Patterns of Inheritance

Gregor Mendel

Gregor Mendel

the Father of Genetics; studied inherited traits of pea plants

Mendels 3 important ideas

1. Traits are dominant and recessive

2. Genes and alleles

3. Segregation of alleles

Dominant Gene

Dominant variant is displayed in hybrids; shown

Recessive gene

Recessive variant is masked by dominant; not shown.

Codominant

Inheritance pattern in which a heterozygote expresses the distinct trait of both alleles.

autosomal dominant

inheritance pattern of a dominant allele on an autosome

autosomal recessive

inheritance pattern of a recessive allele on an autosome

X-linked recessive

What pattern of genetic transmission affects only M and has no M-to-M transmission

X- linked dominant

a mode of genetic inheritance by which a dominant gene is carried on the X chromosome

Genes ; alleles

A ________ has 2 forms

Segregation of alleles

allele pairs separate randomly from each other during production of gametes

Genotype

The genetic composition of an individual. Provides the plan to create phenotype.

TT

homozygous dominant

Tt

Heterozygous

tt

homozygous recessive

Phenotype

Physical or behavioral characteristics that are the result of gene expression.

ex) TT and Tt are tall

tt is short

Punnett Square

Make sure to practice, with genotype and phenotype ratios.

Law of independent assortment

Alleles of different genes assort independently of each other during gamete formation.

Simple mendelian inheritance

Alleles are dominant or recessive; Phenotype ratios follow mendels laws.

Complex forms of inheritance

Incomplete dominance and Codominance are....

Autosomes

All chromosomes except the sex chromosomes(X and Y) are called?

Autosomal dominant

Where the disease is dominant and more common to get then not (Ex. Huntington's disease)

Codominance

A condition in which neither of two alleles of a gene is dominant or recessive.

What plays a significant role on the phenotype of genes?

environment

Male sex chromosome pattern

XY

Female sex chromosome pattern

XX

X chromosome

Which is larger and carries more genes? X or Y?

X-Linked genes

Genes found on the X but not the Y

Maternal inheritance

inheritance of DNA that occurs through the cytoplasm of the egg

Biparental inheritance

inheritance from two parents

Gregor Mendel

"father of genetics" studied peas to figure out if the differences in how the peas looked. He looked at wrinkled vs. smooth peas. he found the principle of independent assortment

Mendellian Genetics

1 gene= 1 trait independent assortment autosomal chromosome traits

genetics

study of how the traits were passed down from parent to offspring

homologous pairs

one maternal one paternal chromosome come together to make.....

Alleles

different genes (possibilities) for the same trait ex: blue eyes or brown eyes

sex chromosomes

The last pair of chromosomes on a karyotype

Letters

= 2 alleles given for a gene

capital letter

dominant gene

lowercase letters

recessive gene

genotype

Ex. sS; dd ; DD

how many alleles so you get from your parents?

dad gives you one because sperm is haploid and mom gives you one because egg is haploid

Homozygous

two alleles that are the same

Homozygous dominant

TT

homozygous recessive

tt

Heterozygous (Hybrid)

Tt

Punnet Square

used to predict the possible gene makeup of offspring

Why does a recessive allele not kill you?

The recessive allele will be masked by a dominant

Incomplete dominance

combination of two alleles two alleles are mixed (mixed person white and black) RR red x rr white = 100% pink

Co Dominance

full expression of both alleles in the heterozygous individual makes an individual with alleles from both parents (no mixing)

3 alleles for blood

IA(A oligosaccharides on the surface of red blood cells)

IB( B oligosaccharides on the surface of red blood cells)

i (O) (no oligosaccharides on the surface of red blood cells)

Universal reciever

type AB- type AB blood can receive blood from all types

-A because it has blood type A

-B because it has blood type B

-O because there are no antigens attached so it wont cause a reaction

universal donor

type O -no antigens on the blood so no reaction will happen if any blood type enter an O blood type cell

Polygenic Inheritance

multiple genes combining together and contributing to one phenotype -the large distribution of a single characteristic ex: skin color eye color

Nondisjunction of chromosome #21

down syndrome

Colorblindness

inherited from dad, when you have Xb and cannot see color

Hemophilia

missing a blood clotting protein and can bleed to death -X linked

Huntington's Disease

loss of muscle control and mental functions; causes death 35-45 years old within 10 years of symptom appearance -autosomal dominant

Sickle Cell Anemia

when the red blood cells are very thin and shape in a crescent moon shape and cause lack of blood flow and oxygen for major organs; immunity to malaria

Phenyiketonuria (PKU)

they lack the able to convert amine=o acid to other amino acids

tay sachs

defective enzyme with fatal death within ages of 3-5 and causes to break down a section of brain lipids; causes seazure

Albinism

lack pigment or melanin at all. no cure and bad sunburns

Which parent determined your gender?

dad because he has the y chromosomes and those determine gender

why cant you get an y from mom?

Mom only has Xs

Pedigrees

a genetic family tree showing disease (circle is woman square is male and colored in box or circle that the disease has affected the individual )

Males can never be.....

Carriers

A carrier

A female who is heterozygous for a disorder

nondisjunction

missing chromosomes or chromosome sections occur -too may or not enough chromosomes in each gamete after cell formation

Cystic Fibrosis

Disorder that affects the mucus build up in the lungs

polydactyly

Have extra digits on your extremities -1/500 has more than 5 fingers/toes -499/500 are homozygous recessive (aa) (arent affected)

environmental affect on genes

-phenotype is controlled by both environment and genes (pH condition, heat sensitive alleles)

duchenne muscular dystrophy

loss of voluntary muscle xlinked

Turner

XO missing other X chromosome (women)

kleinfelter

XXY extra X chromosome (men)

karyotype

shows the complete sets of chromosomes in an individual

Phenotype

Ex. Big ears vs. small ears