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Preliminary Objectives - Chapter 7, Part I

Terms in this set (13)

Describe the process of binary fission in prokaryotes including the shape of prokaryotic genetic material and the significance of the ori and ter sites
Prokaryote
-> Chromosome is circular in shape
-> For the process of binary fission, only one spot replication starts at, which is the Ori site
-> The ter site is the stopping point of replication
Describe the relationships between nucleotides, genes, DNA, chromatin, and chromosomes
...
Identify the events that occur in the G1, S, G2, and M stages of the cell cycle
A) Interphase
-> Occurs when a new cell has just been created through mitosis
G1: Cell is maturing to typical size. Doing typical job of a cell
S (Synthesis): Replicate its DNA, double amount of DNA and form exact copies of sister chromatids
G2: Preparing cell for division, by increasing amount of cytoplasm in cell and mitotic spindles, getting ready for mitosis
Identify how many sets of chromosomes are associated with different ploidy levels (haploid, diploid, tetraploid, ect.)
Ploidy level = # of homologs with # of sets of chromosomes
Diploid: 46 chromosomes 23 sets of chromosomes (?)
Haploid: 4 cells with 23 sets of chromosomes (?)
Tetraploid: 4 sets of chromosomes
Hexaploid: 6 sets of chromosomes
Explain the differences between sister chromatids and homologous chromosomes, and identify them in a diagram
Sister chromatids: exact copy of each other
Homologs: Never separated from each other
Describe how mitosis and meiosis differ in regards to the number of cells they produce, and the ploidy levels of the cells they create
...
Identify the following structures on diagrams, and provide their function:
o Centromeres, centrioles/asters, microtubules, kinetochores, contractile ring, cell plate
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Identify the major events that occur during each phase(s) of mitosis/meiosis:
o The disintegration of the nuclear envelope
o The reformation of the nuclear envelope
o Condensation of chromatin into distinct chromosomes
o The relaxing of chromosomes back into chromatin
o The formation of the mitotic spindle
o The disintegration of the mitotic spindle
o Synapsis and crossing over
o Alignment of chromosomes on the metaphase (equatorial) plate
o Separation of sister chromatids
o Separation of homologous chromosomes
o Migration of chromosomes/chromatids towards centrioles/asters
o Initiation of cell plate formation and cytokinesis
o Initiation of cleavage and cytokinesis
Mitosis
Prophase: condensation of chromosomes; spindle assembly

Pro-metaphase: Nuclear envelope breakdown; chromosome attachment to spindle

Metaphase: Alignment of chromosomes at equatorial plate

Anaphase: Separation of chromatids; migration to poles

Telophase: Chromosomes de-condense; nuclear envelope reforms

Cytokinesis: Cell separation; cell membrane and/or cell wall formation

Meiosis I

Early Prophase I: The chromatin begins to condense following interphase.

Mid-Prophase I: Synapsis aligns homologs, and chromosomes condense further

Pro-metaphase I: The chromosomes continue to coil and shorten. The chiasmata reflect crossing over, the exchange of genetic material b/w non sister chromatids in a homologous pair. The nuclear envelope breaks down

Metaphase I: The homologous pairs line up on the equatorial (metaphase) plate

Anaphase I: The homologous chromosomes (each w/ 2 chromatids) move to opposite poles of the cell

Telophase I: The chromosomes gather into nuclei, and the original cell divides

Meiosis II

Prophase II: The chromosomes condense again, following
a brief interphase (interkinesis) in which DNA does not replicate

Metaphase II: The centromeres of the paired chromatids line up across the equatorial plates of each cell

Anaphase II: The chromatids finally separate, becoming chromosomes in their own right, and are pulled to opposite poles. Because of crossing over and independent assortment, each cell will have a genetic makeup

Telophase II: The chromosomes gather into nuclei, and the cells divide

Outcome: Each of the four cells has a nucleus w/ a haploid # of chromosomes
Describe how cyclin and Cdk work together to deactivate "checkpoint" proteins in the cell cycle
CDK (Cyclindependentkinases) are activated by binding to cyclin; this alters its shape and exposes its active site
Describe the process of syngamy, and the ploidy levels of the gametes, zygote, and embryo
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Describe the difference between haplonic, alternation of generation, and diplontic life cycles in terms of 1) how gametes are formed, 2) the ploidy level of "adult" organisms, and 3) whether their haploid and diploid stages are unicellular or multicellular
A. Haplontic Life Cycle
Haploid stage: Make gametes (egg & sperm). When they fertilize, a zygote (2n, unicellular organism) is formed

B. Alteration of Generation
(Refer to book)
Zygote->Sporaphyte->Spores->Gametophyte->Gametes->Zygote

C. A Diplontic Life Cycle (unicellular)
Describe similarities and the differences between the events of mitosis and meiosis I, and between the events of meiosis I and meiosis II
Meiosis II is similar to Mitosis
(Refer to book)
Describe the process of synapsis, crossing over, nondisjunction, and independent assortment and how they serve to produce genetically diverse gametes
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