unit iv: can you divide?
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Unit IV: Can You Divide?. Cell Reproduction. All organisms REPRODUCE . Why? This allows for growth, development and the survival of the species. There are 2 types of reproduction. A sexual Reproduction Requires A single parent!!! (sorry, just ONE). Asexual Reproduction (cont)…. - PowerPoint PPT PresentationTRANSCRIPT
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Unit IV:Can You Divide?
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Cell Reproduction
• All organisms REPRODUCE.
• Why?– This allows for growth, development and
the survival of the species
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There are 2 types of reproduction
1. Asexual Reproduction
– Requires A single parent!!! (sorry, just ONE).
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Asexual Reproduction (cont)…
• Results in the offspring having the same hereditary material (DNA)
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• In other words, the new cells are an exact copy of its parent (allow for little variation among species)
Asexual Reproduction (cont)…
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Types of Asexual Reproduction
• Fission – cell splits in half (ex: Amoeba)
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Types of Asexual Reproduction (cont)…
• Budding – a new organism grows off from the side of an adult (ex: Hydra)
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Types of Asexual Reproduction (cont)…
• Regeneration – a new organism grows from a severed body part (ex: starfish)
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What is a chromosome?
• Structure found in the nucleus of a eukaryotic cell that contains hereditary material
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The structure of a chromosome
ChromosomeCentromere
Chromatid arm
Gene
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How do we replace old skin cells?• Mitosis
– The process in which the newly duplicated chromosome pairs are separated from each other
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What happens to a cell before Mitosis starts?
• Interphase– Cell grows and develops– Chromosomes duplicate themselves– Centrioles appear
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Steps of Mitosis• Prophase
– Nuclear membrane disappears– Centrioles move to opposite ends of the cell– Spindle fibers appear in the cell
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Steps of Mitosis Continued• Metaphase
– Chromosomes line up in the center of the cell– Centromeres attach to the spindle fibers
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Steps of Mitosis Continued• Anaphase
– Centromeres separate– The two strands of chromosomes are pulled
apart by centrioles towards opposite ends of the cell
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Steps of Mitosis Continued• Telophase
– Centrioles and spindle fibers disappear– Nuclear membrane begins to reappear
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What happens to a cell after Mitosis is complete?
• Cytokinesis– Cell splits into two identical daughter cells
with complete set of organelles
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How did you get here?• Sexual Reproduction
– Reproduction in which two (2) parents are involved
– Sex cells are called gametes (egg and sperm cells are gametes)
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What is sexual reproduction?
• Sexual reproduction– starts with the formation of gametes and
ends when one gamete joins another gamete. The joining of egg and sperm is called fertilization, resulting in the production of a zygote
zygote
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How are gametes produced?
• Meiosis – A process whose purpose is to reduce the
chromosome number in the cells – Produces 4 new cells with half the number of
chromosomes as the parent
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Parent Cell
1st Division
Meiosis – two divisions of the nucleus
2nd Division – 4 new daughter cells with ½ the # of chromosomes
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Meiosis continued• Diploid Cells: have two of every
chromosome (body cells)
• Haploid Cells: have just one chromosome from each pair (gametes)