Genetics

the study of inheritance or inherited traits

Garden peas

the alleles carried by an individual. Bb will have brown eyes, but so will BB. Bb is the genotype. Brown eyes is the phenotype.

An individual’s observable traits.

Forms of a gene that encode slightly different versions of the gene’s product; different forms of the same gene; different instructions for the same trait

Refers to an allele that masks the effect of a recessive allele paired with it... in other words it's trait is expressed even when only one is present. Bb= brown eyes. Always.

the character for which a gene carries instructions: hair color, eye color, etc

• –Region of chromosome with the
• instructions for a specific trait

• –Remember you have two sets of
• genes for every trait

•That is, genes come in pairs

zygotes have same two alleles—homozygous

zygotes have two different alleles

a trait that is only expressed if both alleles are recessive. bb= blue eyes. only.

BB

bb

Bb

Cross in which individuals with different alleles of one gene are crossed.

Means there is a dominant gene that will show if presented, one gene pair controls the trait.

When you try to cross parental gametes to see if possible children will have certain traits

When a trait doesn't have a dominant gene, such as hair texture

traits that have more than two alleles controlling them, and some with more than one dominant alleles. Blood type has three alleles with two dominant and one recessive

Refers to two alleles that are both fully expressed in heterozygous individuals. Blood type is co-dominant

Many sets of genes effect a single trait. Example, human skin color

Two genes control a single trait. In other words, one gene controls the expression of a 2nd gene. Example: Labrador coat color

One gene effects many traits, like people with Marfan sydrome (one gene) people are tall and thin with long arms and long legs, and long fingers

Expression of the gene depends on the surrounding environment. Examples; snowshoe hare's coat turns darker when it warms up. Siamese cat coat turns darker where they are colder (extremities and tips of ears)

Dominant. Blue is the recessive eye color trait. B (brown) b (blue)

Dominant. U (roll) u (can't roll)

allele pairs separate or segregate during gamete formation, and randomly unite at fertilization

The father. The mother can only give X's. Father gives X or Y determining the sex.

Having three or more of each type of chromosome characteristic of the species. Common in plants. Humans with polyploidy generally don't make it to full term

Recessive allele on an autosome causes a disorder. Examples: Sickle cell anemia and Cystic fibrosis, albinism, PKU Tay-sachs. Aa is normal but a carrier. AA is normal. aa is affected.

Dominant allele carries the disorder. AA or Aa has the disorder. aa is normal. Examples: hypercholesterolemia, dwarfism, polydactyly (more than normal number of fingers or toes)

inheriting too few or too many chromosomes, caused by nondisjunction of chromosomes during meiosis ii. Example: Down's syndrome

When sisters fail to separate in meiosis II, or homologous chromosomes fail to separate in meiosis I. It can result in Down's Syndrome, too many chromosomes in a sperm cell, too few chromosomes in an egg cell, aneuploidy

Three copies of chromosome 21, aneuploidy, and nondisjunction occurring from meiosis

• Inversion
• Translocation
• Deletion
• Duplication

ABCDEFGH -------->ABCFEDGH

• ABCDEFGH------->OPQDEFGH
• OPQRSTUV------->ABCRSTUV

ABCDEFGH------->ABC  FGH

ABCDEFGH------->ABCDCDEFGH

A sex chromosome problem. Only a Single X is inherited, no second chromosome

Too many sex chromosomes XXY, produces sterile men with small breasts

Metafemale, superfemale, inherited 3 x's no visible difference to the naked eye

Viruses, radiation, chemicals, etc

Any chromosome other than sex chromosomes

Pair #23

It's on the Y chromosome, there is a Sex-determining Region of the Y chromosome (SRY). When the gene turns on, male characteristics are produced. If it doesn't turn on (even if present) the fetus will be female. For the first 40 days, males and females are exactly alike.

Traits on sex chromosomes other than sex: Blood clotting, male pattern baldness, color vision. All on the X chromosome. Aka sex linked genes. Aka X linked genes. The stuff tends to skip generations

Type O negative

AB