetics > Flashcards

8 - Genetics Flashcards

1
Q

Describe the bacteria chromosome:

A
  1. single circular chromosome
  2. singular DNA molecule
  3. attached to plasma membrane
  4. has coding and noncoding regions
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2
Q

DNA replication

A

genetic information can be transferred between generations of cells (aka DNA synthesis)

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3
Q

Leading strand

A

is the new strand synthesized by DNA polymerase (going towards replication fork)

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4
Q

Lagging strand

A

DNA polymerase starting at replication fork and is synthesized discontinuously and made in Okazaki fragments

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5
Q

Topoisomerase

A

relieves supercoiling

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6
Q

Gyrase

A

relieves supercoiling

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7
Q

Helicase

A

separates two strands from each other

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8
Q

DNA polymerase

A

zips down toward the replication fork - only makes DNA strand 5’-3’ also can proofread

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9
Q

DNA ligase

A

connects fragments to make a complete strand on the lagging strand

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10
Q

DNA Replication Steps

A
  1. supercoiling relieved by topoisomerase (gyrase)
  2. double helix unwound by helicase
  3. new nucleotides are added to two separated strands - DNA polymerase adds to 3’ end of new strand so the new strand is made 5’ - 3’ and parent strand copied 3’ - 5’
  4. Parental strand is unwound further to continue replication at the replication fork
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11
Q

What is DNA transcription?

A

process of copying DNA into into RNA - DNA is transcribed into RNA by RNA polymerase

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12
Q

What are the 3 steps of transcription?

A
  1. Initiation: RNA polymerase binds to specific regions (promoters) of DNA to start transcription
  2. Elongation: RNA polymerase moves down the DNA template (3’-5’) synthesizing the RNA (5’-3’)
  3. Termination: RNA polymerase reaches a DNA sequence that serves as a terminator sequence
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13
Q

What is DNA translation?

A

RNA is used to make proteins - RNA is translated to proteins, in ribosomes

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14
Q

Codon

A

every 3 bases

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15
Q

Reading frame

A

sequence of code

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16
Q

How many total codes and how many total amino acids?

A

total codes = 64
total amino acids = 20

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17
Q

What are the four properties of the genetic code?

A
  1. redundant (a.a. are coded by more than one codon)
  2. unambiguous (single codon never codes for more than one a.a.)
  3. Universal (codons specify the same a.a. in all organisms)
  4. Conservative: codons that specify the same amino acid have the same first 2 bases)
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18
Q

Transfer RNA (tRNA)

A

recognizes the codon and transports the corresponding amino acid and binds with anticodon

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19
Q

What are the 3 sites of the ribosome?

A
  1. E: tRNA with no amino acid, about to leave = “exit”
  2. P: holds growing peptide chain = “peptide”
  3. A: tRNA enter with an amino acid attached = “acceptor”
20
Q

Central dogma

A

DNA -> RNA -> protein

21
Q

What are some differences in transcription and translation between prokaryotes and eukaryotes?

A
  1. location of transcription (p- cytoplasm; e- nucleus)
  2. prokaryotes can transcribe and translate at the same time since prokaryotic cells RNA doesn’t have to leave membrane-bound organelles
  3. eukaryotes have introns and exons - splicing
22
Q

What is gene regulation?

A

not all genes are needed all the time - cells conserve energy by only producing proteins they need

23
Q

What is a constitutive gene?

A

always expressed (i.e. glycolysis)

24
Q

What are operons?

A

specific for bacteria - set of genes that have a similar function that are controlled together - will make all or will make none

25
Q

What are the 3 parts of an operon?

A
  1. promoter: where RNA polymerase initiates transcription
  2. operator: acts as stop or go signal for transcription
  3. operon genes: set of genes with similar function or goal that are controlled together
26
Q

Repressible operon

A

always on unless turned off (tryptophan synthesis genes)

27
Q

Inducible operon

A

always off unless turned on (inducible operon-Lac operon)

28
Q

What are mutations?

A

permanent change in an organism’s DNA

29
Q

How are mutations caused?

A
  1. spontaneously - mistakes during replication
  2. mutagens - chemicals/radiation
30
Q

Missense mutation

A

point mutation changes amino acid sequence

31
Q

Silent mutation

A

point mutation does not change amino acid sequence (3rd base)

32
Q

Nonsense mutation

A

base substitution results in a nonsense codon

33
Q

Frameshift mutation

A

nucleotides are deleted or added, changing the codons

34
Q

What are the general purpose of different mutant tests?

A

identifying mutants and the mutation rate (probability a gene with mutate)

35
Q

Positive selection test

A

detects mutants by rejecting non-mutants

36
Q

Negative selection test

A

selects cells that cannot perform a function

37
Q

Ames test

A

tests a chemical/potential mutagen to determine if it cause mutations

38
Q

Recombination

A

exchange of genes b/w 2 DNA molecules; gives new gene combos

39
Q

Transformation

A

genes are transferred as “naked” DNA - bacteria release DNA into the environment other bacteria pick it up and insert into chromosome - only competent cells are able to pick it up

40
Q

Conjugation

A

transfer of a plasmid through a sex pilus - requires cell-cell contract

41
Q

Transduction

A

DNA is transferred inside a bacteria (bacteriophage)

42
Q

Bacteriophage

A

virus that carries DNA and infects bacteria

43
Q

What is the main difference b/w replication in prokaryotes and eukaryotes?

A

in prokaryotes the 2 replication forks meet when replication is complete

44
Q

Vertical gene transfer

A

from organism to its offspring

45
Q

Horizontal gene transfer

A

between organisms of the same generation

Microbiology (23 decks)

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