1. What kind(s) of cell division do prokaryotes do?    binary fission
2. What kind(s) of cell division do eukaryotes do?    mitosis & meiosis (assuming cytokinesis also occurs)
3. What is the difference between the life cycle of a cell, and the life cycle of a sexually reproducing animal?

The life cycle of a cell can be part of the life cycle of a sexually reproducing animal.  (See figure 6-1 in the lab manual.)
4. To which part of a chromosome do spindle fibers attach?    to the centromere via the kinetochore (a kinetochore is a protein complex that forms at a centromere)
5. What are the stages of the cell cycle? interphase (G₁, S, G₂) and M phase (prophase. metaphase, anaphase, telophase)
6. What are the stages of mitosis?  prophase, metaphase, anaphase, telophase (cytokinesis is cytoplasmic)
7. What makes up a chromosome?   DNA double-helix - can be 1 DNA molecule, or "2" after replication  (chromatin = DNA + protein)
8. What is mitosis?    Replication of DNA, and then separation of the copies so that the 2 "daughter" cells are genetically identical to each other and to the parent cell.
9. Explain the FUNCTION(S) of mitosis.

1) growth - to go from single-celled zygote to multicellular adult
2) repair - to replace dead, lost, or damaged cells
10. In which plant tissue(s) does mitosis occur? meristematic
11. In which adult animal tissue(s) does mitosis occur?    somatic (except nerve and muscle)
12. How does the process of cytokinesis differ between animal and plant cells?

- animal cells "pinch off" the cytoplasm, forming a cleavage furrow
- plant cells, because of their cell walls, can't do this, so plant cells form a cell plate (and then form a new cell wall)
13. How many cells are present at the end of mitosis? two

What is the ploidy of the cells at the end of mitosis?    diploid (assuming started with diploid)
14. Explain the difference between sister chromatids and homologous chromosomes.

Sister chromatids are the result of DNA replication, so they are base-for-base identical.  They are also physically attached from synthesis until anaphase of mitosis (or anaphase II of meiosis).
Homologous chromosomes carry the same genes in the same order as each other (i.e., they have the same morphology), but the base sequences ot the genes are not necessarily identical.  (Individual homologous chromosomes can have sister chromatids.)

1. What are the stages and phases of meiosis? prophase I, metaphase I, anaphase I, telophase I, prophase II, metaphase II, anaphase II, telophase II
2. What distinguishing DNA event do prophase of mitosis and meiosis have in common?

DNA condensation
3. In what type of cells does meiosis occur? germ cells (diploid)
4. What type of cells are produced by meiosis? gametes (haploid)
5. What is the general name of the organs where meiosis occurs?    gonads
6. What type of chromosomes form a tetrad? homologous

When does it form?    prophase I
7. How does interkinesis differ from interphase? DNA replication does not occur in interkinesis, but it does in interphase.
8. How many cells are present at the end of meiosis? four

What is the ploidy of the cells at the end of meiosis?    haploid
9. What is meiosis?    Meiosis reduces the chromosome number in half to produce haploid cells (gametes).
10. Explain the FUNCTION(S) of meiosis. The process of meiosis allows sexual reproduction, which increases genetic variability (as does recombination).  (It also conserves a species' chromosome number from one generation to the next, when there are two parents.)
11. How is synapsis significant in terms of meiotic function(s)?    The pairing of homologues ensures that one half of each pair will end up in different gametes, and allows recombination to occur.

Synapsis occurs when the two halves of a homologous pair of chromosomes pair up and “recognize” each other to form a tetrad.  This tetrad then moves as a whole to the metaphase plate, and the halves of the pair are separated at anaphase I.  This reduction division results in two haploid daughter cells, and this is one of the functions of meiosis.  The pairing of homologues in prophase I (synapsis) ensures that each haploid daughter cell will have one half of every pair - in other words, it allows for an organized separation of homologous chromosomes.  Synapsis is also the time when recombination (crossing over) occurs, and recombination is a large source of variation, which is one of the other functions of meiosis.
12. Give the phase of mitosis or meiosis or the cell cycle described in the questions below:

(Interphase and cytokinesis are technically not stages of mitosis or meiosis, but they are stages of the cell cycle.)
• The nuclear membrane is intact, chromosomes are uncoiled, and DNA is being replicated:    interphase (S)
• The cytoplasm divides in 2 haploid daughter cells:    cytokinesis during telophase I
• Nuclear membranes reform, chromosomes uncoil, the cytoplasm divides into 4 gametes:    telophase II
• Sister chromatids line up on the equator of the cell:    metaphase (of mitosis) or metaphase II
• Synapsis and crossing over occur:  prophase I
• Reduction division occurs:   anaphase I
• In mitosis, chromatids split at the centromere and move apart:    anaphase
• In meiosis, chromatids split at the centromere and move apart:    anaphase II
13. What gamete types can an individual with this genotype produce? AaBbccDDeeFf
ABcDeF          AbcDeF          aBcDeF        abcDeF
ABcDef           AbcDef           aBcDef          abcDef

1. I am willing to try to arrange to meet with students who have questions on the course material - all you have to do is ask.  You are also welcome to email questions to me.  boet0027@umn.edu

• Linked genes, being on the same chromosome, cannot assort independently of each other.
• The meiotic basis of Mendel’s principles is seen in the parallel behavior of gene and chromosomes in meiosis I.  The separation of members of each homologous pair of chromosomes during meiotic anaphase I results in the segregation of alleles.
• The independent alignment of each pair of homologues on the spindle at meiotic metaphase I followed by disjunction accounts for the independent assortment of nonallelic genes present on different chromosome pairs.

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