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Micro Lecture > Microbial genetics > Flashcards

Microbial genetics Flashcards

1
Q

What is a genome?

A

all genetic information in cell

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2
Q

What is a chromosome?

A

molecule of DNA + proteins

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3
Q

How are prokaryotic chromosomes organized?

A

1 circular= genome

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4
Q

How are eukaryotic chromosomes organized?

A

multiple pairs=genome

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5
Q

What is a gene?

A

a segment of DNA encoding a functional product (ie protein)

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6
Q

What is a genotype?

A

just genes of an organism

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7
Q

What are plasmids?

A

exist in prokaryotes

small circular dsDNA

Extrachromosomal (not part of genome)

not essential but often advantageous

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8
Q

How are plasmids advantageous?

A

antibiotic resistance

toxins

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9
Q

How can DNA be described?

A

complementary (A:T and C:G)

antiparallel (opposite directions)

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10
Q

What must happen before a cell divides?

A

DNA replication

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11
Q

What is semiconservative DNA replication?

A

each strand of original molecule serves as template

new DNA contains one conserved “parental” and one new strand

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12
Q

What does helicase do in DNA replication?

A

unzips the DNA

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13
Q

What does topoisomerase do in DNA replication?

A

relaxes

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14
Q

What is the function of primase in DNA replication?

A

RNA primer

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15
Q

What does DNA polymerase do in DNA replication?

A

Reads 3’ to 5’
Synthesizes 5’ to 3’

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16
Q

What does ligase do in DNA replication?

A

glues lagging fragments

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17
Q

What happens in prokaryotic DNA replication?

A

Circular DNA

1 replication bubble

2 forks at each origin (bidirectional forks)

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18
Q

What happens in eukaryotic DNA replication?

A

many origins and bubbles

linear DNA

bidirectional forks (2 forks at each origin)

19
Q

What is a phenotype?

A

physical features/functional traits of an organism

include structures, morphology, metabolism

20
Q

How does transcription stop and start?

A

start: promoter

stop: terminator

21
Q

What happens in transcription?

A

RNA polymerase reads DNA

synthesizes complementary mRNA

22
Q

What happens in translation?

A

ribosomes read mRNA three nucleotides at a time (codon)

start codon is AUG and stop codons

Transfer RNA (tRNA) is an anticodon plus an amino acid

23
Q

What is a genetic code rule?

A

1 start codon- Met

64- other amino acids (19)

3-stop codons- no amino acids

24
Q

Why does more than one codon code for the same amino acid?

A

protects from mutations

25
Q

How does gene expression happen in prokaryotes?

A

coupled

translation can begin before transcription complete

26
Q

How does gene expression happen in eukaryotes?

A

transcription completed in the nucleus before translation in cytoplasm

27
Q

What is point mutation?

A

one nucleotide is changed

28
Q

What is substitution?

A

one nucleotide replaced by another

29
Q

What is frameshift?

A

insertion/deletion of nucleotide

30
Q

What is silent mutation?

A

one result of substitution

only affects genotype

protein not affected

31
Q

What is missense mutation?

A

one result of substitution

amino acid changed

may or may not have an effect on function

sickle cell disease- altered hemoglobin shape

32
Q

What is nonsense mutation?

A

one result of substitution

premature stop codon

often nonfunctional protein

33
Q

What do drastic missense and nonsense mutations do?

A

ribosome reading frame shifted (reads in 3’s remember)

non functional protein

34
Q

What do base analog chemical mutations do?

A

look like normal bases initially but base pair incorrectly once incorporated

induce point mutations

used in research and as drugs

example is 5-bromouracil

35
Q

What do intercalating agents do in chemical mutations?

A

slip in between adjoining nucleotides

bulge in backbone- polymerase makes mistakes (insertion/deletion of nucleotides

frameshifts for ribosomes

example is benzopyrene in smoke

36
Q

What does ionizing radiation do?

A

X-rays and gamma rays

energize electrons in atoms- some electrons escape

free electrons strike other atoms- ions reaction with DNA- point mutations

37
Q

What does non-ionizing radiation do?

A

UV Light

induces thymine dimers- covalent bonds between adjacent T’s

distorts backbone

improper replication- frameshift mutation

38
Q

What is vertical gene transfer?

A

passing of genes down from parent to offspring

39
Q

What is horizontal gene transfer?

A

genes passed down laterally in same generation (same recombination of transferred genes)

Prokaryotes (donor and recipient (recombinant cells)

40
Q

What is transformation?

A

recipient takes up DNA fragments in environment from dead cell

antibiotic resistance has spread this way

41
Q

What happens in conjugation?

A

fertility plasmid allows bacteria to form special pilus (allows plasmid transfer to recipient)

42
Q

How does antibiotic resistance spread?

A

conjugation, transformation, transduction

43
Q

What happens in transduction?

A

new assembling phage accidentally package piece bacterial chromosome (transferred to new cell when phage infects it

dead end for phage but could be good for bacteria (antibiotic resistance)

Micro Lecture (7 decks)

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