Transcript ch 20 sect 1 notes
Chapter 20:1 Notes
Pages 590-597
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Continuing Life
Reproduction
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How offspring are produced
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Species could not go on without
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reproduction
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Parents pass on heredity
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material
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DNA controls how offspring will look because the DNA controls what proteins each cell will produce
Life’s Code - DNA
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DNA is found inside chromosomes
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DNA is your individual blueprint
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DNA determines your hair color, ear shape, blood type, and EVERYTHING else about you!
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The basic shape is like a twisted ladder or zipper
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The ladder rungs contain pairs of bases
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There are 4 bases that pair up in different orders on the ladder
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Cell Division
Mitosis creates new cells due to aging, missing, or injured cells Interphase Chromosomes are duplicated Interphase Prophase The chromosomes are now visible through a microscope Metaphase Chromosome pairs line up in the m iddle of a cell Anaphase The pairs separate ( a part) to opposite ends Telephase – the cell divides into 2 ( t wo) daughter cells
Mitosis
• Mitosis is what occurs after meiosis has taken place. Once you have your full set of chromosomes, mitosis can begin.
• Some cells do not do much division to replace themselves (such as neurons, or nerve cells) • However, many others have a high turnover, such as epidermal cells. If they did not, eventually your skin would wear out.
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Asexual Reproduction (3 types)
1. Budding When a new individual grows on a another one.
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It will eventually break away.
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It has the exact DNA copy of the original
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EX- hydra, potato
2. Regeneration
• Replace a body part (regenerate) due to an injury • EX- starfish, chameleon
3. Cloning
• Exact copy • Initially, plants were cloned • First successful cloned mammal was Dolly the Sheep in 1997
Sexual Reproduction
• An organism is produced from the DNA of 2 cells • Sex cells join together • The sex cells are the male sperm and the female egg
Human Reproduction-
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fertilization
A female sex cell, egg, has 23 chromosomes
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A male sex cell, sperm, has 23 chromosomes
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They unite and create a new cell with 46 chromosomes
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This cell forms into a fully formed baby
Chromosomes
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There are 23 pairs of chromosomes in the human body.
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23+23=46
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46 TOTAL chromosomes
Meiosis
• • • • • • • Sex cells are created through meiosis
Interphase Prophase Chromosomes are duplicated The chromosomes are now visible through a microscope Metaphase Chromosome pairs line up in the m iddle of a cell Anaphase The pairs separate ( a part) to Telephase opposite ends – the cell divides into 2( t wo) daughter cells The process then REPEATS with the two daughter cells to form a total of 4 daughter cells
3 Key Differences Between Meiosis and Mitosis
• A. Mitosis divides one nucleus into two; Meiosis divides one nucleus into four. • B. Mitosis conserves chromosome number; Meiosis reduces it in half (usually from diploid [46 in humans] to haploid [23] ). • C. Mitosis produces genetically
identical
daughter nuclei; Meiosis produces genetically
different
daughter nuclei.
Interphase
Sex Cells in Plants
• Male flower parts produce pollen, which contain sperm cells • Female flower parts produce eggs • When the sperm and egg join they create a cell which is protected in a SEED
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