Mitosis and Cytokinesis Chapter 5.2
KEY CONCEPT Cells divide during mitosis and cytokinesis.
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Chromosomes condense at the start of mitosis. DNA wraps around proteins (histones) that condense it. DNA double helix DNA and histones Chromatin Supercoiled DNA
DNA double helix DNA and histones Chromatin Supercoiled DNA Overall, DNA has a negative charge. Look at the histone proteins above, what type of overall charge do you think they will have? Positive—negative and positive charges attract so if the histones were negatively charged they would repel DNA, instead they coil together.
Vocabulary Chromosome—one long continuous thread of DNA Nucleotides—DNA made of four different subunits Histones—group of proteins associated with chromosomes (help to compact DNA) Chromatin—loose combination of DNA and proteins; ½ is called a chromatid Centromere—sister chromatids held together at their center; a region of condensed chromosome that looks pinched. Telomeres—don’t form genes—end of chromatin
DNA plus proteins is called chromatin. chromatid telomere centromere One half of a duplicated chromosome is a chromatid. Sister chromatids are held together at the centromere. Telomeres protect DNA and do not include genes. Condensed, duplicated chromosome
What is the relationship between a molecule and DNA and a Chromosome? A chromosome is made of one continuous DNA molecule
Mitosis and cytokinesis produce two genetically identical daughter cells. Interphase prepares the cell to divide. During interphase, the DNA is duplicated. Parent cell centrioles spindle fibers centrosome nucleus with DNA
Mitosis divides the cell’s nucleus in four phases. During prophase, chromosomes condense and spindle fibers form.
Mitosis divides the cell’s nucleus in four phases. During metaphase, chromosomes line up in the middle of the cell.
Mitosis divides the cell’s nucleus in four phases. During anaphase, sister chromatids separate to opposite sides of the cell.
Mitosis divides the cell’s nucleus in four phases. During telophase, the new nuclei form and chromosomes begin to uncoil.
Cytokinesis differs in animal and plant cells. In animal cells, the membrane pinches closed. In plant cells, a cell plate forms.
Cytokinesis--Plant cell vs. animal cell
Question How does cytokinesis differ in animal and plant cells? Answer: in animal cells, the membrane pinches together to separate the cytoplasm. In plant cells, a cell plate forms and divides the cell, along which the cell membrane and cell wall re-form.
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