Biology Mutations Genetics Guide

What is genetics?

The study of heredity/how information is passed from parent to offspring.

Gregor Mendel

Known as the "Father of Genetics," he discovered the basics of genetics through experiments with pea plants. Filled up over 3,000 notebooks with observations

Alleles

Different versions of a gene.

Homozygous

Having two identical alleles for a trait.

Heterozygous

Having two different alleles for a trait.

Phenotype

The expressed traits of an organism based on its genotype.

Genotype

The genetic makeup of an organism; the combination of alleles received from parents.

Dominant alleles

Alleles that are expressed over others, represented by a capital letter.

Recessive alleles

Alleles that are hidden by dominant alleles; expressed only when two recessive alleles are present.

Principle of Segregation

Each parent contributes one allele for each trait to their offspring.

Principle of Independent Assortment

The alleles for different traits segregate independently during gamete formation.

Incomplete Dominance

A type of inheritance where heterozygous individuals show a blend of both alleles.

Codominance

A type of inheritance where heterozygous individuals express traits from both alleles distinctly.

Multiple Alleles

A single gene that has more than two alleles, as seen in blood type.

Polygenic Traits

Traits that are determined by more than one gene.

Sex-linked traits

Traits determined by genes on the sex chromosomes.

Karyotype

A picture of a person’s chromosomes arranged in pairs.

Pedigree

A family tree chart used to analyze the inheritance patterns of specific genetic traits.

Autosomal Dominant inheritance

Only one mutated allele is needed to express the disease; typically appears in every generation.

Autosomal Recessive inheritance

Two mutated alleles are needed to express the disease; typically skips generations.

Sex-linked Recessive inheritance

Mutations occur on the X chromosome; more common in males.

Gene Disorders

Disorders caused by a mutation in a single gene.

Chromosomal Disorders

Disorders caused by cells with missing or extra chromosomes.

Mendel’s Experiment

P - F₁ - F₂ genrations used to study in peas

Mendel’s hypothesis of inheritance

Parents pass on discrete genes to their offspring and these factors are responsible for inherited traits

Phenotype

the trait expressed; caused by the genotype

Antigen

molecules that act as ‘markers’ on red blood cells, they determine the blood type

Antibodies

proteins in the blood that will attack foreign blood types ( cause clumping of cells they don’t recognize)

Indicators to determine blood type

anti-B serum and anti-A serum

Pedigree

a family tree chart that can be used to analyze the pattern of inheritance followed by a specific genetic trait/disorder

How to read a pedigree

▢ = Male without trait

◼ = Male with trait

◯ = Female without trait

⬤ = Female with trait

◧ ◨ = Male carrier

◐◑ = Female carrier

I, II, III, = generations

I, 1 & 2 are a couple

III, 1 & 2 are siblings

Sex chromosome

the 2 chromosomes that determine gender

Autosome

the other 22 pairs of chromosomes