Unit 6: Genetics Test Review Answers 1) Play the slide show 2) Read the question then click to see the answer. 3) Click again to go to the next question 1

1. Identify the following descriptions: Is hidden or masked when in the presence of a dominant allele = RECESSIVE

1. Identify the following descriptions: b. The genetic makeup of an organism describing genes = GENOTYPE

1. Identify the following descriptions: c. Study of how traits are passed from parents to offspring = GENETICS

1. Identify the following descriptions: d. When the alleles are different in the genotype or hybrid = HETEROZYGOUS

1. Identify the following descriptions: e. Different forms of the same gene or trait, such as different shades of hair color = ALLELE

1. Identify the following descriptions: f. The outward appearance of a gene determines by its genotype = PHENOTYPE

1. Identify the following descriptions: g. Passing of traits from parent to offspring = HEREDITY

1. Identify the following descriptions: h. Masks or hides the presence of other alleles for the same characteristics = DOMINANT

1. Identify the following descriptions: Unit of hereditary information on chromosomes coding for one protein = GENE

1. Identify the following descriptions: j. When both alleles in the genotype are alike or purebred = HOMOZYGOUS

1. Identify the following descriptions: k. An inherited characteristic = TRAIT

2. For each of Mendel’s laws, describe what it means: Law of Segregation = The 2 factors/alleles for a trait separate (during meiosis)

2. For each of Mendel’s laws, describe what it means: b. Law of Independent Assortment = When factors/alleles separate, it is without regard for other traits *it is RANDOM how alleles separate to the gametes/sex cells in anaphase I & II

3. If a trait is sex-linked, what chromosome is it usually found on? Answer: The X chromosome

4. Who determines the gender or sex of a child – males or females Answer: MALES

5. Who is more likely to inherit a sex-linked condition – males or females? Answer: Males! **Because they have only 1 X chromosome and only need one copy of the gene

6. You must be able to interpret/describe a specific gender location (locus) What does the first number (or later) represent? THE CHROMOSOME

6. You must be able to interpret/describe a specific gender location (locus) b. What does letter p mean? What does letter q mean? P = above centromere Q = below centromere

6. You must be able to interpret/describe a specific gender location (locus) c. What does the number after the p/q mean? Number of units away from centromere

7. What is nondisjunction 7. What is nondisjunction? How are the gametes different at the end of meiosis if nondisjunction occurs? Answer: - Nondisjunction is when chromosomes do not separate correctly during meiosis - The gametes either have extra or missing chromosomes

8. Describe the following chromosomal & genes mutations: Deletion = Part of the chromosome is missing

8. Describe the following chromosomal & genes mutations: b. Insertion = Part of a chromosome is put in as an extra piece

8. Describe the following chromosomal & genes mutations: c. Inversion = Part of a chromosome is flipped around in the wrong order

8. Describe the following chromosomal & genes mutations: d. Translocation = part of one chromosome gets placed into a different chromosome

9. What is a karyotype and why are they important? Answer: Karyotypes are pictures/diagrams of a cells chromosomes arranged into pairs and displayed from largest to shortest They are important because it can help detect genetic disorders

10. What are three methods for genetic screening? Describe each type. Answer: a) Blood tests (check for presence of proteins) b) Amniocentesis = extract fluid surrounding baby and test c) Chorionic Villi Sampling = extract tissue from placenta and test

11. What is a pedigree? Answer: A diagram that shows the inheritance of a trait through several generations. Circles = females Squares = males

12. What do you call an individual who has only one copy of a recessive allele (usually heterozygous)? Answer: CARRIER

13. If a trait is sex-linked, who can never be a carrier for it? Answer: MALES

14. What is polygenic trait? What are some examples? Answer: Traits controlled by multiple genes (or multiple pairs of alleles) Ex: Hair color, eye color, skin color, height

15. What are multiple allele traits 15. What are multiple allele traits? [know examples of human blood types] Answer: Having 3 or more alleles for one trait

16. What do you call a condition where both alleles are expressed in the phenotype but without blending together? Give an example. Answer: CODOMINANCE Ex: Red flower crossed with white flower makes a red & white flower.

17. What do you call a condition where two alleles influence the phenotype by blending together? Give an example. Answer: INCOMPLETE DOMINANCE Ex: Red flower crossed with white flower makes pink flower.

18. What do you call the identification and manipulation of genes from one organism to another organism? Answer: GENETIC ENGINEERING

19. Why do scientists practice genetic engineering? Answer: To remove unwanted genes or add genes that are desirable.

20. Define the following: Recombinant DNA = DNA that has at least 2 different sources

20. Define the following: b. Transgenic organism = Organisms that have DNA from different organisms

21. What are four practical uses of genetic engineering/DNA technology? Answer: 1) Medicine/vaccines 2) Useful bacteria 3) Food crops (more vitamins/nutrients, help in growth) 4) Alter plants (resistant to pesticides/insects, no fertilizer)

22. What is the human genome project? Answer: The sequence of DNA bases in humans that mapped all genes.

23. Name four reasons why the human genome project is important. Answer: Improved diagnosis of diseases Develop gene therapies Detect/predict inheritance better Make custom medications

24. For the following descriptions, identify the genetic disorders: Individuals cannot properly bind oxygen molecules to their red blood cells due to their distorted crescent shaped, caused by an autosomal recessive gene = SICKLE CELL ANEMIA

24. For the following descriptions, identify the genetic disorders: b. Individuals cannot distinguish certain colors which was causes by a recessive gene on the X chromosome = COLORBLINDNESS

24. For the following descriptions, identify the genetic disorders: c. Individuals have mental retardation, muscle weakness, heart defects and short stature because they have three chromosomes at the 21st position due to nondisjunction = DOWN SYNDROME

24. For the following descriptions, identify the genetic disorders: d. Individuals produce excess mucus which clogs their respiratory and digestive tracts due to an autosomal recessive gene = CYSTIC FIBROSIS

24. For the following descriptions, identify the genetic disorders: e. Individuals have deterioration of the brain tissue when middle-aged due to an autosomal dominant gene = HUNTINGTON’S DISEASE

24. For the following descriptions, identify the genetic disorders: f. Individuals have blood that does not clot which was caused by a recessive gene on the X chromosome = HEMOPHILIA

24. For the following descriptions, identify the genetic disorders: g. Individuals with only one X chromosome (XO) due to nondisjunction (missing an entire sex chromosome) = TURNER’S SYNDROME

24. For the following descriptions, identify the genetic disorders: h. Individuals with three sex chromosomes (XXY) due to nondisjunction (receiving an extra sex chromosome) = KLINEFELTER’S SYNDROME

24. For the following descriptions, identify the genetic disorders: i. Individuals with muscle degradation leading to eventual death, caused by a recessive gene on the X chromosome = DUCHENNE MUSCULAR DYSTROPHY

Practice Punnett Squares using the “genetics” of Mr. Spock 25. Dihybrid Punnett Square: Many earthlings have free earlobes (F) but many vulcans have attached earlobes (f). Earthlings tend to have sparkling white teeth (b) but vulcans have brown-spotted teeth (B). Mr. Spock has attached earlobes but has sparkling white teeth (ffbb). If he marries a woman who is a vulcan and is heterozygous for attached earlobes and brown-spotted teeth (FfBb), what percentage of their offspring will have spotted teeth? FB Fb fB fb Key: F = free earlobes f = attached earlobes B = brown spotted teeth b = white teeth fb FfBb Ffbb ffBb ffbb fb fb fb Cross: ffbb x FfBb Answer: 50% have brown spotted teeth fb fb fb fb FB Fb fB fb

Key: Cross: XB = normal vision XBXb x XbY Xb = colorblindness XBXb 26. Sex Linked Punnett Square: Colorblindness (b) is a recessive sex-linked trait that affects many Vulcans – Spock is also colorblind. If Spock marries a female earthling who is a carrier for colorblindness, what percentage of their future daughters will be colorblind? Key: XB = normal vision Xb = colorblindness Cross: XBXb x XbY XB Xb XBXb XbXb XBY XbY Xb Y Answer: 50% of the daughters are colorblind

EE Ee ee Key: EE = tall ears (ee ok) ee = short ears (EE ok) 27. Incomplete Dominance Punnett Square: The height of ears is due to incomplete dominance – so tall ear genes combined with short ear genes can produce medium height ears (Ee). Spock has medium height ears. If he marries someone who is heterozygous for ear height like himself, what percentage of the offspring will have tall ears? Key: EE = tall ears (ee ok) ee = short ears (EE ok) Ee = medium ears Cross: Ee x Ee E e EE Ee ee E e Answer: 25% have tall ears