Genetics Unit

Genetics Unit

Introduction to Genetics-Genetics is the study of heredity.-Heredity is how different genes are passed down from parents to children.

PHENOTYPEA phenotype is the expression of an observable physical trait or characteristic of an organism, such as stature or blood type, based on genetic and environmental influences.Examples vs Non-examples

Hair PHENOTYPE Hair-do: not a phenotype Twins born with A weird girl who fros-outblonde and red hair her hairPhenotypesCan you think of some examples of phenotypes?

Write down at least 2 examples of phenotypes (traits) in your notes

How good are you at judging chimpanzee phenotype?

Which chimps are related?

PolydactylPhenotypes? Yes or no?Phenotypes? Yes or no?

NO! Flamingos get their pink color from the food they eat, not their genes!

HOMOZYGOUS organism with two identical alleles for the same trait

**root word homo = same

HETEROZYGOUS organism with two different alleles for the same trait**root word hetero = differentHomozygous vs. HeterozygousTwo alleles for the height gene might be TALL (T) and SHORT (t)

A homozygous individual would be TT or tt two of the same alleles

A heterozygous individual would be Tt two DIFFERENT alleles

DOMINANT

allele that is expressed when at least one allele is present (TT or Tt = tall)cover up

RECESSIVEallele that is expressed only when homozygous (no dominant allele)

(tt = short)Recessive

DominantaaAA or Aa

DominantRecessivewwWW or WwDimples (D) No dimples (d)

What could AC Slaters genotype be? Zachs?DD or Dddd

SNOWFLAKE rare albino gorillaAlbinismcombination of recessive alleles passed from both parents of an individualprevents the body from making the usual amounts of the pigment melaninNN = Normal pigmentation (dominant)Nn = Normal pigmentationnn = AlbinismAbout 1 in 17,000 people have some type of albinism, although up to 1 in 75 are carriers. My PHENOTYPE is Albino (or no color).

My GENOTYPE is nn.

TRAITa characteristic

Examples:Plant size, seed color, pod shape

GENE(a segment of DNA that controls traits)

Above you see chromosomes. The circled area is a gene on chromosome #22. The absence of this gene causes velo-cardio-facial syndrome (VCFS) which may cause ADD and mental illness Breast Cancer and Genes

ALLELESEach gene comes in different forms called alleles, so the gene that controls flower color may come in two alleles: purple and white.

ALLELESdifferent forms of a gene

GenotypeThe combination of the two alleles for a given gene

MENDELS EXPERIMENTSGREGOR MENDEL

The father of GeneticsLived from 1822-1884Austrian MonkPublished his work in 1866, but no one took him seriously until 1900.Studied Pea Plants!

Mendel experimented with 7 different characteristics

GENESEach feature of the pea plants is controlled by a gene. It may have a gene that controls its color, another size for and another for shape.

Monohybrid cross. First, Mendel kept all the traits the same except for _one___. This is a called a __monohybrid___cross___ ________

One trait disappeared in the _F1_______

It reappear in the F2 in a ratio of 3:1_____30Dihybrid CrossNext, Mendel controlled all traits except for __2__. He called this a _dihybrid cross_____

Again, two traits disappeared in the F1They reappeared in the F2 in a ratio of 9:3:3:1Mendels Principles of InheritanceInherited traits are transmitted by genes which occur in alternate forms called allelesPrinciple of Dominance - when 2 forms of the same gene are present the dominant allele is expressedPrinciple of Segregation - in meiosis two alleles separate so that each gamete receives only one form of the genePrinciple of Independent Assortment - each trait is inherited independent of other traits (chance)32If we saw an organism that had round seeds (round is dominant), how could we figure out what its genotype is?

A cross between an unknown and a homozygous recessive

Test CrossExample of a Test Cross

Unknown

When a combination of the dominant and recessive creates a new phenotype. RR = red, rr = white, and Rr = pink

Incomplete Dominance

Incomplete DominanceRRRrrr

When both traits are expressed equally. Example: AB blood type

Co-dominance

a trait that is found on either the X or Y chromosome

Sex Linked TraitHemophilia is an example of a sex linked trait.

a disease where your blood doesnt clot.

HemophiliaHemophilia only occurs when all of the X chromosomes have a copy of the recessive gene.

SICKLE CELL ANEMIA

Why would African Americans be so much more likely to have Sickle Cell?

chart that shows the relationships within a family

PEDIGREE

Pedigree BasicsMales are squares, females are circles, and unborn babies are triangles or octagonsShaded figures represent individuals with the trait, a carrier could be 1/2 shadedGenerations are numbered with roman numerals (I, II, II, IV) from top to bottomPeople within generations are numbered (1,2,3) from left to righta protein produced by white blood cells in the body in response to the presence of an antigen, for example, a bacterium or virus

ANTIBODY

a substance, usually a protein, on the surface of a cell or bacterium that stimulates the production of an antibody

ANTIGENBlood group AYou have A antigens on the surface of your red blood cells and B antibodies in your blood plasma.Blood group B You have B antigens on the surface of your red blood cells and A antibodies in your blood plasma. Blood Groups

Blood GroupsBlood group ABYou have both A and B antigens on the surface of your red blood cells and no A or B antibodies at all in your blood plasma. Blood group 0You have neither A or B antigens on the surface of your red blood cells but you have both A and B antibodies in your blood plasma.

Genetic Disorders

A technique used to determine the genetic traits of a baby before it is born AMNIOCENTESIS

Klinefelter SyndromeHave male genitalia and internal ducts, but underdeveloped testesDo not produce spermSlight enlargement of the breasts47,XXY1 out of every 500 male birthsTurner SyndromeHas female external genitaliaUnderdeveloped ovariesShort (under 5 feet)Webbed NeckBroad, Shield-like chest45,X1 out of every 3000 female births

Cri-du-Chat SyndromePartial monosomy (part of 1 chromosome is lost)Loss of about 1/3 of the short arm of chromosome 5Anatomical malfomrations (gastrointestinal and cardiac complications)Mentally retardedAbnormal development of the larynx which makes the babys cry sound like a cats cry1 in 50,000 live births

Down SyndromeBKA trisomy 21 (47, 21+); 3 copies of the 21st chromosomeShortSmall round headsProtruding, furrowed tongues which cause mouth to remain partially openMentally challenged (IQ below 70)Shortened life expectancy (