Human Biology: Inheritance, Meiosis, and Genetic Diversity

These vocabulary flashcards cover the fundamental concepts of human genetics, meiotic processes, chromosomal abnormalities, and both Mendelian and non-Mendelian inheritance patterns as presented in the Human Biology lecture notes.

Karyotype

A description of the number and visual characteristics of the chromosomes in a cell.

Gene

A DNA sequence that contains instructions for producing a functional product.

Alleles

Alternate forms of genes.

Locus

The specific position of a gene on a chromosome.

Homologous chromosomes

A pair of chromosomes (one from each parent) that are the same size and shape and carry the same genes at the same loci.

Sister chromatids

Two identical copies of a replicated chromosome joined at the centromere.

Centromere

The constricted region that holds sister chromatids together and serves as an attachment point for spindle microtubules during cell division.

Diploid

A cell or organism containing two sets of chromosomes ($2n$).

Haploid

A cell containing a single set of chromosomes ($n$), typically seen in gametes.

Meiosis

A two-stage reduction division process that halves the chromosome number to produce four genetically unique haploid gametes.

Crossing over

The exchange of DNA between homologous chromosomes during Prophase I that creates new allele combinations.

Chiasma

The specific point where crossing over occurs between homologous chromosomes.

Independent assortment

The random orientation of homologous chromosome pairs at the metaphase plate during Metaphase I, producing many chromosome combinations.

Nondisjunction

The failure of paired chromosomes or sister chromatids to separate properly during cell division.

Aneuploidy

Numerical chromosome abnormalities resulting from nondisjunction during meiosis I or meiosis II.

Gene-dosage

The balance of gene expression and protein production, which can be disrupted by having an extra chromosome (trisomy) or missing one.

Autosomes

Chromosomes numbered 1 through 22 that are not involved in primary sex determination.

SRY gene

The "sex-determining region of Y" gene that typically initiates pathways associated with male sexual development.

Genotype

The specific combination of alleles inherited for a particular gene.

Phenotype

The visible or observable characteristics of an individual determined by the expression of their alleles.

Homozygous

An individual having two identical alleles for a particular gene.

Heterozygous

An individual having two different alleles for a particular gene.

Carrier

A heterozygote for a recessive trait who does not show the phenotype but can pass the allele to offspring.

Monogenic inheritance

Traits that are strongly influenced by variation in a single gene, following Mendelian patterns.

Polygenic inheritance

A pattern where many genes contribute to a single characteristic, such as height, skin pigmentation, or blood pressure.

Codominance

A non-Mendelian inheritance pattern where both alleles are expressed together, such as in the ABO blood groups.

Incomplete dominance

A pattern where neither allele is completely dominant, resulting in a heterozygous phenotype that is an intermediate of the parents' traits.

X-linked inheritance

Inheritance patterns for genes located on the X chromosome, which are more common in males due to having only one X chromosome.

Genetic linkage

The tendency of genes located close together on a chromosome to be inherited together because they are less likely to be separated by crossing over.

Multifactorial inheritance

A pattern where genes interact with environmental influences to determine a phenotype, such as in Type 2 diabetes or coronary artery disease.