Chapter 11 Mendel and Heredity Classical Genetics

Chapter 11 Mendel and Heredity Classical Genetics

Fundamentals of Genetics

Children look like their parents Ideas on inheritance of traits – Pangenesis. Aristotle (384 - 322 BC) – Blending Hypothesis • Traits from parents blend to form offspring

Gregor Mendel “Father of Modern Genetics” Austrian Monk (18221884) Experimented with pea plants in the 1860’s Work wasn’t discovered until 1900

Mendel’s Pea Plants Reasons that Garden Peas worked well – Flower Structure • Male and Female Parts could self fertilize • Easy to control breeding

Self vs. Cross Fertilization Self Fertilization – an individual that breeds with itself Cross Fertilization – one individual fertilizes another, had to prevent self fertilization

Quick Life Cycle Peas mature quickly and produced many offspring

Seven Easily Observable Traits

Disproving the Blending Hypothesis Blending hypothesis – offspring are always intermediates of the parents

Mendel’s Traits didn’t Blend Tall Plants x Short Plants = Tall Plants

Mendel’s Traits didn’t Blend Purple Flowers X White Flowers = Purple Flowers

Mendel’s Traits didn’t Blend Green Peas x Yellow Peas = Yellow Peas

Mendel’s Traits didn’t Blend Green Pods x Yellow Pods = Green Pods

Mendel’s Experiments True Breeding (Purebred) – offspring that were produced by the same type of parents Hybrid – offspring that were produced by different types of parents

P (parent) Generation Mendel crossed plants that were purebred for different traits Purebred Tall x Purebred Short = F 1 F ( filial ) = offspring The F 1 Generation were hybrids, but showed only one form of the trait Mendel stated that this form was DOMINANT

P (parent) Generation

Dominance Gene – section of DNA that controls a trait Alleles - the different forms of the gene When 2 alleles are present, one shows up and the other is hidden Dominant Allele – the one that shows up Recessive Allele – the one that is hidden

F 1 Self Fertilization = F 2 Mendel allowed the hybrid F 1 Plants to self fertilize The resulting offspring were the F 2 generation The Recessive trait reappeared in the F 2 generation Always in the same ratio 3 dominant : 1 recessive

Mendel’s Conclusions Each Individual has 2 alleles for a trait – 1 allele from each parent Homozygous (Purebred) – both alleles are the same – Homozygous Dominant / Recessive Heterozygous (Hybrid) both forms of the allele are present

Phenotype vs Genotype Phenotype – physical traits that can be observed – Purple Flowers or White Flowers Genotype – the alleles that an individual has for a trait Genotype Phenotype – Homozygous Dominant (PP) Flowers – Heterozygous (Pp) Flowers Purple

Law of Segregation When individuals form gametes (sperm or egg) the 2 alleles for a trait are separated

Law of Independent Assortment Different Traits are inherited separately Flower Color and Seed Color are not tied together

Monohybrid Cross Mono – 1 Hybrid – different alleles

Punnett Square Tool used to predict genetic probability

Phenotypic Ratio Purple : White 3: 1 Genotypic Ratio Homozygous D : Heterozygous : Homozygous R PP: Pp : pp 1: 2: 1

Phenotypic Ratio Tall : Short 4: 0 Genotypic Ratio Homozygous D : Heterozygous : Homozygous R TT: Tt : tt 2: 2: 0

Tongue Rolling is a dominant trait in humans

Hitchhiker’s Thumb Hitchhiker’s thumb is a recessive trait in humans

Dimples are a dominant trait in humans

Free vs Attached Earlobes Free Earlobes are a dominant trait in humans

Widow’s Peak a dominant trait in humans

Dihybrid Cross Observing 2 traits parents are hybrids for each Rr. Yy x Rr. Yy Gametes ¼ RY, ¼ Ry, ¼ r. Y and ¼ ry 16 possible outcomes

Easier Way to do multiple traits x • Do a separate Punnett Square for each trait Rr x Rr Yy x Yy R y RR Rr Y YY Yy Rr R r Y r rr y Yy yy 3/4 Round 1/4 wrinkled 3/4 Yellow 1/4 green

Easier Way to do multiple traits x 3/4 Round • • • 1/4 wrinkled 3/4 Yellow 1/4 green Muliply the probabilities of each trait Round and Yellow = ¾ x ¾ = 9/16 Round and Green = ¾ x ¼ = 3/16 Wrinkled and Yellow = ¼ x ¾ = 3/16 Wrinkled and Green = ¼ x ¼ = 1/16

Analyzing Heredity Probability – the likelihood that an event will occur Probability – number of one outcome number of possible outcomes Flipping a Coin Heads Rolling a Dice 1/6 ½

Bikini Bottom Genetics Scientists at Bikini Bottoms have been investigating the genetic makeup of the organisms in this community. Use the information provided and your knowledge of genetics to answer each question. 1. For each genotype below, indicate whether it is a Ho heterozygous (He) OR homozygous (Ho). He Ho Ho TT _____ Bb _____ DD _____ Ff _____ tt _____ He Ho Ho Ho dd _____ Dd _____ ff _____ Tt _____ bb _____ BB _____

Bikini Bottom Genetics TT _____ Bb _____ DD _____ Ff _____ tt _____ dd _____ Dd _____ ff _____ Tt _____ bb _____ BB _____ FF _____ Which of the genotypes in #1 would be TT, DD, tt, dd, considered purebred? ff, bb, BB, FF ________________ Bb, of the genotypes in #1 would be Which Ff, Dd, Tt hybrids? __________________

Bikini Bottom Genetics 2. Determine the phenotype for each genotype using the information provided about Sponge. Bob. Yellow body color is dominant to blue. Yellow Blue YY _____ Yy ______ yy ______ Square Round Square shape is dominant to round. SS ______ Ss ______ ss ______

Bikini Bottom Genetics 3. For each phenotype, give the genotypes that are possible for Patrick. A tall head (T) is dominant to short (t). TT, Tt Tall = _____ Short tt = ______ pp Pink body PP, Pp (P) is dominant to color yellow (p). Pink body = ______ Yellow body = _______

Bikini Bottom Genetics 4. Sponge. Bob Square. Pants recently met Sponge. Susie Roundpants at a dance. Sponge. Bob is heterozygous for his square shape, but Sponge. Susie is round. Create a Punnett square to show the possibilities that would result if Sponge. Bob and Sponge. Susie S s had children. HINT: Read question #2! s Ss ss

Bikini Bottom Genetics S s s Ss ss A. List the possible genotypes and phenotypes for their children. Heterozygous (Ss) Square, Ho Recessive (ss) Round 2 50 B. What 1 are the chances of a child with a square shape? ____ out of ____ or ____% 1 2 50

Bikini Bottom Genetics 5. Patrick met Patti at the dance. Both of them are heterozygous for their pink body color, which is dominant over a yellow body color. Create a Punnett square to show the possibilities that would result if Patrick and Patti had children. HINT: Read. Pquestion #3! p P PP Pp pp

P p P PP Pp pp Bikini Bottom Genetics A. List the possible genotypes and phenotypes for their children. B. What are the chances of a child with 4 a pink 3 body? ____ out 75 ____ or of ____% 1 25 C. What are the 4 chances of a child with

Bikini Bottom Genetics 6. Everyone in Squidward’s family has light blue skin, which is the dominant trait for body color in his hometown of Squid Valley. His family brags that they are a “purebred” line. He recently married a nice girl who has light green skin, which is a recessive trait. Create a Punnett square to show the possibilities that would result if Squidward and his new bride had children. Use B to represent the dominant gene and b B B to represent the recessive gene. b b Bb Bb

Bikini Bottom Genetics B b b Bb Bb Bb A. List the possible genotypes and phenotypes for their children. 100 B. What are the chances of a child with light blue 0 skin? ______% C. What are the chances of a child with light green No, skin? ____% they are all hybrids D. Would Squidward’s children still be considered

Bikini Bottom Genetics 7. Assume that one of Squidward’s sons, who is heterozygous for the light blue body color, married a girl that was also heterozygous. Create a Punnett square to B b show the possibilities that would result if they had children. B BB Bb bb

Bikini Bottom Genetics 7. Assume that one of Squidward’s sons, who is heterozygous for the light blue body color, married a girl that was also heterozygous. Create a Punnett square to show the possibilities that would result if they had children. A. List Ho Dpossible genotypes and phenotypes for the (BB) Blue, He (Bb) Blue, Ho R (bb) green their children. 75 25 B. What are the chances of a child with light blue skin? ____%

Bikini Bottom Genetics 8. Mr. Krabbs and his wife recently had a Lil’ Krabby, but it has not been a happy occasion for them. Mrs. Krabbs has been upset since she first saw her new baby who had short eyeballs. She claims that the hospital goofed and mixed up her baby with someone else’s baby. Mr. Krabbs is homozygous for his tall eyeballs, while his wife is heterozygous for her tall eyeballs. Some members of her family have short eyes, which is the recessive trait. Create a T T Punnett square using T for the dominant gene and t T TT TT for the recessive one. t Tt Tt

Bikini Bottom Genetics T TT TT t Tt Tt A. List the possible genotypes and phenotypes for their children. Ho D (TT) tall eyes, He (Tt) tall eyes B. Did the hospital make a mistake? Explain your Yes, there is no way that their child could answer. have short eyes

Bikini Bottom Genetics 2 1. Use the information for Sponge. Bob’s traits to write the phenotype (physical appearance) for each item. Round Eyes Long Nose (a) LL-_______ (e) Rr-________ Stubby Nose Blue Body (b) yy-________ (f) ll- ________ Round Pants Square Pants (c) Ss-________ (g) ss- _______ (d) RR - _______ (h) Yy -_______ Round Eyes Yellow Body

Bikini Bottom Genetics 2 2. Use the information in the chart in #1 to write the genotype (or genotypes) for each trait below. ll YY, Yy (a) Yellow body - _____ (e) Stubby nose - _____ RR, Rr ss (b) Roundpants - _____ (f) Round eyes - ______ rr (c) Oval eyes - ______ (g) Squarepants - _____ SS, Ss LL, Ll (d) Long nose - ______ (h) Blue body - ______ yy

Bikini Bottom Genetics 2 3. Determine the genotypes for each using the information in the chart in #1. Rr (a) Heterozygous round eyes -_____ SS (b) Purebred squarepants - ______ LL (c) Homozygous long nose - ______ Yy (d) Hybrid yellow body - ______

4. One of Sponge. Bob’s cousins, Sponge. Billy. Bob, recently met a cute squarepants gal, Sponge. Gerdy, at a local dance and fell in love. Use your knowledge of genetics to answer the questions below. (a) If Sponge. Gerdy’s father is a heterozygous squarepants and her mother is a roundpants, what is her genotype? Complete the Punnett square to show the possible genotypes that would result to help you determine Gerdy’s genotype. Ss What is Gerdy’s genotype? _____S s s Ss ss

Bikini Bottom Genetics 2 4. One of Sponge. Bob’s cousins, Sponge. Billy. Bob, recently met a cute squarepants gal, Sponge. Gerdy, at a local dance and fell in love. Use your knowledge of genetics to answer the questions below. (b) Sponge. Billy. Bob is heterozygous for his squarepants shape. What is his genotype? Ss ____

Bikini Bottom Genetics 2 4. One of Sponge. Bob’s cousins, Sponge. Billy. Bob, recently met a cute squarepants gal, Sponge. Gerdy, at a local dance and fell in love. Use your knowledge of genetics to answer the questions below. (c) Complete the Punnett square below to show the possibilities that would result if Billy Bob & Gerdy had children. S s S SS Ss ss Ss x Ss

4. One of Sponge. Bob’s cousins, Sponge. Billy. Bob, recently met a cute squarepants gal, Sponge. Gerdy, at a local dance and fell in love. Use your knowledge of genetics to answer the questions below. (d) List the possible genotypes and phenotypes for the kids. SS Ss ss square round (e) What is the probability of kids with squarepants? 75 _____ % (f) What is the probability of kids with roundpants? _____ % 25 S s S SS Ss ss

Bikini Bottom Genetics 2 5. Sponge Bob’s aunt and uncle, Sponge Wilma and Sponge Wilbur, have the biggest round eyes in the family. Wilma is believed to be heterozygous for her round eye shape, while Wilbur’s family brags that they are a pure line. Complete the Punnett square to show the possibilities that would result if Wilma and Wilbur had children. (a) Give the genotype for each person. Rr RR Wilma - _______ Wilbur - ____

5. Sponge. Bob’s aunt and uncle, Sponge. Wilma and Sponge. Wilbur, have the biggest round eyes in the family. Wilma is believed to be heterozygous for her round eye shape, while Wilbur’s family brags that they are a pure line. Complete the Punnett square to show the possibilities that would result if Wilma and Wilbur had children. (b) Complete the Punnett square below to show the possibilities that would result if they had children. R RR RR r Rr Rr

5. Sponge. Bob’s aunt and uncle, Sponge. Wilma and Sponge. Wilbur, have the biggest round eyes in the family. Wilma is believed to be heterozygous for her round eye shape, while Wilbur’s family brags that they are a pure line. Complete the Punnett square to show the possibilities that would result if Wilma and Wilbur had children. (c) List the possible genotypes and phenotypes for the kids. RR Rr Round eyes R RR RR r Rr Rr

Bikini Bottom Genetics 2 5. Sponge. Bob’s aunt and uncle, Sponge. Wilma and Sponge. Wilbur, have the biggest round eyes in the family. Wilma is believed to be heterozygous for her round eye shape, while Wilbur’s family brags that they are a pure line. Complete the Punnett square to show the possibilities that would result if Wilma and Wilbur had children. (d) What is the probability that the kids would have round eyes? 100 % ____

Bikini Bottom Genetics 2 5. Sponge. Bob’s aunt and uncle, Sponge. Wilma and Sponge. Wilbur, have the biggest round eyes in the family. Wilma is believed to be heterozygous for her round eye shape, while Wilbur’s family brags that they are a pure line. Complete the Punnett square to show the possibilities that would result if Wilma and Wilbur had children. (e) What is the probability that the kids would be 0 oval eyes? ____ %

6. Sponge. Bob’s mother is so proud of her son and his new wife, Sponge. Susie, as they are expecting a little sponge. She knows that they have a 50% chance of having a little roundpants, but is also hoping the new arrival will be blue (a recessive trait) like Sponge. Susie and many members of her family. If Sponge. Bob is heterozygous for his yellow body color, what are the chances that the baby sponge will be blue? Create a Punnett square to help you answer this question. 1/2 or 50% Y y y Yy yy

7. Sponge. Bob’s aunt is famous around town for her itty, bitty stubby nose! She recently met a cute squarepants fellow who also has a stubby nose, which is a recessive trait. Would it be possible for them to have a child with a regular long nose? Why or why not? Create a Punnett square to help you answer this question. l l ll x ll l l ll Stubby

8. If Sponge. Bob’s aunt described in #7 wanted children with long noses, what type of fellow would she need to marry in order to give her the best chances? Create a Punnett square to help you answer this question. L LL l l Ll Long L Ll Long

Complex Inheritance Incomplete dominance – neither allele is completely dominant

RR rr Rr

Rr rr Rr Rr RR

Palamino Horses Heterozygous (Cc) CC x cc always produces Cc palamino

Palamino x Palamino Cc X Cc = 1 CC: 2 Cc : 1 cc

Bikini Bottom Genetics Incomplete Dominance Sponge. Bob loves growing flowers for his pal Sandy! Her favorite flowers, Poofkins, are found in red, blue, and purple. Use the information provided and your knowledge of incomplete dominance to complete each section below. 1. Write the correct genotype for each color if R represents a red gene and B represents a blue gene. Red - _RR_ Blue - __BB_ Purple - _RB__

Bikini Bottom Genetics Incomplete Dominance 2. What would happen if Sponge. Bob crossed a Poofkin with red flowers with a Poofkin with blue flowers. Complete the Punnett square to determine the chances of each flower color. RR x BB (a) Give the genotypes and phenotypes for the offspring. RB, purple B (b) How many of the plants would have red flowers? B __0__% RB R RB (c) … purple flowers? _100_ % (d) … blue flowers? __0__ % R RB RB

Bikini Bottom Genetics Incomplete Dominance 3. What would happen if Sponge. Bob crossed two Poofkins with purple flowers? Complete the Punnett square to show the probability forxeach flower color. RB RB (a) Give the genotypes and phenotypes for the offspring. RR BB RB (b) How many of the plants would have red flowers? _25__% R B (c) … purple flowers? _50____ % RB (d) … blue flowers? ___25__ % R RR B RB BB

Bikini Bottom Genetics Incomplete Dominance 4. What would happen if Sponge. Bob crossed a Poofkin with purple flowers with a Poofkin with blue flowers? Complete the Punnett square to show the probability for plants with each flower color. BR x BB (a) Give the genotypes and phenotypes for the offspring. BB RB (b) If Sponge. Bob planted 100 seeds from this cross, B B how many should he expect to have of each color? RB =1/2 50 plants Purple flowers - ______ plants BB =1/2 50 BB Blue flowers RR = 0 plants - ______ Red flowers - ______ RB R RB

Codominance Both alleles are expressed at the same time Type AB blood is an example, both A and B antigens are present.

RR rr Rr

Rr Rr RR rr Rr

Multiple Alleles ABO blood typing is also an example of multiple alleles. Instead of 2 alleles there are IA, IB and i – IA codes for A proteins – IB codes for B proteins – i codes for no proteins

Blood Types Phenotype Type A Type B Type AB Type O Genotype(s) IAIA or IAi BIB or IBi I AI B I ii

Polygenic (Many genes) Many traits come in many forms – Height, Skin color, Hair color, Eye color These are controlled by several genes

Environmental Factors Some genes are affected by the environment Himalayan Rabbit

Chromosome Number Each species has a specific number of chromosomes. Humans – 46 House fly – 12 Chimpanzee – 48 Horse – 64 Dog – 78 If the species reproduces sexually, the number is even.

Humans chromosomes. Humans have 23 different chromosomes 2 of each = 46 total A cell that has all 46 (or 2 of each) is diploid (di=2) Gametes, sperm or egg cells only have 1 of each or 23 chromosomes. These are haploid cells Sperm (23) + Egg (23) = Zygote (46) Zygote is the fertilized egg

Meiosis – Forms gametes Gametes are specialized haploid sex cells Sperm and Egg cells In meiosis a diploid cell divides twice producing 4 cells Human Diploid cell (46 chromosomes) Meiosis goes through the same steps twice PMAT

Meiosis I separates homologous chromosomes 1 from 1, 2 from 2 etc Homologous chromosomes – chromosomes that have the same information

Prophase I Nuclear envelope dissolves Homologous chromosomes pair up to form a tetrad (four) Spindle fibers form and

Metaphase I Tetrads are lined up in the center of the cell

Anaphase I The homologous pairs are separated

Telophase I and cytokinesis The nuclear membranes reform

Meiosis II is just like Mitosis, but chromosome number has been cut in half. P 2 M 2 A 2 T 2

Mitosis vs Meiosis

Recombination During Prophase I homologous chromosomes can exchange pieces This creates new combinations of genes