Biology Chapter 9

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Terms in this set (...)

Key roles of cell division
Reproduction, Development, and Growth and Repair
What does the division of one cell do?
Reproduces the entire organism
Why do multicellular eukaryotes still need cell division once fully grown?
They need cell repair to renew, repair, or replace cells as needed.
Gametes
sperm and egg cells
Somatic Cells
cells of the body
Mitosis
Process used to create genetically identical daughter cells
Meiosis
Reduction cell division
DNA molecules in a cell are packaged into here
Chromosomes
Genome
all of the cells DNA (2 meters long for humans)
Number of chromosomes in a human body
46, 23 pairs
Number of Gametes in a human body
23
Chromatin
DNA & protein complex
Sister chromatids
joined identical copies of the original chromosome; separate during cell division
Centromere
Where the two chromatids are most closely attached during cell division
What are the chromatids called once seperated?
Chromosomes
If you have 20 chromatids, how many centromeres do you have?
10 centromeres
What are cells 3 choices?
Divide (mitosis or meiosis), Don't divide (arrested cell division), Die (Apoptosis)
What kind of a process is somatic cell division?
Temporal
What is the order of the cell cycle?
G1, S, G2, M
What happens in the G1 phase?
Cell growth & synthesis, 7 hours
What happens in the S phase?
DNA synthesis, chromosomes duplicated, 10 hours
What happens in the G2 phase?
More cell growth, 6 hours
What happens in mitosis?
The division of the genetic material in the nucleus, nuclear division
What happens in Cytokinesis?
The division of the cytoplasm, cell division
What happens in the mitotic phase?
Cell division, Cytokinesis and mitosis, 1 hour
A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 8 picograms of DNA per nucleus. Those cells would have _____ picograms at the end of the S phase and ______ pictograms at the end of G2.
16, 16
A particular cell has half as much DNA as some other cells in a mitotically active tissue. The cell in question is most likely in what stage?
G1, because it is right after the cell division has taken place
What are the 5 phases of mitosis?
Prophase, Pro metaphase, Metaphase, Anaphase, and Telophase
What happens in prophase?
Chromosomes become visible, nucleolus disappears, the mitotic spindle forms, and the nuclear envelope disappears
What happens in pro metaphase?
the spindle microtubules now have direct access to the genetic material of the cell.
What happens in metaphase?
chromosome line up on equatorial plate of cell
What happens in anaphase?
Each sister chromatid of a chromosome has spindle fibers attached to it. These spindle fibers begin to shorten and pull the sister chromatids apart at the centromere
What happens in telophase/cytokinesis?
nuclear membrane re-forms,
Nucleolus re-forms,
Chromsomes uncoil, and
Spindle apparatus disassembled