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Microbiology > Chapter 8 Microbial genetics > Flashcards

Chapter 8 Microbial genetics Flashcards

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Biology 101 flashcards
1
Q

what are introns?

A

regions of DNA that do not encode protein

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2
Q

what are exons?

A

regions of DNA expressed

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3
Q

what are snRNPs?

A

small nuclear ribonucleoproteins
remove introns and slice exons together to help form mRNA

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4
Q

which cell type uses introns, exons, and snRNPs? where exactly?

A

eukaryotes ONLY
within the nucleus

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5
Q

what are genes?

A

segments of DNA that code for functional products

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6
Q

what are chromosomes?

A

structures containing DNA (carry hereditary information)

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7
Q

what are the two types of nucleic acids?

A

DNA
RNA

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8
Q

what are the three parts to a nucleotide?

A

sugar
nitrogenous base
phosphate group

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9
Q

what is the sugar in DNA?

A

deoxyribose

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10
Q

what is the sugar in RNA

A

ribose

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11
Q

what are the nitrogenous bases in DNA?

A

A T C G

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12
Q

what are the nitrogenous bases in RNA?

A

A U C G

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13
Q

what are the enzymes involved in DNA replication?

A

leading strand: DNA polymerase

lagging strand: DNA polymerase
RNA primase
DNA ligase

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14
Q

what is the meaning of semiconservative replication?

A

the process by which DNA makes copies of itself, each strand, as it separates, synthesizing a complementary (daughter) strand. (Uses 1 DNA to make 2)

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15
Q

how is bacterial DNA replication different than eukaryotic DNA replication?

A

eukaryotic DNA replication consists of vertical gene transfer
bacterial DNA replication consists of horizontal gene transfer

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16
Q

how is DNA nucleotide differ than RNA nucleotide?

A

DNA: deoxyribose sugar and is double helix
RNA: ribose sugar and is single strand

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17
Q

what are the three basic forms of RNA?

A

ribosomal RNA (rRNA)
transfer RNA (tRNA)
messenger RNA (mRNA)

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18
Q

what is the job of rRNA?

A

integral part of ribosomes

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19
Q

what is the job of tRNA?

A

transports amino acids during protein synthesis

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20
Q

what is the job of mRNA?

A

carries coded information from DNA to ribosomes

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21
Q

what is transcription?

A

the process by which the information in a strand of DNA is copied into a new molecule of messenger RNA (mRNA)

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22
Q

what is the end goal of transcription?

A

DNA -> mRNA

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23
Q

what key enzyme is responsible for transcription?

A

RNA polymerase

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24
Q

where does transcription occur in eukaryotes?

A

nucleus

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25
Q

where does transcription occur in prokaryotes?

A

cytoplasm

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26
Q

what is translation?

A

the process by which a cell makes proteins using the genetic information carried in messenger RNA (mRNA).

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27
Q

what is the end goal of translation?

A

a protein

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28
Q

where does translation take place in eukaryotes/ prokaryotes?

A

occur in cytoplasm and ribosomes of either eukaryotes/prokaryotes

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29
Q

what is expression broken down into?

A

transcription and translation

30
Q

what is the end goal of expression?

A

using DNA to make a protein

31
Q

what is a codon?

A

mRNA language includes groups of three nucleotides such as AUG, GGC, or AAA

32
Q

what does degeneracy mean?

A

several codons can signal the same one amino acid

33
Q

what is the starting amino acid? which codon signals this?

A

Methionine
AUG

34
Q

what are three stop codons?

A

UAA
UAG
UGA

35
Q

why do these codons cause translation to stop?

A

in order to signal end of protein synthesis

36
Q

why is it that in bacteria, translation can begin before transcription is complete? but in eukaryotes, not?

A

because both steps occur in cytoplasm of bacteria cells
unlike eukaryotes where transcription occurs in nucleus first

37
Q

what is a mutation?

A

change in the nitrogenous base of DNA sequence

38
Q

what are three possible results of base substitution (point mutation)?

A

missense mutation
nonsense mutation
frameshift mutation

39
Q

what is missense mutation?

A

nitrogenous base substitution results in change in amino acid

40
Q

what is nonsense mutation?

A

nitrogenous base substitution results in a nonsense (stop) codon

41
Q

what is frameshift mutation?

A

insertion or deletion of one or more nucleotide pairs (shifts the entire sequence out of reading order)

42
Q

which type of mutation is the worst kind and is also most common?

A

frameshift mutation

43
Q

what is a silent mutation?

A

change in DNA base sequence that causes no change

44
Q

what are the three possibilities of silent mutations?

A
  1. degeneracy of genetic code (might still code for the same amino acid)
  2. function of protein may not change if amino acid is non-vital portion of protein
  3. changed amino acid is chemically similar
45
Q

what are the two major ways DNA can become mutated?

A

base substitution
chemical mutations

46
Q

how does ionizing radiation cause mutations?

A

causes formation of hydroxyl radicals and break the deoxyribose phosphate backbone

47
Q

how does UV radiation cause mutations?

A

cause thymine dimers

48
Q

what is the enzyme that repairs UV damage? how?

A

photolyase
separates thymine dimers

49
Q

what is the process that repairs mutation damage not caused by UV radiation? how?

A

nucleotide excision repair: enzymes cut out incorrect bases and fill in correct ones

50
Q

what is the baseline error rate for DNA polymerase?

A

1 in a million

51
Q

what is the error rate for DNA polymerase when mutagens are added into the mix?

A

1 in a thousand

52
Q

what is the difference between horizontal and vertical gene transfer?

A

horizontal gene transfer: genetic recombination
vertical gene transfer: DNA replication

53
Q

explain transformation

A

genes transferred from one bacterium to another as a “naked” DNA
can occur from “naked/floating” DNA appearing after cell death/lysis has occurred.

54
Q

name the two types of transduction that can occur

A

generalized transduction
specialized transduction

55
Q

describe the difference between generalized and specialized transduction

A

both generalized and specialized transduction involve packaging bacterial DNA inside a phage and transferring it to a recipient cell
but in generalized, random bacterial DNA is packaged.
in specialized, specific bacterial DNA is packaged.

56
Q

describe conjugation

A

plasmids transfer via sex pili
(only transfers plasmids that the other cell does not already contain)

57
Q

what does the F factor indicate?

A

plasmid

58
Q

what does F positive indicate?

A

donor cell

59
Q

what does F negative indicate?

A

recipient cell

60
Q

describe transposons

A

“jumping genes” segments of DNA that can move from one region of DNA to another

61
Q

what does transduction require in order to happen?

A

bacteriophages

62
Q

describe the long process of leading strand and lagging strand in DNA replication

A

Leading strand: enzymes unwind the double helix. DNA polymerase directly adds nucleotides to form new duplicated strand

Lagging strand: enzyme helicase “unzips” DNA helix at the hydrogen bonds, RNA primase indicates the beginnings of the multiple short sections of nucleotides which DNA polymerase then adds nucleotides in a reverse direction, these fragments are called Okazaki fragments, DNA polymerase then has to go back and change all the RNA primase nucleotides with its own, DNA ligase joins all these various attachments

63
Q

what direction does the DNA polymerase add nucelotides?

A

5’ to 3’ direction

64
Q

describe how antibiotic resistance occurs?

A

bacteria undergo random mutations. some mutations are more effective at making them resistant to some antibiotics. while antibiotics kill off the non-resistant mutated bacteria, the more resistant ones have time to transfer their resistant DNA via transformation/conjugation/transduction/transposons making for an abundance of these “super bugs”

65
Q

name some physical examples of how super bugs resist anitibiotics

A

-have cell walls made to be impenetrable
-have enzymes that break down antibiotics before coming into contact
-physically boot antibiotics that are able to enter cell wall

66
Q

where does DNA come from in transformation? do cells need to be in contact for transformation?

A

it is naked and floating around the cell
so no cells do not need to be in contact

67
Q

do cells need to be in contact for conjugation?

A

yes, because they use their sex pili to transfer plasmids

68
Q

what happens to recipient cell after conjugation is complete?

A

(Becomes a F+ cell) cell now has a plasmid that it can also transfer to other bacteria

69
Q

what is a Hfr cell? What does it stand for?

A

high frequency cell
occurs when plasmid has fused with bacterial chromosome

70
Q

what is transferred during conjugation with an Hfr cell?

A

part of the plasmid-containing chromosome of Hfr cell

71
Q

what happens to the recipient cell after conjugation is complete with a Hfr cell?

A

a recombinant F- cell results

72
Q

what do transposons contain that help do their job? What enzyme helps with that function?

A

insertion sequences (IS)
code for transposase that cuts and reseals DNA (can cause neg or pos mutations

Microbiology (23 decks)

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