Patterns of Heredity, Molecular Genetics, and Population Genetics (Chapters 1–19) - Vocabulary Flashcards

Vocabulary flashcards covering key terms from the provided notes.

Gene

A basic unit of heredity; a specific DNA sequence that codes for a product (usually a protein or RNA) and is located on a chromosome.

Allele

Alternative forms of a gene at the same locus; they can be dominant or recessive.

Phenotype

The observable characteristics or traits of an organism resulting from the interaction of its genotype and environment.

Genotype

The genetic makeup of an organism; the specific alleles present for a gene.

Heterozygous

Having two different alleles for a particular gene (e.g., Aa).

Homozygous

Having two identical alleles for a particular gene (e.g., AA or aa).

Dominant

An allele whose trait is expressed in the phenotype when present with a different allele (often represented by a capital letter).

Recessive

An allele whose trait is masked by a dominant allele in a heterozygote (often represented by a lowercase letter).

Crossing over

Exchange of chromosome segments between homologous chromosomes during Prophase I of meiosis, increasing genetic variation.

Homologous chromosomes

Pairs of chromosomes that contain the same genes at the same loci, one inherited from each parent.

Meiosis

A cell division process that produces four genetically diverse haploid gametes from a diploid cell.

Haploid

A cell with one set of chromosomes (n).

Diploid

A cell with two sets of chromosomes (2n).

Prophase I

First stage of meiosis I where homologous chromosomes pair and crossing over occurs. Mirroring synapsis forms tetrads.

Metaphase I

Homologous chromosome pairs align at the cell's equator; orientation is random.

Anaphase I

Homologous chromosomes separate and migrate to opposite poles; sister chromatids stay together.

Telophase I

Chromosomes arrive at poles; cell division begins, producing two haploid cells.

Prophase II

Chromosomes condense again in each haploid cell; spindle apparatus forms.

Metaphase II

Chromosomes align at the equator in each haploid cell; sister chromatids attach to spindle.

Anaphase II

Sister chromatids separate and move to opposite poles.

Telophase II

Nuclei reform and four genetically distinct haploid daughter cells are produced.

Independent assortment

Random orientation of homologous chromosomes during Metaphase I leading to genetic variation.

Mitosis

Cell division that produces two genetically identical diploid daughter cells for growth and repair.

Punnett square

A diagram used to predict the genotype and phenotype combinations of a cross.

Codominance

Both alleles are fully expressed in the heterozygote (e.g., AB blood type).

Incomplete dominance

Heterozygote shows a blended or intermediate phenotype (e.g., red x white = pink).

ABO blood groups

Blood type system with IA, IB, and i alleles; IA and IB are codominant; i is recessive.

X-linked trait

A trait determined by genes on the X chromosome; often shows different patterns in males and females.

Sex-linked

A trait linked to sex chromosomes (XL or Y).

Pedigree

A chart showing inheritance patterns across generations.

Autosomal

A trait located on non-sex chromosomes (autosomes).

Autosomal dominant

Autosomal trait that appears in every generation; affected individuals have at least one dominant allele.

Autosomal recessive

Autosomal trait that may skip generations; affected individuals are homozygous recessive.

X-linked dominant

Dominant allele on the X chromosome; manifests in both sexes but may appear differently.

X-linked recessive

Recessive allele on the X chromosome; more common in males due to single X chromosome.

Y-linked

Traits encoded on the Y chromosome; passed from father to son.

Polygenic inheritance

Traits controlled by multiple genes, often producing a spectrum of phenotypes.

Epistasis

One gene alters or masks the expression of another gene.

Pleiotropy

One gene influencing multiple, seemingly unrelated phenotypic traits.

Test cross

Cross with a homozygous recessive individual to determine the genotype of the other parent.

Mutation

A heritable change in the DNA sequence that can affect phenotype.

Nondisjunction

Failure of chromosome pairs to separate properly during meiosis, leading to abnormal chromosome numbers.

Aneuploidy

Abnormal number of chromosomes, not a complete set (e.g., trisomy, monosomy).

Monosomy

Loss of one chromosome from the normal diploid set (2n-1).

Trisomy

Presence of an extra chromosome (2n+1).

Triploidy

Three complete sets of chromosomes (3n).

Tetraploidy

Four complete sets of chromosomes (4n).

Deletion

Loss of a chromosome segment.

Insertion

Addition of one or more nucleotides into DNA.

Frameshift

Insertion or deletion that shifts the reading frame of a gene.

Missense

A point mutation that changes one amino acid in the protein.

Nonsense

A mutation that creates a premature stop codon, truncating the protein.

Silent

A nucleotide change that does not alter the amino acid due to codon redundancy.

Base analog

Mutagen that substitutes for a nucleotide during replication, causing mispairs.

Tautomeric shift

Temporary change in base structure causing mispairing during replication.

Radiation

Mutagenic energy (UV or ionizing) causing DNA damage such as breaks or crosslinks.

Nucleotide modification

Chemical modification of nucleotides leading to mutagenesis.

PCR

Polymerase chain reaction; technique to amplify a specific DNA sequence.

DNA sequencing

Determining the exact order of nucleotides in a DNA molecule.

Southern blot

A method to detect specific DNA sequences on a gel via a labeled probe.

DNA microarray

A technology to measure expression levels of thousands of genes at once.

Recombinant DNA

DNA molecules formed by combining DNA from different sources; used in cloning and biotechnology.

DNA profiling

Forensic or paternity testing method that analyzes DNA patterns.

Electrophoresis

Technique to separate nucleic acids or proteins by size/charge using an electric field.

Apoptosis

Programmed cell death; controlled process to remove damaged or unnecessary cells.

Senescence

A state of permanent cell cycle arrest; aging-related decline in cell division.

Cancer

Uncontrolled cell growth often linked to accumulated mutations in DNA.