Mitosis [compatibility mode]
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Transcript of Mitosis [compatibility mode]
CELL CYCLE
The Cell Cycle
• Cells must divide to maintain maximum efficiency.
• Mitosis is the process in which somatic (body) cells divide to form a new cell.
• Mitosis consists of four phases.
• Interphase is the period in between each mitotic cell division.
Reproduction
• Asexual Reproduction: A single cell or group of cells each duplicates its genetic material and then splits into two new genetically identical cells. – The offspring are genetically identical
• Sexual Reproduction: Genetic material from each of two parents combines, producing offspring that differ genetically from either parent. – Involves the union of sex cells (egg and sperm)
Cell division = One cell makes two cells
Parent cell
DNA replicates
Two daughter cells are genetically
identical to each other and to parent
cell = clones
Chromatin = uncondensed DNA Chromosome = condensed DNA
The same DNA can appear in two forms
1 Chromosome 1 chromatid per chromosome
1 DNA double helix
1 Chromosome 2 chromatids per chromosome
2 DNA double helices
DNA replication
Cell division in eukaryotic cells:
Cytokinesis = division of the cytoplasm
Interphase
• Interphase is made of 3 stages.
• The Gap 1 and 2 or G1 and G2 phase is when cells grow and make RNA, proteins, and other macromolecules.
• The S or Synthesis phase is when the cell is making DNA.
DNA Replication
• During the S phase of the cell cycle, DNA replicates.
• A short section of the DNA uncoils.
• New nucleotides bond to the open sections of the DNA.
• The “new” and “old” sections of DNA separate and now there are 2 DNA strands.
Interphase
• ATP is synthesized.• Damaged parts are repaired.• Wastes are excreted.• Proteins are made.• Organelles are formed.• Chromosomes are copied.• Specialized tasks are performed .
DNA = Chromatin
Interphase nucleus
Interphase
Chromatin in nucleus
Mitosis
• Mitosis consists of four phases• Prophase• Metaphase• Anaphase• Telophase
Prophase
• Longest phase.• Chromatin coils.• Nucleus disappears.• Centrioles migrate.• Spindle forms.
Prophase
Nuclear membrane disappears
Nucleolus disappears
Chromatin condenses into chromosomes
Spindle fibers appear
Chromatin
Chromosomes
Metaphase
• Chromatids attach to spindle fibers.
• Chromatids migrate to equator of spindle.
MetaphaseChromosomes line up in center of cell
Chromatids (DNA double helix)
Two chromatids per
chromosome
Centromere = holds chromatids together
Anaphase
• Centromere splits.
• Chromatids are separated.
• Chromatids are now called chromosomes.
Anaphase =
Sister chromatids separate from each other
Telophase
• Cytoplasm divides.
• Nucleus reappears.
• Chromosomes uncoil.
Telophase
Cytokinesis makes 2 new cells
Chromosomes decondense into chromatin
Nucleolus reappears
Nuclear membrane reappears
Early Telophase
Late Telophase
Cytokinesis
• In the process called cytokinesis, the cytoplasm divides and two identical daughter cells are formed.
Animal cell membranes
pinches together
between two new cells
Plant cell wall grows
between two new cells
Cytokinesis
Plant Cytokinesis =
division of cytoplasm
Interphase
Telophase
AnaphaseMetaphase
Telophase
Telophase
ProphaseProphase
http://www.unm.edu/~asmund/mitosis.jpg
Interphase
Animal cytokinesis = pinching of plasma
membrane Late Telophase
Early telophase
Anaphase
Prophase Metaphase
Plant or Animal cell
mitosis?
Plant