Ch.8 Microbial Genetics

Question 1

what is a phenotype?

Answer 1

functioning of proteins in a cell

Question 2

how are genotype and phenotype connected?

Answer 2

connected through various RNA molecules

Question 3

how do changes in genotype affect phenotypes?

Answer 3

changes in DNA result in differences in amino acid sequences and are protein detective

Question 4

How is the genotype preserved?

Answer 4

through replication of DNA

Question 5

What is the flow of information?

Answer 5

DNA->RNA->Protein

Question 6

what determines the phenotypic trait?

Answer 6

the inherited genetic makeups of an organism

Question 7

what kind of chromosome does the prokaryote genome have?

Answer 7

single circular chromosome

Question 8

what is the inheritance of a prokaryote genome?

Answer 8

vertical and horizontal transmission of genes

Question 9

1 step in gene expression

Answer 9

Retrieval of information:

*genetic code based on transcript
*Employs different RNAs

Question 10

2 step in gene expression

Answer 10

Transcription:
*transcribe a gene
*RNA Polymers
*mRNA (transcript)

Question 11

3 step in gene expression

Answer 11

Translation:

*Ribosomes(rRNA)
*Transfer RNA’s

Question 12

transition & translation are coupled in what?

Answer 12

prokaryotes

Question 13

what are mutations defined as?

Answer 13

permanent alterations of the DNA base sequence

Question 14

mutation can be

Answer 14

silent (no effect)

Lethal (Kills)

Beneficial(evaluate in the context of what going to happen)

Question 15

what is a mutation caused by?

Answer 15

chemicals
Radiation
Mutagens

Question 16

what is spontaneous mutation?

Answer 16

random mistakes during replication

Question 17

What is a missense mutation?

Answer 17

amino acid substitution

causes:

the loss of function or change of structure

Question 18

what is a nonsense mutation?

Answer 18

premature stop codon forms

(lethal, bad/nonfunctional)

Question 19

what is a frameshift mutation?

Answer 19

insertion or deletion of a single base

change in amino acid sequence following insertion/deletion site

Question 20

What are the mechanisms of horizontal gene transfer?

Answer 20

Tranformation

Conjugation

Transduction

Transpotion

Question 21

describe transformation

Answer 21

uptake of naked DNA from the environment

(comes into the cell)

Question 22

describe conjugation

Answer 22

transfer of DNA via cell-to-cell contact (donor recipient) via sex pilus

physical contact between the cell usually passage of plasmid

Question 23

describe transduction

Answer 23

DNA transfer via a viral intermediate
(virus )

Question 24

describe transposition

Answer 24

transfer of transposons (mobile genetic elements)

Question 25

what did Fredirck Griffith work with?

Answer 25

Streptococcus pneumoniae culture

Question 26

what did Griffith discover?

Answer 26

transformation: the transfer of “naked” DNA from cell to cell in solution

Question 27

describe the experiment by Fredrick Griffith

Answer 27

heat-killed virulent forms of S.pneumoniae lysed

cells released DNA

taken up by live non-virulent forms

Question 28

what is competence?

Answer 28

cell envelope changes occur which enables the uptake of DNA

Question 29

what is artificial transformation?

Answer 29

it is made to be competent via chemical treatment and electrical shock

Question 30

what are plasmids?

Answer 30

small,extra-chromosomal circular segment of DNA

Question 31

what is the size of plasmids?

Answer 31

2-25 kbp

Question 32

how do plasmids replicate?

Answer 32

replicate autonomously
possesses own origin of replication(ori)

Question 33

describe conjugative plasmids

Answer 33

are transferable, F (fertility) Factor

posses ori for conjunctive transfer

Question 34

what can be found on plasmids?

Answer 34

catabolic genes
virulence genes

Question 35

plasmids can transfer only if what?

Answer 35

if there is an F factor

Question 36

The fertility factor(conjugative plasmid) has

Answer 36

donor F+
recipient F- cells

Question 37

the recipient receiving an F factor may integrate it into its chromosome resulting

Answer 37

cell termed Hfr (high-frequency recombination) cell

Question 38

conjugation of Hfr with F- cell:

Answer 38

replication and transfer of chromosome copy;

initiated within integrated F factor

Question 39

conjugation of Hfr with an F- cell: the F- recipient cell remains as an F- following conjugation

Answer 39

the connection between cells is disrupted

the chromosome breaks & the F- factor is not transferred

The F- F-recipient cell acquires whatever genes are received prior to breakage and can express these

Question 40

bacterial viruses (phages) serve as

Answer 40

The vehicle to transfer DNA between donor & recipient cells

Question 41

what is generalized transduction?

Answer 41

any host genes can be transferred

Question 42

what is specialized transduction?

Answer 42

only specific host genes are transferred (very restrictive)

Shiga
toxin
diphtheria toxin
cholera toxin

Question 43

steps to generalized transduction:

Answer 43

1. phage attachment
2. Host DNA cleaved
3. phage assembly; host DNA segments randomly package w/pahge carrying bacterial DNA
4. Donor & recipient DNA recombine

Question 44

what are transposons?

Answer 44

mobile genetic elements (700-40kbp long)

can move within chromosome

can move from cell to cell via

Question 45

what is transposition?

Answer 45

transposons possess a transposase

the gene that recognizes specific inverted repeat sequences

Question 46

simplest transposition:

Answer 46

insertion sequences (IS); have only transposase

Question 47

complex transposition:

Answer 47

have transposase & other genes
Ex: antibiotic resistance

Question 48

what does the Recall protein do?

Answer 48

mediates recombination between donor/recipient DNA