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Chapter 11
Cell Cycle
45
Biology
Undergraduate 1
10/26/2014

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Term
What are Hela cells and why are they so significant?
Definition
Hela cells are cancer cells from a woman long ago that are rapidly dividing and are still being used to this day to do research.
Term
What three major events must occur before cytokinesis can?
Definition
Reproductive signal , replicating of DNA, cell segregation
Term
How does cell division differ from eukaryotic and prokaryotic cells?
Definition
Eukaryotic uses bianry fission and prokarotic uses mitosis or meiosis
Term
What are the three steps of interphase?
Definition
G1 S and G2
Term
What happens in G1 of interphase?
Definition
each cell is single and unreplicated and gets the signal to continue in the cycle
Term
What happens in S of interphase?
Definition
DNA replication
Term
What happens in G2 of interphase?
Definition
Preparations for mitosis
Term
Explain how an unduplicated chromosome becomes a duplicated chromosome containing sister chromatids?
Definition
It replicates in the S phase
Term
How do sister chromatids compare genetically?
Definition
They are genetically identical
Term
Interphase VS mitosis
Definition
Interphase is the preparation for mitosis
Mitosis is nuclear division
Term
What do condensins do for chromosome structure?
Definition
Coat the DNA molecules and make them more compact
Term
What do histones do for chromosome structure?
Definition
Package DNA (holds it together)
Term
What do cohesin do for chromosome structure?
Definition
Hold sister chromatids together
Term
Compare the number of chromosomes and the amount of DNA contained in the nucleus during the G1 phase vs. the G2 phase
Definition
Chromosome count doesn't change
DNA 1:2
Term
What are the 4 stages of mitosis?
Definition
Prophase, Metaphase, Anaphase, and Telophase
Term
What 2 roles do microtubules play?
Definition
1) form spindle
2) attach to two sister chromatids to make sure they end on opposite poles
Term
Centromere vs centrosome
Definition
Centromere- link sister chromatid
Centrosome- main microtubule organizer
Term
What happens in prophase?
Definition
Chromatins are compacting, nuclear envelope is decomposing, spindle starts to form
Term
What happens in metaphase?
Definition
Centromeres align at the cells equator
Term
What happens in anaphase?
Definition
Paired sister chromatids separate, new daughter chromosomes move toward poles
Term
What happens in telophase?
Definition
Daughter chromosomes reach the poles, nuclear envelope and nucleoli re-form, chromatins decondenses
Term
Why are cytokinesis and mitosis different?
Definition
Mitosis is nuclear division and cytokinesis is the splitting of the cytoplasm after mitosis is done
Term
What is the main biological function of mitosis
Definition
to segregate copies of genetic information
Term
How does cytokinesis differ between animal and plant cells? Why does it differ?
Definition
In animal cells it has a contractile ring In plant cells it starts with membranous vesicles from the golgi apparatus appear along the plane of cell division
They differ because of the plant cells rigid cell wall
Term
What is the genetic state of offspring after asexual reproduction? What is a clone?
Definition
Genetic clones
Identical copy of parent
Term
What is the biological function of sex?
Definition
To create diversity
Term
Compare somatic cells with gametes.
Definition
somatic cells are not needed for reproduction and are made in mitosis
Gametes are cells made for sex and made in meiosis
Term
What is fertilization?
Definition
When two haploid gametes are fused to form a zygote
Term
How many nuclear divisions in meiosis vs mitosis
Definition
2:1
Term
What is the main function of meiosis?
Definition
to make gametes
Term
What are four major differences between meiosis and mitosis?
Definition
MITOSIS: 1 Cell Division. 2 Daughter Cells. Daughter Cells are identical to Parent Cells. No crossing over. MEIOSIS: 2 Cell Division. 4 Daughter Cells. Daughter Cells are haploid. Crossing over takes place.
Term
Explain synapsis during prophase I and how this leads to crossing over. What chromosomes typically ‘cross over’?
Definition
The homologous chromosomes pair by adhering along their lengths, the four chromatids of each pair of homologous chromosomes form a tetrad.
Term
How is meiosis II similar to mitosis? How is meiosis II different from mitosis?
Definition
In both cases chromosomes line up and sister chromatids are separated by the action of the spindle fibers. The daughter cells are genetically identical to one another.
end result meiosis produces 4 cells with 1/2 the normal number of chromosomes and mitosis only 2 cells with the normal complement of chromosomes
Term
What is nondisjunction and what genetic problems can it lead to?
Definition
Failure of chromosome pairs or sister chromatids to split properly;Aneuploidy
Term
What is nondisjunction and what genetic problems can it lead to?
Definition
Failure of chromosome pairs or sister chromatids to split properly;Aneuploidy
Term
What is down syndrome? Why does it happen?
Definition
An extra 21st chromosome that leads to intellectual impairments, because of Aneuploidy
Term
What 3 ways does sexual reproduction lead to genetic variations?
Definition
Crossing over in Prophase 1, Random assortment in metaphase 1, fertilization of random gamete
Term
Compare and contrast necrosis with apoptosis.
Definition
Necrosis- cell death from environmental causes Apoptosis- genetically programmed cell death
Term
How can the lack of apoptosis be bad for a human?
Definition
overpopulation of cells, more prone to diseases
Term
What 2 ways do cancer cells differ from normal cells?
Definition
Cancer cells lose control over cell division, cancer cells can migrate to other locations in the body
Term
What is the difference between a benign tumor and a malignant tumor?
Definition
Benign- look like parent tissues, stays in the same location Malignant- don’t look like parent tissue, can move locations
Term
What is metastasis?
Definition
Malignant growth of cells at a distance from primary site
Term
What are oncogenes and what is their role in cancer development?
Definition
Negative regulators, inactive in cancer cells
Term
What are tumor suppressors and what is their role in cancer development?
Definition
Is a gene that protects a cell from one step on the path to cancer. When this gene mutates to cause a loss or reduction in its function, the cell can progress to cancer
Term
Describe how one cancer drug functions in the cell.
Definition
Paclitaxel- interferes with the mitotic spindle, preventing the chromosomes from dividing which keeps cancer cells from dividing. But it also prevents other cells from dividing.
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