Genetics: Meiosis, Karyotypes, and Mendelian Genetics

Meiosis

Two-step cell division producing gametes.

Mitosis

Cell division creating two identical daughter cells.

Sister Chromatids

Identical halves of a duplicated chromosome.

Homologous Chromosomes

Similar, non-identical chromosome pairs from parents.

Meiosis I

First division separating homologous chromosome pairs.

Meiosis II

Second division separating sister chromatids.

Prophase I

Chromosomes condense and homologues pair up.

Crossing Over

Homologous chromosomes exchange DNA segments.

Metaphase I

Homologous pairs line up at cell equator.

Anaphase I

Homologues pulled apart to opposite cell ends.

Telophase I

Chromosomes reach poles; cytokinesis forms haploid cells.

Interphase

Cell growth and DNA replication before meiosis.

Prophase II

Haploid cells' chromosomes condense for division.

Metaphase II

Chromosomes align at metaphase plate.

Anaphase II

Sister chromatids separate to opposite cell ends.

Telophase II

Gametes form; each chromosome has one chromatid.

Cytokinesis

Division of cytoplasm forming new cells.

Haploid Cells

Cells with one chromosome from each pair.

Gametes

Reproductive cells: sperm or egg.

Genetic Variety

Diversity in genetic makeup of gametes.

DNA

Molecule carrying genetic information.

Alleles

Different forms of a gene.

Equator

Imaginary line where chromosomes align during metaphase.

Nuclear Membrane

Barrier enclosing the nucleus.

Chromatid

Single strand of a duplicated chromosome.

Genetic Mixing

Process creating diverse genetic combinations in gametes.

Crossover Frequency

Up to 25 crossovers per homologous pair.

Metaphase Plate

Plane where chromosomes align during metaphase.

Crossover

Exchange of DNA between homologous chromosomes.

Random orientation

Arrangement of homologues during metaphase I.

Gametes

Sex cells produced through meiosis.

Diploid

Cell with two sets of chromosomes (2n).

Karyotype

Photographic representation of an individual's chromosomes.

Aneuploidy

Abnormal number of chromosomes in a cell.

Nondisjunction

Failure of chromosomes to separate properly.

Trisomy

Presence of three copies of a chromosome.

Monosomy

Presence of one copy of a chromosome.

Down Syndrome

Trisomy 21; causes mental limitations and physical traits.

Meta-Female

Trisomy X; 47 chromosomes with XXX configuration.

Turner's Syndrome

Monosomy X; 45 chromosomes with one X.

Klinefelter's Syndrome

XXY males; 47 chromosomes with reduced fertility.

Super Male Syndrome

XYY males; 47 chromosomes with aggressive behaviors.

Chromosomal aberrations

Deviations from normal chromosome structure or number.

Homologous chromosomes

Chromosome pairs, one from each parent.

Metaphase I

Stage where homologues align before separation.

Anaphase I

Stage where homologous chromosomes separate.

Anaphase II

Stage where sister chromatids separate.

Growth medium

Nutrient solution for cell culture.

Staining

Process to visualize chromosomes under a microscope.

Centromere

Region where sister chromatids are joined.

Chromosomal defects

Abnormalities in chromosome number or structure.

Fertilization

Union of sperm and egg to form a zygote.

Embryos

Early developmental stage post-fertilization.

Sterility

Inability to reproduce.

Mental impairment

Cognitive deficits associated with chromosomal disorders.

Physical traits

Observable characteristics resulting from genetic makeup.

Karyotype

Visual representation of an individual's chromosomes.

Autosomes

Non-sex chromosomes; humans have 22 pairs.

Sex Chromosomes

Chromosomes determining an individual's gender; 2 total.

Down's Syndrome

Genetic disorder caused by an extra chromosome 21.

Turner's Syndrome

Condition in females with a missing X chromosome.

Kleinfelter's Syndrome

Condition in males with an extra X chromosome.

Gregor Mendel

Austrian monk known as the father of genetics.

P Generation

Pure-breeding parent generation in Mendel's experiments.

F1 Generation

First filial generation from P generation crosses.

F2 Generation

Second filial generation from F1 generation crosses.

Law of Dominance

One trait is dominant over another in hybrids.

Dominant Trait

Trait expressed in the phenotype of hybrids.

Recessive Trait

Trait not expressed in the presence of dominant.

Alleles

Different forms of the same gene.

Law of Segregation

Alleles segregate during gamete formation.

Homozygous

Individual with two identical alleles for a trait.

Heterozygous

Individual with two different alleles for a trait.

Purebred

Organism homozygous for a specific trait.

Hybrid

Organism heterozygous for a specific trait.

Gametes

Reproductive cells carrying one allele per trait.

Phenotype

Physical expression of a genetic trait.

Genotype

Genetic makeup of an organism.

Self-fertilization

Process where an organism fertilizes itself.

Contrasting Traits

Traits that differ from one another, like tall vs. short.

Mendelian Genetics

Study of inheritance patterns established by Mendel.

Plant Inheritance

Genetic traits passed through generations in plants.

Chromosomes

Structures containing genetic material in cells.

Factors

Historical term for genes used by Mendel.

Hybrid

Offspring of unlike parents; heterozygous.

Homozygous Dominant

Genotype with two dominant alleles (GG).

Heterozygous

Genotype with one dominant and one recessive allele (Gg).

Homozygous Recessive

Genotype with two recessive alleles (gg).

Punnett Square

Tool for visualizing genetic crosses and zygote outcomes.

Gametes

Reproductive cells carrying alleles for traits.

Phenotype

Physical appearance resulting from genotype.

Genotype

Genetic makeup of an individual.

F1 Generation

First filial generation, all heterozygous.

P Generation

Parental generation in genetic crosses.

Dihybrid Cross

Cross involving two pairs of contrasting traits.

Law of Independent Assortment

Genes segregate independently during gamete formation.

FOIL Method

Technique for determining gamete combinations.

Phenotype Ratio

Ratio of different phenotypes in offspring.

Genotype Ratio

Ratio of different genotypes in offspring.

Dominant Trait

Trait expressed in the phenotype if present.