Genetics exam 2

basic/simple mendelian inheritance

-not always seen

-genes that are linked do not show independent assortment

many genes have more than 2 alleles

example of genes with more than 2 alleles

blood types

blood types described

• 3 alleles

  • a, b, o

• genotypes

  • AA, BB, OO, AB, AO, BO,

• HLA more than 30,000 aleles

some aleles are codominant

both alleles expressed equally

(blood type AB is example)

incomplete dominance

neither allele is completely dominant, so heterozygous phenotype is blended or side by side

example: pea flowers redxwhite=pink

epistasis

when the presence of one gene alters the expression of another gene

epigenetics

• when environmental factors have an effect on gene activity

• not permanent, can be reversed

• can be inherited

• what kind of effect

  • diet, medication, PTSD

  • the next gen is showing phenotypes

  • separate newborn mice from parents, trait stiill occurs

  • 4-5 gens

multigenic

many traits due to multiple genes

ie: heart disease, high bp

multifactorial

multiple genes interact with environment

ex: diabetes (environmental influence on trait like diet)

mitochondrial inheritance

maternal

all mitochondria inherited from egg

responsible for energy production

mitochondria has its own dna and genome

mitochondia in depth

ribosomes related to bacterial ribosomes

37 genes

13 proteins

• mutations possible that give rise to phenotype or disease

  • ex: optic neuropathy

  • cardiomyopathy

  • leigh syndrome

sex linked traits

located on x chromosome or y

ex: color blindness, hemophilia

SV40 virus overview

-attacks human cells

-only 7 genes

-protein coat with single chromosome

SV40 virus mechanism

• infects cell

  • begin replication

  • take over cell, make virus proteins

timeline of SV40

• monkey virus (simian)

  • 1960 discovered

    • contaminate monkey primary kidney cells
      
      first cells introduce to the culture
      

      • used to generate polio vaccine

        • used inactivated virus particles

  • 1962

    • found to transform mouse cells into tumor cells

      • transform into cancerous cells

  • 1963

    • found to transform human cells

    • first virus to cause cancer

      • SV40 T antigen, 1st oncogene

      • protein was hitting the right cellular target to transform human cells despite being in a monkey

    • screening for sv40 required in vaccine prep

  • 1964

    • switched to immortal monkey cells called vero cells

    • 10-20 mil in US received received contaminated vaccine

      • report of tumor biopsies with the SV40 DNA

dictyostelium

• single celled soil amoeba

• under situations of starvation

  • they swarm

  • cluster together to make cell strem

  • slug is formed

• they migrate to area that sis more abundant

  • split off into single cell
    
    or fruiting body that differentiates into
    

    • they get blown away to get to different soil

drosophila

• egg to adult is 10 days

• red eyes

• single gene mutation

  • antennapedia

    • changes the antenna into legs

    • single gene

  • ultrabiothorax

    • single gene mutation

    • causes appearance of another set of wings

c elegans cell lineage

• worm in soil

• followed on microscope from fertilization to development

• 959 cells

• can see every cell

• identified by sydney brenner

  • had long history in cell biology

  • got nobel prize

  • 1958

    • worked out genetic code of protein synthesis

  • 1960

    • worked on mRNA

lab mouse

• 85% genetic similarity

  • mammals

  • nurse young

  • uterus

  • hair

• 0ver 6000 mouse models of human phenotypes and diseases

  • cystic fibrosis can be mutated and given to mice

  • inherited obesity

humans as genetic studies

• humans are a poor model system

  • complicated

  • expensive

  • not short life cycle

large families with detailed records

• amish

  • commercially available for research

• mormon

  • large families

  • detailed geneological records

  • medical records

  • willing to participate

  • salt lake city has genetics lab

• rural French communities

• Iceland

  • small population

  • all originated from a few founders

• online human genetc repository

  • all sorts of diseases

pedigree analysis

• diagram illustrating the members and relationships in a family to show the inheritance of a trait and to estimate the risk of ny given family member inheriting the trait

• can be used to help identify the gene responsible

square in pedigree

male

circle in pedigree

female

line in pedigree

mating

double line in pedigree

mating between relatives

roman numerals in pedigree

generations

two split individuals in pedigree

twins

twins with line in between

identical twins

twins with no line in between

fraternal

diamond in pedigree

offspring of unknown sex

darkened triangle in pedigree

aborted or stillborn pregnancy

lne strike through in pedigree

passed away

lighter color in pedigree

not affected by trait

darker color in pedigree

affected by trait

proband in pedigree

first case identified

split light and dark in pedigree

heterozygous

dot in middle in pedigree, carrier

x linked, female

autosomal dominant

common

AA or Aa or A-

no matter hetero or homo, if alele is there will so uo

rare autosomal recessive traits

appear in individuals who have UNaffected parents

not often, hetero parents, homo offspring

example of rare autosomal recessive

cystic fibrosis, sickle cell anemia

common autosomal recessive trait, many unrelated can be carriers

individuals show phenotype from parents that didn’t show phenotype

appear a lot

x linked recessive

traits linked to x chromosome

males show more frequently because they have 1 x

females can show

females can be carriers

male pass down to female

example of x linked recesiive

color blindness, hemophilia, musular dystrophy

x-linked dominant

half od male offspring will inherit dominant

if male has it

• all doaughters will get it

y linked inheritance

sons get trait

mitochondrial inheritance

maternal inheritance

people with the phenotype have mutated mitochondira from mother

gave to all kids but only female passes it on

amino acids

20 different aminos

an be converted tn other systems

3 parts of aminos

amino group-N and HH

carboxyl-acid group-O double bonded to C bonded to OH

side chain or Rgroup-differentiates the 20 aminos

classification by R group

nonpolar, polar, electrically charged

nonpolar

hydrophobic R group, NO OH

Polar

hydrophilic, OH

amino terminis

drawn with free amino on the left hand side, first in chain

carboxyl terminus

carboxyllic acid on the right hand side

primary structure

sequence of amino acids in the protein

secondary structure

localized foldings

linus pauling

nobel prize winner in chemistry

discovered alpha helix

siscovered secondary structure

tertiary structure

more complicates

quaternary structure

mutiple proteins coming together

represents mor than one protein association into a larger structure

alpha helix

common secondary structure

localized small region of the protein

predicted sequences would form helical shape

hydrogen bonding forms helices

beta sheet

certain primary sequences form sheetlike pattern

x-ray crystallography

developed 1912

father/son pair

shared nobel prize om 1015

identify what protein looks like

3d protein structures

ribbon diagrams

steps of xray crytallography

purify the protein

crystallize protein where water evaporated

when they crystallize they arrange in a structure where they line up

xray hits crystall, gets defracted, atom arrangement shows up

protein structure in 2026

ai takes primary sequence puts it into a software and gets a predction

first computer took 2 months,

alpha fold 3

10-20 mins to solve 350-400 amino acid proteins

self assembley

individual subunits linked together

proteins will find each other and form the right structure

result of incorrect protein self assembly

diseases

agreggation

innapropriate accumulation of self assembly

aggregation examples

parkinsons, huntington

prion diseases

proteins that lead to neurological symptoms if they aggregate

acquired through contaminated food

discovery of prion diseases

1960s New Guinea

women and children connection to cannibalism

kuru source

human

scrapie source

sheep

potentially gentetically based

bovine spongiform encephalopathy

mad cow disease

analogous to kuru

outbreak in GB and western europe in 1986-2010

selling infetected cows

cows got from eating sheep byproduct

prion makeup

infectious proteins

only aminos, 254

normal prions

no lethal activity

occurs in brain for copper transport

single protein, alpha helices

abnormal prions

infectious

254 amino acids in bain

forms aggregate plaques

normal prions are recruited and turn into beta sheets and aggregates

allostery-induced allosteric conformation changer

required for proper function of proteins

primary sequence doesn’t change, SHAPE DOES

alters proetin activities

turns on or off

makes more or less active

changes function

allostery basic def

some proteins can undergo a regulated/induced conformational change in shape that alters proteins’ activity

motor proteins

through movement, carry out work, move via conformational change

kinesin basic

vesicle and organelle transport

made of 4 proteins and accessory proteins

heavy kinesin chains

2, 1200 amino

kinesin light chains

2, 600 amino

kinesin function

bind to microtubles, binds atp, binds tubulin, motor domain causes movement

cargo binding-vesicle, mitochondria, protein

atp-regulator, as each phosphate is release it moves along

dynein

protein and RNA transport

myosin

organelle movement, muscle contraction

helicase

unwind dsDNA

atp synthetase

use h+ gradient to make atp or use atp to pump h plus

nerve cells

neuron, axon, dendrite

nucleus in cell body

proteins in dendrites synthesized at end of axon

nucleic acids

polymers of nucleotides

dna and rna

DNA stats

3,000 nucleotides-small

100 mil-human chromosome

function-info storage

RNA stats

10-15-snRNA

100,000-large mRNA

2,000-avg mRNA

RNA function

info storage

gne expression

dna replication

enzymatic

nucleotide parts

nitrogenous base

ring structure, phosphate group

purines

2 rings

adenine, guanine, larger

pyramidines

thymine and cytosine

smaller

bigger name, smaller structure

RNA bases

no thymine Uracil instead(pyramidine)

bases get linked together

phosphate links on 3 to 5 bond

it’s a DNA if….

number 2 oxygen is not there and thymine is there

phosphate group

weak acid

sugar phosphate backbone

sugar RNA

ribose-5 carbon

OH off 2nd carbon

1 carbon attached to base