BIO 311C Lecture Notes - Lecture 12: Cell Plate, Separase, Prometaphase

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Chapter 12: The Cell Cycle

1. The Key Roles of Cell Division

a. The ability of organisms to produce more of their own kind best distinguishes living things from

nonliving matter

b. The continuity of life is based on the reproduction of cells, or cell division

c. In unicellular organisms, division of one cell reproduces the entire organism

d. Multicellular eukaryotes depend on cell division for

i. Development from a fertilized cell

ii. Growth

iii. Repair

e. Cell division is an integral part of the cell cycle, the life of a cell from formation to its own division

2. Concept 12.1: Most cell division results in genetically identical daughter cells

a. Most cell division results in daughter cells with identical genetic information, DNA

i. The exception is meiosis, a special type of division that can produce sperm and egg cells

b. Cellular Organization of the Genetic Material

i. All the DNA i a ell ostitutes the ell’s genome

1. A genome can consist of a single DNA molecule (common in prokaryotic cells) or a

number of DNA molecules (common in eukaryotic cells)

ii. DNA molecules in a cell are packaged into chromosomes

iii. Eukaryotic chromosomes consist of chromatin, a complex of DNA and protein that condenses

during cell division

1. Every eukaryotic species has a characteristic number of chromosomes in each cell

nucleus

iv. Somatic cells (non-reproductive cells) have two sets of chromosomes

v. Gametes (reproductive cells: sperm and eggs) have half as many chromosomes as somatic cells

c. Distribution of Chromosomes During Eukaryotic Cell Division

i. In preparation for cell division, DNA is replicated and the chromosomes condense

ii. Each duplicated chromosome has two sister chromatids (joined copies of the original

chromosome), attached along their lengths by cohesins

iii. The centromere is the arro aist of the dupliated hroosoe, here the two

chromatids are most closely attached

iv. During cell division, the two sister chromatids of each duplicated chromosome separate and

move into two nuclei

1. Once separate, the chromatids are called chromosomes

d. Eukaryotic cell division consists of

i. Mitosis, the division of the genetic material in the

nucleus

ii. Cytokinesis, the division of the cytoplasm

e. Gametes are produced by a variation of cell division called meiosis

f. Meiosis yields non-identical daughter cells that have half as many chromosomes as the parent cell

3. Concept 12.2: The mitotic phase alternates with interphase in the cell cycle

a. In 1882, the German anatomist Walther Flemming developed dyes to observe chromosomes during

mitosis and cytokinesis

b. Phases of the Cell Cycle

i. The cell cycle consists of

1. Mitotic (M) phase (mitosis and cytokinesis)

a. Mitosis is conventionally broken down into five stages:

i. prophase

ii. prometaphase

iii. metaphase

iv. anaphase

v. telophase

2. Interphase (cell growth and copying of chromosomes in preparation for cell division)

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Related Questions

-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.

Match the terms to the definitions provided.

Question 1 options:

	gamete
	somatic cells
	zygote
	sexual reproduction

1.	Reproductive life cycle that involves an alternation between haploid and diploid cells
2.	A single cell with a diploid number of chromosomes resulting from the fusion of an egg and a sperm.
3.	Cells (egg or sperm) resulting from a meiotic division of germ-line cells
4.	The non-reproductive cells found in embryos and mature individuals

Question 2 (5 points)

Match the terms to the definitions provided.

Question 2 options:

	syngamy
	haploid
	meiosis
	diploid
	germ-line cells

1.	The cells that will eventually undergo meiosis to produce gametes.
2.	The number of chromosomes found in gametes (eggs or sperm).
3.	The process by which two haploid gametes fuse to form a new diploid cell.
4.	A specialized reduction division that produces cells with half the normal number of chromosomes.
5.	Two sets of chromosomes present in the somatic cells of adult individuals.

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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BIO 311C Lecture Notes - Lecture 12: Cell Plate, Separase, Prometaphase

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