Genetics Lecture Notes chapter 23

These flashcards cover important vocabulary and concepts related to genetics, inheritance patterns, genetic disorders, and Mendelian principles.

Mendelian Patterns of Inheritance

Genetics explains the process of inheritance and why there are variations between offspring from one generation to the next.

Genes

Distinct factors that are transmitted to offspring, as concluded from Gregor Mendel's work.

Homologous Chromosomes

Pairs of chromosomes, one from each parent that have the same length, centromere location, and carry similar genes.

Alleles

Alternate forms of a gene for a trait, represented by letters like G (dominant) and g (recessive).

The Law of Segregation

Mendel's principle stating that factors (alleles) segregate during gamete formation, with each gamete carrying one allele for each trait.

Phenotype

An individual’s actual appearance which may include physical and metabolic characteristics.

Genotype

The alleles carried by chromosomes responsible for a specific trait.

Homozygous

An individual with two identical alleles for a trait.

Heterozygous

An individual with two different alleles for a trait.

Punnett Square

A diagram used to predict the genotypes and phenotypes of offspring from genetic crosses.

Monohybrid Cross

A genetic cross between parents that differ in one trait.

Dihybrid Cross

A genetic cross between parents that differs in two traits, illustrating the law of independent assortment.

Independent Assortment

The principle that alleles for different traits segregate independently during gamete formation.

Pedigree Chart

A diagram that shows the occurrence of a genetic trait across generations within a family.

Autosomal Recessive Disorders

Genetic conditions that require two copies of the recessive allele for the trait to be expressed.

Tay-Sachs Disease

An autosomal recessive disorder caused by a deficiency in the enzyme hexosaminidase A, resulting in harmful accumulation of substrates in the brain.

Cystic Fibrosis

A lethal genetic disorder characterized by the buildup of thick mucus in the lungs and digestive system due to defective chloride ion transport.

X-Linked Inheritance

Traits controlled by genes on the sex chromosomes, particularly the X chromosome, which can exhibit recessive or dominant patterns.

Nondisjunction

A failure of chromosomes to separate properly during meiosis, leading to gametes with abnormal chromosome numbers.

Trisomy

A genetic condition where an individual has three copies of a chromosome instead of two.

Klinefelter Syndrome

A genetic condition in males characterized by the presence of an extra X chromosome, leading to various physical and reproductive issues.

Barr Body

An inactive X chromosome in a female cell that compensates for the dosage of X-linked genes.

Translocations

Chromosomal mutations where a segment of one chromosome is transferred to another chromosome, which can lead to genetic disorders.

Incomplete Dominance

A genetic situation in which one allele does not completely dominate another allele, resulting in a new phenotype.

Codominance

A situation in genetics where both alleles express their phenotypes simultaneously, as seen in blood type AB.

Polygenic Inheritance

When multiple genes determine a single trait, resulting in a continuous range of phenotypes, such as skin color.

Environmental Influences

External factors, such as nutrition and temperature, that can affect the expression of genetic traits.