Week 1: The Cell Cycle, Mitosis and Meiosis
In Part A of this week’s module you will explore the cell cycle and mitosis. This process of cell replication and division is essential for organism growth and development, cell and tissue repair and replacement, and asexual reproduction. The result of mitosis in a single cell is the production of two identical daughter cells, clones of the original parent cell. Each daughter cell contains the same number of chromosomes as its parent cell (in diploid organisms, a full set of homologous pairsof chromosomes—for a total of 46, or 23 pairs, in humans).
In Part B of this module you will investigate a second type of cell division called meiosis. In this process of cell division, the end product is not two identical clone cells, but four daughter cells that are genetically distinct from one another. The resulting daughter cells have a full set of singlechromosomes (a total of 23 chromosomes in humans). This type of cell division results specifically in gametes (sex cells) such as eggs and sperm in most animals, or egg and pollen in most plants. Meiosis is essential for sexual reproduction.
Part A
Learning objectives
At the end of this module you should be able to do the following:
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Describe and compare the structural organization of the prokaryotic and eukaryotic genomes.
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Describe and name the sequence of phases of the cell cycle, identifying key events throughout interphase and mitosis.
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Describe the structure and functions of the mitotic spindle, including centrosomes, kinetochore microtubules, nonkinetochore microtubules, and asters.
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Compare cytokinesis in animals and plants.
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Discuss binary fission and explain how mitosis may have evolved from binary fission in bacteria.
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Describe key “checkpoints” in the cell cycle, and explain how the abnormal cell division of cancerous cells escapes normal cell cycle controls.
Check List
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Read Chapter 12 of Campbell and Reece’s Biology, 8th Ed.
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As you are reading, address each of the learning objectives listed above.
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Watch the video clip “Mitosis,” and complete the mitosis practice worksheet.
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Consider making flash cards for the terminology list provided below. This will help when studying for the midterm and final exams later in the semester.
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Watch the video clip “DV Fighting Cancer.” Post a response to the following question on the discussion board in the “DV Fighting Cancer Response” folder. Read and respond to two of your classmate’s posts.
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Review the Power Point Lecture “Bio 102 Lecture 1a: The Cell Cycle and Mitosis”
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For extra practice, try the Self Quiz or Practice Test on the Mastering Biology Website. To log onto the website, use the access code provided in your textbook. You will also find other resources, such as downloadable MP3 tutorials for each chapter, a glossary, and an electronic copy of your text—you can catch up on your reading anywhere!
Key Terms
aster
bacteria
binary fission
cell cycle
cell plate
centromere
centrosome
chromatin
chromosome
cleavage
cleavage furrow
cytokinesis
gamete
genome
growth factor
interphase
kinetochore
metaphase plate
metastasis
mitosis
mitotic spindle
sister chromatids
somatic cell
Root Words to Know
ana- = up, throughout, again (anaphase: the mitotic stage in which the chromatids of each chromosome have separated and the daughter chromosomes are moving to the poles of the cell)
bi- = two (binary fission: a type of cell division in which a cell divides in two)
centro- = the center; -mere = a part (centromere: the narrow "waist" of a condensed chromosome)
chroma- = colored (chromatin: DNA and the various associated proteins that form eukaryotic chromosomes)
cyclo- = a circle (cyclin: a regulatory protein whose concentration fluctuates cyclically)
cyto- = cell; -kinet = move (cytokinesis: division of the cytoplasm)
gamet- = a wife or husband (gamete: a haploid egg or sperm cell)
gen- = produce (genome: a cell's endowment of DNA)
inter- = between (interphase: time when a cell metabolizes and performs its various functions)
mal- = bad or evil (malignant tumor: a cancerous tumor that is invasive enough to impair functions of one or more organs)
meio- = less (meiosis: a variation of cell division that yields daughter cells with half as many chromosomes as the parent cell)
meta- = between (metaphase: the mitotic stage in which the chromosomes are aligned in the middle of the cell, at the metaphase plate)
mito- = a thread (mitosis: the division of the nucleus)
pro- = before (prophase: the first mitotic stage in which the chromatin is condensing)
soma- = body (centrosome: a nonmembranous organelle that functions throughout the cell cycle to organize the cell's microtubules)
telos- = an end (telophase: the final stage of mitosis in which daughter nuclei are forming and cytokinesis has typically begun)
trans- = across; -form shape (transformation: the process that converts a normal cell into a cancer cell)
Part B
Learning objectives
At the end of this module you should be able to do the following:
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Distinguish between the following terms: somatic cell and gamete; autosome and sex chromosomes; haploid and diploid.
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Describe the events that characterize each phase of meiosis.
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Compare and contrast meiosis and mitosis, including the ultimate purpose of each.
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Distinguish between asexual and sexual reproduction and outline the benefits of each.
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Describe alternation of generation in animals, plants and fungi.
Check List
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Read Chapter 13 of Campbell and Reece’s Biology, 8th Ed.
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As you are reading, address each of the learning objectives listed above.
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Watch the video clip “Meiosis,” and complete the meiosis practice worksheet.
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Make flash cards for the terminology list provided (optional). This will be beneficial for studying for the midterm and final exams later in the semester.
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Review the Power point Lecture “Bio 102 Lecture 1b: Meiosis”.
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For extra practice try the Self Quiz or Practice Test on the Mastering Biology Website. To log onto the website, use the access code provided in your textbook. You will also find other resources, such as downloadable MP3 tutorials for each chapter, a glossary, and an electronic copy of your text—you can catch up on your reading anywhere!
Key Terms
allele
alternation of generations
asexual reproduction
autosome
clone
crossing over
diploid cell
gametophyte
gene
genetics
haploid cell
heredity
homologous chromosomes
karyotype
life cycle
recombinant chromosome
sex chromosome
sexual reproduction
spore
sporophyte
synapsis
variation
zygote
Root Words to Know
a- = not or without (asexual: type of reproduction not involving fertilization)
-apsis = juncture (synapsis: the pairing of replicated homologous chromosomes during prophase I of meiosis)
auto- = self (autosome: the chromosomes that do not determine gender)
chiasm- = marked crosswise (chiasma: the X-shaped microscopically visible region representing homologous chromosomes that have exchanged genetic material through crossing over during meiosis)
di- = two (diploid: cells that contain two homologous sets of chromosomes)
fertil- = fruitful (fertilization: process of fusion of a haploid sperm and a haploid egg cell)
haplo- = single (haploid: cells that contain only one chromosome of each homologous pair)
homo- = like (homologous: like chromosomes that form a pair)
karyo- = nucleus (karyotype: a display of the chromosomes of a cell)
meio- = less (meiosis: a variation of cell division that yields daughter cells with half as many chromosomes as the parent cell)
soma- = body (somatic: body cells with 46 chromosomes in humans)
sporo- = a seed; -phyte = a plant (sporophyte: the multicellular diploid form in organisms undergoing alternation of generations that results from a union of gametes and that meiotically produces haploid spores that grow into the gametophyte generation)
syn- = together; gam- = marriage (syngamy: the process of cellular union during fertilization)
Sources
Campbell, N. A. (2008). Biology, Eighth Edition. San Francisco: Pearson, Benjamin Cummings.
Pearson Education. (2010). Retrieved 2010, from Mastering Biology : http://session.masteringbiology.com
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