Mutation

Question 1

Definition: Mutant

Answer 1

Organism that is direct offspring of wild-type but is different

Question 2

Definition: Strain

Answer 2

Organisms of the same species isolated from nature that have different properties (because it is no possible to know which the mutant)

Question 3

Definition: Phenotype

Answer 3

All the observable properties of an organism

Question 4

Definition: Genotype

Answer 4

The actual sequence of an organism’s DNA

Question 5

Definition: Mutation

Answer 5

An heritable change in DNA sequence

Question 6

Definition: Allele

Answer 6

Different forms of the same gene. Bacteria are haploid therefore it has one allele

Question 7

Nomenclature: lac

Answer 7

lactose metabolism

Question 8

Nomenclature: his

Answer 8

histidine biosynthesis

Question 9

Nomenclature: dna

Answer 9

DNA synthesis

Question 10

Nomenclature: pol

Answer 10

DNA polymerase

Question 11

Nomenclature: uvr

Answer 11

UV repair

Question 12

Nomenclature: rec

Answer 12

Recombination

Question 13

Letters distinguish different genes that affect or function in the same process. Give an example.

Answer 13

lacZ, lacY, lacA ; hisA, hisB, hisC (all undercase should be italicized)

Question 14

Protein products of genes are given the same name. (but it is not “italicized” and the first letter is capitalized) Give an example

Answer 14

RecA ; DnaA

Question 15

What are the consequences of mutations?

Answer 15

• Some are harmless
• Some may cause a change in phenotype
• Some are bad
• Some are lethal

Question 16

Bac Phenotypes: Prototroph and auxotroph. (based on growth on particular media)

Answer 16

An auxotroph can not make or lacks the ability to grow on a particular nutrient. [Ex. A mutant strain that has lost the ability to synthesize its own supply of tryptophan is a Trp auxotroph and is designated Trp]

Question 17

Bac Phenotypes: Ability to utilize substrates (based on growth on particular media)

Answer 17

The ability to utilize a particular carbon and energy source can also be used as a phenotype. [Ex. A strain harboring a mutation rendering it unable to utilize the sugar galactose is galactose-, of Gal-]

Question 18

Bac Phenotypes: Antibiotic resistance (based on growth on particular media)

Answer 18

The ability to grow in the presence of an antibiotic

Question 19

Bac Phenotypes: Other markers (2 examples) (based on growth on particular media)

Answer 19

Colony morphology and resistance to phage.

Question 20

Auxotrophic mutants can be isolated because?

Answer 20

They have mutations in genes whose products are required under certain conditions.

Question 21

What are the conditions that DNA changes would be lethal?

Answer 21

• Temperature sensitive mutants
• Cold sensitive mutants
• Nonsense mutations

Question 22

What are the two types of Temperature-sensitive mutation from DNA changes?

Answer 22

• Permissive temperature: the protein function

* Nonpermissive temperature: higher temperature

Question 23

Lethal DNA mutation def: Temperature-sensitive mutants

Answer 23

Change an amino acid of the protein so that protein no longer function at high temperature but still function at lower temp

Question 24

Lethal DNA mutation def: Cold sensitive mutants

Answer 24

Cells with proteins that fail to function at lower temperature. The mutation occurs in genes whose products must form a large complex (ex. Ribosome_
-At higher temp, the mutated protein can entered in the complex, but it will not be able to do so a lower temperature

Question 25

Lethal DNA mutation def: Nonsense mutations

Answer 25

Mutation that change a codon in a gene to one of the three nonsense codons (UAA, UAG, or UGA)
-Translation of the gene doesn’t stop unless the cell has a “nonsense suppressor” tRNA

Question 26

Resistance: Luria and Delbruck experiment demonstrates that in bacteria, genetic mutations arise in the absence of selection, rather than being a response to selection. What are the two types of hypothesis and their definitions

Answer 26

1. Random mutations: If it is correct among of mutated will varied in all cultures, depending of when the mutation occur
2. Direct change: If it is correct each bacterium will have same chance of becoming a mutant

Question 27

T or F: Random mutations hypothesis is correct

Answer 27

True; If correct among the mutated will vary in all cultures, depending of when the mutation occur.

Question 28

What are the two ways that could cause mutations?

Answer 28

1. Environmental insults

2. Errors in DNA replication

Question 29

Mutations are?

Answer 29

Permanent changes in the DNA sequence that are inherited

Question 30

Depending upon the nature of the mutation, they can what?

Answer 30

Be expressed as abnormal proteins

Question 31

Depending upon the function of the protein, mutations that affect that protein might what?

Answer 31

Result in an easily observable phenotypic change

Question 32

Some mutations (phenotypes) only appear under what kind of conditions?

Answer 32

Only under certain conditions, such as exposure to a certain environmental agent or condition

Question 33

Base Pair changes have 4 different type that can cause it. What are they?

Answer 33

1. Transitions
2. Transversions
3. Missense mutations
   4 Nonsense mutations

Question 34

Base pair changes are one of the types of mutations. What are the other 4?

Answer 34

1. Frameshift mutations
2. Deletion mutations
3. Inversion mutations
4. Tandem duplications

Question 35

Mispairing during the replication can what?

Answer 35

Lead to a base pair change in DNA