BIOL 141 Lecture Notes - Lecture 10: Dna Replication, Cytokinesis, Thymidine

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25 Oct 2017

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Cell division: cells arise through the division of preexisting cells, two types of cell division: meiosis and mitosis, both forms involve cytokinesis: division of the cytoplasm into two distinct daughter cells. Before the s (synthesis) phase, each chromosome will consist of a single, long, uncondensed stretch of dna: genes are located throughout the chromosome. Humans have 23 pairs of chromosomes, total of 46 chromosomes: these 23 pairs consist of maternal and paternal copies of chromosomes. Dna condenses during mitosis, giving rise to the classic x shape of the chromosome. Why might cell want to condense its genetic material: more efficient sorting of genetic material for mitosis or meiosis. You can tell which stage of the cycle a cell is in by looking at how condensed its dna is. The cell cycle is: an orderly sequence of events, occurs from the formation of a eukaryotic cell, requires duplication of chromosomes, culminates in eventual cell division via cytokinesis.

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13. Meiosis differs from mitosis in that:
a. meiosis results in the production of two new cells, whilemitosis results in the production for four new
cells., b. meiosis is used for growth and repair, while mitosis isused for production of eggs and sperm., c.
cytokinesis can be unequal following meiosis, but is approximatelyequal following mitosis., d. meiosis
involves one cell division, while mitosis involves two celldivisions., e. meiosis results in the production of
diploid cells, while mitosis results in the production of haploidcells.
14. Bits of maternal and paternal chromosomes are exchanged betweenhomologous chromosomes during
synapsis of meiosis I. This process is called:
a. crossing over., b. random mating., c. random fertilization., d.random shuffling of parental
chromosomes.,
e. mutation.
15. The advantage of sexual reproduction over asexual reproductionis that:
a. all young are genetically identical to the parent., b. malesmust evolve a copulatory organ., c. genetic
variability in the population is increased., d. females must evolvea vagina., e. mates are not needed.
16. Many different types of information are used to constructphylogenetic trees. Which of the following types
of information is the most direct measure of evolutionaryrelatedness?
a. physiology, b. gene sequence data, c. the fossil record, d.information about the structure of ribosomes.,
e. information about the structure of enzymes
17. A species is:
a. a group of individuals that can interbreed under naturalconditions and produce fertile offspring., b.
denoted by both a genus and a species name., c. the onlybiologically defined taxon., d. a group of
organisms with a large number of traits in common., e. all of theabove.
18. The process of spermatogenesis results in:
A. 4 diploid sperm; B. 1 diploid sperm and 3 haploid polar bodies;C. 1 haploid sperm and 3 haploid
polar bodies; D. 4 haploid sperm
19. Which cell division process results in an unequal division ofthe cytoplasm?
A. Spermatogenesis; B. Testiculargenesis; C. Oogenesis; D. None ofthe above
20. Meiosis is the process by which:
A. 1 diploid cell becomes 4 haploid cells; B. 1 diploid cellbecomes 1 haploid cell and 3 haploid polar
bodies; C. 1 haploid cell becomes 4 diploid cells; D. Both A andB
21. The phase of mitosis where chromosomes line up at the equator(middle) of the cell is called:
A. Anaphase; B. Telophase; C. Interphase; D. Metaphase
22. Chromosome #6 from Mom and Chromosome #6 from Dad form achromosome pair called:
A. Sister Chromatids; B. Centromeres; C. Homologous Chromosomes; D.Spindle Apparatus

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-Complete the following sentences: metaphase of mitosis, prophase II of meiosis, crossing over, anaphase I of meiosis, variable, random fertilization, identical, random orientation, metaphase I of meiosis, prophase I of meiosis, metaphase II of meiosis, reduction division

Two processes that occur during meiosis produce genetically ____________ cells.

In a process called ____________ , paired homologous chromosomes align randomly at the cell equator. This occurs during this stage of cell division: ____________ .

In a process called ____________ , genetic material is exchanged between homologous chromosomes. This occurs during this stage of cell division: ____________ .

-Complete the following paragraph to describe nondisjunction and the resulting effects on chromosome number.

words: euploidy, primary nondisjunction, nomal, nondisjunction, secondary nondisjunction, homologous chromosomes, abnormal, trisomy, monosomy, sister chromatids, aneuploid

1.During meiosis I, ____________ separate and move towards opposite ends of the poles.

2.During meiosis II, ____________ separate and move towards opposite ends of the poles.

3.During meiosis I, if both members of a homologous pair go into the same daughter cell, ____________ is said to occur and no normal gametes are produced.

4.During meiosis II, if the sister chromatids fail to separate and both daughter chromosomes go into the same gamete, ____________ is said to occur. Half the gametes are aneuploid while the other half are euploid.

5.If an egg that contains 24 chromosomes instead of 23 chromosomes is fertilized by a normal sperm, ____________ is said to have occurred.

6.If an egg that contains 22 chromosomes instead of 23 chromosomes is fertilized by a normal sperm, ____________ is said to have occurred.

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 141 Lecture Notes - Lecture 10: Dna Replication, Cytokinesis, Thymidine

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