Term
| What happends in sexual reproduction? (5) |
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Definition
1. 2 parents
2. Exchange of DNA
3. Offspring genetically different from parents
4. Involves specialized sex cells (gametes)
5. Creates diversity |
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Term
| Conjugation - in simple organisms |
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Definition
1. Cytoplasm bridge forms between 2 cells and an exchange of DNA takes place
2. Occurs between two cells with different mating types
3. Mating types are usually called plus (+) and minus (-) |
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Term
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Definition
| sex cell - sperm or egg - one set of chromosomes |
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Term
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Definition
| The two gametes combine and produce a ZYGOTE |
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Term
| How are gametes produced? |
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Definition
| To produce gametes egg and sperm need to be made then joined. We make gametes from meoisis |
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Term
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Definition
| stomatic cells are body cells that have 2 sets of chromosomes (diploid) |
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Term
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Definition
| chromosomes that are paired and have the same information |
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Term
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Definition
| same copy of chromosomes (body cell) |
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Term
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Definition
Special cell division that occurs in sexually reproducing organisms
Makes gametes |
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Term
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Definition
| Meiosis actually reduces the number of chromosomes by creating haploid - gamete - sex cells |
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Term
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Definition
| DNA replicates; cell grows |
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Term
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Definition
Homologous chromosomes pair up and form a tetrad
- crossing over occurs |
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Term
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Definition
| occurs during synapsis - the tetrads exchange parts of DNA - helps to create diversity |
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Term
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Definition
Tetrads line up at the equator.
Centromeres attach chromosomes to the spindle fibers |
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Term
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Definition
| Homologous chromosomes separate and move to the poles |
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Term
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Definition
Homologous Chromosomes pair up and form a tetrad.
Occurs during prophase 1 |
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Term
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Definition
| Cytoplasm divides, forming two new daughter cells |
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Term
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Definition
| Occurs simultaneously with telophase I |
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Term
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Definition
Spindle forms
Sister chromatids move toward the equator |
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Term
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Definition
Sister chromatids line up at the equator
Similar to mitosis
Spindle fibers attach at the centromere |
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Term
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Definition
| Sister chromatids separate and move to opposite poles |
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Term
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Definition
Nuclei form at poles and cytokinesis occurs
After completion of cytokinesis there are 4 daughter cells |
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Term
| What is a positive effect of meiosis? |
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Definition
| it creates genetic diversity |
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Term
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Definition
Chromosomes are separated and combined independently of each other during meiosis
Produces many different combinations for the gametes (genetic diversity) |
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Term
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Definition
| Sometimes chromosomes don’t separate properly |
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Term
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Definition
Gametes develop within specialized organs called gonads
Females - ovaries
males - testes |
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Term
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Definition
Gametes fuse inside the body of a female
Occurs in many land animals
Offspring have a better chance of survival
Fewer offspring are produced |
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Term
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Definition
Gametes fuse outside the body of a female
Occurs in many water animals
Many offspring produced
Fewer offspring survive |
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Term
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Definition
Development of an unfertilized egg into an adult animal
E.g. rotifers, some insects such as bees, wasps,
E.g. Queen bee can produce fertilized or unfertilized eggs. |
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Term
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Definition
Sometimes chromosomes don’t separate properly
result in a cell with too many or too few chromosomes |
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Term
| Trisomy 21– Downs Syndrome |
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Definition
| an extra chromosome on the 21st chromosome pair. |
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Term
| How many useable haploid cells does Spermatogenesis produce? |
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Definition
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Term
| How many functional (useable) haploid cells does oogenesis create? |
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Definition
| Produces 1 haploid egg and 3 haploid polar bodies |
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Term
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Definition
Hermaphrodites have both testes and ovaries
E.g. earthworm, snails, and hydra |
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