Heredity and Genetics – Key Vocabulary

Vocabulary flashcards covering fundamental terms and concepts from the Heredity and Genetics lecture notes.

Gene

A string of nucleotides within a DNA molecule that is the basic structural and functional unit of genetics.

Allele

One of a number of different forms of a gene.

Phenotype

The physical characteristics of an organism.

Genotype

The genetic makeup of an organism.

Heterozygous

Having two different alleles for a trait.

Homozygous

Having two identical alleles for a trait.

Dominant

A trait that covers over, or dominates, another form of that trait.

Recessive

An allele that is masked when a dominant allele is present.

Meiosis

Cell division that produces four haploid reproductive cells from one diploid cell.

Interphase

Phase of the cell cycle during which chromosomes replicate before meiosis begins.

Prophase I

Stage of meiosis where chromosomes condense, nuclear envelope disappears, and spindle forms.

Metaphase I

Paired homologous chromosomes line up at the cell equator, attached to spindle fibers.

Anaphase I

Paired chromatids separate and move toward opposite poles of the cell.

Telophase I

Cytoplasm divides to form two haploid cells.

Prophase II

Unpaired chromosomes, each with two sister chromatids, become visible in each haploid cell.

Metaphase II

Twenty-three unpaired chromosomes align at the equator of each haploid cell.

Anaphase II

Spindle fibers pull sister chromatids apart in each haploid cell.

Telophase II

Chromosomes uncoil, nuclei reform, and four haploid cells are produced.

Crossing Over

Exchange of chromatids between homologous chromosomes during Prophase I, increasing genetic variation.

Principle of Segregation

Mendel’s first law: gene pairs separate during gamete formation, so each gamete carries one allele.

Principle of Independent Assortment

Genes for different traits segregate independently during gamete formation.

Incomplete Dominance

One allele is not completely dominant, resulting in blended phenotypes (e.g., red + white = pink flowers).

Codominance

Both alleles are fully expressed in the phenotype (e.g., ABO blood types).

Autosomal Recessive

Inheritance pattern where affected individuals can have unaffected parents; affects sexes equally.

Autosomal Dominant

Inheritance pattern where every affected individual has at least one affected parent; affects sexes equally.

X-Linked Dominant

Affected males have affected daughters; more females than males are affected.

X-Linked Recessive

Mostly males are affected due to recessive allele on X chromosome.

Y-Linked

Inheritance through the Y chromosome; all affected males transmit trait to all sons.

Polygenic Traits

Traits controlled by two or more genes, producing a range of phenotypes.

Discontinuous Variation

Variation showing only a few distinct phenotypes with large differences.

Continuous Variation

Variation with many possible phenotypes showing a continuous spectrum.

Polyploidy

Increase in the number of chromosome sets in a cell.

Triploidy

Polyploidy with three sets of chromosomes.

Tetraploidy

Polyploidy with four sets of chromosomes.

Aneuploidy

Gain or loss of a single chromosome.

Monosomy

Loss of a single chromosome (2n-1).

Trisomy

Gain of a single chromosome (2n+1).

Nondisjunction in Meiosis I

Homologous chromosomes fail to separate at Anaphase I, creating gametes with extra or missing chromosomes.

Nondisjunction in Meiosis II

Sister chromatids fail to separate in one cell at Meiosis II, producing abnormal gametes.

Missense Mutation

Base substitution that changes one amino acid in a protein.

Nonsense Mutation

Base substitution that converts an amino-acid codon into a stop codon.

Sense Mutation

Mutation that changes a stop codon into one coding for an amino acid.

Silent Mutation

Base change that does not alter the encoded amino acid.

Frameshift Mutation

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

Deletion (Mutation)

Frameshift mutation removing one or more nucleotides.

Insertion (Mutation)

Frameshift mutation adding one or more nucleotides.

Point Mutation

Change of a single nucleotide pair in DNA.

Tautomeric Shift

Spontaneous structural change in bases altering pairing and causing mutation.

Radiation

Environmental mutagen that creates DNA damage via hydroxyl radicals.

Chemical Modification of Nucleotides

DNA changes caused by environmental chemicals leading to mutations.

Base Analogs

Chemicals similar to normal bases that can be incorporated into DNA, causing mutations.

Senescence

Cell’s permanent dormancy response to DNA damage.

Apoptosis

Programmed cell death triggered by severe DNA damage.

Cancer

Uncontrolled cell growth resulting when DNA damage bypasses normal cell-cycle control.

DNA Polymerase Proofreading

Enzyme’s ability to remove mispaired nucleotides during DNA replication.

DNA Repair Enzymes

Proteins that detect and correct DNA distortions and damage.

PCR (Polymerase Chain Reaction)

Laboratory method to amplify specific DNA sequences.

DNA Microarray

Technique using immobilized DNA fragments to analyze gene expression or identify sequences.

DNA Sequencing

Process of determining the exact order of nucleotides in DNA.

Southern Blot

Technique for locating specific DNA sequences in a complex sample.

Recombinant DNA

Artificial DNA created by combining DNA from different organisms.

DNA Profiling

Analysis of DNA fragments to identify individuals.

Biopharming

Use of genetically engineered organisms to produce pharmaceuticals and industrial products.

Genetically Modified Organism (GMO)

Organism whose genetic material has been altered by engineering techniques.

Stem Cells

Unspecialized cells capable of self-renewal and differentiation.

Cloning

Creation of a genetically identical copy of DNA or an organism.

Hardy–Weinberg Equilibrium

Set of five conditions describing a non-evolving population’s allele frequencies.

Founder Effect

Genetic drift where allele frequencies change because a new population is established by few individuals.

Genetic Drift

Random fluctuations in allele frequencies, especially in small populations.

Natural Selection

Differential survival and reproduction of individuals due to inherited traits.

Nonrandom Mating

Mating based on phenotypic similarities or differences rather than at random.

Speciation

Formation of new, distinct species through evolutionary processes.

Mutation

Creation of new alleles through changes in DNA.