Bio Chapter 6 & 7 Test

Also study Punnet Squares & Pedigrees!

Gregor Mendel

The person who laid the groundwork for genetics

Traits

Distinguishing characteristics that are inherited

Genetics

The study of inheritance patterns & variation

Discrete Units

The name Mendel gave to genes

Pea Plants

The plants Mendel studied

P Generation

The name Mendel gave to the parents

F1

The name Mendel gave to the first generation of offspring

F2

The name Mendel gave to the second generation of offspring

Mendel’s Law of Dominance

States that some traits are recessive, while others are dominant

Law of Segregation

States that organisms inherit two copies of each gene, one from each parent, and donate one copy of each gene in their gametes

Alleles

The different versions of one trait an organisms receives from parents

Homozygous Dominant

Two dominant alleles

Heterozygous

One dominant & one recessive alleles

Homozygous Recessive

Two recessive alleles

Genome

An organism’s genetic material

Genotype

The genetic makeup of a specific set of genes

Phenotype

The physical characteristics of an organism

Monohybrid cross

A Punnet Square involving one trait

Dihybrid Cross

A Punnet Square involving two traits

Law of Independent Assortment

The law that states that allele pairs separate independently of each other during meiosis & genes are inherited separately

Linked Genes

Genes located on the same chromosome that are frequently inherited together

More

Genes that are closer together are _____ likely to be inherited together

Crossing Over

One way genetic variation occurs, during Prophase I genetic information is exchanged between homologous chromosomes

Independent Assortment

One way genetic variation occurs, during metaphase I homologous pairs arrange themselves randomly

Random fertilization

One way genetic variation occurs, male & female gametes that fertilize are selected randomly

Control over breeding

Use of purebred plants

Observation of “either-or” traits

The key decisions Mendel made during his experiment

To map the location of every gene & determine human DNA sequences

The goal of the Human Genome Project

Sex-Linked Gene

A gene found on sex chromosomes, usually X chromosomes

Males

Sex-Linked disorders are most commonly found in ______

X-Chromosome Inactivation

When one of two X-chromosomes are randomly turned off after the organism begins developing

Holandric Genes

Genes found on Y-chromosomes

Cystic Fibrosis

An example of an Autosomal Recessive Disorder

Huntington’s Disease

An example of an Autosomal Dominant Disorder

Color Blindness

An example of a Sex-Linked Chromosome

Hairy Ears

An example of a Holandric Gene

Incomplete Dominance

Traits in which neither allele is completely dominant, so a blending is shown in the phenotype

Codominance

A trait in which both alleles are expressed completely

Multiple Allele Traits

Traits that are determined by multiple different alleles

Polygenic Traits

Traits determined by 2 or more genes

Skin and eye color

Examples of polygenic traits

Epistasis

A trait in which one gene can override the others

Albinism

Example of Epistasis

Methylation

Chemicals that affect the expression of genes that are caused by the environment, often by stress

Pedigree

A chart for tracing genes in families

Karyotype

A picture of all chromosomes in a cell

Identify genetic disorders caused by too many or few chromosomes

What do Karyotypes do?

Down Syndrome

The genetic disorder in which someone has an extra chromosome 21.

Cannot

A child (can/cannot) be born with too few autosomes

Turner’s Syndrome

The genetic disorder in which someone only has one X chromosome

Klinefelter’s Syndrome

The genetic disorder in which someone has and extra X chromosome. (XXY)

Males will mostly be affected, females will mostly be carriers

Using a pedigree, how do you tell it is a sex-linked trait?

Often, traits will skip a generation

Using a pedigree, how do you tell it is an autosomal recessive trait?

Blood type

Example of multiple allele trait