Microbial Genetics

Question 1

Nucleic acids

Answer 1

Building block=nucleotide composed of a nitrogenous base, a five carbon sugar (ribose or deoxyribose) and up to three phosphate groups

Question 2

Components of Nucleic acids

Answer 2

Pyrimidines have a six carbon ring
Purines consist of two joined carbon rings with five and six members
Elements in a nitrogenous base are labelled numerically
Elements in sugar are labelled numerically with a ‘
The sugar is connected to the nitrogenous base via position 1’
The nitrogenous base is linked to position 1’ of the sugar by glycosidic bond from NA of pyrimidine and N9 of purine

Question 3

Bases

Answer 3

Adenine
Guanine
Cytosine
Thymine
Uracil

A with T by 2 hydrogen bonds
G with C by 3 hydrogen bonds

Question 4

Central dogma of genetic information

Answer 4

DNA -(transcription)-> RNA -(translation)-> protein

Question 5

DNA has

Answer 5

Coding or sense strand-bearing same sequence as mRNA
Template or antisense strand-directing synthesis of mRNA via complementary base pairing
Read from 5 to 3 this is sense strand

Question 6

DNA replication

Answer 6

Is semiconservative

Parental strand and a daughter strand in new molecule

Question 7

DNA replication sumamry

Answer 7

1. Helicases unwind the parental double helix
2. single-stranded binding proteins stabilize the unwound parental dna
3. the leading strand is synthesized continuously in the 5 to 3 direction by DNA polymerase
4. the lagging strand is synthesized discontinuously. Primase synthesizes a short RNA primer which is extended by dan polymerase to form an okazaki fragment
5. after the RNA primer is replaced by DNA, dna ligase joins the okazaki fragment to the growing strand

Question 8

Spontaneous mutation

Answer 8

Background generation in bacteria

Question 9

Induced mutation

Answer 9

mutagens- act directly by modifying a particular base or being incorporated into the nucleic acid

Question 10

Silent mutation

Answer 10

Mutations without apparent effect
base change in DNA no change in AA
Change in AA not function change for protein

Question 11

Missense mutation

Answer 11

change in codon –> change in AA –> change in protein function

Question 12

Nonsense mutation

Answer 12

change in coding codon to a termination codon resulting in premature termination

Question 13

Framshift mutation

Answer 13

inserting or deleting number of bp other than a multiple of 3

Question 14

Transformaiton

Answer 14

acquisition of new genetic markers by incorporation of added DNA

Question 15

Conjunction

Answer 15

mating between two bacteria involving transfer of genetic material

Question 16

Transduction

Answer 16

transfer of bacterial gene from one to another by a phage

Question 17

Transposition

Answer 17

Movement of a transposon to a new site in the genome