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Cell Reproduction. Prokaryotes Bacteria Eukaryotes Plants & animals. Prokaryotes. Lack a nucleus Have a single chromosome Reproduce asexually by binary fission Include bacteria. Asexual Reproduction contd. Binary fission happens in bacteria, amoeba, some algae - PowerPoint PPT Presentation
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Cell ReproductionCell Reproduction
ProkaryotesBacteria
EukaryotesPlants &
animals
ProkaryotesProkaryotes
Lack a nucleus Have a single chromosomeReproduce asexually by
binary fission Include bacteria
Asexual Reproduction contdAsexual Reproduction contd..
Binary fission– happens in bacteria, amoeba, some
algae– one parent cell splits into 2 identical
daughter cellsBudding
– happens in yeast, hydra, corals– parent produces a bud– bud gets detached and develops into
offspring which is identical to parent
Steps in Binary FissionSteps in Binary Fission
Used by bacteria Cells increase their
cell mass slightly DNA & cell
components are replicated
Each cell divides into 2 daughter cells
Binary Fission of Bacterial Binary Fission of Bacterial CellCell
BuddingBudding
EukaryotesEukaryotes
Contain a nucleus & membrane bound organelles
Asexually reproduce cells by mitosis
Also reproduce sexually
Sexual Reproduction in AnimalsSexual Reproduction in Animals involves specialized sex cells called gametes (haploid
Cells) the union of a male and female gamete results in the
formation of a zygote that develops into a new individual
Cell CycleCell Cycle
Stages in growth & division
G0 Resting Phase
G1 Phase S Phase G2 Phase M Phase Cytokinesis
G0 PhaseG0 Phase
After Cell DivisionCell At RestFrom here some cells will remain in the G0 Phase and others will go into G1.
G1 PhaseG1 Phase
First growth stageCell increases in sizeCell prepares to copy its DNA
Synthesis PhaseSynthesis Phase
Copying of all of DNA’s instructions
Chromosomes duplicated
G2 PhaseG2 Phase
Time between DNA synthesis & mitosis
Cell continues growingNeeded proteins produced
Mitosis PhaseMitosis Phase
Cell growth & protein production stop
Cell’s energy used to make 2 daughter cells (Diploid Cells)
Called mitosis or karyokinesis (nuclear division)
Life Cycle of a CellLife Cycle of a Cell
Mitosis is a cycle with no beginning or end.
Interphase – Resting StageInterphase – Resting Stage
Cells carrying on normal activities
Chromosomes aren’t visibleCell metabolism is occurringOccurs before mitosis
InterphaseInterphase
Stages of MitosisStages of Mitosis
ProphaseMetaphaseAnaphaseTelophase
Cells Undergoing MitosisCells Undergoing Mitosis
Steps in ProphaseSteps in Prophase
DNA coils tightly & becomes visible as chromosomes
Nuclear membrane disappears Nucleolus disappears Centrioles migrate to poles Spindle begins to form
ProphaseProphase
Eukaryotic ChromosomeEukaryotic Chromosome
Human ChromosomesHuman Chromosomes
Steps in MetaphaseSteps in Metaphase
Spindle fibers from centrioles attach to each chromosome
Cell preparing to separate its chromosomes
Cell aligns its chromosomes in the middle of the cell
MetaphaseMetaphase
Steps in AnaphaseSteps in Anaphase
Cell chromosomes are separated
Spindle fibers shorten so chromosomes pulled to ends of cell
Mitotic SpindleMitotic Spindle
AnaphaseAnaphase
Steps in TelophaseSteps in Telophase
Separation of chromosomes completed
Cell Plate forms (plants)Cleavage furrow
forms(animals)Nucleus & nucleolus reformChromosomes uncoil
TelophaseTelophase
Plant Animal
CytokinesisCytokinesis
Occurs after chromosomes separate
Forms two, identical daughter cells
CytokinesisCytokinesis
Cell Plate Forming in Plant Cells
Cell that do not go through Cell that do not go through MitosisMitosis
Muscle Cell-Why? Fused fibers preventing cell division
Some Neuron Cells –Why? Have lost there centrioles and can no longer reproduce.
Blood Cells-Why? Mature and No longer have a nucleus
Sex Cells: They go through meiosis. Most of the cells never leave the G0 phase.
CanceCancerr Cancer is a disease of uncontrolled cell division. It
starts with a single cell that loses its control mechanisms due to a genetic mutation. That cell starts dividing without limit, and eventually kills the host.
Normal cells are controlled by several factors. – Normal cells stay in the G1 stage of the cell cycle
until they are given a specific signal to enter the S phase, in which the DNA replicates and the cell prepares for division. Cancer cells enter the S phase without waiting for a signal.
– Normal cells are mortal. This means that they can divide about 50 times and then they lose the ability to divide, and eventually die. This “clock” gets re-set during the formation of the gametes. Cancer cells escape this process of mortality: they are immortal and can divide endlessly.
THE ENDTHE END