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Completed > Ch 9 Microbial Genetics > Flashcards

Ch 9 Microbial Genetics Flashcards

0
Q

Name and describe a purine

A

Double ringed nitrogenous base; adenine and guanine

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1
Q

Name the 3 parts of a nucleotide

A

Nitrogenous base, pentose, phosphate group

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2
Q

Name and describe pyrimidines

A

Single ringed nitrogenous bases; thymine (DNA), cytosine (both), uracil (RNA)

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3
Q

“Students at TCU are PRIMADONNA’S because they are single”

A

Pyrimidine’s are single ringed, T, C, U

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4
Q

Describe base pairings in DNA and RNA

A

DNA: A—T and G—C
RNA: A—U and G—C

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5
Q

What is the principle of base pairing

A

A purine will always H bond and be opposite a pyrimidine in the “rungs” of the DNA

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6
Q

Explain Chargaff’s rule

A

The conc of A=T; the conc of C=G therefore A + C = T + G

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7
Q

Describe the Watson & Crick model for DNA

A

Double helix; strands run antiparallel: one side is 5’–>3’ the other is 3’–>5’ (but both sides run from 5’–>3’ direction)

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8
Q

Explain the sugar-phosphate backbone

A

The 3rd carbon in the sugar of one nucleotide bonds with the phosphate group of another nucleotide below it

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9
Q

What serves as a template to build a new strand from

A

Each strand of the DNA molecule

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10
Q

Where does theta replication take place

A

In prokaryotic circular chromosome or plasmid

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11
Q

What does helicase do

A

Unwinds and separates the parental DNA strands (unwinds helix and breaks the H bonds)

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12
Q

What does DNA polymerase III do

A

Catalyze the synthesis of new DNA by adding nucleotides to a pre-existing chain can only add to the free 3’ end of the pre-existing primer chain

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13
Q

What does DNA polymerase I do

A

Removes the RNA primer and substitutes DNA nucleotides in their place, after DNA polymerase III has synthesized its DNA

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14
Q

What does DNA ligase do

A

Joins all synthesized pieces together; “DNA glue”

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15
Q

What is the origin of replication

A

Where replication begins; short stretches of DNA having specific sequences

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16
Q

What is the replication bubble

A

Created when the H bonds between the paired bases break and the two strands of the DNA molecule separate

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17
Q

What is the replication fork

A

Found at each end of the replication bubble; Y shaped region where the parental strands of DNA are being unwound

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18
Q

Describe the leading strand

A

Synthesized as one long continuous section in the 5’–>3’ direction; overall direction is the same direction 5’–>3’

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19
Q

Lagging strand

A

Synthesized in short discontinuous sections in the 5’–>3’ direction; overall direction of synthesis is
3’–>5’

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20
Q

What are the sections of the lagging strand called

A

Okasaki fragments

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21
Q

Describe the product of semi-conservative replication

A

2 double stranded DNA molecules, each consisting of half old (original) and half new material; one strand is original, the other is new; produces 2 copies!!

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22
Q

Explain proofreading

A

During synthesis, DNA polymerase reviews the synthesized strands and corrects mismatched nucleotide pairs or missing nucleotides (deletions)/ extra nucleotides (insertions)

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23
Q

Explain what is meant by “central dogma”

A

The universal direction of genetic flow: DNA—>RNA—>proteins

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24
Q

What is gene expression

A

Process by which DNA directs the synthesis of proteins

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25
Q

Producing mRna from DNA is called

A

Transcription

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26
Q

What is a codon

A

Triplet code; mRNA that is decoded in groups of 3 bases Ex: AUG/UUU/CAC are all codons

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27
Q

How is tRNA produced

A

Translation

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28
Q

Explain translation

A

When mRNA codons are translated by matching its anticodon in base pairing Ex: AUG becomes UAC; UUU becomes AAA; CAC becomes GUG

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29
Q

Explain make-up of rRNA

A

Major component of a ribosome; 1/2 rRNA + 1/2 enzymatic protein

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30
Q

What is the enzymatic protein in ribosomes

A

Ribozyme

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31
Q

Prokaryotic vs eukaryotic ribosome size

A

Pro= 70S euk= 80S

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32
Q

Names of the 3 active sites on a ribosome

A 
P= peptide site E= exit site 
A= amino site
33
Q

What binds to the RNA binding sites

A

tRNA

34
Q

What are wobbles

A

Flexible 3rd position bases in the codons; sometimes when a mistake is made it still codes for the same amino acid

35
Q

Explain the genetic code

A

Is the universal code for all lifeforms; based on the triplet code; each of the 64 triplet codons corresponds to a specific amino acid or a start or stop signal

36
Q

Promotor (region)

A

The DNA sequence where RNA polymerase attaches and initiates transcription

37
Q

Coding region

A

The DNA sequence that is transcribed and will code for a polypeptide

38
Q

Terminator region

A

The DNA sequence that signals the end of transcription

39
Q

Nontemplate strand

A

5’–>3’ Can be called cDNA for complementary

40
Q

Template strand

A

3’—>5’ can be called tDNA for template

41
Q

RNA polymerase

A

Pries the 2 DNA strands apart and joins together RNA nucleotides complementary to the DNA strand

42
Q

What direction does RNA polymerase assemble the mRNA molecule? Does it require a primer?

A

5’–>3’ direction only; does NOT require a primer to start

43
Q

What is the product produced from transcription

A

A mRNA 5’–>3’ sequence that can be translated

44
Q

Where does the mRNA strand go?

A

Exits the nucleus and moves out to the ribosomes

45
Q

Translation changes _____ into ____

A

mRNA into polypeptide ( protein primary level)

46
Q

Translation is the conversion of the language of ____ to the language of ____

A

Conversion of the genetic information language of RNA to the language of proteins

47
Q

What is a point mutation

A

Nucleotide base pair substitution; results in 1 of 3 mutations

48
Q

Silent mutation

A

Codon still codes for the same amino acid (due to a wobble)

Ex: UGU—>UGC both code for cysteine

49
Q

Missense mutation

A

Codon codes for a different amino acid Ex: UGU—>UGG will code for tryptophan instead of cysteine

50
Q

Nonsense mutation

A

The codon does not code for an amino acid but becomes a terminator codon; premature termination; Ex: UGU—>UGA signals stop instead of cysteine

51
Q

Frameshift mutation

A

The reading frame of the mRNA is shifted over one position resulting in a completely different amino acid chain being assembled or premature termination

52
Q

Frameshift mutation is due to ____ or _____

A

Insertion (addition) or deletion (removal) of a nucleotide

53
Q

Operons

A

Collections of genes in bacteria

54
Q

Promotor region

A

RNA polymerase binding site

55
Q

Operator region

A

Repressor protein binding site; acts as a control switch to turn on or off the operon

56
Q

Repressor protein

A

Allosteric protein with 2 binding sites

57
Q

Inducer

A

Molecule that will bind to the repressor protein to change its shape so that it will be unable to bind to the operator region; operon will be “on”

58
Q

Corepressor

A

Molecule that will bind to the repressor protein to change its shape so that it will be able to bind to the operator region; operon will be normally “off”

59
Q

Inducible operons

A

Most are catabolic operons; producing enzymes that function in the hydrolysis and breakdown of molecules

60
Q

Are inducible operons normally off or on? What changes that?

A

Normally off until turned on; the substrate turns the operon on (induces)

61
Q

In the lac operon, what is the inducer and what is the corepressor

A

Inducer: lactose;
corepressor: glucose

62
Q

What is beta-galactosidase

A

Enzyme produced by the structural genes of the lac operon to hydrolyze the beta bond between glucose and galactose in lactose

63
Q

Repressible operons

A

Most are anabolic operons, producing enzymes that function in assembly of molecules

64
Q

Are repressible operons normally on or off? What changes that?

A

Normally on until shut off; the product turns the operon off (represses)

65
Q

In the Arginine operon what is the corepressor?

A

Arginine

66
Q

Recombinant

A

Any organism that contains and expresses genes that originated in another organism

67
Q

Explain horizontal gene transfer

A

A DNA transfer the did not directly come from parent cells

68
Q

Conjugation

A

Mode of genetic exchange in which a plasmid or other genetic material is transferred by a donor cell to a recipient cell via a direct connection between the two cells

69
Q

F factor or fertility plasmid

A

Carries genes for the synthesis of the sex pilus. Only found in gram-negative bacteria. Called a conjugated plasmid

70
Q

R or resistant factor plasmid

A

Carries genes for the synthesis of proteins that will allow the bacteria to be resistant to antibiotics or other drugs or heavy metals

71
Q

VIrulence plasmid

A

Carries gene for the synthesis of proteins that will allow the bacteria to be more virulent or pathogenic

72
Q

What are three virulence properties

A

Ability to infect, invade, produce toxins; (infectivity, invasiveness, toxigenicity)

73
Q

Transformation

A

The non-specific acceptance by a bacteria cell of small fragments of soluble DNA from the surrounding environment. Do not need to living cells to accomplish

74
Q

Explain the difference between an R strain and an S strain

A

R strain is rough, no capsule

S strain is smooth, has a capsule that allows it to stick and evade

75
Q

Explain Griffith’s experiment

A

Mouse + live S = dead mouse
Mouse + live R = mouse is alive
Mouse + heat killed S strain = live
Mouse+ heat killed S strain+live R strain = dead mouse and live S strain on autopsy

76
Q

What is a competent cell

A

Cells capable of accepting genetic material through transformation; ability to take up free DNA

77
Q

Transduction

A

The process by which a bacteriophage (virus) can carry DNA from a donor bacteria cell to a recipient bacteria cell

78
Q

Three examples of transduction

A

Toxin formation in diphtheria botulism and anthrax; enzymes for sugar fermentation; drug resistance

79
Q

Transposons-jumping genes – transposable elements

A

Have ability to shift from one part of the genome to another; can relocate a gene from a plasmid to a chromosome and vice versa within its own self

80
Q

Transposon’s – jumping genes – transposable elements are involved in

A

Transfer of drug resistance, replacement of damaged DNA, changes in the colony morphology of the bacteria (pigmentation, etc)

Completed (12 decks)

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