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Microbiology > Module 16/17 > Flashcards

Module 16/17 Flashcards

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Biology 101 flashcards
1
Q

Genome

A

genetic information of the cell

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2
Q

Genes

A

segments of DNA that code for functional products

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3
Q

Codon

A

a group of three nucleotides on mRNA

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4
Q

Genotype

A

genetic makeup, potential properties

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5
Q

Phenotype

A

expressed properties of the genotype, the manifestation of the genotype

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6
Q

Anticodon

A

complementary sequence on the tRNA (to codon on mRNA); decides which amino acid is brought to the ribosome

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7
Q

What is the genome of a bacterial cell?

A

1 chromosome total not a pair

  • Single chromosome
  • Haploid
  • Low amounts of noncoding regions
  • Circular chromosome
  • No histones-other proteins used
  • Attached to the plasma membrane
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8
Q

What is the typical genetic flow of information?

A

DNA to DNA (replication)

DNA to RNA (transcription)

RNA to Protein (translation)

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9
Q

codon

A

a group of three nucleotides on mRNA

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10
Q

anticodon

A

complementary sequence on the tRNA (to codon on mRNA); decides which amino acid is brought to the ribosome

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11
Q

What is replication? What is transcription? What is translation?

A
  • DNA supercoiling relaxed and parental DNA strands unwound by enzymes
  • RNA polymerase bonds gene promoter and DNA unwinds; mRNA is synthesized (with RNA nucleotides) using DNA as a template in 5’-3’ direction until reaching terminator
  • Ribosome subunits form with mRNA; mRNA codons determine which tRNA (each carry a different amino acid) “docks’ in ribosome; tRNA leaves amino acid for the forming polypeptide; synthesis of polypeptide continues until reaching a stop codon on mRNA
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12
Q

What does semiconservative replication of DNA mean? What experiment demonstrated this?

A

Each new double-stranded DNA molecule is one parental (old) strand and one daughter (new) strand

Meselson and Stahl experiment

        First step: grow E. coli with N15 isotope to incorporate it into DNA-heavy DNA

Second step: grow E coli with N14

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13
Q

List the general steps for DNA replication.

A

Leading strand- synthesized continuously by DNA polymerase in 5’-3’ direction toward fork (with DNA nucleotides)

Lagging strand- synthesized discontinuously via Okazaki fragments by DNA polymerase in 5’-3’ direction away from the fork (with DNA nucleotides)- more complex- fragments extending from RNA primers.

Replication in bacterial cells is bidirectional

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14
Q

Why does the DNA polymerase of replication have a low error rate?

A

It has proofreading capability- DNA polymerase

checks the work as it goes

Errors 1 in 10^10 bases incorporated

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15
Q

Why does HIV have a high error (natural mutation) rate?

A

It has reverse transcriptase, which mutates quicker and faster

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16
Q

List the three types of RNA and their importance?

A

rRNA
-ribosomal RNA
-makes up ribosome-important for protein synthesis
-protein makes up protein

tRNA
-transfer RNA
-molecule brings the amino acid into ribosome during protein synthesis
-one for every amino acid

mRNA
-messenger RNA
-brings the message from the DNA to the ribosome

17
Q

List the general steps for transcription.

A
  • RNA polymerase binds gene promoter and DNA unwinds
  • mRNA is synthesized (with RNA nucleotides) using DNA as template in 5’-3’ direction until reaching terminator
18
Q

List the general steps for translation

A
  • ribosome subunits form with mRNA
  • mRNA codons determine which tRNA (each carry a different amino acid) “docks” in ribosome
  • tRNA leaves amino acid for the forming polypeptide
  • synthesis of polypeptide continues until reaching a stop codon on mRNA
19
Q

Where does transcription and translation occur in the prokaryotic cell?

A

Simultaneous transcription and translation going on in cytoplasm (no nucleus)

20
Q

Where does transcription and translation occur in the eukaryotic cell?

A

Transcription- nucleus

Translation-cystoplasm

21
Q

How are bacteria able to transfer DNA (define vertical vs. horizontal gene transfer)?

A

Genetic recombination- exchange of genes between two DNA molecules to form new combinations of genes
-Survivability of bacteria
-Somewhat like sexual reproduction, so it contributes to genetic diversity

Vertical gene transfer- genes are passed from parent to offspring- plants, animals. Bacteria

Horizontal gene transfer- genes are passed between different bacteria
-3 methods:
—Transformation
—Conjugation
—Transduction

22
Q

What is transformation? What does competency mean?

A

Uptake of DNA from the environment

First discovered in 1928 with Federick Griffiths experiments- transforming principle

Cells must be competent- alterations in the cell wall that make it permeable to DNA

-Strains without DNase

-Haemophilus, bacillus, staphylococcus, and streptococcus are competent

-Can make E. coli cells competent

23
Q

What is conjugation?

A

DNA transfer with plasmids through pili

24
Q

Explain the mechanism of conjugation and all of the important factors involved (names of the cells, etc.)

A

With F factor- The first plasmid studied for conjugation in E. coli

Donor cell contains fertility plasmid, is F+, male cell

The recipient cell does not, is F-, female cell

After conjugation F- cell becomes F+ (receive copy of F+)

Factor has genetic information for transfer/pili

DNA transfer during conjugation

—Rolling circle-ssDNA is transferred than made into dsDNA in cell it was transferred to

25
Q

What is Hfr conjugation?

A

F plasmid may combine with genome and thus have Hfr cell

Conjugation of some of the genome from Hfr leads to recombination in recipient cell

26
Q

What is a plasmid? What are some characteristics of plasmids and functions they code for?

A

Plasmids- small extra-chromosomal element

            i.     1-5% of bacterial genome size

           ii.     Self replicates-rates vary

          iii.     Mobile during conjugation

         iv.     Cured if nonessential

Functions of plasmids

              i.     Resistance genes

              ii.     Metabolic genes

              iii.     Virulence factors

             iv.     Fertility- has genes for conjugation
27
Q

What is transduction?

A

DNA transfer with viruses

Mechanism

-Defective phage

—Phage introduces bacterial DNA into a different bacterial cell and then have chance for recombination

—Generalized vs specialized

Microbiology (21 decks)

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