Ch4 Gene Interaction

In Gene interaction there are many ways genes interact to influence a BLANK

Phenotype

There are several important types of gene interactions can you list the four?

1.There may be more than two alleles for a given locus within a population

2. Dominance of one allele over another may not be complete

3.Two or more genes may affect a single trait

4.the expression of a trait may depend on the interaction of more than one gene and/or the interaction of genes with non-genic factors

Mendel chose to examine traits with just BLANK alternative forms

*in one case one form was BLANK over the other such that individuals heterozygous for the two alleles showed the BLANK phenotype

*research in the early and mid-20th century was aimed at better understanding the BLANK nature of dominance

Two

*completely dominant, dominant

*molecular

The terms dominant and recessive have a BLANK basis

Biological

The dominance of one allele over another is determined by the BLANK of that allele

Protein product

The overall BLANK is the consequence of the activities of the protein products of the alleles of the gene

Phenotype

Example 1: Mutant Alleles BLANK to Wild Type

• a wild type alleles (R+) produces and active enzyme (50 units) and a mutant allele ( r) produces little or no active enzyme (0 units)

• 40 or more units of enzyme activity will produce a wild type phenotypes thus R+R+ (100 units) or R+r (50 units) individuals are wild type

• r/r individuals (0units) have the mutant phenotype this the mutant allele is recessive

• In this case the wild type allele is BLANK meaning that?

Haplosufficent, one copy of it is enough for normal function

Example2: Mutant Allele Dominant to Wild Type

*An Allele (T1) produces an active enzyme (10 units) and a mutant allele (T2) produces less active enzyme (5 units)

*18 or more units of enzyme activity will produce a wild type phenotypes, thus only T1T1 (20 units) individuals will be wild type

*the mutant allele is dominant to the wild type allele because individuals heterozygous for both alleles or homozygous for the mutant allele are both mutant in phenotype

In this case the wild type allele is BLANK meaning?

In this case the wild type allele is haploinsufficent meaning that one copy of it is NOT enough for normal function

What causes a wild-type phenotype is always be produced?

When an organism has two copies of the wild type allele

Mutant alleles can either be? (2 things) and describe

Gain-of function- when the gene product acquires a new function or shows increased leave of wild type activity

Loss- of function- when there is a significant decrease or complete loss of functional gene product

Loss of function. Mutation produce BLANK which is called a BLANK or BLANK often these are lethal when homozygous

No functional protein product, null mutation, amorphic mutation

Loss of function mutations that result in a BLANK are called BLANK or BLANK the severity of the phenotype depends on the level of activity of the leaky mutation

Partial loss of function, leaky mutation as, hypomorphic mutations

Mutimeric proteins, composed of two or more polypeptides that join together to form a functional protein are particularly subject to BLANK

Dominant Negative mutations

Dominant Negative Mutations are dominant due to?

The loos of function of the multimeric protein complex due to an amino acid change in one subunit

Dominant negative mutations are negative mutations due to their BLANK on the protein as a whole

Spoiler effect

What type of mutations (usually dominant can be either hypermorphic or neomorphic?)

Gain-of-function mutations

Define hypermorphic

Mutations produce more gene activity than wild type

Define neomorphic

Mutations acquire novel gene activities not in the wild type

Often the dominance of one allele over the other is BLANK in this case allele designations such as A1, A2, or B1, B2 are used instead of capitol or lowercase letters

Not complete

What is the term (s) for when heterozygous individuals display intermediate phenotypes between either homozygous type (typically the heterozygote is more similar to one of the homozygous types than the other)

Incomplete dominance or partial dominance

What type of dominance does blood type ABO alleles reveal?

Codominance

The ABO blood type has BLANK different types results from different combinations of BLANK alleles

4, 3

Which two alleles are codominant in blood types

IA and IB

What does codominance produce?

Heterozygotes with a phenotype different than that of either homozygote

IA and IB alleles are BLANK over the i allele (i fully recessive)

Completely dominant

Blood type A- RBCs have type BLANK on surface

Blood type B- RBCs have type BLANK on their surface

Blood type AB- have both BLANK and BLANK antigens

Blood type O- have neither BLANK or BLANK antigens

A

B

A, B

A,B

The two blood group antigens are BLANK with the lipid portion anchored in the red blood cell membrane

Glycolipids

The blood group antigens are based on a BLANK sugar molecule, called the BLANK which is then modified by the addition of an extra (6th) sugar of one type A or another type B or no extra sugar molecule added O

5

H antigen

The H antigen is created by a separate enzyme- individuals homozygous recessive for the loss of this enzyme (h/h) display the BLANK and lack the H antigen and thus are not A, B, or O, this is found in 1:8000 in Taiwan, 1:10000 in Indian and 1 in a million in Europe, there is no adverse effect

Bombay phenotype

Many BLANK required to produce and distribute pigment to the hair follicles or skin cells where they give rise to skin or coat color

Genes

What gene is responsible for coat color in mammals?

C Gene

The C gene produces an enzyme involved in BLANK production, there are dozen of BLANK of the gene, 4 form a clear BLANK BLANK

Melanin, alleles, allelic series

Which Allele of the C gene produces a functional enzyme and full coat color?

C (wt)

Which allele of the C gene produces a “dilute” phenotype called chinchilla?

Cch (superscript)

Which C gene allele produces a phenotype called Himalayan with little pigment on the body but full color on the extremities (temp sensitive protein)

Ch (superscript)

Which c gene allele produces a fully recessive null allele and produces an albino phenotype?

C

Penetrance sample problem

BLANK is seen in individual who show a phenotype but to a varying degree of severity

BLANK syndrome has four principle features can you name them?

Ex- perigee each family member with the syndrome has same genotype but different combination of symptoms

Variable expressivity

Waardenburg syndrome, premature graying, hearing loss, white forelock, hearing loss, different colored eyes

The human autosomal recessive conditions BLANK is caused by the absence of an enzyme involved in phenylalanine breakdown

PKY (phenylketonuria)

BLANK is one of the hereditary disorder routinely screened for in infants

Infants with BLANK are normal at birth, but over time, the inability to break down phenylalanine is BLANK to developing neurons

PKU

PKU

Toxic

The key to preventing PKU is BLANK in the diet of infants with BLANK

Thousands of people with PKU are living normal lives due to the simple dietary modification that prevents the expression of PKU phenotype

Restricting phenylalanine

PKU

BLANK is the alteration of multiple distinct traits by a mutation in a single gene

Pleiotrophy

BLANK is an autosomal recessive condition caused by a mutation in the B-globin gene

Many red blood cells of people with this conditions take on a BLANK shape and can cause numeral physical problems and complications

Sickle Cell disease

Sickle

The collaboration of multiple genes in a produce of a single phenotypic characteristic or group of related characteristics is termed BLANK

Gene interaction

Both anabolic and catabolic pathways involves gene working together through an multi-step biochemical process with intermediate products

BLANK pathways involve biosynthesis of complex compounds

BLANK pathways involve degradation of complex compounds

Signal transduction pathways and developmental pathways involve interaction of multiple genes

Anabolic

Catabolic