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Micro Lecture Exam 3 > Microbial Genetics > Flashcards

Microbial Genetics Flashcards

1
Q

How does DNA relate to the behavior of a microorganism?

A

-DNA contains inheritable instructions for protein construction (amino acid sequences)

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2
Q

What is the connection between a pathogens DNA and its ability to cause disease?

A
  • all mediated by proteins

- controlled by DNA (template)

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3
Q

What do coding genes control?

A

-protein amino acid sequences

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4
Q

What do regulatory genes control?

A

-timing of coding gene expression

Ex. Promoter
-recruits RNA polymerase

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5
Q

What is the mRNA info used for?

A

-used by ribosome to build proteins during translation

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6
Q

What is a reasonable size for a bacterial coding gene?

A

1000 bp (base pairs)

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7
Q

How many coding genes does a typical bacterial cell?

A
  • approximately 5000 genes
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8
Q

What does RNA polymerase build?

A

-builds RNA by reading 1 strand of DNA (template) and building complementary RNA

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9
Q

RNA characteristics

A
  • single stranded or fold to form double stranded regions

- contains protein sequence info

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10
Q

What are the types of RNA?

A

mRNA, tRNA etc

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11
Q

Is mRNA +sense or -sense?

A

+ sense

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12
Q

Is template DNA +sense or -sense?

A

-complementary (-sense)

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13
Q

RNA polymerase binds DNA to make mRNA at DNA sequences called?

A

-promoters

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14
Q

What are promoters?

A

-Where RNA polymerase binds to DNA to make mRNA

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15
Q

What part of a promoter can a regulatory protein bind to?

A

-operator

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16
Q

What type of gene is a promoter?

A

Regulatory gene

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17
Q

What are the 2 types of transcriptional regulation proteins?

A
  • activator proteins bind regulatory genes and attract RNA polymerase
  • repressor proteins bind regulatory genes and block RNA polymerase
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18
Q

Transcription regulation occurs in what two ways?

A
  • Negative Regulation

- positive regulation

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19
Q

Weak promoter characteristics

A
  • weakly attract RNA polymerase
  • low baseline rate of transcription
  • some become strong promoters when activator proteins attach to them
  • found near coding genes
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20
Q

Strong promoter characteristics

A
  • attracts RNA polymerase very well
  • high baseline rate of transcription
  • some become blocked when reporters or proteins attach to them=transcription repressed
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21
Q

What is induction?

A

-increases the amount of a specific protein

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22
Q

What is repression?

A

-decrease the amount of a specific protein

23
Q

Explain the 2 ways how induction can occur

A

1) an inducer binds an activator protein causing the activator to bind to a promoter
2) an inducer binds to a repressor protein, causing the repressor protein to detach from the promoter

24
Q

Explain how repression occurs

A

-co-repressor binds to a repressor, causing it to attach to a promoter (blocks RNA polymerase)

25
Q

Example of an inducer and how s causes induction

A
  • lactose (sugar) binds to the Lac repressor protein and causes it to detach from a promoter
  • iron
26
Q

Example of a co-repressor and how is causes repression

A

-tryptophan (amino acid) binds to the Lac repressor and causes is to bind a promoter

27
Q

What is an Operon?

A
  • set of genes that are regulated at the same time

- ex. Genes encoding 5 enzymes needed to build tryptophan (amino acid) are turned on or off at the same time

28
Q

What does the start codon represent?

A

-beginning of codons

29
Q

What is the function of a stop codon?

A

-cause ribosome to release mRNA and polypeptide

30
Q

What is a messenger (rRNA)?

A

Amino acid sequence information (from coding DNA genes)

31
Q

What are codons?

A
  • Nucleic acid words
    • 3 bases long
    • encoding enough info for 1 amino acid
32
Q

What is a transfer (tRNA)?

A

-adaptor molecule that carries amino acids to ribosome

33
Q

What is an anticodon?

A

-portion of tRNA that base pairs with a codon in mRNA

34
Q

What are mutations?

A

-changes in DNA sequence

35
Q

Characteristics of a mutation

A
  • may or may not alter proteins
  • can be lethal (cell death), detrimental (- effect), neutral, or beneficial (+effect)
  • spontaneous or induced
36
Q

What are point mutations?

A

-small scale mutations where 1 or a few bases affected

37
Q

Explain what happens in large scale mutations

A

-aka chromosomal aberration

  • involves large regions of a chromosomes being duplicated, repeated or moved from 1 place to another
    • 1000 bp
38
Q

What are spontaneous mutations?

A

-replication errors (DNA polymerase errors)

39
Q

What are induced mutations?

A

-mutagens (UV, ROS, carcinogenic chemicals) damage DNA and cause increase number of replication errors)

40
Q

What are mutagens? Examples?

A
  • something that causes mutations

- UV, ROS, carcinogenic chemicals

41
Q

What is a missense mutation?

A
  • a type of point mutation
  • DNA change results in one changed amino acid in a protein
  • may have no effect on protein function
  • may have drastic effects if amino acid that changed is important for protein function
    • ex. Enzyme active site
42
Q

How do cells detect and repair damaged DNA?

A

-proofreading proteins detect damaged DNA and direct repair enzymes to the damaged sites

43
Q

What are the 2 types of gene transfer in unicellular microbes?

A
  • vertical gene transfer

- horizontal gene transfer

44
Q

Explain the vertical gene transfer process

A

-parent cell DNA is passes to daughter cells during the cell division process
(Parents to offspring)-most common form of inheritance

45
Q

Explain the horizontal gene transfer process

A

-transfer of DNA from 1 cel to another, not during the cell division process
(No parent, daughter cell relationship)

46
Q

What are the 3 types of horizontal gene transfer?

A
  • transformation
  • transduction
  • conjugation
47
Q

What is the typical size of a plasmid?
Range?
How many genes?

A
  • typically 5000 bp
  • range: 800-30000 bp
  • approx 5 genes
48
Q

What is the conjugation process?

A
  • transfer of plasmids through a mating bridge
    • f plasmid instructs cell to make mating bridge
    • sometimes donor cell and recipient cell are connected by sex pious prior to mating bridge
49
Q

Important components of bacteriophage vision

A
  • phage head
  • tail sheath
  • tail fiber (binds to host cell)
  • DNA
50
Q

What is a bacteriophage?

A
  • aka ‘phage’

- viruses that infect bacteria

51
Q

Lytic cycle process

A
  • Phage attaches to host cell and inserts DNA
  • Linear dsDNA cyclizes to circular DNA
    1) cell synthesizes capsid proteins
    2) cell replicates phage DNA. DNA packaged into capsids
    3) phage lyses cell, and progeny phases are released
52
Q

What is a prophage?

A

-when a phage DNA integrates into a host genome

53
Q

What is recombination?

A

-one DNA molecule can insert into another DNA molecule creating a new DNA sequence

54
Q

What is a transposon?

A

DNA molecules that inserted and cur out repeatedly (jumping genes)

Micro Lecture Exam 3 (5 decks)

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