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notes.

• EQ: How are traits passed from parent to offspring.

Genetics

• The study of how traits are inherited from parent to offspring.                                

Heredity

• The passing of genetic material from parents to offspring.

Gregor Mendel

• Austrian Monk who performed the first major experiments investigating heredity.

• Studied the inheritance of traits among pea plants.

• Known as the father of genetics

Genes and alleles• Genes are segments of

DNA found in chromosomes.

• One version of the same gene comes from each parent.

• Alleles are the different form of gene for the same trait. One from the mother and one from the father. You have 2 alleles for every trait you have.

Dominant

• This trait covers up the other allele and is the one that the offspring shows

• If one chromosome in the pair contains a dominant allele the other recessive one is hidden.

• Dominant alleles are represented by a capital letter

                                        

Dimplesare dominant.

Recessive

• The recessive trait is the allele that is covered up by the dominant one.

• The only way to express a recessive trait is to have both alleles recessive.

• Recessive alleles are represented by a lower case letter

Genotype and phenotype

• The combination of alleles you inherited from your parents is your genotype

• Your observable traits make up your phenotype

Homozygous

• If both alleles are dominant or recessive then they are said to be homozygous for that trait.

• The prefix homo means same.

Heterozygous

• If both alleles for a trait are different then they are heterozygous.

• The prefix hetero means different.

Multiple Alleles

• Some traits are controlled my many genes acting together

• Skin tone, shades of eye color, fingerprints etc…

Incomplete Dominance

• Each allele in a heterozygous individual influences the phenotype. The result is a blend.

Codominance

• Both Alleles are expressed in an offspring

• Blood type alleles have codominance

• There are 3 alleles that play a role in determining blood type. A B O

Punnett Square

• A graphic used to predict the possible genotypes of offspring

• Top of the Punnett square show the genotype from one parent and the side shows the genotype of the other parent.

• Each compartment shows an allele combination in potential offspring.

Sex determination

• XX chromosomes girl• XY chromosome boy• You will get one allele

from each parent

Sex linked gene disorder

• Some inherited disorders are linked to the sex gene. Usually they are linked on the X chromosome. In order to have the disorder you must have it on all of your X chromosomes.

• Colorblindness and hemophilia are two examples

X Y

X XX XY

Xh XhX XhY

Recessive genetic disorder

• A genetic mutation or disorder. You must have both recessive alleles to express the trait.

• cystic fibrosis  : a disease that causes the respiratory system to produce thick mucus that clogs the lungs

• sickle cell disease : a disease where red blood cells form a "sickle" shape, rather than the typical donut shape, get caught in blood vessels, and cut off oxygen to tissues

• Tay-Sachs disease : a disorder causing mental retardation, blindness, seizures, and death

Pedigree

• A tool used to trace a trait through a family.

Pedigree