IB BIO D1.3

Mutation

A change in the DNA sequence that occurs during DNA replication.

Types of mutations

Substitutions, insertions, and deletions.

Base substitution

A mutation where a single nucleotide is changed, also known as a single-nucleotide polymorphism (SNP).

Frameshift mutation

A mutation caused by the insertion or deletion of nucleotides that alters the reading frame of the gene.

HTT gene

An insertion of multiple CAG repeats on chromosome 4 that causes Huntington’s disease.

Delta 32 mutation

A deletion of 32 nucleotides in the CCR5 gene that prevents HIV from attacking cells.

Mutagens

Chemicals that can cause genetic mutations, originating from inside the body or the environment.

Satellite DNA

Non-coding DNA found in the centromere with a higher mutation rate than coding DNA.

Germ cells

Sex cells that can pass mutations to offspring.

Somatic cells

Body cells that do not pass mutations to the next generation and are often associated with cancer.

Genetic variation

Mutations can be beneficial, harmful, or neutral, influencing natural selection.

Gene knockout

A method to study gene function by removing a gene and observing the effects.

CRISPR-Cas9

A gene-editing technology that allows for precise modifications of DNA.

Conserved sequences

DNA sequences that are similar across species, indicating evolutionary importance.

Cytokinesis

The process where two cells split into separate cells after division, differing in animal and plant cells.

Equal cytokinesis

When daughter cells receive equal distribution of DNA and organelles.

Unequal cytokinesis

When daughter cells do not receive equal resources, as seen in oogenesis.

Mitosis

A type of cell division resulting in two identical daughter cells.

Meiosis

A reduction division producing four genetically different haploid cells.

Interphase

The stage of the cell cycle where DNA replication occurs, divided into G1, S, and G2 phases.

DNA condensation

The process of supercoiling DNA around histone proteins for proper segregation during cell division.

Prophase

The first phase of mitosis where chromatin coils and the nuclear envelope disappears.

Metaphase

The phase of mitosis where sister chromatids align at the cell's equator.

Anaphase

The phase of mitosis where sister chromatids separate and move to opposite poles.

Telophase

The final phase of mitosis where the nuclear envelope reforms and chromosomes uncoil.

Meiosis I

The first round of meiosis where homologous chromosomes are separated.

Crossing-over

The exchange of genetic material between homologous chromosomes during Prophase I of meiosis.

Bivalent

A pair of homologous chromosomes during meiosis.

Meiosis II

The second round of meiosis where sister chromatids are separated.

Haploid

Cells that contain half the number of chromosomes (n) compared to diploid cells (2n).