Exam 3 Learning Objectives: Molecular Biology, Genetics, and Inheritance

Vocabulary practice flashcards covering central dogma exceptions, cell division, Mendelian rules, non-Mendelian extensions, pedigrees, and genetic linkage mapping.

Central Dogma of molecular biology

The framework describing the flow of genetic information in cells from gene to protein via DNA, mRNA, and proteins.

Reverse transcriptase

An enzyme that catalyzes the synthesis of DNA from an RNA template, acting as an exception to the classic central dogma.

Homologous chromosomes

Pairs of chromosomes that carry the same genes and segregate during meiosis I, leading to a reduction in ploidy.

Sister chromatids

Two identical copies of a single replicated chromosome that are generated during interphase prior to cell division.

Non-sister chromatids

Chromatids belonging to opposite members of a homologous pair that participate in crossing over during meiosis.

Ploidy

The number of complete sets of chromosomes in a cell, which is halved during meiosis I through the segregation of homologous chromosomes.

Somatic cells

General body cells that undergo mitosis to produce genetically identical diploid daughter cells.

Germ cells

Specialized reproductive cells that undergo meiosis to produce genetically diverse haploid gametes.

Crossing over

The exchange of genetic material between non-sister chromatids of homologous chromosomes during meiosis that generates genetic diversity.

Principle of segregation

Mendel's principle explaining how paired alleles separate into different gametes during meiosis so each gamete carries only one allele.

Principle of independent assortment

Mendel's principle explaining how alleles of different genes distribute independently into gametes due to random chromosome alignments at metaphase.

Multiple allelism

An inheritance pattern in which a single gene locus has three or more alternative allele forms within a population.

Codominance

A pattern of inheritance in which the phenotypes produced by both alleles are clearly and simultaneously expressed in a heterozygote.

Incomplete dominance

A pattern of inheritance where the heterozygous phenotype is an intermediate blend between the phenotypes of the two homozygous parents.

Incomplete penetrance

A genetic phenomenon in which individuals who carry a particular genotype do not all express the expected phenotype.

Epistasis

A gene interaction pattern in which the phenotypic expression of one gene alters or masks the phenotypic expression of a different gene.

Polygenic inheritance

An inheritance pattern where multiple independent genes collectively influence a single trait, typically producing continuous variation.

X-inactivation

The random transcriptional silencing of one X chromosome in female mammalian cells, altering the expression of heterozygosity relative to autosomal genes.

Linked genes

Genes located on the same chromosome that do not assort independently and deviate from standard Punnett square frequency predictions.

Recombination frequency

The proportion of recombinant gametes or offspring produced by crossing over, used to reflect the relative genetic distance between genes on a chromosome.