Mitosis and Cytokinesis Chapter 5.2. KEY CONCEPT Cells divide during mitosis and cytokinesis.
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Transcript of Mitosis and Cytokinesis Chapter 5.2. KEY CONCEPT Cells divide during mitosis and cytokinesis.
Mitosis and Cytokinesis
Chapter 5.2
KEY CONCEPT Cells divide during mitosis and cytokinesis.
• Show biology presentation film clip mitosis 2
Chromosomes condense at the start of mitosis.
• DNA wraps around proteins (histones) that condense it.
DNA doublehelix
DNA andhistones
Chromatin
SupercoiledDNA
• 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.
DNA doublehelix
DNA andhistones
Chromatin
SupercoiledDNA
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.• 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
chromatid
telomere
centromere
telomere
• What is the relationship between a molecule and DNA and a Chromosome?
• A chromosome is made of one continuous DNA molecule
Parent cell
centrioles
spindle fibers
centrosome
nucleus withDNA
• Interphase prepares the cell to divide.
• During interphase, the DNA is duplicated.
Mitosis and cytokinesis produce two genetically identical daughter cells.
• 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.
Get Textbook
• Go to page 142• Read the Data Analysis box (in orange)Then answer the two questions:1. Display Data2. Apply