Exam 1, Mass Flashcards (The Last Two Lectures)

Mendel’s Law of Dominance

when an individual, ONLY the dominant allele will be expressed

Dominance Relationship in ducks is an example of ____ dominance

Cascading

True or false:It is not possible for there to be more than 2 alleles at a given locus and each allele has its own dominance relationship

False

what does “M^r > M> m^{d “} mean in ducks genes

M^r is dominant to M, which is dominant to m^d

White Morphs Are Abundant in Nature Because

1. Loss of function mutations are more popular than gain of function mutations

2. There a discrete biochemical pathways for color & one perturbance in the pathway disallows color

Incomplete Dominance (define)

an intermediate phenotype where one allele is not expressed more than the other (neither is dominant to the other)

• mixed

• Red x White = Pink

Incomplete Dominance ___ to the number of possible phenotypes

adds, so if you have two initially, the incomplete phenotype counts as one

*****In incomplete dominance the genotypic ratio and phenotypic ration are __

equal to one another

Codominance (define)

• Both of the alleles of a gene pair are FULLY expressed (just in different areas)

• vitiligo

• calicos

Mechanism of Cystic Fibrosis

• having faulty CTFR membrane proteins, causing lack of regulation of Cl- in lung cells, impairing lung function

Cystic Fibrosis is ___ but ___

1. recessive

2. co-dominant

True or False: Cystic Fibrosis severity varies due to the co-dominance of faulty CFTR & proper CTFR

True

Penetrance (define)

the percentage of individuals having a particular genotype that express the expected phenotype

Are Incomplete dominance & codominance fully or incompletely penetrant

incompletely

Penetrance Equation

p = # of people with phenotype/ # of people with genotype

Expressivity (define)

the degree to which a trait is expressed

An Example Of Incomplete Penetrance

polydactyly, because it is dominant but most humans have exactly 5 digits on each limb

Draw increasing polydactyl expressivity

ok

Epistasis (define)

interaction among genes in which the phenotype of a gene is dependent on the presence of one or more modifier genes

Genetic Background

modifier genes that influence epistasis and in turn, phenotype

Epistasis breaks which of Mendel’s Laws?

1. Law of independent assortment

2. law of segregation

Epistatic Genes

when a gene or locus suppressed or masks the phenotypic expression of another gene

Hypostatic Genes

the gene or locus that is suppressed by the epistatic gene, messing up phenotypic expression

Epistasis Event

when an epistatic gene suppresses the hypostatic gene, thereby effecting phenotypic expression

The Two Types of Epistasis (main)

dominant & recessive

Dominant Epistasis

when only a single copy of the heterozygous allele is required to inhibit phenotypic expression of the hypostatic gene

• need BB or Bb to have an effect

Recessive Epistasis

when the presence of two recessive alleles inhibits the expression of an allele at a different locus

• must be bb

• ee with the labrador puppies

Cascading Epistasis Pathways

When a single epistatic gene interacts with multiple hypo- or epistatic genes, resulting in one final hypostatic gene

In a heterozygous dihybrid cross, there is a ___ ratio

9:3:4 ratio

Two Types of Duplicate Epistasis

recessive & dominant

Recessive Duplicate epistasis (define)

Two recessive alleles at either of two different loci can suppress a genotype

Duplicate Epistasis

when two sets of alleles are needed for epistasis

Dominant Duplicate Epistasis

A single dominant allele at either of two loci is capable of suppressing a genotype

Is gender a biological or social phenomenon & do other species outside of humans exhibit it ?

1. Social phenomenon

2. Only humans have gender

How Biological Sex is Defined

Only by the gametes the individual produces

Defntitons of gametes

sex cells, either sperm or eggs

Characteristics of Male Gametes

1. Smaller & Mobile

Characteristics of Female Gametes

1. Bigger and non-mobile

Chromosomal Sex Determination Systems (definition)

Sex is determined by specific chromosomes (non-autosomes) that result in different se4xes having different chromosomes.

Autosomes Definition

any chromosome pair that is not differentiated between sexes

Heteregamtekic

a sex chromosome pair that is different (XY, ZW)

Homogametic

a sex chromosome air that is the same in a given sex (XX, ZZ)

XX-XO system

• XX is female

• XOw (where O is nothing at all, no Y)

• seen in grasshoppers and insects

ZZ-ZW system (Missy Elliot system)

• ZZ is male

• ZW is female

• In birds, snakes, butterflies, & some amphibians & fishes

XX-XY system

• XX is female

• XY is male

• homogametic sex is female

• seen in mammals

Definition of Haplodiploidy Sex Determination System

Sex determination system that results in one sex being haploidy(1n) and the other sex being diploidy (2n)

• bees, wasps & ants

Haplodoploidy Sex Determination System

Haploids are male, Diploids are females, when males are created they are unfertilized, when females are create they are fertilized

Genic Sex Determination System

• Sex is determined by sex determining genes in autosomes only

• The genes matter

• Found in some plants, fungi, & fish

Environmental Sex Determination System

• system that determine ssex base don the environment

• ex is the crocodiles, males are at the bottom of the divot while females are at the top of the divot

Hermaphroditism

both sexes are in the same organism

• both eggs and sperm are in the same exact flowers in the same tree

Monoecious

both male and female reproductive systems in the same organism

• egg and sperm on different flowers in the same tree

Dioecious (us)

either male or female reproductive structures sin one organism, not both.

All Sex Determination Systems

1. Genic

2. Environmental

3. Chromosomal

4. Haplodiploidy

Human Sex Determination

1. Humans are diploid (2n)

2. Chromosomes 1-22 are autosomes

3. Chromosome 23 is an allososme

Allosome

non homologous chromsomes

Which Sex Chromosome is more important and why?

The X chromosome is much more important because

• it contains information pertaining to both sexes,

• -has more genes than Y,

• is required while Y is not

SRY gene

gene only found in the Y chromosome that makes males males,

• once it is there, the male phenotype is created, without it the female genotype is created.

DSDs (abv meaning )

disorder of sexual development

Definition of DSDs

congenital conditions that effect reproductive development

Swyer Syndrome

a DSD that o caused by a mutation in the SRY gene that causes XY indiuvudals to develop as female (because SRY is not working correctly) but they lack estrogen making them infertile

Nondisjunction

An error during meiosis or mitosis in which sister chromatids fail to separate, resulting in daughter cells with an abnormal number of chromosomes.

The cause fo aneuploidy

True or False: aneuploidy can be n+-1

True

XXX

Triple X Syndrome

XOw

Turnery Syndrome (O means that they only have an X chromosome)

XXY, XXXY, XXXXXY, XXYY

Klienfelter’s Syndrome

OY

nonviable, no X means no life

Sex Linked Genes

• genes linked to sex chromosomes

• includes sex determination and developmental genes

Reciprocal Cross

• a breeding experiment designed to ties the role of parental sex on a given inheritance pattern

Requirement for Reciprocal Cross

In the P generation, both parents must be true breeding

Dosage Compensation

The process by which an organism equalizes gene expression from the sex chromosome between individuals of different biological sexes

MAIN way Dosage Compensation is seen in humans

in females, one of the X chromosomes is inactive at random so only one of them is actually being expressed

X-Inacvitaiton

process by which one of the copies of X in a cell is randomly inactivated, creating a barr body

Barr Body

the inactive X chromosome in a female somatic cell

Sex Influenced Traits

• autosomal traits that are expressed differently in different sexes, one phenotype has higher penetrance than the other

• sometime resulting in a flipped dom-recessive relationship

Sex Limited Traits

• autosomal trait that results in a phenotype ONLY BEING SEEN in one sex, zero penetrance in the other

Cytoplasmic Inheritance

• inheritance that doesn’t abide by the medelian rules of genetics

• applies to organelle genes (mitochondria comes from mom only)

• usually uniparental and zero combination