Genetics Lec 19

Mutation

Heritable change in genetic material.

Allelic Variation

Differences in gene variants within a population.

Positive Mutation Effects

Foundation for evolutionary adaptation.

Negative Mutation Effects

Often harmful and disease-causing.

DNA Repair

Mechanisms to fix damaged DNA.

Chromosome Structure Mutation

Alterations in chromosome arrangement.

Chromosome Number Mutation

Changes in the total number of chromosomes.

Gene Mutation

Molecular changes in a gene's DNA sequence.

Point Mutation

Change in a single base pair.

Base Substitution

Replacement of one nucleotide with another.

Transition Mutation

Pyrimidine to pyrimidine or purine to purine change.

Transversion Mutation

Pyrimidine to purine or vice versa change.

Silent Mutation

No change in amino acid sequence.

Missense Mutation

Amino acid change occurs in polypeptide.

Nonsense Mutation

Normal codon changed to a stop codon.

Frameshift Mutation

Addition/deletion not divisible by three shifts reading frame.

Germ-Line Cells

Cells that produce gametes (eggs, sperm).

Somatic Cells

All body cells excluding germ-line cells.

Germ-Line Mutation

Mutation in gametes, passed to offspring.

Somatic Mutation

Mutation in body cells, not inherited.

Genetic Mosaic

Individual with genetically different cells.

DNA Repair Systems

Multiple mechanisms to correct DNA damage.

Photolyase

Enzyme that repairs thymine dimers using light.

Alkyltransferase

Repairs alkylated bases by transferring groups.

Base Excision Repair (BER)

Removes damaged bases using DNA N-glycosylases.

Nucleotide Excision Repair (NER)

Repairs various DNA damages, including thymine dimers.

Uvr Proteins

Key proteins in E. coli NER system.

Core Promoter Mutation

Affects transcription levels of a gene.

Regulatory Element Mutation

Disrupts gene regulation mechanisms.