Study Guide Test 1: Introduction to Genetics

Study Guide #1 1. a) Gregor Mendel is known as the “Father of ___________” because he discovered the fundamental principles of genetics while experimenting on __________ plants. b) He discovered that traits were passed on to offspring by what he called ___________. Now we know that they are ____________.

Study Guide #1 1. a) Gregor Mendel is known as the “Father of Genetics” because he discovered the fundamental principles of genetics while experimenting on Pea plants. b) He discovered that traits were passed on to offspring by what he called factors. Now we know that they are genes.

Study Guide #2- Vocabulary and Definitions 1)Gene-a section of DNA that controls a trait 2)Allele- a version of a gene 3)Dominant – the trait for this allele will be seen if it is present 4)Recessive- the trait for this allele will only be seen if the dominant allele is not present

1)Gene-a section of DNA that controls a trait 2)Allele- a version of a gene 3)Dominant – the trait for this allele will be seen if it is present 4)Recessive- the trait for this allele will only be seen if the dominant allele is not present 5)Heterozygous- two different alleles for the same trait 6)Homozygous- two of the same allele for the same trait 7)Genotype- the alleles, represented with a letter 8)Phenotype- the physical trait or observable characteristic Study Guide #2- Vocabulary and Definitions

1)Gene-a section of DNA that controls a trait 2)Allele- a version of a gene 3)Dominant – the trait for this allele will be seen if it is present 4)Recessive- the trait for this allele will only be seen if the dominant allele is not present 5)Heterozygous- two different alleles for the same trait 6)Homozygous- two of the same allele for the same trait 7)Genotype- the alleles, represented with a letter 8)Phenotype- the physical trait or observable characteristic 9) True-breeding- plants that produce offspring identical to themselves when self-fertilized. (homozygous) 10) Hybrid – heterozygous offspring of two true-breeding plants 11)P generation - Parental generation 12) F 1 – first Filial generation 13) F 2 - second Filial generation Study Guide #2- Vocabulary and Definitions

Study Guide #3 3a) Mendel concluded from his experiments with one trait that offspring inherit _____ allele from each parent. b) Mendel’s Law of Segregation states:_________

Study Guide #3 3a) Mendel concluded from his experiments with one trait that offspring inherit one allele from each parent. b) Mendel’s Law of Segregation states: When a plant/organism produces gametes, it has two alleles which segregate from each other. Each gamete carries only a single copy of each gene.

Study Guide #3 3a) Mendel concluded from his experiments with one trait that offspring inherit one allele from each parent. b) Mendel’s Law of Segregation states: When a plant/organism produces gametes, it has two alleles which segregate from each other. Each gamete carries only a single copy of each gene. 4) The gene for flower color is represented with the letter “P.” Purple is dominant over white. a) Draw a Punnett Square for the cross: Pp x Pp b) Write the Genotypic and Phenotypic Ratios for the offspring. c) A Punnett Square shows the probabilities of types of offspring. Probability means ______.

Study Guide #4 4) The gene for flower color is represented with the letter “P.” Purple is dominant over white. a)Draw a Punnett Square for the cross: Pp x Pp P p P PP Pp p Pp pp b) Write the Genotypic and Phenotypic Ratios for the offspring. Genotypic ratio is 1 PP: 2 Pp: 1 ppPhenotypic ratio is 3 purple: 1 white c) A Punnett Square shows the probabilities of types of offspring. Probability means the likelihood that a specific event will occur.

Study Guide #5 Mendel concluded from his experiments with two traits that the genes for one trait do not affect how the genes for a different trait are passed on to offspring. Mendel’s Law of Independent Assortment states: Allele pairs separate independently during the formation of gametes. 6) The gene for pea shape is R with round being dominant over wrinkled. The gene for pea color is Y, with yellow being dominant over green. a) Draw a Punnett Square for the cross: RrYy x rryy. b) Write the Genotypic and Phenotypic Ratios for the offspring. c) What is the probability of Round peas? Does this mean the parents will have exactly 8 offspring with round peas? Why or why not? d) What is the probability of Round Yellow peas?

Study Guide #6 The gene for pea shape is R with round being dominant over wrinkled. The gene for pea color is Y, with yellow being dominant over green. a) RrYy x rryy RY, Ry, rY, ry ry Gametes ry RYRrYy RyRryy rYrrYy ryrryy

Study Guide #6 b) Genotypic Ratio 1 RrYy: 1 Rryy: 1rrYy:1rryy Phenotypic Ratio 1 Round Yellow: 1 Round Green:1 wrinkled yellow: 1 Wrinkled green ry RYRrYy RyRryy rYrrYy ryrryy

Study Guide #6 ry RYRrYy RyRryy rYrrYy ryrryy c) The probability of Round peas is 50%. It does not mean there will be exactly 8 round pea offspring, because probability does not determine the actual outcome. d) The probability of Round Yellow peas is 25%

Study Guide #7 a)Incomplete dominance- one allele is not completely dominant over another. Heterozygous offspring are a blend of the parents (ex: red and white flowers produce pink flowers. b)Codominance- both alleles appear as part of the phenotype of the heterozygous offspring (ex: black chicken and white chicken produce black and white chicken). c)Multiple Alleles-Genes that have more than two alleles (ex: human blood types A, B, and O) d) Polygenic- A single trait controlled by more than one gene (ex: skin color) e) Pleiotropy- a single gene affects phenotype in many ways (ex: Sickle Cell Disease) f) Sex-linked traits- caused by X-linked genes affect males more because they are XY.

Study Guide #8 a)What is a Pedigree? A pedigree is a chart that shows the genetic relationship of family members and their phenotypes. b) How is a Pedigree used? A pedigree is used to determine the inheritance of a genetic trait, especially genetic diseases, across several generations of a family. c) Who commonly uses pedigrees to help couples determine if they can have healthy children? Genetic counselors use pedigrees to educate couples about the probabilities of certain traits being passed on to their offspring.

Study Guide #9 Copy and define each of the following symbols used in Pedigrees. “carriers”

Study Guide #10 What does it mean for a gene to be Autosomal? Autosomal means the gene for the trait is found on any of the chromosomes EXCEPT the X and Y chromosomes (NOT SEX LINKED).

Study Guide #11-17 Reading a Human Pedigree 11) How many generations are shown on the pedigree? 12) Which parent in the first generation is a carrier for sickle cell disease? 13) How many children were born in the second generation? How many are carriers of sickle cell disease? 14) How many children in the third generation have sickle cell disease? How many are carriers? 15) Is sickle cell disease a sex-linked trait? How can you tell? 16) Is the gene for sickle cell disease more likely to be dominant or recessive? Explain. 17) How could a genetic counselor use a pedigree to advise parents who are worried about passing on an inherited disorder to their children.

Study Guide #11-17 Reading a Human Pedigree 11) How many generations are shown on the pedigree? There are 4 generations in this pedigree. 12) Which parent in the first generation is a carrier for sickle cell disease? The father is the carrier. 13) How many children were born in the second generation? How many are carriers of sickle cell disease? There are three children in the second generation. All three are carriers.

Study Guide #11-17 Reading a Human Pedigree 14) How many children in the third generation have sickle cell disease? How many are carriers? One daughter has sickle cell disease in the third generation. There are 3 children born carriers. 15) Is sickle cell disease a sex-linked trait? How can you tell? Sickle cell disease is not a sex-linked trait. Males can be carriers. 16) Is the gene for sickle cell disease more likely to be dominant or recessive? Explain. This is a recessive trait, because there are carriers who are heterozygous and not affected. 17) How could a genetic counselor use a pedigree to advise parents who are worried about passing on an inherited disorder to their children. A genetic counselor uses a pedigree to help two parents determine the probability of producing offspring with a specific trait.

Study Guide # ) Color-blindness is a sex-linked trait, and is due to a recessive allele (b) on the X- chromosome. The allele for normal vision, B, is dominant. Write the genotypes for a color blind mother and a normal vision father._____________________ 19) a) Draw a Punnett Square for a color blind mother and a normal vision father. b) Out of the two girls, what is the probability of these parents having a color blind daughter? A carrier daughter? c) Out of the two boys, what is the probability of these parents having a color blind son? 20) Flower color is an example of incomplete dominance. A heterozygous flower is pink (Rr). A homozygous red flower (RR) is crossed with a homozygous white flower (rr). Draw a Punnett Square. Write the Genotypic and Phenotypic ratios of the offspring.

Study Guide # ) Color-blindness is a sex-linked trait, and is due to a recessive allele (b) on the X- chromosome. The allele for normal vision, B, is dominant. Write the genotypes for a color blind mother and a normal vision father. X b X b X B Y 19) a) Draw a Punnett Square for a color blind mother and a normal vision father. X B Y X b XBXbXBXb XbYXbY XBXbXBXb XbYXbY

Study Guide # ) b) Out of the two girls, what is the probability of these parents having a color blind daughter? A carrier daughter? Probability of color blind daughter (X b X b ) = 0% Probability of a carrier daughter (X B X b ) = 100% c) Out of the two boys, what is the probability of these parents having a color blind son? Probability of color blind son(X b Y) = 100% X B Y X b XBXbXBXb XbYXbY XBXbXBXb XbYXbY

Study Guide #20 Flower color is an example of incomplete dominance. A heterozygous flower is pink (Rr). A homozygous red flower (RR) is crossed with a homozygous white flower (rr). Draw a Punnett Square. Write the Genotypic and Phenotypic ratios of the offspring. RR x rrr r R Genotypic Ratio 1 RrPhenotypic ratio 1 Pink P GENERATION F 1 GENERATION Red RR Gametes R r White rr Pink Rr Rr