Chapter 8

Genetics

The study of heredity

Mutation

A change in a gene

Vertical gene transfer

The transfer of DNA from parent to child

Horizontal gene transfer

The transfer of DNA from one organism to another

Genotype

Genetic makeup

Phenotype

Appearance

Wild type

An organism as it normally occurs in nature

Autotroph

A mutant that need a requirement its parents did not

Point Mutation

A base substitution in DNA Replication

Missense mutation

causes and amino acid change

Nonsense mutation

Causes a premature stop

Frameshift mutation

Disruption of the entire code due to the addition or deletion of a base

Mutagens

Substances that cause mutations

Base analogs

Similar in structure to a base, causes incorrect bonding within the DNA molecule or cause an incorrect base to be matched with it

Intercalating agents

Insert between bases pushing them apart and increasing the chance that insertion or deletion will occur

Radiation

Causes breaks in DNA, damages bases, causes two thymines that are side by side to bond instead of crossing to over to bond with adenine

Carcinogens

Substances that cause cancer

Types of Carcinogen testing

Animals- takes a long time

Ames test - apply chemical to bacteria and look for mutations

Mismatch repair

Occurs during replication; endonuclease cuts the DNA backbone where a wrong base is; exonuclease cuts out incorrect base; DNA polymerase adds correct base

Light repair of damaged DNA

An anzye uses visible light for energy to repair any thymines that have joined side to side

Excision repair of DNA

DNA glycosylases or endonucleases recognize abnormal bases and cut the DNA on either side of the damage, DNA polymerase replaces the missing piece

SOS repair of damaged DNA

Massive damage; special enzyme is prepared to bypass all replication rules and makes new DNA of it’s own kind

Recombination

Exchange between 2 DNA

Transformation

Absorbing loose DNA into the cell

Conjugation

The transfer of DNA from one cell to another through Pili

Bacteriophage

A virus that infects bacteria

Transduction

The transfer of DNA through a virus

Transposons

Pieces of DNA that can move from one chromosome to another

Methods bacteria use to protect themselves against invading DNA

1.Restriction enzymes but DNA at specific sequences so bacteria can use them to destroy foreign DNA that gets into them

2. The CRISPR system- Cas protiens cut phage DNA that entered a bacterium thane fragments are inserted into the bacterium’s chromosome; produce new Cas proteins capable of degrading that phage in future