BIO TEST 4 STUDY GUIDE PDF

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Detailed study guide for 4th bio test. Includes all material needed for the fourth test and tophat questions as well as diagrams needed....

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TRAIT INHERITANCE ● Define homologous chromosomes, alleles, and ploidy (haploid, diploid, or polyploid). ○ Homologous chromosomes: chromosomes that are the same size, have the same genes, and pair during meiosis ○ Alleles: different version of the same gene ○ Ploidy: how many sets of chromosomes in the nucleus ■ Haploid: single chromosome set (n) ■ Diploid: two chromosome sets (2n) ■ Polyploid: greater than two sets of chromosomes (3n, 4n, 5n, 6n) ● Compare meiosis with mitosis in terms of the major events that occur and outcomes. ○ Meiosis: more complex, division of nucleus into 4 nuclei that contain half the number of chromosomes and are not identical to each other. ○ Cytokinesis has to happen twice ○ DNA replication is the same for meiosis as mitosis. ○ Meiosis 1: chromosomes condense, spindle forms, nuclear envelope disappears. Homologous chromosomes pair up. Tetrads are UNIQUE to meiosis. Crossing over appears. ○ Meiosis 2: identical to mitosis. Does not cause a change in chromosomes. ● Discuss how genetic diversity is produced through meiosis and sexual reproduction. ○ Offspring is produced by sexual reproduction and are genetically different from both parents and also from each other. ○ This is from: ■ Independent assortment: assignment of tetrads during metaphase of meiosis I is independent and random. ■ Fertilization: the fusion of gametes. Produces an incredible amount of genetic diversity. ■ Crossing over: produces new combinations of alleles in the chromosomes that are distinct from either parents. Unlimited variety of gametes and offspring. ● Explain why saying “I’m a quarter Irish!” is most likely inaccurate based on meiosis ○ Due to independent assortment, fertilization, and crossing over you will never exactly inherit “25%” of your grandparents. Top Hat Question The HBA gene is found on chromosome 16 and encodes the alpha chain of hemoglobin. During our evolutionary past, this gene was duplicated to form HBA1 and HBA2. How many copies of the HBA gene do human somatic cells contain? (A) 1

(B) 2 (C) 4 (D) 8 Top Hat Question During meiosis, when do cells first contain half the number of chromosomes as the parent cell? (A) Middle of meiosis I (B) End of meiosis I (C) Middle of meiosis II (D) End of meiosis II MEIOSIS ● Define nondisjunction and provide examples. ○ An error that happens during meiosis where chromosomes are incorrectly distributed to the daughter nuclei. ○ Can end up with too many or too little ○ Caused by spindle not pulling apart the chromosomes correctly. ○ Having the wrong number of chromosomes is usually not survivable. ○ Sex chromosomes are usually more forgiving than autosomal chromosomes. ○ Examples of nondisjunction are ■ Trisomy 21(down’s syndrome) ● The only autosomal chromosome were you can have three and survive ■ Klienfelter’s syndrome (only in males) ● Three sex chromosomes ● Describe how meiosis is different in male and female mammals and discuss the implications. ○ Gametogenesis ○ Eggs and sperm have different meiosis. ○ For eggs: the eggs are already present before birth. Begin meiosis before birth but stops after meiosis I until puberty. One or a few eggs start up meiosis until meiosis II, it stops to wait to be fertilized. Never finishes unless it is fertilized. Much larger than sperm. POLAR BODY DOES NOTHING. Higher error rate in eggs. ○ For sperm: begins at puberty and is continuous for life. Takes about two months. Sperm is much younger than eggs.

● Use the paradox of sex as a model to compare outcomes of sexual and asexual reproduction. ○ Paradox of sex: asexual reproduction is far more efficient for producing offspring than sexual reproduction

○ What is an advantage of sexual reproduction? ■ Genetic variation ● Illustrate the life cycles of animals and plants

Top Hat Question Would you hypothesize that nondisjunction happens more frequently in eggs or sperm? (A) Eggs (B) Sperm (C) Same If HIV appeared in human populations 300+years ago (no medicine or education),do

you think humanity would have been wiped out? (A) Yes (B) No GENETICS ● Define traits and the science of genetics. ○ Traits: a characteristic of an individual that can be visible, molecular, or behaviors ○ Branch of biology that deals with heredity ○ Heredity: inheritance of traits. ● Differentiate genotype from phenotype. ○ Genotype: refers to the alleles of individuals ○ Phenotype: refers to observable traits. ● Describe the three principles of genetics that were stated by Mendel (dominance, segregation, independent assortment). ○ Principle of dominance: heterozygotes express only the dominant trait according to this principle. ○ Principle of segregation: hereditary components segregate during gamete production, each gamete will carry only one allele of a gene. ○ Principle of independent assortment: genes for different traits are transmitted independently of each other to offspring. ● Solve Mendelian genetics problems that involve traits with complete dominance. Top Hat Question Which of the following statements are true? (A) Dominant traits are always beneficial in comparison to recessive traits (B) Recessive traits are always less common than dominant traits (C) Both statements are true (D) Neither statement is true Assume earlobe shape is controlled by a single gene with two alleles. The dominant allele will produce free earlobes, while the recessive allele generates attached earlobes. Leonard has free earlobes, while Penny and their first child both have attached earlobes. What is the probability that their second child will have free earlobes? (A) 0% (B) 25% (C) 50% (D) 100% William and Kate are normal, but each has a parent with Wilson’s disease. This condition is autosomal recessive and caused by a mutation in the ATP7B gene, resulting in the inability to dispose of copper. What is the probability that all three of their royal children will be normal? (A) 27/64

(B) 3/4 (C) 9/16 (D) 1/64 Assume earlobe shape is controlled by a single gene with two alleles. The dominant allele generates free earlobes, while the recessive allele produces attached earlobes. A second gene on a different chromosome controls earwax consistency, where wet is dominant and dry is recessive. Bella has free earlobes with wet earwax and is heterozygous for both traits. Edward has attached earlobes with dry earwax. What is the probability that their only child will inherit the free earlobes or the wet earwax or both dominant traits? (A) 25% (B) 50% (C) 75% (D) 100% MENDELIAN GENETICS ● Solve advanced Mendelian genetics problems that involve traits with complete dominance. ● Understand how the events of meiosis explain the Mendelian principles of trait inheritance. ○ Principle of dominance: heterozygotes express only the dominant trait according to this principle ○ Principle of segregation: alleles of a gene separate during gamete production, each gamete carries one allele for a gene ○ Principle of independent assortment: genes for different traits are transmitted independently of each other to offspring. ○ Menedlian principles allowed biologists to link inheritance of traits with the events of meiosis. ○ Meiosis is the foundation of genetics. ● Solve non-Mendelian genetics problems that involve incomplete dominance, codominance, and the sex-linked forms of trait inheritance. ○ Incomplete dominance: a non-mendelian pattern of inheritance where heterozygotes express a phenotype that is intermediate to the phenotypes of homozygous individuals.

■ ○ Codominance: non-mendelian pattern of inheritance where heterozygotes will express both phenotypes of homozygous individuals. ■ Example: ABO blood groups ● A and B alleles are codominant when paired together but dominant when paired without. ○ Sex-linked inheritance: Thomas Hunt Morgan’s experiments with fruit flies showed a relationship between trait inheritance and sex of offspring. Top Hat Questions Kim and Kanye are normal, but each has one parent with Wilson’s disease. This condition is autosomal recessive and caused by a mutation in the ATP7B gene, resulting in the inability to dispose of copper. What is the probability that two of their three children inherit the disease? (A) 3/64 (B) 3/16 (C) ½ (D) 1/16 (E) 9/64 Assume hair curliness is controlled by a gene that is on an autosome and has two alleles. Dominant alleles result in curly hair, recessive alleles produce straight hair, and heterozygotes have wavy hair. Han has curly hair, while Leia has wavy hair. Han and Leia are both normal, but their first child has maple syrup urine disease, which is an autosomal recessive disorder. What is the probability that their second child will be a daughter who has wavy hair and is also a carrier for maple syrup urine disease? (A) ¾ (B) ⅛ (C) 3/16 (D) ¼ (E) 3/8 Ned has type A blood, which is common, while Catelyn has type AB blood, which is the rarest type in the world. What is the probability that their two children will both have type A blood? (A) 0%

(B) 50% (C) 25% (D) Not enough info One of the genes that controls color vision is found on the X chromosome. The dominant allele results in normal color vision, and the recessive allele causes colorblindness. Ginny has normal color vision and is heterozygous, but Harry is colorblind. If Ginny and Harry have three children, what is the probability that at least one of them is a colorblind son? (A) ¾ (B) 27/64 (C) 9/16 (D) 37/64 (E) 1/4 SEX DETERMINATION ● Contrast sex determination in mammals with systems of other organisms, especially birds. ○ Sex is determined by males in mammals. ○ Slight bias to male gender in humans. ○ Female embryos are more likely to not make it through the 9 months. ○ Around the age of 35 females become more common because of occupation accidents and that men tend to make decisions that get them milled. ○ Birds and some reptiles: sex is determined by mom not dad. ■ Males: ZZ ■ Females: ZW ○ Ants(haploid-diploid system) ■ Male ants do not have a father ■ If the queen fertilizes an egg, its female ■ If the egg is not fertilized, its male ○ Alligators and turtles ■ Dependent on temperature ○ Fish ■ Clownfish all start out as males, but then become females ■ Dominance hierarchy ● If the dominant female dies, the dominant male becomes female Solve genetics problems that involve multiple alleles,pedigrees, and polygenic inheritance. ○ Multiple allelism: the existence of more than two alleles for a gene in populations. ■ Example: ABO blood groups. Where three alleles are common.

○ Pedigrees: family trees that also provide info about inheritance of traits ● Differentiate discrete and quantitative traits. ○ Quantitative traits: characteristics which differ on a continuous scale ■ Examples: hair and eye color, height, and intelligence. ○ Discrete traits: traits that fall into defined categories ■ Examples: smooth or wrinkled peas. ● Describe X-inactivation in female mammals. ○ One of the x-chromosomes are shut down. ○ Which chromosome shut down is random. ○ An example of seeing X-inactivation is in cats ■ On tortoiseshell cats you see the different colors due to which X chromosome being shut down. ■ There are no male tortoiseshell cats unless they have XXY chromosomes. Top Hat Questions One of the genes that controls feather color is located on the Z chromosome in pigeons. The dominant allele results in blue feathers, while recessive alleles produce brown feathers. If a blue female pigeon mates with a brown male, what is the probability of having a blue chick? (A) 0% (B) 25% (C) 50% (D) 75% (E) 100% One of the genes that controls feather color is located on the Z chromosome in pigeons. The ash-red allele is dominant to blue and brown alleles, and the blue allele is also dominant to the brown allele. If a blue male mates with an ash-red female, what is the probability that a chick will be female and have blue feathers? (A) 0% (B) 50% (C) 25% (D) Not enough info A tomato plant with the genotype AabbCcDd for a quantitative trait self-fertilizes. What is the probability that an offspring of the plant will inherit a completely recessive genotype? (A) 0 (B) ⅛ (C) 1/16 (D) 1/64 (E) 1/256...