1. 2 Unit Goals cell cycleDescribe the phases of the cell cycle. MitosisDescribe the process of...
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Transcript of 1. 2 Unit Goals cell cycleDescribe the phases of the cell cycle. MitosisDescribe the process of...
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Unit Goals•Describe the phases of the cell cell
cyclecycle.•Describe the process of MitosisMitosis.
–Describe the functions of mitosis.
•Describe the process of MeiosisMeiosis.–Describe the functions of meiosis.–Explain the consequences of mistakes.
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Somatic cell cycle • G1 phase- Gap phase, cell
undergoes growth.
• S phase- DNA synthesis
• G2 phase- Gap phase. Preparation for Mitosis. Organelles are produced.
• M phase- Cell division (Mitosis and cytokinesis)
Interphase
Regular Cells
Sex cells are
called gamete
s
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S Phase• Chromosomes
Condense• Chromosomes
are inherited genetic information
• Chromosomes are made up of DNA
• Can only be seen when cells are dividing
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S Phase• Chromosomes Chromosomes
replicate-or copy is replicate-or copy is mademade
• The two copies areThe two copies are• --attached together at a attached together at a
point called a point called a centromerecentromere..• -are called sister -are called sister
chromatidchromatid..
When a cell divides, its two daughter cells must receive the required number of DNA molecules.
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GG2 2 PhasePhase
Organelles must be Organelles must be replicated (copied)replicated (copied)
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M PhaseM PhaseTwo parts:Two parts:
1.1.Nuclear divisionNuclear division– MitosisMitosis
2.2.Cytoplasmic DivisionCytoplasmic Division– CytokinesisCytokinesis
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MitosisMitosis• Nuclear Division.• Nucleus divides into two new nuclei
Mitosis keeps the number of chromosomes constant from one cell generation to the next.
• In eukaryotes, it is the main process by which growth and tissue repair is accomplished.
• Mitosis is also the main process by which single-celled and many multi-celled eukaryotes reproduce asexually.
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4 Steps of Mitosis (PMAT)• Prophase: Chromosomes condense and attach to
the spindle fibers at their centromere.
• Nuclear
Membrane
breaks down.
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Steps of Mitosis (PMAT)• Prophase: Prophase: Centrioles move to opposite sides of Centrioles move to opposite sides of
the cell and organize the spindle fibersthe cell and organize the spindle fibers
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Metaphase:Metaphase: Chromosomes attach to
spindle fibersand line up in the middle
of the cell
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Telophase• Nuclear Envelope reforms
There are now TWO nuclei in one cell!
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…And they contain the
SAME genetic information
*SAME NUMBER OF
CHROMOSOMES
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CytokinesisCytokinesis• Cytoplasmic divisionCytoplasmic division• Each cell gets half of the Each cell gets half of the
organelles.organelles.• After mitosis: cell pinches After mitosis: cell pinches
in half to form two new in half to form two new cells.cells.
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CytokinesiCytokinesiss
•Animal cells Animal cells pinch. pinch.
•Cytokinesis in Cytokinesis in plant cells is plant cells is different from different from that in animal that in animal cells.cells.
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•TwoTwo new cells.•The new cells- called daughter cells-called daughter cells- have the same number of same number of chromosomeschromosomes as the mother cell.
Results of Mitosis and Results of Mitosis and CytokinesisCytokinesis
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Results of Mitosis and Results of Mitosis and CytokinesisCytokinesis
•This occurs in all somatic cells in your body.
•You have 46 chromosomes in all of your somatic cells-23 pair!
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Cells during Mitosis
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http://www.youtube.com/watch?v=VlN7K1-9QB0&feature=related
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includes
is divided into
is divided into
Concept Map
Cell Cycle
M phase (Mitosis)
Interphase
G1 phase
S phase
ProphaseG2 phase
Metaphase TelophaseAnaphase
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Meiosis:Reproduction of Sex
Cells•Sex cells- Sperm and egg•Process is called Meiosis•Similar to Mitosis
Meiosis Introduction Clip
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MeiosisMeiosis•Cell divides Cell divides
twicetwice•First division is First division is
like mitosis like mitosis and then the and then the cell divides cell divides again to create again to create 4 haploid cells.4 haploid cells.
Not genetically identical!Contains ½ (HAPLOID) of the genetic information.
DIPLOID= 2 copies)31
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MEIOSIS=CHROMOSOME REDUCTION DIVISION
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Not genetically identical!Contains ½ of the genetic
information.
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MeiosisMeiosis• Meiosis is also know as Meiosis is also know as
chromosome reduction division.chromosome reduction division.• In Humans, starts with 46 and In Humans, starts with 46 and
ends up with 23.ends up with 23.• Why?Why?• Fertilization creates the diploid Fertilization creates the diploid
condition againcondition againDiploiDiploidd
HaploidHaploid
34 Meiosis Square Dance
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• Sperm formationSperm formation- 4 haploid sperm cells are formed.
• Egg formationEgg formation-most of the cytoplasm is used in one cell and the other three disintegrate. One haploid egg cell is formed.
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Crossing Over• Sometime
during meiosis the chromosomes can exchange information
• This is called Crossing Over
• Major source of genetic diversity in the species
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Prokaryotic CellsProkaryotic Cells
• Binary fission
• Occurs in Prokaryotic Cells
• DNA is copied and then the cell splits in half.
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Regulation of the Cell Cycle
• How do cells know when to divide?
• When to stop dividing?
• Cyclins-proteins that regulate the cell cycle.
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