MICROBIO LEC: LECTURE 5 QUIZ

Expression

genetic info used within a cell

to produce proteins needed for the cell to function

rRNA

integral part of ribosomes

> cellular machinery for protein synthesis

Recombination

possibly transfer from 1 bacterium to another

Replication

• carry genes to resist many different antibiotics

• used in research bc DNA strands can be extracted fr bacteria then manipulated

some mistakes in DNA replication

results to high mutation rates

may cause food-borne diseases

E. Coli serotype 0157:H7

STEC strain

shiga toxin producing E. Coli, produced by Shigella

Drug mutation can cause drug resistance however

not all mutations lead to drug resistant

study of Genes & how they’re replicated

Genetics

Genome

genetic info in the cell

structures containing DNA that carry genes

Chromosomes

Genes

segments of DNA

clusters of genes

Operons

Nucleotides

repeating units consisting of nucleobase (A-T, C-G)

adenine-thymine, cytosine-guanine

Base pairs

Genetic code

converted into amino acid sequence

theory by Francis Crick, 1956

Central Dogma

Central Dogma

sequence of nucleotides in DNA determines sequence of amino acids in DNA-RNA-Protein

serves as the master template

DNA

RNA

acts as a messenger

Proteins

final products that perform cell functions

relaxes supercoiling ahead of the replication fork 

DNA Gyrase

DNA Ligase

• discontinued fragments; okazaki fragments

• make covalent bonds to join DNA strands

synthesize DNA

DNA Polymerase

Helicase

unwinds double-stranded DNA

relaxes supercoiling

separates DNA circles

Topoisomerase

mRNA

carries coded info

Adenine in DNA template

dictates a Uracil in mRNA

RNA contains what

uracil instead of thymine

process of transcription requires DNA polymerase

mRNA

AUG

start codon

stop codons

UAA, UAG, UGA

need mRNA, ribosomes for protein synthesis

Translation

tRNA

bring specific amino acid encoded by genetic code in mRNA

ribosomes reads what

mRNA codons (3-base codes)

each codon corresponds to what

a specific amino acid

amino acids are joined together,

forming a polypeptide

permanent change in the base sequences of DNA

Mutations

Mutations

• very important for genetic info

• may affect the function of protein, sometimes making bacteria resistant to antibiotics

most common type involving single base pairs

Base substitution/point mutation

single based at 1 point in the DNA sequence is what

replaced with different base

Silent mutation

amino acid changed, function of protein may not change (if AA is in nonvital portion of the protein)

1 nucleotide’s substituted for another in the DNA is what

results to new codon that might still code for the same amino acid

Missense mutation

substitution of a different amino acid

creates a stop codon, prevents synthesis

Nonsense mutation

Frameshift mutation

deletion or insertion in a nucleotide

(shifting will occur)

Spontaneous mutation

arise in the absence of known mutagens

following treatment with a mutation

Induced mutation

Mutagenesis

process of forming mutations

increase the frequency of mutation

Mutagens

happens when DNA from 2 source combine

Genetic Recombination

In Genetic Recombination, this creates what

new gene combinations, increasing diversity

in bacteria, this happens thru transformation, conjugation, or transduction

Vertical Gene Transfer

passed from parent cell to daughter cells during cell division

explains how offspring inherit same genetic traits as their parent bacterium

vertical gene transfer

Horizontal Gene Transfer

bacteria shares genes laterally

(how antibiotic resistance spreads)

a non resistant bacterium can receive DNA from a resistant one in

Horizontal Gene Transfer

gives portion of its DNA to the recipient

Donor cell

receives DNA

Recipient cell

Recombinant

recipient successfully integrates donor DNA

Transformation

bacteria takes in naked DNA from its surroundings

Transformation transforms bacteria bc of

integration of specific gene into its own DNA

Heat skilled or dead bacteria results in

transferred from 1 bacterium to another as naked DNA

direct cell to cell contact

(opposite mating type (+) or (-)

Conjugation

gram negative

sex pili

gram positive

sticky surface molecules (form mating bridge after sticking together to transfer)

Transduction

bacterial DNA is transferred from donor to recipient inside a virus

(infects bacteria called bacteriophage)

Phage infects what

donor bacterial cell

(phage DNA & proteins are made,

bacterial chromosome’s broken into pieces)

In Genetic Recombination, when transferred,

there’s a crossing over

DNA from donor aligns w/complementary base pair (A-T,C-G)

RecA catalyzes what

the joining of the 2 strands

In Genetic Recombination,

• RecA catalyzes the joining of the 2 strands 

• result to integration of part of donor DNA into the recipient

• resolved by 2 important enzyme: ligase & DNA polymerase (esp in joining the complementary base pair) 

• donor is now integrated w the recipient, and will eventually degrade 

• recipient cell will now have new integrated DNA

• recipient cell = recombinant (already integrated the donor DNA into its own DNA)