Microbiology Chapter 16

_______ are strains that are unable to grow on a minimal medium that supports growth of the wild type strain but are able to grow on the minimal medium if one or more nutritional supplements are added.

Auxotrophs

Transfer of genetic information via direct cell-cell contact is called

Conjugation

__________ are physical or chemical agents that cause mutation.

Mutagens

__________ mutations affect only a single base pair in a gene.

Point

photoreactivation.

Repair of thymine dimers using light to split the dimers apart into separate monomers

Lethal mutations can be recovered in haploid organisms if they are

conditional

Plasmids that have genes for pili and can transfer copies of themselves to other bacteria during conjugation are called __________ plasmids.

conjugative

A plasmid that can either exist independently of the chromosome or be integrated into it is called a(n) __________.

episome

Transfer of genes from one mature independent organism to another

horizontal gene transfer.

Mutations resulting from exposure to physical or chemical agents are called __________ mutations.

induced

Mutations that result in the death of an organism when expressed are called __________ mutations.

lethal

A mutation that changes the amino acid sequence of the resulting protein by substitution is called a __________ mutation.

missense

Which mutation may play an important role in driving evolution because they are often nonlethal and, therefore, remain in the gene pool?

missense

A __________ mutation is one that causes premature termination of the synthesis of the protein product.

nonsense

A __________ is a piece of extrachromosomal DNA that has its own replication origin.

plasmid

Microbial strains that can grow on minimal medium are called __________.

prototrophs

Lethal mutations can be maintained in diploid organisms if they are

recessive

Plasmids that have genes that decrease bacterial susceptibility to antibiotics are called __________ factors.

resistance

A __________ mutation does not alter the amino acid sequence of the resulting protein.

silent

The Ames test

used to measure the mutagenicity of chemicals

The __________ __________ is the most prevalent form of a gene in a population.

wild type