Term
| What is the function of meiosis in sexual reproduction? |
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Definition
| meisosis occurs during gamete formation, producing cells with half the normal number of chromosomes. The subsequent fusion of these two cells ensures a consistent chromosome number from one generation to the next. |
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Term
| Distinguish bewtween germ-line cells and somatic cells: |
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Definition
| somatic cells are all of the nonreproductive cells, but germ-line cells are the ones set aside from somatic cells early in developement and will eventually undergo meiosis to produce gametes. |
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Term
| How many cells contribute information for sexual reproduction? |
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Definition
| 2! The sperm and the egg. both haploid cells (one one set of chromosomes are present) |
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Term
| Distinguish the difference between : Gametes, Zygote, and Fertalization. |
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Definition
- Gametes (egg and sperm) each contained two chromosomes.
- Egg and sperm fuse together to form the Zygote.
- The fusion of gametes to produce new cells is know as Fertalization.
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Term
| What is it meant by the term "reductive division"? |
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Definition
| Meiosis produces cells with half the normal number of chromosomes so that the produced number of chromosomes does not explode |
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Term
| A cell starts out with 2n chromosomes -- How many cells are produced through mitosis? How many chromosomes are in each cell? |
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Definition
| 2 cells and 2 copies of every chromosomes |
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Term
| A cell starts out with 2n chromosomes -- How many cells are produced through meiosis? How many chromosomes are in each cell? |
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Definition
| 4 cells and 1 set of chromosomes in each cell |
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Term
| How do homologous chromosomes pair during meiosis? |
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Definition
| During prophase 1 of meiosis, homologous chromosomes find each other and become closely associated, a process called pairing or synapsis |
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Term
| How many rounds of division are there in meiosis in a diploid organism? what are they called? What phases are in each of these rounds? |
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Definition
| two rounds of division called meiosis I and meiosis II, which each round containing prophase, metaphase, anaphase, and telophase stages. |
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Term
| Do homologous chromosomes pair during mitosis? |
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Definition
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Term
| Do homologous chromosomes pair dusring meiosis? |
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Definition
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Term
| What is the name for this pairing in meiosis? When does this occur (what phase)? What complex is necessary? Why is the structure formed called a tetrad? |
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Definition
| The pairing is called synapsis which occurs during prohase I. The necessary complex needed is synaptonemal complex. It is called a tetrad because four chromatids of the two homolouges are closely associated during this phase of meiosis making a tetrad. |
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Term
| What is crossing-over/genetic recombination in meiosis? What are the sites of crossing over called? |
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Definition
| This process literally allows the homolouges to exchange chromosomal material. The sites for crossing over are called Chiasmata. |
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Term
| How is movement of chromosomes to the metaphase plate different in mitosis and meiosis? |
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Definition
| During metaphase I, the paired homologues move to the metaphase plate and become oriented with homologues of each pair attached to opposite poles of the spindle. In contrast, in mitosis homolouges behave independently of one another. |
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Term
| What is pulled apart in the first anaphase? how is this different in meiosis than in mitosis? |
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Definition
| During anaphase I, homologues are pulled to opposite poles for each pair of chromosomes. This again is in contrast of mitosis, in which sister chromatides, not homologues are pulled to opposite sides. |
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Term
| Explain the importance of monopolar attachment of homologous pairs at metaphase I: |
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Definition
| The monopolar attachment of chromatids would be disasterous in mitosis, but is critical to meiosis I. It produces tension on the homologues, which are joined by chiasmata and sister chromatid cohesion, pulling paired homologues to the equator of the cell. In this way each joined pair of homologues lines up on the metaphase plate. |
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Term
| Differentiate between the events of anaphase I and anaphase II of meiosis: |
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Definition
| Kinetochore microtubules shorten, and homologous pairs are pulled apart. One duplicated homologues goes to one pole and the other to the other pole. Sister chromatides do not seperate, unlike in the second phase of anaphase which is more similar to mitosis, where the centomeres split and sister chromatides are pulled to opposite poles. |
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Term
| What are the 4 distinct features of meosis? |
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Definition
- homologous pairing and crossing over joins maternal and paternal homologues during meiosis I
- Sister chromatides remain connected at the centromere and segregate together during anaphase I.
- Kinetochores of sister chromatids are attached to the same pole in meiosis I and to opposite poles in mitosis.
- DNA replication is supressed between the two meiotic division.
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Term
| Describe the difference of chromatid cohesion in mitosis and meosis: |
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Definition
| Sister chromatid cohesion is maintained through meiosis I nut released during mitosis. |
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Term
| Explain the importance of supression of replication between meiotic divisions: |
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Definition
| After meotic division, a new round of DNA replication must occur before the next division. For meiosis to suceed in halfing the number of chromosomes, this replication must be suppressed between the two divisions. |
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Term
| What is the purpose of meiosis? contrast it with the purpose of mitosis. |
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Definition
| Meiosis ensures a consistent chromosomes number from one generation to the next. meiosis has the purpose to reproduce the sex cells for an organism and has an end result of 4 new cells. Mitosis is for reproduction of all other cells and only has 2 new cells made. |
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Term
| In animals, __________ cells have the ability to ungergo meiosis. |
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Definition
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Term
| (T/F) During s phase of interphase before meiosis, the chromosomes are not replicated. Explain your answer: |
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Definition
| False, Chromosomes are still repilicated in the S phase before meiosis. The genetic material still has to be replicated because there will be 4 new cells when meiosis is over. |
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Term
| Homologous chromosomes pair during meiosis, a process know as ________. The process of ____________ results in the exchange of chromosomal material. |
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Definition
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Term
| Meiosis results in genetic variation in two ways. Describe the two ways that variation is produced. |
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Definition
- Recombination/Crossing-Over - DNA segments are exchanged between non-sister chromatids, so genetic material gets gets crossed over to another chromatid, causing a variation
- Independent assortment - maternal or paternal chromosomes are randomly pulled toward opposite poles and leaves sister chromatids attached or they ---- which leaves genetic material with them?
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Term
| Meiosis II is similar to mitosis in that______. |
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Definition
| Sister chromatids seperate during anaphase |
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Term
Which of the following is INCORRECT regarding meiosis?
- It provides for genetic variation in offspring
- It halves teh chromosome number in reproductive cells
- It occurs only in species or organism which have sexual reproduction
- It occurs in most body cells at some point during the life of an individual
- It keeps the chromosome number constant from generation to generation
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Definition
| It occurs in most body cells at some point during the life of an individual |
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Term
| Little brown bats, a particular species of bat that lives in this area, have 44 chromosomes in their somatic cells. How many pairs of homologous chromosomes does this little brown bat have? |
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Definition
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Term
| Using the information about the bat, how many chromosomes would be found in the gametes of little brown bats? |
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Definition
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