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Chapter 5
cell division (1st semester, 9th grade)
Question | Answer |
---|---|
What is the difference between large cells and small cells? How are small cells more practical than larger cells? | smaller cells have more surface area w less volume which makes it easier to transport nutrients across them membrane |
What is cell division? | splitting one cell into 2 |
What is cell division essential for? (3 things) | growth repair and reproduction |
What is growth? | result of cells producing cells through cells division |
What is repair? | new cells are formed to replace cells that are lost or injured |
What are the 2 types of reproduction? | sexual/asexual |
What is asexual reproduction? | process when offspring is produced by one parent |
What is sexual reproduction? | produces offspring that have a combination of genetic material from 2 parents |
What are the 2 main divisions of reproduction? | interphase/cell division |
What is G1? | g=gap, characterized by growth and development |
What is G2? | cell will synthesize orgenelles and other materials |
interphase definition | part of cell cycle that happens between divisions |
what happens during interphase? | calls are very active, producing all materials needed for growth and prep for cell division |
how much does interphase account for? | 90% |
what are the 3 phases of interphase? | G1, G2, S |
what does the "s" stand for in S phase? | s- synthesis |
what happens during S phase? | chromosomes of nucleus duplicate , and replication occurs when material makes copy of itself |
what does DNA stand for? | Deoxyribonucleic acid |
where is DNA found? | in nucleus and holds all genetic info for organisms |
why do we need DNA? | so genetic info can be passed from parent to child to continue human species |
what happens during S phase to DNA? | each chromosome replicates, then the chromatin is formed into chromatids which are short. |
what do sister chromatids have in common? | they're identical structures that result from chromosome replication, and they become visible during cell division |
what is the point where sis chromatids are joined? | centromere |
What are chromatin? | thin, fiberous form of DNA and protein |
What are the chomatin formed into? | chromatids |
What are sister chromatids? | 2 identical structures that result from chromosome replication |
What is mitosis? | continuous process that forms 2 new nuclei in preparation for 2 new daughter cells |
What are the 4 phases of mitosis? | propahse, metaphase, anaphase, telophase |
What is metaphase? | chromosomes are pulled into the center of the cell where they line up on the metaphase plate |
where does prophase happen? | cytoskeleton |
what happens during prophase? | proteins assemble into microtubules forming structures called spindle fibers |
what's going on during late prophase? | nuclear envelope disintegrates and part of each chromosome centromere attaches to spindle fiber. fibers then pull sis chromatids toward center of cell |
what happens during anaphase? | centromeres divide and spindle fibers pull 1 set of chromatids toward opposite sides of cell, then separated chromatids are identical sets of daughter chromosomes |
what happens at end of anaphase? | 2 sets of daughter chromosomes are at opposite "poles" of cell |
what happens during cytokinesis in animals? | is cytoplasm where cell finally divides to form 2 identical cells |
What is telophase? | 2 daughter nuclei are formed around each set of chromsomes which uncoil to form loose mass of chromatin spindle fibers disassemble |
what happens during cytokinesis in plants? | cell plate begins to form during late anaphase which develops into new cell wall |
What happens reproduction? | genetic information of a patent is combined with the other parent to produce a child |
how many chromosomes are in a human cell? | 46 |
What is a diploid cell? | cell that has 2 complete sets of chromosomes and are usually somatic |
Why is it important for sex cells to be haploid? | because if each parent had 46 chromosomes then the child would have 92. haploid cells are only 23 |
How does meiosis work? (2) | meiosis I and meiosis II |
What are the differences btwn meiosis and mitosis? | meiosis- 4 genetically diverse haploid cells mitiosis-2 genetically identical diploid cells |
What is prophase I? | chromosomes condense and each homologous pair becomes attached to one another (this formation is called tetrad) |
which process is meiosis part of? | process of developing genetic diversity through cell divisions |
where does meiosis happen? | 2 types: -somatic=almost all cells in body -reproductive =(gametes) egg and sperm cells |
are human sex cells haploid (n)? | yes. only contain half of # of chromosomes as diploid cells |
what are haploid reproductive cells called? | gametes/ sex cells |
what is meiosis part of? | cellular reproduction in which # of chromosomes is reduced by half so daughter cells are haploid |
what is homologous? | all but one of those 23 cells are called homologous pairs, which means that they are same size and code for same info |
what happens b4 meiosis 1? | diploid cell replicates its chromosomes so each chromosome consists of 2 sis chromatids |
What happens during tetrad formation? | process called crossing over |
what is crossing over? | sister chromatids cross to each other and exchange genetic info |
What is anaphase I? | homologous pairs are pulled to opposite sides of cell (sister chromatids are still attached) |
What is the difference btwn meiosis I and meiosis II? | w reg meiosis metaphase doesn't include the tetrad form |
What is variation? | differences btwn members of a population |
where does the variation of genetic info come from? | the mixing of parent genes during sexual reproduction |
meiosis process | prophase 1, metaphase1, anaphase1, telophase 1 |
what's metaphase 1? | chromosomes line up along middle of cell like in mitosis but w/ homologous pairs still in tetrad form |
telophase 1 is...? | ends as mitosis w/ 2 new nuclei w/. chromosomes inside them. difference is that sis chromatids are still attached. cell will then divide and go right into meiosis 2 |
3 main differences between meiosis and mitosis | 1- daughter cells haploid instead diploid 2- daughter cells are not genetically identical 3- cell division takes place twice producing 4 daughter cells instead of 2 |
what happens to gametes? | combine randomly during fertilization |