Genetic Diversity: Mutations & Meiosis

These flashcards cover essential vocabulary and concepts related to genetic diversity, mutations, and meiosis based on the provided lecture notes.

Genetic Mutation

A change in the sequence of base pairs in a DNA molecule that may result in an altered polypeptide.

Spontaneous Mutation

A type of gene mutation that occurs randomly during natural biological processes, such as DNA replication errors.

Deletion Mutation

Occurs when a nucleotide (and its base) is randomly deleted from the DNA sequence, potentially altering the amino acid sequence.

Substitution Mutation

A mutation where a base in the DNA sequence is randomly swapped for a different base, which can change the amino acid sequence.

Degenerate Genetic Code

The property of the genetic code where more than one codon can specify the same amino acid, meaning some base substitutions may not alter the protein's amino acid sequence.

Frameshift Mutation

A mutation caused by a deletion that changes the triplets of three bases in the DNA sequence, dramatically altering the amino acid sequence.

Mutagenic Agents

Environmental factors, such as high-energy radiation and toxic chemicals, that increase the mutation rate of cells.

Non-disjunction

The failure of chromosomes to separate during meiosis, potentially leading to an abnormal number of chromosomes in resulting gametes.

Overall Result of Meiosis

Two successive nuclear divisions that typically result in the formation of four genetically distinct haploid daughter cells from a single diploid parent cell.

Mitosis vs. Meiosis: Outcomes

Mitosis produces two genetically identical diploid cells for growth and repair, while meiosis produces four genetically distinct haploid gametes for sexual reproduction.

Independent Segregation

The process during meiosis where homologous chromosomes are segregated into daughter cells independently of each other.

Crossing Over

The process during meiosis where homologous chromosomes exchange genetic material, leading to genetic variation among daughter cells.

Haploid Cells

Cells that contain half the number of chromosomes; produced during meiosis.

Down's Syndrome

A genetic disorder caused by an extra copy of chromosome 21, resulting in a total of 47 chromosomes.

Recombination

The exchange of alleles between homologous chromosomes during crossing over, leading to new genetic combinations.

Meiosis I

The first division of meiosis that separates homologous chromosomes and reduces the chromosome number by half.

Meiosis II

The second division of meiosis that separates sister chromatids, similar to mitosis, resulting in four haploid cells.

Sickle Cell Anaemia

A disease caused by a single substitution mutation that alters a single amino acid in the hemoglobin polypeptide.

Cystic Fibrosis

A genetic disorder caused by a nonsense mutation that creates a premature STOP codon in the protein-coding sequence.

Genetic Diversity

The variety of genetic characteristics within a species, which can be enhanced through meiosis and fertilization.

Combinations of Chromosomes

The number of distinct chromosome arrangements possible after meiosis, calculated as 2^n where n is the haploid number.

Random Fertilisation

The unpredictable fusion of any male gamete with any female gamete, which significantly contributes to the genetic variation within a species.