Patterns of Heredity, Molecular & Population Genetics Review

Vocabulary flashcards covering heredity, meiosis, Mendelian and non-Mendelian inheritance, molecular genetics, biotechnology, and population genetics concepts.

Gene

A segment of DNA that encodes information for a specific trait or protein.

Allele

Alternative form of a gene found at the same locus on homologous chromosomes.

Phenotype

Observable physical or biochemical characteristics of an organism determined by its genotype and environment.

Genotype

The specific allelic composition of an organism, often represented by letter symbols (e.g., Aa).

Heterozygous

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

Homozygous

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

Dominant

Allele that masks the expression of another allele in the heterozygous state.

Recessive

Allele expressed only when two copies are present; masked by a dominant allele in heterozygotes.

Meiosis

Specialized cell division producing four genetically unique haploid gametes from one diploid cell.

Haploid

Cell containing one complete set of chromosomes (n), typical of gametes.

Crossing Over

Exchange of genetic material between nonsister chromatids of homologous chromosomes during Prophase I of meiosis.

Independent Assortment

Random orientation of homologous chromosome pairs in Metaphase I, producing varied allele combinations in gametes.

Principle of Segregation

Mendelian rule stating that paired alleles separate during gamete formation so each gamete carries one allele for each gene.

Codominance

Inheritance pattern where both alleles in a heterozygote are fully expressed (e.g., AB blood type).

Incomplete Dominance

Inheritance where heterozygotes show an intermediate phenotype (e.g., red × white flowers → pink).

ABO Blood Group

Human blood type system controlled by three alleles (IA, IB, i) exhibiting codominance and multiple allelism.

X-linked Trait

Gene located on the X chromosome; shows sex-specific inheritance patterns (e.g., color blindness).

Polygenic Inheritance

Trait controlled by two or more genes, producing continuous variation (e.g., human height).

Pedigree Chart

Diagram showing familial relationships and inheritance of traits using standardized symbols.

Aneuploidy

Abnormal chromosome number due to nondisjunction (e.g., trisomy 21).

Polyploidy

Condition of having more than two complete chromosome sets (e.g., triploidy, tetraploidy).

Monosomy

Type of aneuploidy with one chromosome missing from a pair (2n – 1).

Trisomy

Type of aneuploidy with one extra chromosome (2n + 1).

Missense Mutation

Point mutation that changes a codon to specify a different amino acid.

Nonsense Mutation

Point mutation converting a codon into a premature stop codon.

Silent Mutation

Point mutation that changes a codon but not the encoded amino acid.

Frameshift Mutation

Insertion or deletion of nucleotides that shifts the reading frame, altering downstream codons.

Point Mutation

Single nucleotide substitution in DNA (also called single-nucleotide replacement).

Nondisjunction

Failure of homologous chromosomes or sister chromatids to separate during meiosis, leading to aneuploid gametes.

Mutagen

Physical or chemical agent that increases mutation rate by altering DNA.

DNA Polymerase Proofreading

Enzymatic correction of mismatched bases during DNA replication.

Apoptosis

Programmed cell death triggered when damage is irreparable or physiologically required.

Senescence

Permanent loss of a cell’s ability to divide, often in response to DNA damage.

PCR (Polymerase Chain Reaction)

Technique that amplifies specific DNA segments exponentially in vitro.

Gel Electrophoresis

Method to separate DNA fragments by size through a gel matrix under an electric field.

Sanger Sequencing

Chain-termination method to determine the nucleotide order of DNA fragments.

Recombinant DNA

DNA molecule created by joining DNA from different sources, often via restriction enzymes and ligases.

DNA Microarray

Chip containing thousands of DNA probes used to analyze gene expression patterns or genotypes.

DNA Fingerprinting

Technique using variable DNA regions (e.g., STRs) to identify individuals in forensics or paternity testing.

Hardy-Weinberg Equilibrium

Model stating allele and genotype frequencies remain constant in a large, randomly mating population absent evolutionary forces.

Genetic Drift

Random change in allele frequencies in small populations, independent of fitness.

Founder Effect

Genetic drift occurring when a small group colonizes a new area, carrying only a subset of the original population’s alleles.

Natural Selection

Differential reproductive success of individuals with advantageous traits, shifting allele frequencies over time.

Mutation (as a source of variation)

Spontaneous or induced change in DNA sequence that introduces new alleles into a population.

Nonrandom Mating

Selection of mates based on phenotype or relatedness, altering genotype frequencies without changing allele frequencies.

Speciation

Formation of new species when populations become reproductively isolated and genetically divergent.