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50 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What are chromosomes?
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Major carriers of genetic information
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What are chromosomes made up of?
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Chromatin-consists of Dna & proteins
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Describe chromosomes & chromatin when a cell is not dividing.
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Extended partially unraveled form. Long thin threads, granular appearence.
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Histones?
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Chromosome packaging is facilitated by these proteins
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Nucleosomes?
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"beads on a string" 8 histone molecules wrapped with DNA.
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What is a karyotype?
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chromosomal constitution of an individual
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What does the cell cycle consist of?
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M phase & interphase
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M Phase?
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Mitosis & Cytokinesis
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Mitosis?
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Division of the nucleus with its associated chromosomes
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Cytokinesis?
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Division of the cytoplasm.
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Interphase?
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Stage of growth between succesive cell divisions
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Interphases' 3 stages?
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S, G1, G2
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S phase?
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Dna is replicated. DNA systhesis occurs.
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G1 phase?
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When cell is making preparations for DNA sythesis. Precedes S phase.
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G2 phase
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Follwing the S phase. Cell makes preparations to divide.
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Sister chromatids?
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identical, double-stranded DNA sequences.
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kinetochore?
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Formed from proteins, to which microtubules can bind.
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Mitotic spindle?
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When microtubules radiate from each pole, these fibers elongate towards chromosomes. Seperates chromosomes during anaphase.
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MTOC?
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Microtubule organizing center. In animal cells-centrioles. where micrutubeles connect to chromosomes.
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Centrioles in interphase
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are duplicated to form 2 pairs.
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Asters?
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The microtubules that radiate from the centrioles.
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Aster movement
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Move towards opposite ends of the nucleus-> poles of mitotic spindle.
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Prophase?
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Aster movement. Nucleolus shrinks/disappears. Nuclear envelope breaks. Spindle forms.
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ANNS
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Metaphase
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Cell's chromosomes align at the cell's midplane (METAPHASE PLATE)
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Mitotic spindles: Microtubules
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Polar and Kinetochore
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Polar Microtubules
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extend from each pole to the equilateral region, where they overlap.
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Kinetochore Microtubles
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extend from each pole and attatch to kinetochores.
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Anaphase
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Sister chromatids separate. Chromosomes move to opposite poles. Ends when all chromosomes have reached the poles.
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Telophase
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Chromosomes arrive at poles, return to interphase:
1- chromosomes condense 2- Nuclear envelope forms 3- nucleoli reorganize 4-Spindle microtubules disappear |
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Cytokinesis
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Division of the cytoplasm to yield 2 daughter cells, overlaps mitosis, beginning during telophase.
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Cytokinesis: animal
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Ring of actin microfilaments encircle the cell in the equilateral region. The ring contracts producing a CLEAVAGE FURROW, that seperates the cytoplasm into to 2 daughter cells. outside->inward
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Cytokinesis: plant
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Forming a cell plate, partition constructed in the equilateral region of the spindle and growing laterally toward the cell wall. center->outward
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Asexual reproduction
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Single parent splits, buds, fragments to produce 2 or more individuals. All cells are result of mitotic divisions.
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Sexual reproduction
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2 sex cells (gametes) form a zygote. Results in genetic variation. (genetically different from parents).
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Homologous chromosomes
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Similiar in size, shape, and position of their centromeres
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"Set" of chromosomes
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One of each kind of chromosome. 1 member of each homologous pair. 2 sets-dipoloid. 1 set- haploid. 3 or more-polyploid
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chromosome number n
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Haploid chromosome # is n. Diploid is 2n. Humans: n=23
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Meiosis
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Division that reduces the chromosome number by half. A diploid cell undergoes 2 cell divisions potentially yielding 4 haploid cells.
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Prophase I
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Homologous chromosome pairs synapse to make tetrads (4 chromatids).
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Synaptonemal complex
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structure that holds homologous chromosomes together when they synapse. Plays role in crossing over.
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Crossing-over
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Paired homologous chromosomes exchange genetic material (DNA). Produces new combinations of genes.
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Prophase & Prophase I
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Similar-xcept- the homologous chromosomes are held by "Chiasmata".
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Chiasmata
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Site at which homologous chromatids exchange genetic material.
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Metaphase I
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Tetrads line up on cell's midplane
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Anaphase I
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Homologous chromosomes seperate and move to opposite poles.
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Telophase I
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Chromatids recondense, nuclear envelope may reorganize, cytokinesis may take place. Each nucleus contains the haploid number of chromosomes.
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Interkinesis
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Stage following Telophase I, that has interphse like stages without the S-phase.
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Telophase II
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Nuclear envelopes reform, chromosomes elongate to form chromatin fibers, cytokinesis occurs.
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Sources of genetic variation
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1- maternal and paternal chromosomes of homologous pairs seperate independently. The chromosomes are shuffled.
2- DNA segments are exchanged between maternal and paternal homologues during cross over. |
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Parent cell is 2n, what is the chromosome number of daughter cells?
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Mitosis-2n
Meiosid-n |
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