Heredity Heredity by Brainpop

I. Heredity & Genetics parent to offspring oThe passing of traits from parent to offspring genes oTraits are controlled by genes

II. ALLELES FORM oONE FORM of a gene one oSex cells have one two oBody cells have two forms or ALLELES for a single gene dominant oOne may be dominant over another.

III. DOMINANT AND RECESSIVE mask oDominant will always be expressed and will “mask” recessive dominant oA recessive trait can only be expressed if there are no dominant alleles present.

oExample dominant oExample: Eyecolor—Brown color is dominant and blue is recessive.

capital lower caseDominant alleles are represented with a capital letter, recessive with a lower case letter.

IV. GREGOR MENDEL father o“father of genetics”

peas oMendel worked with peas

V. PROBABILITY ochance ochance something will happen 50% oEx: heads or tails on a coin is 50% (1/2 chances) accurate omore accurate with more trials

Why is it that if a couple has 2 children, they don’t always have one boy and one girl? 2 is a really small trial #…so won’t always “see” the ratio!

VI. Using a Punnett Square oUsed to predict probability of traits otrait is given TWO letters, one for each allele.

o“Purebred” =BB or bb. o“heterozygous”(hybrid). Bb GENOTYPE = Gene Combinations located on chromosomes

PHENOTYPE oThe PHYSICAL trait =PHENOTYPE. oBlue Eyes.

Incomplete dominance Heterozygous expresses a different phenotype

Multiple alleles - Blood type 3 alleles, codominance A,B,o

4 blood types from 3 alleles AA or Ao= type A BB or Bo= type B AB = type AB oo = type O

Polygenic inheritance = many genes for one character.

SEX-LINKED and SEX INFLUENCED TRAITS

SEX CHROMOSOMES CAN CARRY OTHER GENES TOO = _________________ SEX LINKED TRAITS

Sex chromosomes can carry other genes Y-LINKED GENES: Genes carried on Y chromosome EX: Hairy pinna _______ genes only show up in __Y linked males.

Sex chromosomes can carry other genes X-LINKED GENES: Genes carried on the X chromosome EX: _____________ _____________ _________________________ Hemophilia Colorblindness Duchenne Muscular Dystrophy

SEX INFLUENCED TRAITS Genes ___________ on sex chromosomes BUT affected by ____________ of individual with gene not carried sex hormones

PEDIGREE CHART Normal Male = Normal Female = Has trait =

CARRIER Individual with one copy of a recessive autosomal allele Carriers DON’T SHOW the trait themselves but can pass it on to their offspring NORMAL DEFECTIVE

CHROMOSOMES

DNA Nucleic acid made of nucleotide subunits A T G C Found in nucleus Carries the genetic code in its sequence

DNA can appear in 2 forms Spread out in nucleus as _____________ in NON-DIVIDING cells Scrunched into bundles as ________________ in DIVIDING cells CHROMATIN CHROMOSOMES

________ PROTEINS maintain shape of chromosome Histone

Cancer cells Don’t stop dividing ___________ damage DNA Ex: Radiation, cigarette smoke, chemicals in environment Carcinogens

CANCER

Chromosome structure ____________ 2 identical arms ____________ constricted area holds chromatids together __________________ PAIR 2 of each chromosome (one from mom; one from dad) CHROMATIDS CENTROMERE HOMOLOGOUS

CHROMOSOME NUMBERS Each species has a characteristic number of chromosomes HUMANS have 46 chromosomes (23 pairs )

DIPLOID & HAPLOID Cells with 2 copies of each chromosome are _______________ (one from mom; one from dad) All body cells Cells with only one copy of each chromosome are ____________________ Sperm and egg 1n + 1n = 2n egg + sperm new organism DIPLOID2n HAPLOID1n

KARYOTYPES ________ = picture of organism’s chromosomes KARYOTYPE

Chromosomes that determine the sex of an organism = _________________________ All other chromosomes = _________________ Sex chromosomes autosomes Humans have two sex chromosomes X y

A KARYOTYPE can tell the sex of an organism In humans XY is a male

In humans XX is a female

Guess who? XY

You can’t judge a critter by its chromosomes This critter has 54 chromosomes

Corn has 10 pair of chromosomes

Snails have 18 pairs of chromosomes

A mouse has 40 chromosomes

Nondisjunction Chromosomes fail to separate during meiosis gametes may have too few or too many chromosomes Disorders: –Down Syndrome – three 21 st chromosomes –Turner Syndrome – single X chromosome –Klinefelter’s Syndrome – XXY chromosomes 45

Eric has Down’s Syndrome 1 in 750 births Has extra #21 chromosome Mental retardation

Down’s syndrome (trisomy 21) Simian line on palm Eye fold

Down’s syndrome (trisomy 21) Most common chromosomal abnormality 50% have heart defects Mental retardation Risk increases with age of mom

Patau syndrome (trisomy 13)

1 in 7000 births (rare)

Patau syndrome (trisomy 13) Cleft lip & palate Eyes too small or missing

Patau syndrome (trisomy 13) Low set ears Polydactyly

TURNER’s SYNDROME XO- only 1 X, no Y Short stature Immature ovaries heart problems hearing loss decreased mental ability

Turner Syndrome Normal uterus, tubes and ovaries and ovaries Non-functional Ovaries

Kleinfelter syndrome XXy

Kleinfelter syndrome 1 in 1000 births Male = XXy Aslight decrease in intelligence Small testes/can’t have children

Xyy syndrome Xyy males Taller, more aggressive