Meiosis vs. Mitosis PunnettsMeiosis Mistakes in Meiosis Pedigrees

Question Cells that undergo mitosis (not meiosis) end with how many sets of chromosomes?

Answer 1 – 10 2 (diploid) Cells that undergo mitosis go through one division and end with 2 sets of chromosomes (2n)

Question Which process is shown in this picture and what is the word for the final number of chromosome sets in this process?

Answer 1 – 20 Meiosis; Haploid This picture shows the process of meiosis. In the first step there are two sets of chromosomes that are replicated (S phase of interphase) and then divided twice, resulting in a singular set (haploid) of chromosomes in each gamete.

Question Which of the following would be found in a gamete? A B C

Answer 1 – 30 A Twenty-three unreplicated chromosomes would be found in a human gamete.

Question No matter which process, mitosis or meiosis, the hierarchy of genetics remains the same. Use the letters to order the following from largest to smallest. A.Chromosome B.Deoxyribose C.Gene D.Genome E.Nucleotide

Answer 1 – 40 D, A, C, E, B Genome>Chromosomes>Genes>Nucleotides>Deoxyribose The GENOME includes all the DNA of an organism. It is divided up into separate collections of DNA called CHROMOSOMES. Chromosomes are made of smaller segments that code for a protein called GENES. Genes are made of sequences of NUCLEOTIDES. DNA Nucleotides are made of 3 parts; a nitrogenous base, a phosphate group, and DEOXYRIBOSE sugar.

Question Name the process that occurs in meiosis that creates genetic variation and what phase it occurs in.

Answer 1 – 50 Crossing over and it occurs in Prophase I.

Question A heterozygous organism is crossed with another heterozygous organism. What percent of their offspring is homozygous?

Answer 2 – percent Remember, both BB and bb are homozygous

Question A heterozygous blue flower is crossed with a yellow flower. Assuming complete dominance, what percent of offspring will be blue?

Answer 2 – percent Heterozygous blue = Bb Yellow must be = bb because complete dominance means the heterozygote shows the dominant phenotype.

Question A homozygous dominant specimen is crossed with a homozygous recessive specimen. What percent of their offspring would be expected to be homozygous?

Answer 2 – 30 0%! All offspring would be heterozygotes.

Question Matthew has homozygous blood type A (I A I A ). Kayli has blood type B (I B ?) and Kayli’s mother was blood type O (ii). What are the possible genotypes and phenotypes of Matt and Kayli’s offspring’s blood?

Answer 2 – 40 I A I B (50%) IAi (50%) Matt’s genotype is I A I A. Kayli’s is I B i. We know this because if she has type B blood and her mother has type O. Her mother can only donate the (i) allele. She must have received the I B from her father. Using a standard Punnett square, we find that I A I B and I A i are the only two possible genotypes of their offspring.

Question Hemophilia is a sex-linked (x- linked) disorder. If Mary is a carrier of the trait and George is unaffected, what are the phenotypic probabilities of their offspring?

Answer 2 – 50 XHXH- Normal female (25%) XHXh- Carrier female (25%) XHY- Normal male (25%) XhY- Hemophilic male (25%) George is an unaffected male so he is X H Y. Mary is a carrier, she is X H X h Use a Punnett square to determine the probabilities!

Question In what phase of meiosis does crossing over occur?

Answer 3 – 10 Prophase I of meiosis

Question How do homologous chromosomes (ex. chromosome 1 from mom, chromosomes 1 from dad) differ?

Answer 3 – 20 They differ at the A-T-C-G sequence of nucleotides for a given gene. In other words, their characters are the same but their traits vary.

Question Name two of Mendel’s laws.

Answer 3 – 30 Law of Independent Assortment- homologous pairs randomly pair up during Metaphase I Law of Segregation – alleles get separated during Anaphase I & II Rule of Unit Factors Rule of Dominance

Question What are the advantages and disadvantages of asexual and sexual reproduction in terms of time and genetic variation?

Answer 3 – 40 Asexual- quick reproduction (+) no variation unless mutation occurs (-) Sexual- slow reproduction (-) Great generational variation (+)

Question Put these steps of meiosis in the order of occurrence: a.Chromosomes replicate b.Crossing over occurs c.Four genetically different cells are made d.Homologous chromosomes pair up (synapsis into tetrads) e.Sister chromatids separate

Answer 3 – 50 A, D, B, E, C DNA is replicated during ‘S’ phase of interphase. Homologous chromosomes synapse, forming tetrads and chiasmata where crossing over occurs. Homologous chromosomes line up randomly during metaphase and separate. During the next anaphase (II) sister chromatids separate. The end result is 4 haploid cells that are genetically unique.

Question What is it called when two human gametes combine?

Answer 4 – 10 Zygote.

Question What does filial mean?

Answer 4 – 20 Son/daughter

Question The following chromosome is found in a gamete. Which of the gene segments will be inherited by the receiving offspring?

Answer 4 – 30 All of them. These genes are on the same chromosome and that chromosome is already in a gamete. There is no further divisions after gametes are formed. All of these genes would be considered linked since they will be inherited together.

Question Describe the individual based on the given karyotype.

Answer 4 – 40 It’s a male (XY) affected with Down Syndrome (Trisomy 21, three of chromosome 21)

Question Sickle Cell Anemia is the result of a single nucleotide mutation which changes the amino acid sequence and therefore the protein for which the gene codes. One copy gives an individual sickle cell trait, while two gives you sickle cell disease. This affects men and women equally. What is the pattern of inheritance?

Answer 4 – 50 Autosomal Recessive Autosomal because it affects men and women equally. If it were x-linked it would affect men predominantly. Recessive because it requires two copies of the mutated allele to have the disease.

Question What is the pattern of inheritance for this pedigree, recessive or dominant?

Answer 5 – 10 Recessive, it skips a generation(s) and two unaffected parents have affected children.

Question How many generations are present and are more male or females affected?

Answer 5 – 20 2; males

Question What is the pattern of inheritance?

Answer 5 – 30 Dominant. Aa, Aa The pattern of inheritance cannot be recessive (aa) because both children would also have to be recessive. So we know the shaded shapes must have at least 1 dominant allele (A). Since the parents have one affect child (A?) and one unaffected (aa) both parents must be heterozygotes. It is the only way the female child could receive 2 recessive alleles…one from mom, one from dad.

Question What is the probability of the offspring being affected?

Answer 5 – 40 3 out of 4; 75% Using the justification in 5-30 we know that the parents must be heterozygous (Aa) Using a monohybrid cross we can determine that 3 out of 4 possibilities would be affected.

Question Create a pedigree with 3 generations. Generation 2 has 3 individuals. Generation 3 has 2 individuals. Make sure to label the individuals and the generations.

Answer 5 – 50

Final Jeopardy Make your wager!