Gene Expression

Law of segregation

Alleles seperate 3:1 ratio

50/50 chance for particular allele

Law of Independent assortment

Alleles inherited independently

2factor cross - 2 traits

Mendels vs Morgan Experiments subjects

pea plants. Vs flies eye color X linked

Cystic Fibroses

Cystic fibrosis transmembrane protein regulates ion transport - imbalanced

Pancreas intestine, sweat, lungs

Pedigree analysis

determine inheritance in humans

What does accuracy on prob depend on

size of sample

Variable expressivity

Degree that trait is expressed

1 extra finger- low expressivity

5 extra fingers- high

Gain of function

Protein encoded by the mutant gene is changed so it gains a new or abnormal

function

loss of function

Recessive mutant allele that "defect" ability to express functional protein

also called "knockout"

incomplete penetrance

dominant allele does not influence the outcome of a trait in a heterozygote individual "you got it or you dont "

population level measurement

dominant traits can skip generations bc of incomplete pen

dominant neg mutation

Protein encoded by the mutant gene acts antagonistically to the normal protein

incomplete dominance

Heterozygote exhibits a phenotype that is blended between the corresponding homozygotes red+white=pink

Codominance

Both alleles expressed and affect phenotype

AB bloodtype

red and white splotched flowers

Overdominance

two alleles produce slightly different protein variants -> combination produces a favorable phenotype in the heterozygote

Disease resistance -sickle cell

Homodimer formation

Variation in functional activity

pleiotropy

single gene influences multiple, seemingly unrelated traits.

epistasis

effect of one gene (the epistatic gene) masks, inhibits, or modifies the phenotypic expression of another gene

paralogs vs orthologs

Orthologs different species that evolved from a common ancestor, speciasion, same function.

Paralogs are genes within the same genome that evolved, duplication, new functions.

how to classify and identify chromosomes

location of the centromere, size, and banding patterns

acentric fragment

lacks a centromere

CNV Copy Number Var

Duplications and deletions

1,000 bp ; the same species

Euploidy vs Aneuploidy

describe variations in chromosome numbers. Euploidy refers to having complete sets of chromosomes Aneuploidy is the abnormal presence or loss of individual chromosomes

most common disorders involving abnormalities in the number of autosomes are trisomies of chromosomes

Chromosome 21 → Down syndrome

Chromosome 18 → Edwards syndrome

Chromosome 13 → Patau syndrome

endopolyploidy

phenomenon where cells contain multiple sets of chromosomes (polyploidy) due to DNA replication without cell division (endoreduplication), while the rest of the organism remains diploid. This process leads to highly specialized, large cells

Genetic polymorphism

more than 1 wild type in population

Why are recessive alleles not observed in

heterozygous individuals?

50% of the normal protein is enough to accomplish the protein's cellular function

normal is "upregulated" to make up for non functioning protein

Haploinsufficiency

mutant is loss-of-function, BUT heterozygote does not make enough product to give the wild type phenotype

Reaction norm

vary according to enviroment linked to variable expressivity

Why is sickle cell persistant?

sickle deforms blood shape = anemia, blood clots inside

Resistant to malaria so if heterozygous, infected blood cell burst so paraste has no host

Gene interaction

2+ influence outcome of 1 trait

exhibit epistasis and complementation

epistasis

gene mask phenotypic effects of another gene bc gene interaction

Genetic vs Allelic variation

genetic - members of same species

allelic - particular gene

cytogenetics

microscope examination of chromosomes

Karyotype

micrograph all chromosomes in single cell are arranged

large - small

telomeres

end of chromosomes, highly repetitive, and protect against incorrect binding

inversion

segment breaks, flips, reaattatch

periI - span centromere (centromere inside when loop)

parA - 1 side centromere

break point effect- in vital gene seperating it to 2 broken parts

position effect- alters gene expression

for heterozygous inver chromo synapse- inversion loop

translocation

segment attatched to another non homo chromo

recirpocal- 2 non homo exhange mat via bad cross or broken chromo

unbalanced- change total amt genes, more likely to have phenotype

deletions

terminal - end

interstitial - middle

detrimental when phenotypic affect

caused by unequal cross or breakage

Duplication

caused by shit recombination (repetitive seq)

crossover - nonallelic homologous recombination

can lead to new genes/functions "gene fam evolution"

which changed to chromosomes structure change genetic mat and which stay same amt

deletion and duplication change

translocation and inversion same

Paralog

carry out similar but distinct functions

globin

proteins bind to O2

ex of gene fam evolution

Roberstson translocation

down syndrome 14 has extra from 21

break acrocentric chromo and rejoin into 1 long one

fragments lost

aneuploidy

imbalance in gene products

common in gamete formation

may cause miscarriage

semisterility

Having fewer viable gametes lowers an individual's fertility

nondisjunction

failure chromosomes to seperate cause anueploidy

Primary oocytes arrested in prophase 1 higher chance

slide 60-

Alt Segregation

viable gametes

2 norm and 2 translocated

Adj.-1 and 2 segregation

4 unbalanced gametes

1- non homo chromo more common

2- homo

all 4 cells result in 1 normal and 1 translocated

A pattern in which the loss of function in a single gene has no phenotypic effect, but the loss of function of two genes has an effect. Functionality of only one of the two genes is necessary for a normal phenotype.

Gene Redundancy

A phenomenon in which two different parents that express the same or similar recessive phenotypes produce offspring with a wild-type phenotype.

complementation

What are the chances that the first two children are unaffected AND the third child is affected for sickle cell disease (parents are both carriers)

(3/4)(3/4)(1/4)=9/64

"Exactly one of the first three children is affected" (parents are both carriers)

9/64 x 3 (amount of children)

What is the probability that a phenotypically normal sixth child will be a carrier?”

carrier 1/2 / phenotypically norm (3/4)

if it didnt say phenotypically normal then 1/2

Meiosis I nondisjunction → all gametes abnormal

Meiosis II nondisjunction → half normal, half abnormal