Mutations

Structural Variation

Differences, or variations in DNA sequence from one individual to another

Euploidy

Presence of chromosome number which is the multiple of the basic chromosome set

Autopolyploidy

Type of polyploidy where the chromosome complement consists of more than two copies of homologous chromosomes

Autopolyploidy

Arises by fusion of gametes of the same species

Autopolyploidy

Contains homologous chromosome sets

Autopolyploidy

Caused by nondisjunction of chromosomes

Allopolyploidy

Refers to a type of polyploidy where the chromosome complement consists of more than two copies of chromosomes derived from different species

Allopolyploidy

Arises by the fusion of gametes of the different species

Allopolyploidy

Do not contain homologous chromosome sets

Allopolyploidy

Caused by mating of different species

Autopolyploidy

Does not undergo meiosis since it has arisen from one parent

Allopolyploidy

Can undergo meiosis

Aneuploidy

Occurs when one or more chromosomes is missing or included as excess

Characterized by incomplete genomes

Nullisomic

Euploid minus one pair of chromosomes

Monosomic

Euploid minus one chromosome

Trisomic

Euploid plus one chromosome

Tetrasomic

Euploid plus one pair of chromosomes

Chromosome Aberration

Changes in chromosome structure

Deletion

Loss of a chromosome segment

Duplication

Repetition of a chromosome segment

Inversion

A segment breaks off, flips, and reattaches

Translocation

A piece of one chromosome attaches to another chromosome

Chri du chat

A part of the short arm (p arm) of chromosone 5 is missing

High-pitched, cat-like cry in infants

Charcot-Marie-Tooth Disease Type 1A

Duplication of a gene on chromosome 17 (specifically the PMP22 gene)

Causes muscle weakness, difficulty walking, loss of sensation in the arms and legs

Trisomy 21

47 chromosomes, instead of 46

Developmental delays, characteristic facial features, increased risk for certain medical conditions

Mutation

A permanent change in an organism’s DNA sequence.

Mutagens

Agents that increase the likelihood of mutations

Microlesions

Small, localized changes in the DNA sequence

Base pair substitution

A type of microlesion where one nucleotide in a DNA sequence is replaced by another

Transition Mutation

Mutations that occur naturally without the influence of external factors.

Occurs when one purine is substituted with another purine, or one pyrimidine is substituted with another pyrimidine

Tautomeric shift

Propised by Watson and Crick

Causes spontaneous transitions

Tautomeric shift

A tempory and spontaneous change in the chemical structure of a nitrogenous base

Transversion mutation

A type of point mutation where a purine base is replaced by a pyrimidine base, or vice versa

Mutant cell lineage

The new sequeunce caused by both transition and transversion mutations will be perpetuated

Silent mutation

A point mutation that happens when a base pair substitution changes the DNA sequence but does not change the amino acid that is produced during translation

Missense mutation

A point mutation where a single nucleotide change in DNA leads to a different amino acid being incorporated into a protein

Nonsense mutation

A type of point mutation in DNA where a single nucleotide change converts a codon that normally encodes an amino acid into a stop codon

Frameshift Mutation

A genetic mutation caused by the insertion or deletion of several nucleotides in a DNA sequence that is not a multiple of three (1 or 2 nucleotides usually)

Mutator Genes

Genes that serve as breaking points for mutations to occur

INS gene

Codes for insulin production

Type 1 diabetes

Lack of enough insulin

Transposons

Genes that transfer from one spot along the sequence from another

Auxotrophy

Losing the ability to produce a nutrient

Reverse Mutations

Occurs when a mutant genotype reverts back to the wild type

Histidine Auxotrophy

Loses the ability to produce histidine

Carcinogens

First mutagens to be identified

Ionizing Radiations

X-Rays - Break the DNA strand

Non-Ionizing Radiation

UV Light - produces thymine dimer

Temperature Shocks

Changes result in higher frequency of polyploidy cell in plants

Centrifugation

Causes aneuploidy and structural aberration of chromosome

Cell Generation

Callus Formation

Alkalyting Agents

Adenine-hypoxantine - induces transition mutation

Base analogues

5-Bromouracil = TA

Tautomerism - changes shape

Intercalating Agents

Proflavine - very flat molecules that slip into the DNA molecule

Induces frameshift mutation

Hybridization

The naturally occuring and the experimental allopolyploide are products of interspecific or intergeneric hybridization

Colchicine

Inhibits spindle formation and prevents anaphase