BIOL 2330 Lecture Notes - Mutation, Chromosome, Gamete

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10 May 2013

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These pairs line up diff random combinations in every sex cell every time they divide. The line of chromosome pairs separate into 2 daughter cells. Each daughter cell will enter either the father"s or the mother"s version of each chromosome. What this means for humans with their 23 sets of chromosomes. The number of different possible combinations for each gamete (male or female) is over 8,000,000. The number of different individuals that could possibly result from one human mating is about 70,000,000,000,000! The human male can produce several hundred million sperm a day from puberty until death, and the odds are that no two will be identical. Crossing-over occurs during meiosis when double strands come together to form tetrads. However, there is already significant variability for natural selection to act on random mutations are not necessary for evolution to progress in most species.

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23. During meiosis, one way that diversity is achieved is throughthe differential ways maternal and paternal
chromosomes line up at the equator. This phenomenon is knownas:
A. Crossing under; B. Random mating; C. Crossing over; D. Randomshuffling
24. What is the correct order of classification from the leasttraits in common to the most traits in common?
1. Order; 2. Genus; 3. Kingdom; 4. Species; 5. Phylum; 6. Family;7. Class
A. 3,5,1,7,2,6,4; B. 3,7,5,6,1,2,4; C. 3,5,7,6,1,4,2; D.3,5,7,1,6,2,4; E. None of the above 25. Humans are currentlyclassified as Homo sapiens. An earlier human ancestor was Homoerectus. Please
identify the Genus of the earlier human ancestor. A. sapiens; B.Homo; C. Human; D. erectus
26. Whales utilize which type of fertilization? A. Internal; B.External; C. Terrestrial; D. None of the above
27. During internal fertilization, sperm are deposited directlyinto the femaleâs body in order to protect the
gametes. In some female animals, after the sperm fertilizes theeggs, the eggs continue to develop inside the
female, and the developing embryos receive ALL of their nourishmentfrom the mother. These animals are
considered to be: A. Oviparous; B. Viviparous; C. Precocial; D.Ovoviviparous
28. In humans, which gender has separate openings for the urinaryand reproductive systems?
A. Men; B. Women; C. Both A and B; D. None of the above
29. An animalâs anatomical structures can be used to constructphylogenetic trees. What is the term given to the
structures of two animals whereas the structures are very similarbut have different functions? Ex: Forearm of a
human and the wing of a duck:
A. Vestigial Structures; B. Analogous Structures; C. HomologousStructures; D. None of the above
30. Humans have 46 chromosomes in every somatic cell nucleus. Thereare 23 chromosomes from mama and
23 chromosomes from papa. Chromosome #3 from mother and Chromosome#3 from father contain
information to control the same genetic traits. During meiosis 1,duplication of chromosomes results in 2 copies
of chromosome #3 from the father and 2 copies of chromosome #3 fromthe mother. The pair of chromosomes
#3 from the father are refered to as:
A. Sister chromatids; B. Centromeres; C. Homologous chromosomes; D.Spindle apparatus

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Ploidy refers to the number of complete sets of chromosomes (genes) present in a cell. The number of chromosomes in a complete set is a fixed characteristic of a species. Humans are diploid with two sets of 23 chromosomes. Fruit flies are diploid with two sets of 4 chromosomes. Sexually reproducing organisms are diploid, each somatic cell of an organism has two complete sets ("di" is a prefix indicating 2.). To complete a life cycle and reproduce new members of a species, mating is required. Mating brings a donation from a male and a donation from a female together. However, if the male and female cells remain diploid, the fertilization will result in a tetraploid zygote. In general, these are not viable. A mechanism is needed to form special haploid cells, gametes. The diploid set is split precisely into two complete haploid sets. That mechanism is meiosis.

The complete set of chromosomes of a species is also the complete set of genes of a species, the genome. (Yes, there is a minor contribution from mitochondria and chloroplasts. Inheritance of this information is "cytoplasmic".)

Please answer the following questions:

1. How many chromosomes in a brain cell of a fruit fly? How many chromosomes are in a liver cell of a human? Explain both answers.

2. How many chromosomes are in a fruit fly unfertilized egg? How many chromosomes are in a human egg? Explain both answers.

3. Why is meiosis necessary for sexually reproducing organisms? How many chromosomes are in a human zygote? Relate the two answers.

4. What is a gene allele? Suppose there is a gene called "bingo" and it is present once in a complete haploid set. How many alleles of "bingo" does a diploid individual have? How many copies or versions of the gene "bingo" are present in a diploid individual?

5. Modern DNA sequencing clearly identifies alleles by showing the different DNA sequence of each allele. These alleles may be termed structural alleles (I coined the term for this problem.). Classical genetics only dealt with phenotypes or visible traits. As a result, alleles of genes were identified by functionality, usually normal or non-functional. Using your knowledge of gene structure and gene expression, postulate a relationship between structural alleles and functional alleles. (include relative amounts; more, less, or equal).

What is a genome? What is a genome made of? Describe the bacterial genome. How do bacteria reproduce? What is binary fission? Distinguish between a chromosome and chromatin. Where are chromosomes located in eukaryotic cells? What is the chromosome made of? What is a centromere? What is the centromere's role? What are sister chromatids and how do they arise? Distinguish between somatic cells and germ (gametes) cells. Describe the cell cycle. What are the different phases? What occurs during S phase? What is interphase? How is the cell cycle controlled?

Describe mitosis. What are the phases of mitosis? What occurs in each of the phases of mitosis? What is cytokinesis? How does this differ between plant and animal cells? What is a kinetochore? Where does it form? What is its role? What is the role of microtubules in mitosis? What is a centriole and what is it composed of? What is a centrosome and what is its role in mitosis? What is the metaphase plate and why is this important? What is the mitotic spindle, its role and its makeup? What defines a diploid cell? How many copies of each chromosome is in a diploid cell? What about a haploid cell? Why do the daughter cells of mitosis always have the same complement of chromosomes?

Describe meiosis. What are the phases of meiosis? What occurs in each of the phases of meiosis? Distinguish between meiosis I and meiosis II and describe how each of these processes compare to mitosis. Why do animal cells undergo meiosis? What is a gamete? What is a zygote? What are recombination, crossing-over, and chiasma? When and why does this occur? What is meant by 'homologous pair of chromosomes'? Why don't the daughter cells of meiosis have the same genetic makeup? What controls the segregation of chromosomes into the gametes?

What are genetic characters? What are genetic traits? What is an allele? What is a locus? How many alleles at each locus would a human cell have and why? Distinguish between genotype and phenotype. What is meant by a dominant gene? What is meant by a recessive gene? How do these differ? What is the genotype of a homozygous dominant organism? What is its phenotype? What is the genotype of a homozygous recessive organism? What is its phenotype? What is the genotype of a heterozygous organism? What is its phenotype? What is a genetic cross? Distinguish between the P, F1, and F2 generations. What is a true-breeding line? What is the genotype and phenotype of a cross between homozygous dominant and homozygous recessive parents? If the F1 progeny are crossed, what would be the genotype and phenotype of the F2 generation? What would be the phenotypic ratio? What would be the genotypic ratio? Be ready to generate Punnet square tests or probability analyses of crosses involving more than one genetic locus. Describe a dihybrid cross where two alleles are homozygous dominant in one parent and homozygous recessive in the other. What would be the phenotypic ratio of the F2 generation from this dihybrid cross? What is meant by independent assortment? Be prepared to calculate probabilities resulting from different crosses.

Distinguish between complete and incomplete dominance. How would incomplete dominance alter the results of a hybrid cross? What would the resulting F2 generation phenotype and genotype ratios be? What is codominance? How does this affect the results of crosses? Be prepared to determine likely blood types of parents based on the blood types of their offspring. What is a polygenic trait? What is a carrier state for a genetic disease? What is meant by linked genes? How does this affect expected outcomes of genetic crosses? How is gene linkage used for chromosomal mapping? Distinguish between autosomes and sex chromosomes. What sex chromosomes are found in women? What sex chromosomes are found in men? What are sex-linked traits? Be prepared to give the results of crosses that involve sex-linked recessive traits. What is the process of nondisjunction? What are the likely results? Why is this important? What is a Barr body? Recognize the genetic abnormality of Downs Syndrome, Turner's Syndrome, and Klinefelter's Syndrome.

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BIOL 2330 Lecture Notes - Mutation, Chromosome, Gamete

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