Chapter Nine

Relate cell reproduction to the replacement of skin cells
Skin cells constantly die and fall off as new ones replace them. In cell reproduction, cells reproduce and constantly replace one another
Describe two ways in which asexual and sexual reproduction differ
Asexual reproduction produces offspring with one parent, whereas sexual reproduction requires two
How is cell division involved in growth?
It’s how organisms reproduce
Describe how the appearance of chromosomes changes as a cell is about to divide
As the cel prepares to divide, its chromatin fibers condense and becomes visable as a compact structure
Interphase used to be described as a “resting phase.” Why is this description inaccurate?
It’s ironic and incorrect because it does anything but rest. It carries out its metabolic process and perform its functions
Summarize the events that occur during mitosis and cytokinesis
During mitosis the nucleus and the duplicated chromosomes divide and are evenly distributed, forming two “daughter” nuclei. In cytokinesis, the cytoplasm is divided by two.
Describe a significant event that occurs in each of the four stages of mitosis
Prophase- The nucleolous disappears and the cell stops making ribosomes. The nuclear envelope breaks down and chromatids attach to microtubules and make up the spindle.
Metaphase- The chromosomes gather across the middle of the cell. The miotic spindle is fully formed
Anaphase- Chromatids seperate from their partners and spindle microtubules that are not attached to the centromeres grow longer and push poles apart
Telophase- Process of prophase is reversed. Two nuclear envelopes form, and the cell splits in two
Compare and contrast cytokinesis in animal and plant cells
Cytokinesis in animal and plant cells both end in two daughter cells.
In plant cells, a cell plate forms inside the cell and grows outwards, which will divide the cell in two.
In animal cells, a microfilament ring pulls and pinches the cell into two daughter cells
In what sense may prophase and telophase in mitosis be characterized as opposites?
In telophase, the spindle formed in prophase comes undone. The nuclear envelope that broke down in prophase has reformed and multiplied into two. Whatever occurs in prophase is opposite in telophase.
List two differences between benign tumors and malignant tumors
Benign tumors are an abnormal mass of normal cells. They sometimes cause health issues, but can be easily removed through surgery. Malignant tumors, however, are masses of mutated cells that result from the reproduction of cancer cells
How might drugs that interfere with mitosis be effective in treating cancer
The cancer spreads through the division of it’s cells, therefore if a drug stops them from multiplying, it’s easier to get rid of the remaining cells
How is cancer related to cell reproduction
The cancer cells grow and divide, but at an uncontrollable rate and don’t perform apoptosis.
Describe how homologus chromosomes are different from sister chromatids
Sister chromatids are duplicated copies of a single chromosome that are attached and identical. Homologus chromosomes is one of a matching pair of chromosomes, one inherited from each parent
Compare the number of sets of chromosomes in human gametes with the number of sets in other cells in the body
Gammales have 23 chromosomes, and all others have 46
How does meiosis I reduce the number of chromosomes in the daughter cells
1. In prophase I the homologous chromosomes find their partners and synapse, pairing up with each other.
2. In metaphase I the paired, synapsed homologous chromosomes line up on the equator of the spindle.
3. In anaphase I the two chromosomes of each homologous pair are pulled apart from each other and moved to opposite poles of the spindle.
What is the final result of meiosis?
Produces 4 haploid cells
Describe how crossing over during meiosis is an individual organism recombines the genetic material of the organism’s two parents
It occurs during prophase I, when crossing over occurs, the outer two chromatids are not affected, and they still have the gene combo.
Describe two differences between meiosis and mitosis
Mitosis makes two identical cells and has two divisions. Meiosis makes tetards and has only one division
What process occurs in eukaryotic organisms that only reproduce asexually
What is the key event during the S phase of the cell cycle?
The genetic material is duplicated
When is the cytoplasm divided into two daughter cells
What step occurs during prophase in mitosis?
Nuclear envelope reappears
The spread of cancer cells beyond their original tumor site is called…
What is the product of meiosis from one parent cell
Four haploid cells

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