I'm not sure how to answer any of the questions attached, help and show work plz

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I'm not sure how to answer any of the questions attached, help and show work please! Its' the Lab 7 Worksheet, and everything else is additional to help answer the questions!


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Core lab #7 Core lab #7 worksheet Remember to go go through the Powerpoint and the lab video - they will help you understand how to complete this worksheet. The two files attached to this assignment, Geneticshelp.doc and Sex-Linked.doc, will also help! Mendelian Genetics: Corn is a great model for exploring Mendelian inheritance. • Corn’s importance as a food crop means its genetics have been well studied. • Many contrasting phenotypes have been identified, some of which exhibit Mendelian inheritance patterns. • With the proper crosses, Mendelian patterns can be observed in a single ear of corn because each kernel is the product of an independent pairing of gametes. 1-4) Corn Kernel Color Gene P Several genes contribute to kernel color in corn. One gene for kernel color that exhibits Mendelian inheritance is the P gene. This gene has two alleles, P and p. P exhibits complete dominance, and when present, causes purple kernel color. The following genotypes are possible, note you only need ONE P to be purple: i) PP: ii) Pp: iii) pp: 1 Core lab #7 1) Given the images above, describe the recessive phenotype. 2) When a true breeding purple (PP) line is crossed with a true breeding yellow line (pp), the resulting genotype(s) is/are 3) When a true breeding purple line is crossed with a true breeding yellow line, the resulting phenotypes(s) is/are 4) What are the possible genotypes of the kernels of corn shown below?: 5-7) Single Trait Cross Part 1 Look closely at the ear of corn below: 5) What is the phenotype ratio for the two kernel colors? a) 1:1 b) 3:1 c) 10:1 choose the closest 6) Which paring is most likely to have produced this ratio? a) PP x PP b) Pp x PP c) PP x pp d) Pp x Pp e) pp x pp 2 Core lab #7 (hint: draw the Punnett squares needed to figure out the offspring ratios produced by each cross and compare them to your answer in question 5) 7) True or false: the parents both have the same phenotype. 8) Hemophilia is a type of bleeding disorder that causes the blood to take a long time to [clot]. This can cause abnormal bleeding, or bleeding that won't stop. People with hemophilia have too little—or even none—of a protein in the blood called [clotting factor]. Hemophilia most often affects males and, in most cases, is inherited (passed down through families). Hemophilia is carried only on the X chromosome. It is called an X linked genetic disorder. A women who is a carrier for hemophilia has the genetic mutation on one of her X chromosomes (thus she is HXX). She thus has one non mutated X chromosome that will usually somewhat compensate for the defect in the other. It is not uncommon for women who carry the hemophilia gene to have low levels of clotting factor and have bleeding problems. A man (HXY) who has hemophilia has the genetic mutation on his only X chromosome. He does not have another X chromosome to compensate for the defect so he will have hemophilia.. What are the possible outcomes from the following cross shown in the picture below? 9) If you had a female that was color blind, and she mated with a male with normal vision ... what types of children could they possibly have? Remember, this is a sex-linked problem! The possible genes on the X chromosome are: XC = normal, and Xc = color blind (Note: That's a lowercse "c" on the color-blind.) Show your Punnet Square. 3 Speaking of color-blindness, check out the test below (just for fun) ............... Most of the circles to the right are nothing but spots to someone with color blindness.. Below are the correct answers to what a person with normal color vision would see The full Ishihara test consists of a set of 38 plates and tests in-depth for color blindness. The plates here are a small representative sample of the whole, but will help spot the most common forms of colorblindness. Depending on the color balancing of your monitor, the tests may be somewhat more or less effective (e.g. if your monitor is not rendering the proper colors). Results For Ishihara Test(above) Normal Color Vision Left Right Top 25 29 Middle 45 Bottom 6 Red-Green Color Blind Left Right Top 25 Spots 56 Middle Spots 56 8 Bottom Spots Spots 10) Earlobes. These can be either attached, where the earlobe blends smoothly into the neck, or unattached, where the earlobe hangs free (see Figure). Unattached earlobes (U) are dominant to attached (u) so both males and females can have a genotype of UU, Uu or uu. Widow's peak (W) is dominant to continous hairline (w) so both males and females can have a genotype of WW, Ww or ww). If you crossed a male who was homozygous dominant for widow’s peak and had attached ear lobes with a female who had a continuous hairline and was heterozygous for unattached ear lobes ….what types of children could they possibly have? Show your Punnett square. Remember to create 4 types of sperm from the male, with all combinations of one gene for widow's peak with one gene for hairline...and do the same for 4 types of eggs. 11) LAST PROBLEM! You have two mice. You know that B=black and b=brown. The gene for color is on one chromosome, but there is another gene on a different chromosome (independent assortment) that codes for whether the pigment is ever expressed or not; C=color pigment is expressed, c=color pigment is NOT expressed. If you mated a male mouse that was heterozygous for both color and pigment expression with a white female mouse that had color geneotype (bb), what are the possible phenotypes of the offspring? Note that the female has to be ccbb because she is white! Show your Punnet Square for this problem! (Note: use Slide 38 from the Powerpoint as a guide.) Color expressed-brown No color expressed Color expressed-black Well, you should have the idea that each individual has TWO alleles (or factors) that influence each trait. We can give an example with: P= allele or factor for purple color, and p=allele or factor for white color. Since each individual has two factors, the combinations could be: PP = purple, Pp= purple (note that P is DOMINANT so that when present even as only one of the two possible factors the flower is still purple, and pp=while (hey! There is NO P factor, so with both factors for while, the flower is white. So, given this how do we determine what happens if we cross two plants? Suppose we have a purple plant (either PP or Pp) and we want to establish which it is! We can do a text cross, which means we cross it with a white flower (pp). Let’s see the Punett Square that shows how the “factors” are passed on by the parents, and how the recombine in the possible offspring. We know that one of the parents will be pp (white flower), and we want to know if the other parent is PP or Pp (this information is give in the Powerpoint under Test Cross). For now let’s see what would happen if the other flower was PP. Flower #1 Flower #2 pp PP P P --------------! PP PP ! ! Pp Pp p p Hey! ALL the flowers are purple! Now, let’s see what would have happened if the parent purple flower was Pp rather than PP and we crossed it with a white flower (pp). pp Pp p P P p -------------! ! Pp pp ! ! Pp pp Wait a second! Half of the offspring are White (pp) compared to the previous cross where they were ALL purple. So, you can test cross and find out the genotype (specifically what the combination of factors were) of the purple flower! The next problem involved what happens when TWO sets of genes, a factor for type of color AND another factor for whether the first gene is even expressed or not, are involved. The two genes are on Different Chromosomes, and that means that they are passed on INDEPENDENTLY of each other. So, we can have a factor for color: B=black and b=brown. But, we also have a factor that determine whether the color genes work or not: C=color is expressed and c=color is NOT expressed (hey! No color expressed and you are a white individual, not black or brown). Examples of possible mice would be: BBCC – a black mouse BbCC – a black mouse BbCc – a black mouse bbCc – a brown mouse BBcc – a WHITE mouse Etc. (what are all the combinations of two factors for color and two factors for expression?) Suppose we have two mice. One is BbCc and the other is also BbCc. Well, we have two black mice. What kinds of combinations for factors can they pass on? They can pass ONE factor for color and ONE factor for expression on. So, what are the possible combinations that can be passed on for each mouse? BC is one, Bc is another, bC is the third, and bc is the fourth. They thus pass one of the factors for color and one of the factors for expression on to the next generation. To make the Punett Square you thus have: BC Bc bC bc BC Bc bC bc -----------------------------------! ! ! ! ! ! ! ! You need to fill in the Punett Square to make up to possible offspring, each with TWO factors for color and TWO factors for expression. For example, BC and BC would combine to make a mouse that was BBCC (black), Bc and Bc would combine to make a mouse that was BBcc (opps! This mouse has the black color factor, but does NOT have the factor for color to be expressed so it is WHITE). What kind of possible mice do we get? Sex-Linked Genes: There is yet another, unrelated, special case that means something totally different, yet has a similar-sounding name (just to confuse freshman biology students?). This is sex-linked genes, genes located on one of the sex chromosomes (X or Y) but not the other. Since, typically the X chromosome is longer, it bears a lot of genes not found on the Y chromosome, thus most sexlinked genes are X-linked genes. One example of a sex-linked gene is fruit fly eye color. An X chromosome carrying a normal, dominant, red-eyed allele would be symbolized by a plain X, while the recessive, mutant, white-eyed allele would be symbolized by X' or Xw. A fly with genotype XX' would normally be a female with red eyes, yet be a carrier for the white-eyed allele. Because a male typically only has one X chromosome, he would normally be either XY and have normal, red eyes, or X'Y and have white eyes. The only way a female with two X chromosomes could have white eyes is if she would get an X' allele from both parents making her X'X' genotype. The cross between a female carrier and a red-eyed male would look like this: X Y X XX XY X' XX' X'Y Notice that while there is a “typical” ratio of ¾ red-eyed to ¼ white-eyed, all of the white-eyed flies are males. Typically, X-linked traits show up more in males than females because typical XY males only have one X chromosome, so if they get the allele on their X chromosome, they show the trait. If a typical XX female is a carrier, 50% of her sons will get that X chromosome and show the trait. In order for an XX female to exhibit one of these X-linked traits, most of which are recessive mutations, she would have to have two copies of the allele (X'X'), which would mean that her mother would have to be a carrier and her father have the trait so she could get one allele from each of them. In humans, two well-known X-linked traits are hemophilia and red-green colorblindness. Hemophilia is the failure (lack of genetic code) to produce certain substance needed for proper blood-clotting, so a hemophiliac’s blood doesn’t clot, and (s)he could bleed to death from an injury that a normal person might not even notice. One of the most famous genetic cases involving hemophilia goes back to Queen Victoria. While both of her parents were perfectly normal, it is usually assumed that a chance mutation in either the egg or sperm that came together to make her, caused her to be a carrier for the hemophilia allele (XX') [see the yellow box, below, for an alternative hypothesis that some people have suggested]. When she grew up, she married Prince Albert, who was normal XY, so the Punnett square for their marriage would look like the one just drawn. The Punnett square would predict that ½ of their sons (¼ of their children) would be hemophiliacs and ½ of their daughters (¼ of their children) would be carriers. Their children married other royalty, and spread the gene throughout the royal families of Europe. Genetics The work of Gregor Mendel Who was this Mendel and what the heck is he doing in a monastery? • born in 1822 • trained himself to be a naturalist early in life • worked as a substitute science teacher • failed the qualifying exams to be a regular high school teacher! • joined a monastery in Brunn, Austria • sent to Vienna U. to study science and math MendelWeb Mendel’s first published work: "Versuche über Pflanzen-Hybriden“ or Experiments in Plant Hybridization was a landmark in clarity and insight! He figured out the laws of inheritance…mathematically!! The work of Gregor Mendel • worked with pea plants… …he called them his children! Why pea plants??? There was a long-standing tradition of breeding pea plants at the monastery where Mendel lived and worked So…they were readily available and they come in lots of varieties! …there were plants with different flower colors, seed color, flower position etc.. And best of all… Pea plants can have sex with themselves This allowed Mendel to see if strains were true breeding and to produce hybrids How Mendel made hybrids… He’d then tie little bags around the flowers to prevent contact with stray pollen. Mendel’s hybridization experiments… Monohybrid crosses: Parental Generation F1 generation True-breeding purple flower x True-breeding white flower All purple flowers (the hybrids) Allowed F1 offspring to self-fertilize F2 generation 705 purple 224 white The results of Mendel’s monohybrid crosses led him to propose… 1. All organisms contain two “units of heredity” for each trait (alleles). 2. Dominant and recessive alleles… …and organisms can have any combination of the two alleles (2 dominants, 2 recessives or a mixture 1 dominant and 1 recessive). 3. The Law of Segregation – during gamete (sperm and egg) formation, alleles separate randomly into separate gametes. A bit of genetic jargon… phenotype vs. genotype What the organism looks like What alleles the organism has - its genetic makeup More jargon… homozygous vs. heterozygous P 2 of the same alleles: PP or pp 2 different alleles: Pp p A Punnett square A Punnett square… Gametes from one parent p P Gametes from other parent P PP purple p Pp purple Pp purple pp white Ratio: 3:1 or ¾ purple, ¼ white Let’s relate Mendel’s findings to what we now know about gamete formation True-breeding purple flower Note two chromosomes in the parent, each with a gene for color. In this case, both are P P P all purple P P P P True-breeding white flower x P p p p p p p In the above case, the parent was diploit (had a pair of chromosomes). The blue chromosome came from dad, the orange from mom. Each chromosome had a gene for color (P for both). Each chromosome replicates, and either a blue OR an orange gets passed on….NOT both p F1 generation purple hybrid This adult is diploid (has a pair of chromosomes)…but note that the gene for color is NOT the same on each chromosome! One or the other is potentially passed on to the next generation P F2 p P purple hybrid p P P P x p P p P p p p P PP - purple Pp - purple Pp - purple pp - white p Based on the previous examples, try to determine the following… Determine the phenotypic and genotypic ratios for each of the following monohybrid crosses. Aa x Aa Phenotypic ratio 3:1 (dom:rec) Genotypic ratio 1:2:1 (hd:H:hr) AA x Aa 1:0 (dom:rec) 1:1:0 (hd:H:hr) or all dominant aa x Aa 1:1 (dom:rec) 0:1:1 (hd:H:hr) AA x aa 1:0 (dom:rec) 0:1:0 (hd:H:hr) or all dominant hd = homozygous dominant; H = heterozygous; hr = homozygous recessive Definitions 1 • Must know these!!! • Trait—A variable characteristic of organism • Gene—A segment of chromosomal DNA controlling a specific trait • Locus—Chromosomal position where DNA for a specific gene lives Definitions 2 • Must know these!!! • Alleles—Different forms of a gene – “Flower color” is a gene; – “Purple” is one flower-color allele – “White” is another flower-color allele • Genotype—List of alleles an individual has at specific genes – Familiar organisms are diploid (two alleles – one from father, one from mother) – Allele pairs may be same (homozygous) or different (heterozygous) Definitions 3 • Homozygous—Maternal & paternal alleles same – Father donates purple-flower allele – Mother donates purple-flower allele • Heterozygous—Maternal & paternal alleles differ – Father donates purple-flower allele – Mom donates white-flower allele Definitions 4 • Phenotype: – List of traits exhibited by individual – Doesn’t always represent genotype • Dominant—Allele that is expressed 100% in heterozygote • Recessive—Allele that is not expressed in heterozygote • Incomplete dominance—heterozygote displays intermediate trait We noted in the video that genes are really segments of a long strand of DNA, with each gene containing enough DNA to code for a trait We noted that we have pairs of chromosomes (one from mom and one from dad…hence we are diploid) and that each chromosome of the pair has a gene for a particular trait…hence we have pairs of genes for each trait….Mendel demonstrate that, and noted how they interact (dominant, recessive, homozygous, heterozygous) A karyotype showing the 23 pairs of human chromosomes…note on the final pair (23) that if you get a Y chromosome from dad you are a male (XY), while if you get an X from dad you are a female (XX) Mendel’s Model of Heredity • Parents transmit discrete physiological trait information (factors) to offspring. • Each individual receives two factors that may code for same, or alternative, character traits. • Not all copies of a factor are identical. – alleles • homozygous - same alleles • heterozygous - different alleles Mendel’s Model of Heredity • Alleles do not influence each other in any way. • Presence of a particular allele does not ensure its encoded trait will be expressed. – genotype - totality of an individual’s alleles – phenotype - physical appearance Interpretation of Mendel’s Results • Notational convention – P - dominant allele (purple) – p - recessive allele (white) • PP - homozygous dominant • Pp - heterozygous • pp - homozygous recessive Interpretation of Mendel’s Results • F1 generation – PP x pp (parental generation) yielded all Pp offspring • F2 generation – Pp x Pp yielded: (1:3:1) ratio • 1 PP • 3 Pp • 1 pp • Punnett squares (aka “Mendel’s Cross”) Mendel’s Cross Mendelian Inheritance • Mendel’s First Law of Heredity – (Law of Segregation) • Alternative alleles of a character segregate from each other in heterozygous individuals and remain distinct. An example… Testcross: We have a purple flower. Is its gneotype PP or Pp? We can cross it with a white flower (pp) and note if we get any white offspring Note that we used a Punnett Square to show how gametes are formed (each parent can donate one of their genes) and how gametes are reformed to the possible combinations in offspring Mendelian Inheritance • Mendel’s Second Law of Heredity – (Law of Independent Assortment) • Genes that are located on different chromosomes assort independently of one another • Remember, each pair of chromosomes separates independently of each other pair…thus the genes on those separate chromosomes are passed on independently of each other. Here the Y and y alleles for the gene that determines color are on DIFFERENT chromosomes that the R and r alleles for the gene which determines shape. So, you can get ALL combinations of ONE of the color alleles and ONE of the shape Alleles in the gametes! Note that for the F1 generation which is YyRr that there are FOUR different possible types of gametes produced when ONE gene for color (Y or y) is paired up with ONE gene for shape (R or r). Sex-Linked Genes: • There is yet another, unrelated, special case that means something totally different, yet has a similar-sounding name (just to confuse freshman biology students?). This is sex-linked genes, genes located on one of the sex chromosomes (X or Y) but not the other. Since, typically the X chromosome is longer, it bears a lot of genes not found on the Y chromosome, thus most sex-linked genes are X-linked genes. One example of a sex-linked gene is fruit fly eye color. An X chromosome carrying a normal, dominant, red-eyed allele would be symbolized by a plain X, while the recessive, mutant, white-eyed allele would be symbolized by X' or Xw. A fly with genotype XX' would normally be a female with red eyes, yet be a carrier for the white-eyed allele. Because a male typically only has one X chromosome, he would normally be either XY and have normal, red eyes, or X'Y and have white eyes. The only way a female with two X chromosomes could have white eyes is if she would get an X' allele from both parents making her X'X' genotype. The cross between a female carrier and a redeyed male would look like this: Note that X=normal red eyes, while X’=white eyes! And, the Y chromosome carries NO information for eye color X X XX Y XY X’ X’X X’Y Note that if the male gets An X’ from mom, then he has White eyes!!! The consequences! • Typically, X-linked traits show up more in males than females because typical XY males only have one X chromosome, so if they get the allele on their X chromosome, they show the trait. If a typical XX female is a carrier, 50% of her sons will get that X chromosome and show the trait. In order for an XX female to exhibit one of these X-linked traits, most of which are recessive mutations, she would have to have two copies of the allele (X'X'), which would mean that her mother would have to be a carrier and her father have the trait so she could get one allele from each of them. More consequences! • In humans, two well-known X-linked traits are hemophilia and red-green colorblindness. Hemophilia is the failure (lack of genetic code) to produce certain substance needed for proper blood-clotting, so a hemophiliac’s blood doesn’t clot, and (s)he could bleed to death from an injury that a normal person might not even notice. One of the most famous genetic cases involving hemophilia goes back to Queen Victoria. While both of her parents were perfectly normal, it is usually assumed that a chance mutation in either the egg or sperm that came together to make her, caused her to be a carrier for the hemophilia allele (XX'). When she grew up, she married Prince Albert, who was normal XY, so the Punnett square for their marriage would look like the one just drawn two slides ago. The Punnett square would predict that ½ of their sons (¼ of their children) would be hemophiliacs and ½ of their daughters (¼ of their children) would be carriers. Their children married other royalty, and spread the gene throughout the royal families of Europe.
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