genetics 2: topic 1 on final

what is incomplete dominance

neither allele is fully dominant

how is incomplete dominance different than blending inheritance

blending inheritance is the idea that traits blend together in offspring, but incomplete dominance is where one allele doesn’t fully mask the other (intermediate phenotype)

what is codominance

both alleles are expressed at heterozygote

blood type A genotypes

IA IA, IAi

blood type B genotypes

IBIB IBi

blood type AB genotypes

IAIB

blood type O genotypes

ii

what does i code for

a nonfunctional version of that enzyme

O is the

universal donor

AB is the

universal acceptor

immune system reacts to

the blood type that you don’t have

type A can donate to___ and recieve from

A or AB, A and O

type B can donate to__ and receive from

B or AB, B and O

type AB can donate to__ and receive from

AB, A B O AB

type O can donate to__ and recieve from

A, B, AB, O and receive from O

what is polygenic inheritance

phenotypic traits based on multiple genes, each with their own alleles, working simultaneously

examples of polygenic inheritance

height, skin color, eye color, obesity

polygeinc means

many genes code for one trait

polygenic makes gene editing

wayyyy more complicated

black is inherited - if black is the dominant allele

complete dominance

can’t tell what is inherited without knowing the genotypes of other genes

polygenic

inheritance is patches of black and white, if parents are black and white

codominance

inheritance is grey if parents are black and white

incomplete dominance

in incomplete dominance nether allele is

dominant

the phenotype of an individual in incomplete dominance is

a mix of both the parents, ex; red and white flower would give you pink

in ABO blood types O is completely

recessive to both A and B, meaning A and B are codominant

in sickle cell anemia heterozygotes have

normal and sickle cell hemoglobin

what is sex linked genes

some genes only found on X or Y chromosome

hemophilia and red-green colorblindness are from

recessive alleles on X

why are recessive alleles on the X chromosomes more likely to show up in the phenotype of males than of females

because males only have 1X chromosomes so if that X has the gene then the phenotype will show up. In females both their x’s have to have the recessive trait for the phenotype to show up

what is the principle of independent assortment

genes for different traits can segregate independently during the formation of gametes

mendel’s two important inheritance principles

segregation and independent assortment

sex linked genes can exhibit

complete dominance, incomplete dominance, codominance

punnett squares for two trait crosses assume that the loci of the genes for these traits are on

separate chromosomes which will separate independently during meiosis (principle of independent assortment)

crossing over is rare

between genes that are close together

crossing over occurs more often between genes that are

far apart

what are linked genes

genes located on the same chromosome that tend to be inherited together

what is pleitropy

one gene has multiple phenotypic effects one gene codes for many phenotypes

what is epistasis? ex?

one genes expression of another gene masking the presence of one gene ex: widows peak/male baldness

not all genes are in the

nucleus, some are found in the mitochondria

what kind of effects are mutations in the mitochondrial genome likely to have

typically, muscle weakness, exercise tolerance, loss of neural function

what plays a large role in many phenotypes

environment

sex linkage

a gene located on a sex chromosome

linked genes typically do not assort

independently

linkage is

2 or more genes are located on the same chromosomes

what is multiple allelism

in a population there are more than two common alleles for a locus

if two genes are on the same chromosomes, a punnett square

often won’t predict the probabilities of offspring genotypes correctly

crossing over makes what harder

predicting inheritance of alleles of genes that are located on the same chromosome

the closer together the genes are on the chromosome the more likely

that they will be inherited together (will not be separated by crossing over)

recessive lethal genetic disorders include

cystic fibrosis and tay sachs

heterozygous individuals can be

carriers for the recessively inherited diseases

what is phenylketonuria PKU

a disease allele, can’t make enzyme that breaks down phenylalanine, an amino acid builds up and creates a toxic by product

what is tay sachs

can’t make an enzyme that breaks down sphingolipids
gradual deterioration of motor and brain function; death by 3 years

what is cystic fibrosis

most common fatal genetic disease in north america
causes organs that usually produce thin mucus to produce a very thick mucus

there is a pattern here as to why healthy allele is dominant and the disease allele is recessive for these diseases, what is the pattern

as long as you have 1 version hereto, you can make up for not having one of the alleles

what is the huntington’s disease

dominant lethal genetic disorder
causes nerve degeneration that leads to mental and physical deterioration ultimately death

if huntington’s disease is lethal to have, how does it persist in the population

symptoms don’t show up until later in life so you may have kids already before you knew you had the disease

lethal recessive alleles are usually due to the

mutations that cose for defective proteins

one copy of the functioning allele can

usually produce enough protein to make up for the defective allele

two copies of the defective allele

makes it so that there is not functioning proteins of that gene produced

lethal recessive alleles are ___ than lethal dominant alleles

more common because they can be passed down through carriers

dominant alles are not necessarily

common (polydactyly) or beneficial (huntington)

males are denoted by ____ females are denoted by ___

square, circle

affected is denoted by ___ unaffected is denoted by ___ carriers are

filled in, unfilled, half filled,

recessive traits tend to

skip generations, dominant traits do not

sex linked traits have different

inheritance patterns in males vs females