BIOL 190A Ch. 15 Transmission of Genetic Information: Mendel's Laws

Inheritance

Transmission of traits from parents to offspring.

Particulate Inheritance

Traits are inherited as discrete units called genes.

Gene

Unit of heredity responsible for traits.

Dominant Trait

Trait expressed in the F1 generation.

Recessive Trait

Trait masked in the F1 generation, reappears in F2.

Genotype

Genetic composition of an individual.

Phenotype

Physical or behavioral characteristics expressed.

Alleles

Variant forms of a gene.

Monohybrid Cross

Cross examining a single trait inheritance.

True-Breeding Line

Plants consistently exhibit the same trait.

Hybridization

Breeding individuals with different characteristics.

Punnett Square

Tool for predicting genetic cross outcomes.

Law of Segregation

Alleles separate during gamete formation.

Law of Independent Assortment

Genes for different traits segregate independently.

F1 Generation

First filial generation from parental cross.

F2 Generation

Second filial generation from F1 self-fertilization.

3:1 Ratio

Observed ratio of dominant to recessive traits in F2.

Homozygous Dominant

Genotype with two dominant alleles (TT).

Heterozygous

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

Homozygous Recessive

Genotype with two recessive alleles (tt).

Gametes

Reproductive cells carrying alleles.

Self-Fertilization

Fertilization by gametes from the same plant.

Quantitative Analysis

Statistical method used to analyze Mendel's results.

Traits

Identifiable characteristics of an organism.

Characters

General features found in organisms.

Variants

Different forms of a character.

Gregor Mendel

Austrian monk known as the father of genetics.

Mendel's Laws

Principles governing inheritance patterns in organisms.

Garden Pea

Plant chosen by Mendel for inheritance studies.

Trait

Identifiable characteristic of an organism.

Male gametes

Pollen produced by stamens in plants.

Female gametes

Ovules produced by ovules in plants.

True-breeding line

Plants that consistently exhibit the same trait.

Hybrids

Offspring resulting from hybridization.

Monohybrid crosses

Crosses examining inheritance of a single trait.

P generation

True-breeding parental generation in experiments.

F1 generation

First filial generation from P generation.

Monohybrids

F1 offspring that are single-character hybrids.

3:1 ratio

Observed ratio of dominant to recessive traits.

Recessive trait

Trait masked in F1, reappears in F2.

Particulate inheritance

Traits inherited in discrete, unchanging units.

Unit factors

Determinants of traits, now known as genes.

Genotype Ratio

Proportions of genotypes: 1:2:1 (TT:Tt:tt)

Phenotype Ratio

Proportions of phenotypes: 3:1 (tall:dwarf)

Dihybrid Cross

Cross involving two traits from true-breeding parents.

True-Breeding

Organisms that produce offspring identical to themselves.

Dihybrid Phenotype Ratio

Phenotype ratio for dihybrid cross: 9:3:3:1.

Chromosome Theory of Inheritance

Genes located on chromosomes, passed to offspring.

Meiosis

Process where homologous chromosomes segregate.

Allele

Different forms of a gene at a locus.

Locus

Physical location of a gene on a chromosome.

Homologous Chromosomes

Chromosome pairs carrying same genes, different alleles.

Diploid Cell

Cell containing two sets of chromosomes.

Haploid Cell

Cell containing one set of chromosomes.

Segregation

Separation of alleles during gamete formation.

Random Alignment

Chromosomes align randomly during meiosis.

Pedigree Analysis

Chart used to trace inheritance patterns in humans.

Parental Generation

Original generation in a genetic cross.

Alleles for Seed Traits

Y/y for color, R/r for shape.

Recessive Disorders

Disorders requiring two mutant alleles for expression.

Dominant Disorders

Disorders expressed with one mutant allele present.

Wild-Type Allele

Common allele typically associated with normal function.

Mutant Allele

Rare allele that may cause disease or dysfunction.

Autosomal Inheritance

Inheritance patterns not linked to sex chromosomes.

Cystic Fibrosis

Autosomal recessive disease affecting chloride transport.

Huntington Disease

Autosomal dominant disorder causing neurodegeneration.

Pleiotropy

Single gene mutation causing multiple phenotype effects.

Incomplete Dominance

Heterozygote exhibits an intermediate phenotype.

Norm of Reaction

Phenotype range under varying environmental conditions.

X-Linked Inheritance

Inheritance patterns linked to genes on X chromosome.

Hemizygous

Having only one copy of a gene, as in males.

Mendelian Inheritance

Patterns of inheritance based on Mendel's laws.

Protein Function

Role of proteins in determining phenotypic traits.

Environmental Influence

External factors affecting phenotype expression.

Gene Regulation

Mechanisms controlling gene expression levels.

Cl- Transporter

Protein affected in cystic fibrosis patients.

Microtubule Proteins

Proteins involved in cell division and movement.