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56 Cards in this Set
- Front
- Back
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Define cell devision |
Allows a single called fertilized egg to grow into an organism with trillions of cells. |
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What kind of cell continue to undergo cell division as an adult? |
Somatic |
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Define and explain Apoptosis. |
Programmed cell death. It prevents cancer and gets rid of unwanted tissue. Fragments engulfed by white blood cells. |
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Define cell cycle |
Sequence of stages that occurs between the cell is made, to the time it divides again. |
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Define cell cycle |
Sequence of stages that occurs between the cell is made, to the time it divides again. |
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What are the 2 main phases of the cell cycle? |
Interphase Mitotic stage (M stage) |
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What are the 3 stages of interphase? |
G1 - growth S - DNA synthesis G2 - growth |
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What are the 2 stages of the mitotic stage? |
Mitosis - division of nucleus Cytokinesis - division of cytoplasm |
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Which cells do not complete the cell cycle and what extra stage occurs? |
Nerve and muscle; Go |
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What does the "S" phase of interphase stand for and what happens? |
Synthesis; DNA is duplicated and in the chromatin form. Centrioles are duplicated |
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Explain the differences between chromosomes, chromatids, chromatin, and centromeres |
Chromosomes are condensed DNA, chromatids are half a chromosome, chromatin is long stringy DNA, and centromeres hold chromatids together |
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What are chromosomes? (Details) |
Compact DNA; DNA wrapped around his tones like thread on a spool |
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What happens in mitosis? |
The sister chromatids separate into daughter chromosomes |
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The 2 types of signals in the cell cycle and what they do |
Internal signals: ensure the stages follow each other in the normal sequence External signals: tell the cell whether or not to divide |
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What are the 3 checkpoints of the cell cycle? |
G1- stops if DNA is damaged G2- stops if DNA did not finish replicating M- stops if chromosomes aren't properly distributed |
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How many chromosomes do humans have? |
46, 23 pairs |
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What are cells that have a pair of each type of chromosome called? |
Diploid (2n) |
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What are cells with half the diploid # of chromosomes called and how do they result? |
Haploid (n); meiosis |
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Define mitosis |
Nuclear division in which chromosome number stays constant |
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When chromatids are pulled apart at the centromere they each become ____. |
Daughter chromosomes |
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Mitosis ____s the chromosome number |
Maintain |
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Meiosis ____s the number of chromosomes |
Reduces |
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What are the stages of the human life cycle? |
2n diploid Meiosis Gametes (haploid) Fertilization 2n diploid zygote Mitosis |
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When 1 diploid cell divides by mitosis, how many daughter cells are produced and are they diploid or haploid? |
2, diploid |
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When 1 diploid cell divides by meiosis how many daughter cells are produced and are they diploid or haploid? |
4, haploid |
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What are the phases of meiosis? |
Prophase, metaphase, anaphase, telophase |
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What happens in prophase? |
DNA condenses from chromatin to chromosomes; nuclear membrane disintegrates |
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What are spindle fibers for and what are they made of? |
Pull apart chromatids; microtubules |
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Where are centrioles found and what's their pattern? |
Centrosomes of animal cells; 9 + 0 of microtubules |
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What happens in metaphase? |
Chromosomes line up in the middle Spindle fibers attach |
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What happens in anaphase? |
Chromosomes are pulled apart and separated into chromatids; spindle fibers shorten |
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What happens in telophase? |
Cytokinesis. The nuclear membrane reforms |
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What the only difference between mitosis in plants and animals? |
Plants don't use centrioles or asters and a cell plate has to be made during cytokinesis |
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What does cytokinesis do in animal cells? |
Cleavage furrow forms and contractile ring contracts |
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What happens during cytokinesis in plant cells? |
A cell plate forms, new cell walls are built, plasma membranes are formed. |
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What are the 4 things meiosis does? |
-Produces sex cells -Reduces chromosome number in half -gives offspring a different combination of traits from both parents -variation in DNA |
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What is a homologous pair? |
1 chromosome from each parent that codes for the same trait |
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After meiosis I the cells are ___loid and after meiosis II the cells are ___loid. |
Haploid; haploid |
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What are the phases of meiosis I? |
-prophase 1 -metaphase 1 -anaphase 1 -telophase 1 |
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In what phase of meiosis does crossing over occur? |
Prophase 1 |
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What are the 2 forms of genetic variation? |
1) crossing-over 2) independent assortment |
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What is synapsis and when does it occur? |
Members of homologous pairs line up; prophase 1 |
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In what phase of meiosis does independent assortment occur? |
Metaphase 1 |
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How many possible combinations are there for a human with 23 pairs of chromosomes? |
2 to the 23 power |
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What is interkinesis? |
The period of time between meiosis I and meiosis II |
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What happens in meiosis II? |
2 haploid cells divide to form 4 haploid cels |
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What do the daughter cells of meiosis mature into? |
Gametes (sperm & egg) |
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What restores the diploid number after meiosis? |
Fertilization |
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What are the 2 main differences between mitosis and meiosis? |
1) Meiosis has 2 divisions, mitosis has 1 2) meiosis produces 4 daughter cells, mitosis produces 2 |
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Meiosis in the testes of males is called ____. |
Spermatogenesis (produces sperm) |
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Meiosis in the ovaries of females is called ___. |
Oogenesis (produces eggs) |
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When does spermatogenesis begin and stop? |
Begins at puberty, continues throughout life |
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In spermatogenesis, which divides and multiplies? |
Primary spermatocytes |
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In oogenesis, 1 ___ divides in meiosis to generate 1 ___. |
Primary oocyte; viable egg |
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What is the cycle of oogenesis? |
-begins at puberty -pauses in prophase 1 -resumes at puberty -1 oocyte continues the cycle for each menstrual cycle - |
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What happens to the oocyte in meiosis? |
-starts off diploid -a small non-functional piece is broken off in meiosis 1 making them both haploid -another small non-functional piece is broken off in meiosis 2 -the big piece is the viable egg |
