Genetics and Evolution Lecture Review

Flashcards covering key vocabulary terms related to genetics, evolution, meiosis, and chromosomal abnormalities discussed in the lecture notes.

Evolution

Change in population genetic makeup over time, or change in population genetic and physical variation over time.

Genotype

The genetic makeup of an organism, which interacts with the environment and development.

Phenotype

The observable physical or biochemical characteristics of an organism, resulting from the interaction of its genotype with the environment.

Epigenetic Modifications

Changes in gene expression not caused by changes in DNA sequence, such as histone modifications and DNA methylation, influenced by environment.

Genes

Small parts of DNA that code for a specific physical trait.

Genetic Variation

Presence of different genes or alleles within a population, essential for evolution.

Somatic Cells

Non-sex cells that typically contain a diploid number of chromosomes.

Haploid

A cell (like an egg or sperm) that contains a single set of chromosomes (n), half the number of a diploid cell.

Diploid

A cell that contains two sets of chromosomes (2n), one from each parent. Formed by the fusion of two haploid cells.

Meiosis

A type of cell division that reduces the number of chromosomes in the parent cell by half, creating four haploid cells (gametes) from a diploid cell.

Fertilization

The fusion of two haploid gametes (egg and sperm) to form a new diploid organism.

Homologous Chromosomes

A pair of chromosomes (one from each parent) that are similar in length, gene position, and centromere location.

Centromere

The region on a chromosome that joins two sister chromatids.

Sister Chromatids

Two identical copies of a single replicated chromosome that are connected by a centromere.

Karyotype

An organized profile of a person's chromosomes, arranged by size and type.

Autosomes

Any chromosome that is not a sex chromosome.

Sex Chromosomes

Chromosomes that determine an individual's biological sex (e.g., X and Y in humans).

Interphase

The phase of the cell cycle where a cell grows, duplicates its DNA, and prepares for cell division (occurs before meiosis I).

Meiosis I

The first meiotic division, where homologous chromosomes separate, resulting in two haploid cells with duplicated chromosomes.

Meiosis II

The second meiotic division, where sister chromatids separate, resulting in four haploid cells with unduplicated chromosomes.

Independent Assortment

The random orientation and separation of homologous chromosome pairs during meiosis I, contributing to genetic variation. The number of possible combinations is 2^n.

Crossing Over

The exchange of genetic material between homologous chromosomes during Prophase I of meiosis, creating recombinant chromosomes and increasing genetic diversity.

Random Fertilization

The unpredictable fusion of any sperm with any egg, leading to an immense number of possible genetic combinations.

Mitosis

A type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, typical of ordinary tissue growth.

Nondisjunction

The failure of homologous chromosomes (in meiosis I) or sister chromatids (in meiosis II or mitosis) to separate correctly during cell division.

Aneuploidy

A condition resulting from the fusion of a normal gamete with an abnormal gamete, leading to an abnormal number of chromosomes in the zygote.

Monosomy

A type of aneuploidy characterized by the loss of one chromosome (2n - 1). Often lethal for autosomes but sometimes viable for sex chromosomes.

Trisomy

A type of aneuploidy characterized by the presence of one extra chromosome (2n + 1).

Down Syndrome (Trisomy 21)

A genetic disorder caused by an extra chromosome 21, characterized by developmental delays, heart defects, and increased susceptibility to certain health issues.

Edwards Syndrome (Trisomy 18)

A severe genetic disorder caused by an extra chromosome 18, leading to mental and physical retardation, facial abnormalities, and early death.

Patau Syndrome (Trisomy 13)

A severe genetic disorder caused by an extra chromosome 13, resulting in mental and physical retardation, wide variety of organ defects, and high mortality within the first year of life.

Klinefelter Syndrome (XXY)

A sex chromosome trisomy in males, characterized by male sex organs that are sterile, low intelligence, and common female characteristics.

Jacobs Syndrome (XYY)

A sex chromosome trisomy in males, where individuals are typically tall but otherwise more 'normal' in phenotype.

Triple X Syndrome (XXX)

A sex chromosome trisomy in females, where individuals are typically tall but otherwise more 'normal' in phenotype.

Turner Syndrome (X)

The only known viable monosomy, where females have only one X chromosome, resulting in sterility due to immature sex organs and other developmental issues.