Mendel's Laws and Genetic Inheritance Principles

Mendel's Law of Segregation

Inheritance of a single character during gamete formation.

Homologous Chromosomes

Chromosomes bearing alleles for the same character.

Law of Independent Assortment

Inheritance of one character does not affect another.

Dihybrid Cross

Mating of parental varieties differing in two characters.

P Generation

Parental generation in genetic crosses.

F1 Generation

First filial generation, offspring of P generation.

F2 Generation

Second filial generation, offspring of F1 generation.

Phenotypic Ratio

Ratio of different phenotypes in offspring.

9:3:3:1 Ratio

Typical phenotypic ratio from a dihybrid cross.

Testcross

Mating with homozygous recessive to determine genotype.

Recessive Inheritance

Two recessive alleles needed to express a trait.

Dominant Inheritance

One dominant allele needed to express a trait.

Cystic Fibrosis

Recessive genetic disorder causing thick mucus.

Carrier

Individual with one recessive allele, not expressing trait.

Inbreeding

Mating between close relatives increasing recessive disorders.

Genotype

Genetic makeup of an individual.

Allele

Different forms of a gene.

Gametes

Reproductive cells carrying alleles.

Homozygous

Having two identical alleles for a trait.

Heterozygous

Having two different alleles for a trait.

Lethal Alleles

Dominant alleles that can cause death.

True-breeding

Organisms that produce offspring identical to themselves.

Achondroplasia

Genetic disorder causing dwarfism in humans.

Huntington's Disease

Degenerative nervous system disorder with genetic basis.

Genetic Testing

Analyzing DNA to assess genetic conditions.

Ethical Considerations

Concerns regarding genetic testing confidentiality and implications.

Incomplete Dominance

Neither allele is dominant; intermediate phenotype results.

Hypercholesterolemia

Condition with high cholesterol due to incomplete dominance.

Codominance

Both alleles expressed distinctly in heterozygous individuals.

ABO Blood Group

Blood type determined by three alleles: A, B, O.

Pleiotropy

Single gene influences multiple phenotypic traits.

Sickle-cell Disease

Example of pleiotropy affecting red blood cell shape.

Heterozygous

Individual with two different alleles for a gene.

Homozygous

Individual with identical alleles for a gene.

Phenotype

Observable traits resulting from genotype expression.

Genotype

Genetic makeup of an individual for a trait.

LDL Receptors

Proteins that help remove cholesterol from blood.

Blood Group A

Has carbohydrate A; genotypes IAIA or IAi.

Blood Group B

Has carbohydrate B; genotypes IBIB or IBi.

Blood Group AB

Has both carbohydrates A and B; genotype IAIB.

Blood Group O

No carbohydrates present; genotype ii.

Antibodies in Blood

Proteins that react with specific blood group carbohydrates.

Intermediate Phenotype

Phenotype that is a blend of parental traits.

Sickle-cell allele

Genetic variant causing abnormal hemoglobin production.

Sickle-shaped cells

Red blood cells deform due to abnormal hemoglobin.

Polygenic inheritance

Multiple genes influence a single phenotypic trait.

Human skin color

Example of a trait affected by polygenic inheritance.

Law of segregation

Homologous chromosomes separate during anaphase I.

Independent assortment

Chromosomes orient randomly during metaphase I.

Linked genes

Genes located close together on the same chromosome.

Sex chromosomes

Chromosomes determining biological sex in organisms.

X-linked recessive trait

Trait carried on the X chromosome, often affecting males.

Hemophilia

Disorder causing excessive bleeding due to clotting protein deficiency.

Red-green color blindness

Vision disorder caused by malfunctioning light-sensitive cells.

Duchenne muscular dystrophy

Progressive muscle weakness and coordination loss condition.

Environmental influence

External factors affecting genetic traits, like skin color.

Chromosome theory of inheritance

Genes are located on chromosomes and segregate during meiosis.

Anaphase I

Stage in meiosis where homologous chromosomes separate.

Metaphase I

Stage in meiosis where chromosomes align for separation.

Male inheritance pattern

Males inherit X-linked traits from their mothers.

Female inheritance pattern

Females require two X-linked alleles to express traits.

Kidney failure

Organ damage resulting from sickle-cell disease complications.

Brain damage

Impaired mental function due to sickled cell effects.

Joint problems

Physical issues arising from sickle-cell disease.

Anemia

Condition characterized by a deficiency of red blood cells.

F1 generation

First filial generation resulting from parental cross.

F2 generation

Second filial generation resulting from F1 self-cross.