Term
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Definition
| any type of cell in a multicellular organism except eggs, sperm, and their precursor cells; body cells; mitosis makes these types of cells |
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Term
| ___________ is used to make gamete cells |
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Definition
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Term
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Definition
| having one set of chromosomes; a cell or an individual organism with one set of chromosomes |
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Term
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Definition
| having two sets of chromosomes; a cell or an individual organism with two sets of chromosomes, one set inherited from the mother and one set inherited from the father |
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Term
| Humans have __ chromosomes in somatic cells (diploid 2n) |
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Definition
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Term
| Humans have __ chromosomes in a gamete cell (haploid n) |
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Definition
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Term
| What events precede a cell's entry into meiosis? |
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Definition
| Cells replicate each of their chromosomes before undergoing meiosis |
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Term
-Its role in an organism's life cycle is asexual reproduction in some eukaryotes and cell division for growth
-one cell division
-same number of chromosomes in daughter cells compared with parent cell
-No synapsis of homologs
-No crossing-over events
-Identical makeup of chromosomes in daughter cells |
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Definition
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Term
-Its role in an organism's life is halving the chromosome number in cells that will produce gametes
-two cell divisions
-half number of chromosomes in daughter cells compared with parent cell
-synapsis of homologs occur
-one or more per pair of homologous chromosomes have a crossing-over event
-different makeup of chromosomes in daughter cells (various combinations of maternal and paternal chromosomes, paternal and maternal segments mixed within chromosomes) |
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Definition
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Term
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Definition
-replicated chromosomes condense and the spindle apparatus forms
-synapsis of homologs forms pairs of homologous chromosomes, or bivalents |
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Term
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Definition
-breakdown of the nuclear envelope
-microtubules of the spindle apparatus attach to kinetochores
-chiasmata becomes visible, marking sites where crossing over occurs
-crossing over results in an exchange of segments between maternal and paternal chromosome |
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Term
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Definition
| the two identical chromatid copies in a replicated chromosome |
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Term
| Homologous chromosomes (homologs) |
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Definition
| in a diploid organism, chromosomes that are similar in size, shape, and gene content |
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Term
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Definition
| chromatids belonging to homologous chromosomes |
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Term
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Definition
| homologous replicated chromosomes that are joined together during prophase I and metaphase I of meiosis |
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Term
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Definition
| the physical pairing of two homologous chromosomes during prophase I of meiosis; crossing over is observed |
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Term
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Definition
| the X-shaped structure formed during meiosis by crossing-over between non-sister chromatids in a pair of homologous chromosomes |
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Term
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Definition
| a protein complex at the centromere where microtubules attach to the chromosome |
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Term
| During ______________ of meiosis, homologous chromosomes pairs are separated |
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Definition
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Term
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Definition
-6 total chromosomes
-3 chromosomes in 2 identical daughter cells |
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Term
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Definition
-12 chromosomes
-3 chromosomes in 4 daughter cells |
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Term
| Three sources of genetic variation for sexually reproducing organisms |
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Definition
-Random alignment of homologous chromosomes pairs during metaphase I
-Crossing over
-Random fertilization |
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Term
| The offspring from an organism that reproduces asexually are... |
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Definition
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Term
| The offspring from organisms that reproduce by self-fertilization are very likely to be... |
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Definition
| Genetically different from the parent |
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Term
| Terms of increasing genetic diversity of offspring |
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Definition
-Traditional asexual reproduction: offspring are identical to each other and to the parent
-Self-fertilization: offspring are very likely to be genetically different from the parent
-Sexual reproduction: variable and diverse amount of offspring that resemble parents, but are genetically different |
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Term
| Paradox of Sexual Reproduction |
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Definition
| mathematical model showing that because asexually reproducing individuals do not have to produce male offspring, their progeny on average can produce twice as many offspring as individuals that reproduce sexually |
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Term
| Conclusion of Figure 13.14 |
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Definition
| Outcrossing is favored because of exposure to evolving pathogens |
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Term
| For a diploid organism that has 12 total chromosomes in each somatic cell, how many unique combinations of alleles are possible in the gametes of this individual (not taking crossing over into account)? |
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Definition
4096 possible unique combinations
(2^12) |
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Term
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Definition
| a non-sex chromosome (ex chromosomes 1-22 in humans) |
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Term
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Definition
| chromosome associated with an individual's sex (X and Y chromosome for humans) |
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Term
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Definition
| XXY on the 23rd chromosome |
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Term
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Definition
| XO (only one X chromosome by itself) on the 23rd chromosome |
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Term
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Definition
| trisomy on 21st chromosome |
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Term
| Explain how a nondisjunction event can cause chromosomal disorders. |
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Definition
| If both homologs in meiosis I, or both sister chromatids in meiosis II move to the same pole of the parent cell, the products of meiosis will be abnormal |
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Term
| T/F: The father is more often the source of the chromosome abnormality |
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Definition
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Term
| T/F: The older you are the higher chance a nondisjunction event can occur |
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Definition
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Term
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Definition
| the state of having only one copy of a particular type of chromosome in an otherwise diploid cell |
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Term
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Definition
| the state of having three copies of one particular type of chromosome in an otherwise diploid cell |
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Term
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Definition
| the state of having more than two full sets of chromosomes, either from the same species (autopolyploidy) or from different species (allopolyploidy) |
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Term
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Definition
| the state of having three full sets of chromosomes |
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Term
| What are homologous chromosomes? |
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Definition
| Chromosomes that are similar in their size, shape, and gene content |
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Term
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Definition
| A group of four chromatids produced when homologs synapse |
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Term
| T/F: Half of the chromosomes in a human skin cell are paternal chromosomes |
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Definition
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Term
| Meiosis II is similar to.... |
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Definition
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Term
| Explain the relationship between homologous chromosomes and the relationship between sister chromatids |
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Definition
| Homologous chromosomes are similar in size, shape, and gene content, and originate from different parents. Sister chromatids are exact copies of a chromosome that are generated when chromosomes are replicated |
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Term
| Meiosis is called a reduction division, but all the reduction occurs during meiosis I – no reduction occurs during meiosis II. Explain why meiosis I is a reduction division but meiosis II is not. |
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Definition
| Meiosis I is a reduction division because homologs separate-daughter cells have just one of each type of chromosome instead of two. Meiosis II is not a reduction division because sister chromatids separate-daughter cells have un-replicated chromosomes instead of replicated chromosomes and chromatids will be present in each daughter |
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Term
| Dogs have 78 chromosomes in their diploid cells. If a diploid dog cell enters meiosis, how many chromosomes and chromatids will be present in each daughter cell at the end of meiosis I? |
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Definition
-39 chromosomes
-78 chromatids |
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Term
| Triploid (3n) watermelons are produced by crossing a tetraploid (4n) strain with a diploid (2n) plant. Briefly explain why this mating produces a triploid individual. Why can mitosis proceed normally in triploid cells, but meiosis cannot? |
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Definition
| Tetraploids produce diploid gametes, which combine with a haploid gamete from a diploid individual to form a triploid offspring. Mitosis proceeds normally in triploid cells because mitosis doesn't require forming pairs of chromosomes. But during meiosis in a triploid, homologous chromosomes can't pair up correctly. The third set of chromosomes does not have a homologous partner to pair with |
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Term
| Some plant breeders are concerned about the susceptibility of asexually cultivated plants, such as seedless bananas, to new strains of disease-causing bacteria, viruses, or fungi. Briefly explain their concern by discussing the differences in the genetic “outcomes” of asexual and sexual reproduction. |
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Definition
| Asexually produced individuals are genetically identical, so if one is susceptible to a new disease, all are. Sexually produced individuals are genetically unique, so if a new disease strain evolves, at least some plants are likely to be resistant |
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Term
| The gibbon has 44 chromosomes per diploid set, and the siamang has 50 chromosomes per diploid set. In the 1970s a chance mating between a male gibbon and a female siamang produced in offspring. Predict how many chromosomes were observed in the somatic cells of the offspring. Do you predict that this individual would be able to form viable gametes? Why or why not? |
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Definition
| The gibbon would have 22 chromosomes in each gamete, and the siamang would have 25. Each somatic cell of the offspring would have 47 chromosomes The offspring should be sterile because it has some chromosomes that would not form homologous pairs at prophase I of meiosis |
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