Gentics exam 2

Neo Mendelian Gentics

Expansion of Mendelian basic principal of gentics explaining why inheritance can be more complicated (incomplete, codominence)

Wild type allele

“Normal” most common most frequently scene (basic info on expressing allele)

Incomplete dominance

Neither allele is completely expressed (phenolic blend )

-its a heterozygous phenotype that is intermediate

-ex red and white snapdragon = pink

Codominance

Both alleles are FULLy EXPRESSED

-EX human blood

Multiple allele

Multiple allele in a population (Blood type ) but only 2 can be expressed within a population

• Studied for genetic diversity

Lethal allele

Single allele can cause death when present in a genotype

Essential allele

Necessary for survival can lead to death of disabled

Recessive lethal allies

Expressed ONLY AS HOMO

• causes yellow mice

• YY causes death

• 2 to 1 ratio

Dominant Lethal allele

Only requires one for death (after Reproduction)

Huntington’s disease (nuericolical disorder that happen in the HTT gene) located on tip of short ae number 4 chromosome

-anticipation

1 wild or dominant allele can allow for survival

Epistasis

1 gene (epistatic) mask a phenotypic expression of another gene ( called the hypostastic)

EX Black and brown bear (ee)

Gene interaction

2 or more genes interacting to produce a novel phenotype

Pentrace

The percentage of phenotype expressed of a genotype

-Incomplete less that 100

Complete 100

Expressitivity

Is the degree and intensity the phenotype is expressed

-Polydactyl (the increase of finger and toes) some have mild case and other have severe

Age of onset

Age creates internal and external environment that influences gene expression and function

aging occurs because most somatic cell somatic cells lack telomeres which causes shortening and cell death of chromosome

Telomeres

Protective cap on chromosome end that gets shorter and shorter with each division

TelomerASE

Enzyme hat exptned telmerse in active stem cells and cancer cells

Sex linked traits

Genes located on chromosome to control the traits

-blindness and hemophilia

Sex influences

autosomal trait influence sex hormone (1 dominant alle in male and 2 in female)

-badness

Sex limited

Limited to male or female

Dosage expression

Mechanism to equalize gene expression

-more common in female

Temperature

Certain allers are temperature sensitive

-hemalan rabbits and Siamese cats have dark spots on the colder areas of there body

Phenylketunria PKU

When individuals can’t metabolize phenalnine ( blood test occurs at birth)

-is controlled by diet

Phenocopy (Phake copy)

Non genetic change that appears to be one

EX exposure to thalimide looks like a limb disorder but it is a chemical change

Nature vs nurture

How much a trait is influenced by environmental conditions vs genetic

Norm of reaction

The potential phenotypes a genotype can express due to its environment

Polygenic trait

TRAITS controlled by many genes

-each dominant allele adds a phenotype

(Hight skin color and intelligence)

Continuous variation

Range of phenotype not discreet trait (no variation)

-WIDE variation

Multi factorial inheritance

Traits influenced by inheritance and environment

-diabetes heart disease

Many diseases are multi factorial

Pleitrophy (Plenty of traits)

1 gene influence many traits simultaneously

Marian syndrome → effects connective tissue which lead to long limbs which can cause heart defects and vision problems

Sickle cell anemia→ causes able normal RBC which leas to malaria residents and multiple organ system failure

Sexual dimorphism

Different ion betaween male and female (Not by reproductive organs)

-male body hair, height, muscle definition

Sex determination

Identifying sex

Sex establishing systems

XX/XY system (SRY triggers growth of male characteristics)

ZZ(m) /ZW (f)

XX(f)/XO (m)

Homogametic

Same XX gamete

Heterogaetic

Different XY

50 ;50 sex cell ratio during meiosis

100 % x from female and 50 x and 50 y from male

Pseudoatoumsomal region

Found on both end of chromosome x and y

Allows for cross over

These are homologous

Male specific region of y (MSY)

MSY makes up majority of Y chromosome and the unique male genes

-divided into euromatic and heterochromic

Euromatic

DNA rich lightly packed it’s important for fertility and male traits

Heterchroamtic

Inactive structural and does not code for DNA

Tightly pack

Located on Y chromosome

SEX determining region SRY

Location on short arm of Y chromosome right by MSY

Codes for testies determine factor TDF which start production of testies which then develop and produce testosterone (a major male characteristic)

Genetic sex determing system

Some organism aren’t deterred by whole chromosome but by a specific loci located on oci

Environmental Sex determination

Sex can be determined by environmental factors during development

Temp development. (Reptiles determine male or female by cold or hotness)

Social environment (if male fish dies femal becomes male)

Chemical cue and pop can effect it

Sex chromosome abnormalities

Arise from nondisjunctioin during meiosis

Turner Disease

XO

-45 ch

-web neck short stature infertility and underdeveloped ovaries

Klinefelter (XXY)

47

Extra ch

Tats low test, sterile, man boobs

Poly x (XXX)

47 or more

Tall usually fertile but can give birth to an underdeveloped child

Jaaacobe Syndrome (XYY)

47

Male, tall, normal fertility but can cause aggression

Xx male syndrome

SRY was already on chromosome but it was transcripted to x so genetically they are a male but phenotypically they are a female

Primary ration

Ratio of male to female zygotes before birth

Secondary

Ratio of male to female after birth

Normally more male but it makes up for ther higher mortality rate

Aneuplodidy

When an granite has 1 or more missing or Gaines chromosomes (46/47)

Monopsony and trisomy

Euploidy

Chromosomes has exact multiple of haploid number

Not missing no extra

Polyploidy

Posses more that two complete set of chromosomes

(2n, 3n, 4n,6,)

Autopolyploidy

All chromosomes sets are from the SAME population

Allopoploidy

Chromosomes from DIFFERENT species

Nondisjunction

Failure to split resulting in aneuploidy

Examples of nondisjunciton (Aneuploidy)

Klinefeller syndrome

Turner

Trisomy 21

Cri du Chat (deletion of 5 chromosome)

Mosaciasm

When an individual can have 2 or more cells with different genetic makeup

Translocation In DS

Familia Down syndrome

-chromosome 21 is translocated with 14

Deletion

Lost of chromosome

Terminal (end )

Intercalary (middle)

Clued by error in crossing over transposable element and radiation

EX Cri du chat and William syndrome

A centric chromosome

Without centromere

Competition loop

Loop created between deletion and norm chromosome

Duplication

Segment replication

-causes unequal cross over

EX Idiosentric syndrome (replication of 15 can cause autism )

Inversion

Reverse end to end

Pericentric (including t chromosome)

Paracentrc (no centromere)

Translocation

Segment of 1 chromium some exchanged or moved to another

Reciprocal

Translocation exchange between 2 non homolgeous chromosom

Non reciprocal

1 piece more to another chromosome NO exchange

Robertonian Translation

Exchange between 2 acrocentric chromosome

EX familial Down syndrome

Chromic Myelogenous Leukemia 9 and 22

Fragile X syndrome

Area that is prone to breaking makin gaps

Replication of trinceutide in the FMR1 gene (CGG)

Causes intelicial disorder

Displays anticipation

Trinucleutide repeat

Humans have limited number of chromosomes the can repeat before it becomes unstable

-Huninftons

-fragile x

My tonic dystrophy

Linkage

2 genes on one chromosome are inherited together due to how close they are

Map until-. Centimorgan

Measures genetic distance between genes

1 % percent = 1 cm difference

Over 50 % it is not linkage

Genetic distance e

Chromosome map

Shows order and relative distance

-perform cross

-calculate recombinant frequencies

-arange in order of distance

Genetic map (Linkage)

Shows how often cross overs occur

3 aspects of duplication

1 extra copy

2 change get it traits

3 duplication and division

Cytogenetic map

Visual chromosome map that locate genes bases on banding pattern (uses microscope)

Complete linkage

Chromosomes are so close 0 recombianation

Parental (dosnt recombiante)

Recombination (crosses over )

LOD ( logarithm of odds)

Statistic wether two Genoese are linked

Prop of linkage

Not rop of linkage =log 10

Positional cloning

Identify and isolate a gene based location

Use linkage analysis

DNA marker near region

Identify spefic gene

Cri