Lesson 4 Non-Mendelian Genetics PDF

MODIFICATIONS TO BIO 170| MENDEL’S CLASSIC RATIOS GENETICS WHAT COLOR OFFSPRING WOULD YOU GET WHEN YOU CROSS A PURE (HOMOZYGOUS) RED SNAPDRAGON WITH A PURE WHITE SNAPDRAGON? ? 2 ODDLY ENOUGH,...

MODIFICATIONS TO BIO 170| MENDEL’S CLASSIC RATIOS GENETICS WHAT COLOR OFFSPRING WOULD YOU GET WHEN YOU CROSS A PURE (HOMOZYGOUS) RED SNAPDRAGON WITH A PURE WHITE SNAPDRAGON? ? 2 ODDLY ENOUGH, NEITHER RED NOR WHITE Snapdragon Flower Color is controlled by Incomplete Dominance and a new 3rd phenotype is seen. 3 HOW DOES INCOMPLETE DOMINANCE WORK? INCOMPLETE DOMINANCE IS A BLENDING Like Paint, the RED Pigment “MIXES” with the WHITE to create PINK- FLOWERED offspring 5 INCOMPLETE DOMINANCE CAN BE SEEN IN: Horses ( Chestnut x Cremello → Palomino) Snapdragons Japanese Four O’ Clocks Many flowers exhibit incomplete dominance 6 ALLELE NOTATION HOW DO YOU WRITE OUT THE GENOTYPE WHEN BOTH ALLELES ARE DOMINANT? 7 YOU MUST USE DIFFERENT LETTERS Choose different letters to represent each form (In this case we’ll use “W” for the white allele and “R” for the Red allele). Remember to always use CAPITAL letters. This is incomplete DOMINANCE. 8 SO…THE CROSS BETWEEN PURE SNAPDRAGONS LOOKS LIKE THIS R R W RW RW W RW RW 9 YOU’VE SEEN A CROSS BETWEEN PURE SNAPDRAGONS, NOW DO THE PUNNET SQUARE FOR A CROSS BETWEEN TWO HYBRIDS (HETEROZYGOTES). What are the alleles of a heterozygous snapdragon? RW What is the genotypic ratio? 1 RR : 2 RW : 1 WW What is the phenotypic ratio? 1 Red : 2 Pink : 1 White 10 WHAT KIND OF GENETICS DO THESE ORGANISMS EXHIBIT? 11  A cross between 2 tabbies (the CODOMINANCE heterozygotes) results in 1 black : 2 tabbies : 1 tan cat black-cat The same ratios as Incomplete 1178198189563 Dominance occur: A ratio of 1:2:1 for both genotype and phenotypes of a monohybrid cross → 5561b6d64ca720aa71b5945c6ebb4d16-grande tan%2520cat%2520002 Different Phenotype: The two original phenotypes are combined to give a SPOTTED or MULTICOLORED phenotype. 12 NOTATION FOR CODOMINANCE 1. Choose a letter to represent the gene. 2. Choose different letters to represent each of the alleles. 3. Take the letters representing the alleles and turn them into superscripts. 4. Combine the two. Remember to use capital letters. 13  WRITING OUT THE GENOTYPE 1. We’re going to use C to represent Coat Color of a shorthorn cow. 2. Roan coat color is a combination of Red and White hair so we’ll use “R” to represent Red and “W” to represent white. 3. R → R and W → W 4. C + R → CR and C + W → CW 5. So a Red Cow would be CRCR , a white cow would be CWCW, and a roan cow would be CRCW 14 CODOMINANCE OCCURS IN: Shorthorn Cow (White + Red) Blue Roosters (White + Black) Human Blood Typing (AB) Tabby Cats (Black and Tan Fur) 15 LET’S PRACTICE Tabby cats exhibit codominance between tan and black fur. 1. Can Tan Cat be heterozygous? Why or Why not? 2. If you mate a tabby with a black cat, what is the phenotypic ratio of their offspring? 3. If the offspring of two cats are composed of 36 tabbies and 40 black cats, what are the parental phenotypes and genotypes? 16 NEXT: ABO BLOODTYPING 17 BLOOD TYPING Human blood typing is an example of both CODOMINANCE and MULTIPLE ALLELES What does Multiple Alleles Mean? 18 THE ALLELES A and B blood types are coded for by the alleles: IA and IB respectively. These two alleles are CODOMINANT. Blood type O is coded for by the allele i and is recessive to both IA and IB (notice the lower case letter). I designation stands for isoagglutinogen, another term for antigen 19 ALLELES AND THEIR BLOOD TYPES 20 21  LET’S PRACTICE Could a man with AB blood have an AB child with a woman with type O blood? If a child has type B blood, what are all the possible blood types for his/her parents? A paternity test is being performed. The child has type A blood. The mother is type A. Potential Dad #1 has type B blood. Potential Dad #2 has type O blood. Who is the father? Challenge: What two parents could produce the most diverse children as far as blood type is concerned? 22 PUNNETT SQUARE – BLOOD GROUPS: Show a cross between a person who has heterozygous A type blood & a person who has homozygous B type blood. IAi x IBIB Genotypes: Phenotypes: 23 MULTIPLE ALLELES Bombay Phenotype Due to a rare recessive mutation h, at a locus separate from that controlling the A and B antigens Woman in bombay (hh phenotype) Blood type O Parents (one is AB) Children (type B) 24 Rh COMPATIBILITY Landsteiner (blood typing pioneer) Antisera against monkey (Rhesus macacca) Rh-factor Rh+ = RR or Rr Rh- = rr Rh- mother and Rh+ father Erythroblastosis fetalis Serious anemia or breakdown of RBC among newly born fetuses 25 Rh COMPATIBILITY An Rh negative person is born without the antigen and does not form antibodies unless he or she is specifically sensitized to it. Sensitization can occur with RBC transfusions from an Rh positive person or exposure during pregnancy and birth. An Rh positive person can receive an RBC transfusion from an Rh negative donor. Rh negative people MUST NEVER receive Rh positive blood. 26 27 Rh COMPATIBILITY 28  LET’S PRACTICE Suppose a newborn baby was accidentally mixed up in the hospital. In an effort to determine the parents of the baby, the blood types of the baby and two sets of parents were determined. Baby 1 had type O Mrs. Brown had type B Mr. Brown had type AB. Mrs. Smith had type B Mr. Smith had type B a. Draw Punnett squares for each couple b. To which parents does baby #1 belong? Why? 29  MORE PRACTICE In the 1950’s, a young woman sued film star/director Charlie Chaplin for parental support of her illegitimate child. Charlie Chaplin’s blood type was already on record as type AB. The mother of the child had type A and her son had type O blood. a. Complete a Punnett square for the possible cross of Charlie and the mother. b. The judge ruled in favor of the mother and ordered Charlie Chaplin to pay child support costs of the child. Was the judge correct in his decision based on blood typing evidence? Explain why or why not. 30  NEXT..LETHAL ALLELES 31 https://www.pinterest.ph/pin/292522938286671169/  PREVENTION It is important to immunize Rh- negative mothers after their first pregnancy to guard against future Rh incompatibility reactions. Immediately after childbirth, anti-Rh antibody (RhoGAM) is injected in the mother (also known as antibody D). Immunization must be repeated after each pregnancy, including ectopic pregnancies and miscarriages. 32 MULTIPLE ALLELES: DUCK FEATHER PATTERNS Three alleles determine the type of plumage in mallard ducks: MR (Restricted) > M (Mallard) > md (Dusky) 33  LET’S PRACTICE MR (Restricted) > M (Mallard) > md (Dusky) The ducks in the following lists are crossed to produce the offspring shown. Give the genotypes of the parent and offspring in each cross: A. restricted x dusky Progeny : ½ mallard ; ½ restricted B. restricted x mallard Progeny : ½ restricted; ¼ mallard; ¼ dusky C. mallard x dusky Progeny : 100% mallard 34 https://www.thespruce.com/pictures-of-mallards-4121965 MULTIPLE ALLELES: COAT COLOUR IN RABBITS Four phenotypes and four alleles: Allelic series is C > cch > ch > c (which is most dominant) Coat Color Phenotype Genotype Full Color CC, Ccch, Cch, Cc Chinchilla cchcch, cchch, cchc Himalayan chch, chc Albino cc 35 LET'S PRACTICE What types of offspring could be produced by a full color rabbit that had a genotype of C cch that was bred with a Himalayan rabbit that was ch c? 36 MORE PRACTICE Allelic series is C > cch > ch > c (which is most dominant) Predict the phenotype for a rabbit with a c h cch genotype. Predict the phenotype for a rabbit with a Cch genotype. Would it be possible to obtain white rabbits if one parent is white and the other is chinchilla? Would it be possible to obtain chinchilla rabbits if one parent is Himalayan and the other is white? A chinchilla rabbit is mated with a Himalayan. Some offspring are white. What are the parents’ genotypes 37 NOW SOLVE THIS 38 LETHAL GENES: Some genes are lethal when present in the homozygous https://evolutionaryedges.weebly.com/achondroplasia/archives/04-2017 condition (dominant or recessive) Achondroplasia, cystic fibrosis, sickle- cell anemia (recessive lethal) Huntington’s disease (dominant lethal) https://www.britannica.com/science/sickle-cell-anemia 39 "CREEPER" ALLELE IN CHICKENS Chicks In chickens, when an embryo heterozygous for contains two copies of the dominant gene known as creeper, the embryo dies inside the eggshell. the gene survive. 40 MANX CATS Show the cross between a manx cat and a normal cat. 41 42  A Agouti (wild type allele) MOUSE COAT COLOR AY Yellow (mutant allele) 43 EXAMPLE WITH MOUSE COAT COLOUR Yellow is dominant to grey Cross hybrid yellow mice Yy x Yy Resulting offspring: 2 yellow to 1 grey One genotype is missing Somehow the YY genotype is lethal The 2:1 ratio is the typical ratio for a lethal gene. 44  ANSWERS TO SAMPLES: A child’s phenotype is O, the genotype must be ii (recessive) father (A) and mother (B) must both carry the recessive allele B Father’s genotype IAi and mother’s genotype IBi C Chance of having an AB type baby is 25% 45 a) The offspring occur in three types, classified as long, round and oval (intermediate), suggesting incomplete dominance Long (L) Round (L’) Oval (LL’) - heterozygous Test this idea…. LL’ x LL’ Gives a ratio of 1 long to 2 oval to 1 round radishes. b) (LL x LL), all the offspring will be long. c) (L’L’ x L’L’), all the offspring will be round. 46 A) Since ¼ of the eggs don’t hatch – lethal gene Crested (C) and non-crested (c) then both parents would have to be Cc ( eg. Cc x Cc) All the eggs with CC genotype would not hatch Viable offspring would hatch in a ratio of 2 crested to 1 non-crested B) Cc x cc Ratio: 1Cc to 1 cc 1 crested to 1 non 47 A) Bull’s genotype RR, Cow’s genotype R’R’ B) RR’ x R’R’ All of the offspring have RR’ genotype and will be roan Ratio of 2 roan to 2 white calves 48 BIO 170 | GENETICS JT IMPERIAL SEX DETERMINATION & SEX-LINKED TRAITS 50 Red-green colourblindness Hemophilia Duchenne muscular dystrophy 51 WHAT IS THE DIFFERENCE BETWEEN AN AUTOSOME AND A SEX- CHROMOSOME? Autosomes are the first 22 homologous pairs of human chromosomes that do not influence the sex of an individual. Sex Chromosomes are the 23rd pair of chromosomes that determine the sex of an individual 52 SEX CHROMOSOMES: Which is male?… female? What is the genotype of each sex? Which parent determines the sex of the offspring? 53  HOMOZYGOUS VS HEMIZYGOUS https://ib.bioninja.com.au/standard-level/topic-3-genetics/34-inheritance/types-of-zygosity.html https://www.differencebetween.com/difference-between-homozygous-and-hemizygous/ 54  one of the two X chromosomes present in females is inactivated X - INACTIVATION ensures that females do not produce twice as many X-linked gene proteins as males who possess one X chromosome) who possess one X chromosome) 55 SEX DETERMINATION: How many chromosomes do humans have? How many of these are “sex” chromosomes? Which parent determines the sex of an offspring? Are there any traits/conditions that are more common in one sex than the other? 56 Sex linked The gene (pair) that determines a character (e.g. hemophilia) is trait located on the sex chromosomes X-linked A sex-linked trait is where the gene or allele for the trait is found trait on the X chromosome Y-linked A sex-linked trait where the gene or allele for the trait is found on trait the Y- chromosome 57 SEX-LINKED TRAITS Traits (genes) located on the sex chromosomes Sex chromosomes are X and Y XX genotype for females XY genotype for males Many sex-linked traits carried on X chromosome 58 SEX-LINKED TRAITS Example: Eye color in fruit flies Sex Chromosomes fruit fly eye color XX chromosome - female Xy chromosome - male 59 SEX-LINKED TRAIT PROBLEM Example: Eye color in fruit flies (red-eyed male) x (white-eyed female) XRY x XrXr Remember: the Y chromosome in males does not carry traits. Xr Xr RR = red eyed Rr = red eyed XR rr = white eyed XY = male Y XX = female 60 SEX-LINKED TRAIT PROBLEM Example: Eye color in fruit flies (red-eyed male) x (white-eyed female) XRY x XrXr Remember: the Y chromosome in males does not carry traits. Xr Xr RR = red eyed Rr = red eyed XR rr = white eyed XY = male Y XX = female 61 SEX-LINKED TRAIT SOLUTION: Xr Xr 50% red eyed XR XR Xr XR Xr female 50% white eyed Y Xr Y Xr Y male 62 FEMALE CARRIERS 63 QUESTION: IS IT POSSIBLE FOR A FEMALE CARRIER OF HEMOPHILIA TO HAVE A DAUGHTER WITH HEMOPHILIA? XH Xh Xh XH Xh XhXh Y XH Y Xh Y 64 Color blindness An X-linked recessive trait where a affected individual could not distinguish red from green color (red green color blindness) Hemophilia An X-linked recessive trait where an affected individual suffers from delayed blood clotting during injuries because of the absence of certain blood clotting factors Hypertrichosis pinnae auris A Y-linked trait where affected males have hair growing from their external ears 65  X-LINKED RECESSIVE DISORDERS https://www.tumblr.com/intelligentliving/189094834117/x-linked-recessive-inheritance 66 https://healthjade.net/duchenne-muscular-dystrophy/#google_vignette X-LINKED RECESSIVE DISORDERS 67 68 COLOURBLINDNESS SELF TEST: Can you see the hidden numbers? NUMBERS: 5 | 8 | 9 | 5 | 3 | 5 | 9 | 10 | 69 HIDDEN SHAPES: SHAPES: Plate 1 - Circle and arch Plate 2 - Circle, star and square 70 SEX-LINKED TRAITS: Some genes are found on the sex chromosomes Some are found on the X sex chromosome but not the Y Ex – the colour vision gene is on the X chromosome - NOT FOUND ON THE “Y” Sex-linked traits are RECESSIVE (mostly) traits that are found on the ‘x’ sex chromosome 71 A human pedigree of the X-linked color-blindness trait. The photograph is of an Ishihara color-blindness chart, which tests for red–green color blindness. Red–green color-blind individuals see a 3 rather than the 8 visualized by those with normal color vision. 72 HYPERTRICHOSIS – HUMAN WEREWOLF SYNDROME: Congenital generalized hypertrichosis (CGH) Rare, X-linked dominant trait Found in a single multigenerational Mexican family 73 Red-green colorblindness is a recessive sex-linked trait, found on the X chromosome, not the Y. Males only have one X chromosome, they have a much greater chance of having red-green colorblindness. Females would have to be homozygous recessive in order to have red-green colorblindness. 74 Calico cat 75 Solve : A black female cat is mated with an orange male cat. They produce two tortoiseshell females, two black males, one orange female, and one tortoiseshell male, for a total of six kittens. What are the genotypes of all the individuals in this cross. 76 https://www.chegg.com/homework-help/questions-and-answers/x-linked-genetics-calico-cat-calico-coat-color-found-cats-caused-sex-linked-codominant-all-q99260142 HUMAN X-LINKED TRAITS 77 WRITING SEX-LINKED GENOTYPES: 78 MORE PRACTICE: In humans the gene from normal blood clotting, H, is dominate to the gene for hemophilia, h. This is a sex- linked trait found on the X chromosome. Serena with normal blood clotting has four children. They are a normal son, a hemophiliac son, and two normal daughters. The father, Simon has normal blood clotting. What is the probable genotype for each member of the family? 79 ANOTHER ONE…. James with normal vision marries Kath who is a carrier for color blindness. What are the possible genotypes and phenotypes of their children. 80 JUST ONE MORE…. A hemophiliac man, Rudy Dots marries Lenny Robs who is a carrier for the disease. What are the possible genotypes and phenotypes of their children? Should they even consider having children? 81 OTHER SEX-RELATED TRAITS 82 Sex influenced characteristics are determined by autosomal genes and are inherited according to Mendel’s principles, but they are expressed differently in males and females 83 84 PATTERN BALDNESS IS A SEX-INFLUENCED TRAIT This trait is seen in three generations of the Adams family: a) John Adams, 2nd President of USA, was father to b) John Quincy Adams, who was father to c) Charles Francis Adams Pattern baldness reults from an autosomal gene that is thought to be dominant in males and recessive in females 85 PATTERN BALDNESS 86 Sex- Limited Characteristics extreme form of sex-influenced inheritance, a sex limited characteristic is encoded by autosomal genes that are expressed in only one sex—the trait has zero penetrance in the other sex 87  Cock feathering in chickens, an autosomal Mandrills : males exhibit a more vibrant coloration Pheasants : In addition to their larger size, male recessive trait that is limited to males on their faces and behinds pheasants differ from females in their colorful, decorative plumage and extra-long tails. Elephant Seals : These pinnipeds are named for Mandarin Ducks: Males are especially striking the males' large proboscises (noses) that elongate with their red bills, pronounced crests, and array of during puberty and wind up looking like stunted Orangutans : At sexual maturity, male orangutans colorful feathers elephant trunks. begin to develop enlarged cheek flaps and throat sacs meant to exhibit their dominance SEXUAL DIMORPHISM 89 90