Goal 3.03 Interpret and predict patterns of inheritance. Let there be PEAS ON EARTH! And let it begin with me! math.uit.no

Gregor Mendel Modern genetics began in the mid-1800s in an abbey garden, where a monk named Gregor Mendel documented inheritance in peas used good experimental design used mathematical analysis collected data & counted them excellent example of scientific method He studied at the University of Vienna from 1851 to 1853 where he was influenced by a physicist who encouraged experimentation and the application of mathematics to science and a botanist who aroused Mendel’s interest in the causes of variation in plants. After the university, Mendel taught at the Brunn Modern School and lived in the local monastery. The monks at this monastery had a long tradition of interest in the breeding of plants, including peas. Around 1857, Mendel began breeding garden peas to study inheritance.

When a flower pollinates itself. No new genes are introduced. Mendel’s work Pollen transferred from white flower to stigma of purple flower Bred pea plants cross-pollinate true breeding parents raised seed & then observed traits allowed offspring to self-pollinate & observed next generation When bred to themselves will always produce organisms with same phenotype. EX. White bred to white always produces white; purple bred to purple always produces purple. anthers removed all purple flowers result P = parents F = filial generation When a flower pollinates itself. No new genes are introduced. self-pollinate ?

Mendel collected data for 7 pea traits Each of these traits is represented by a specific allele on a specific chromosome. Allele = genes that determine a specific trait. Flower color Seed color Seed shape Pod color Pod shape Flower location Plant size

1st 100% 3:1 2nd X self-pollinate true-breeding purple-flower peas true-breeding white-flower peas X Parents 100% 1st generation (hybrids) purple-flower peas self-pollinate 2nd generation 3:1 75% purple-flower peas 25% white-flower peas In a typical breeding experiment, Mendel would cross-pollinate (hybridize) two contrasting, true-breeding pea varieties. The true-breeding parents are the P generation and their hybrid offspring are the F1 generation. Mendel would then allow the F1 hybrids to self-pollinate to produce an F2 generation.

Some traits mask others What did Mendel’s findings mean? Some traits mask others purple & white flower colors are separate traits that do not blend purple x white = light purple purple masked white Dominant allele functional protein affects characteristic masks other alleles recessive allele no noticeable effect allele makes a non-functioning protein mutant allele malfunctioning protein allele producing functional protein homologous chromosomes

Difference between how an organism “looks” & its genetics Genotype vs. phenotype Difference between how an organism “looks” & its genetics phenotype Form of the trait that gets expressed “what you see” genotype An organism’s actual alleles F1 P X purple white all purple Explain Mendel’s results using …dominant & recessive …phenotype & genotype

Environment effect on genes Phenotype is controlled by both environment & genes Coat color in arctic fox influenced by heat sensitive alleles Human skin color is influenced by both genetics & environmental conditions The relative importance of genes & the environment in influencing human characteristics is a very old & hotly contested debate a single tree has leaves that vary in size, shape & color, depending on exposure to wind & sun for humans, nutrition influences height, exercise alters build, sun-tanning darkens the skin, and experience improves performance on intelligence tests even identical twins — genetic equals — accumulate phenotypic differences as a result of their unique experiences Color of Hydrangea flowers is influenced by soil pH

Phenotype is a result of both genetics and environment. www.safeandsoundlostandfound.org Cold Environment Siamese cats that grow up in a cold environment are darker… www.cats-central.com …than those that grow up in a warmer environment. Warm Environment

Inheritance of genes On the chromosomes passed from Mom & Dad to offspring are genes may be same information may be different information eye color (blue or brown?) eye color (blue or brown?)

This separation is called the Law of Segregation. Remember how Meiosis separates the alleles into sex cells? This separation is called the Law of Segregation.

Effect of genes Genes come in different versions - alleles brown vs. blue eyes brown vs. blonde hair Alleles = different forms of a gene

Heterozygous = different Homozygous dominant = AA Homozygous recessive = aa Heterozygous = Aa Homozygous = same Heterozygous = different aa rr XY Ss Ww Tt Aa Yy BB RR bb Ee AB Bb

Genes affect how you look… Where did the blue eyes go?? X bb BB Bb Bb Bb Bb Where did the blue eyes go??

Why did the blue eyes stay?? X bb Bb Bb Bb bb bb Why did the blue eyes stay??

Where did the blue eyes come from?? X Bb Bb BB or Bb BB or Bb BB or Bb bb Where did the blue eyes come from??

Genes come in “versions” brown vs. blue eye color Alleles (different forms of a gene) Alleles are inherited separately from each parent brown & blue eye colors are separate & do not blend either have brown or blue eyes, not a blend Some alleles mask others brown eye color masked blue

How does this work? Paired chromosomes have same kind of genes but may be different alleles gene eye color (blue?) eye color (brown?) allele hair color

Traits are inherited as separate units For each trait, an organism inherits 2 copies of a gene, 1 from each parent a diploid organism inherits 1 set of chromosomes from each parent diploid = 2 sets (copies) of chromosomes 1 from Mom homologous chromosomes 1 from Dad

Making gametes Remember meiosis! B BB BB = brown eyes bb = blues eyes Dominant = can mask others bb  brown is dominant over blue  blue is recessive to brown B b Recessive = can be hidden by others Bb Remember meiosis!

How do we say it? B 2 of the same alleles Homozygous BB BB = brown eyes bb = blues eyes bb b homozygous dominant homozygous recessive 2 different Heterozygous Bb B b Bb = brown eyes

Punnett square practice. Punnett squares Bb x Bb male / sperm B b X BB Bb B b female / eggs Bb bb Punnett square practice.

Genetics vs. appearance There can be a difference between how an organism looks & its genetics appearance or trait = phenotype brown eyes vs. blue eyes genetic makeup = genotype BB, Bb, bb 2 people can have the same appearance but have different genetics: BB vs Bb

Genetics vs. appearance How were these brown eyes made? eye color (brown) eye color (brown) eye color (brown) eye color (blue) vs. BB B Bb B b

PP pp Pp Making crosses x Can represent alleles as letters flower color alleles  P or p true-breeding purple-flower peas  PP true-breeding white-flower peas  pp F1 P X purple white all purple PP x pp Pp

phenotype & genotype can have different ratios Punnett squares Aaaaah, phenotype & genotype can have different ratios Pp x Pp 1st generation (hybrids) % genotype % phenotype P p male / sperm PP 25% 75% Pp 50% P p female / eggs PP Pp Pp Pp pp 25% 25% pp 1:2:1 3:1

Any Questions?? Assignment: Punnett Square Practice Worksheet www.publispain.com

Beyond Mendel’s Laws of Inheritance 2007-2008

Extending Mendelian genetics Mendel worked with a simple system peas are genetically simple most traits are controlled by single gene each gene has only 2 version 1 completely dominant (A) 1 recessive (a) But its usually not that simple!

Incomplete dominance Hybrids have “in-between” appearance RR RR = red flowers rr = white flowers Rr = pink flowers make 50% less color RR WW or R’R’ RW or RR’ RR Rr rr

Incomplete dominance P 1st 100% 1:2:1 2nd X true-breeding red flowers white flowers 100% 100% pink flowers 1st generation (hybrids) self-pollinate 25% white 2nd generation 25% red 1:2:1 50% pink

Incomplete dominance RW x RW RR R W RW R W RW WW 25% 25% 50% 50% 25% genotype % phenotype RR 25% 25% R W male / sperm 50% 50% RW R W female / eggs RW WW 25% 25% 1:2:1 1:2:1

Codominance x = Equal dominance Chickens A black-feathered chicken is crossed with a white-feathered chicken. All of the babies are white with black speckling. Both white and black show up equally. x =

More Codominance… x

Multiple Alleles More than one allele to select from. Blood “types” can be A, B, AB, or O. The alleles to make these types include A, B and i. “i” is the recessive allele and A and B are both dominant. So to get… Type A you must have AA or Ai Type B you must have BB or Bi Type AB you must have AB Type O you must have ii

BLOOD Antigens are tiny receptors on the outside of the blood cell that matches the “type.” Multiple Alleles Blood cells have antigens and antibodies. Antibodies are what the cell doesn’t like (which is anything different from the “type.”)

Blood Types Multiple Alleles Anti-B Anti-A Type B Type A B A Antigens (none) Type O Anti-A and B none

Genetics of Blood type A A A or A i B BB or B i AB O i i pheno-type Multiple Alleles pheno-type genotype antigen on RBC antibodies in blood donation status A A A or A i type A antigens on surface of RBC anti-B antibodies Receive A or O B BB or B i type B antigens on surface of RBC anti-A antibodies Receive B or O AB both type A & type B antigens on surface of RBC no antibodies universal recipient O i i no antigens on surface of RBC anti-A & anti-B antibodies universal donor

One gene : Many effects? The genes that we have covered so far affect only one trait But most genes are affect many traits 1 gene affects more than 1 trait dwarfism (achondroplasia) gigantism (acromegaly) The genes that we have covered so far affect only one phenotypic character, but most genes are pleiotropic

Acromegaly: André the Giant

Inheritance pattern of Achondroplasia Aa x aa Aa x Aa A a A a a Aa aa A AA Aa a Aa aa a Aa aa 50% dwarf:50% normal or 1:1 67% dwarf:33% normal or 2:1

Polygenic = “many genes” Many genes : One trait Polygenic = “many genes” Polygenic inheritance additive effects of many genes humans skin color height weight eye color intelligence behaviors

Polygenic = “many genes” Human skin color AaBbCc x AaBbCc range of shades most children = intermediate skin color some can be very light & very dark

Albinism melanin = universal brown color Johnny & Edgar Winter albino Africans

OCA1 albino Bianca Knowlton

Coat color in other animals 2 genes: E,e and B,b color (E) or no color (e) how dark color will be: black (B) or brown (b) eebb eeB– E–bb E–B–

SEX and GENES X & Y 2 X chromosomes = female: XX Women & men are very different, but just a few genes create that difference In mammals = 2 sex chromosomes X & Y 2 X chromosomes = female: XX X & Y chromosome = male: XY X only = XO (Turner’s Syndrome) X X X Y

Who you are… Autosomes Sex Chromosomes

Sex-linked traits Sex chromosomes have other genes on them, too X X X especially the X chromosome hemophilia in humans blood doesn’t clot Duchenne muscular dystrophy in humans loss of muscle control red-green color blindness see green & red as shades of gray X X Duchenne muscular dystrophy affects one in 3,500 males born in the United States. Affected individuals rarely live past their early 20s. This disorder is due to the absence of an X-linked gene for a key muscle protein, called dystrophin. The disease is characterized by a progressive weakening of the muscles and loss of coordination. X Y

XHY HH XHXh Hh x XHY Y XH XH Y XHXH XHXH XHY XHY XH Xh XHXh XH Xh XHXh sex-linked recessive x 2 normal parents, but mother is carrier XHY Y XH XH Y male / sperm XHXH XHXH XHY XHY XH Xh female / eggs XHXh XH Xh XHXh XHXh XhY XhY

Most Common Allele Dominant or Recessive Either One! Because an allele is dominant does not mean… it is better, or it is more common Polydactyly dominant allele

Polydactyly Recessive allele far more common than dominant individuals are born with extra fingers or toes the allele for >5 fingers/toes is DOMINANT & the allele for 5 digits is recessive Recessive allele far more common than dominant  only 1 individual out of 500 has more than 5 fingers/toes  so 499 out of 500 people are homozygous recessive (aa)

Hound Dog Taylor Any Questions? Assignment: Coach Book L17 http://www.last.fm/music/Hound%2BDog%2BTaylor%2B%2526%2Bthe%2BHouse%2BRockers Any Questions? Assignment: Coach Book L17 Textbook pg 180-181 #1-6