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Mitosis/Meiosis. How do your cells divide?. A few words before we start…. Haploid : ( n ) 1 set of unpaired chromosomes Diploid : (2n) 2 haploid sets of chromosomes (1 pair). Interphase. A Cell’s Life.
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Mitosis/Meiosis How do your cells divide?
A few words before we start….. • Haploid: (n) 1 set of unpaired chromosomes • Diploid: (2n) 2 haploid sets of chromosomes (1 pair)
Interphase A Cell’s Life G1 is a growth phase. S phase is the synthesis phase or when DNA is replicated. During the G2 phase, organelles and molecules required for cell division are produced
Why Do Cells Divide? Surface area to volume ratio Damaged cells Sex cells
CellReproduction is either sexual or asexual
Asexual Reproduction(one parent) • Binary Fission- • Budding • Vegetative Propagation • Regeneration
DNA Structure Ch. 9 • Made up of nucleotides • There are 3 parts to each nucleotide • Deoxyribose sugar • Phosphate group • One of 4 Nitrogen bases
T A C G C G Phosphate group Nitrogen Base Nucleotide Deoxyribose Sugar
T A C G Nitrogen Bases There are four possible nitrogen bases: Adenine (A) Thymine (T) Cytosine (C) Guanine (G)
T A C G Nitrogen Base Pairing These bases always pair together in DNA: Adenine (A) Thymine (T) Cytosine (C) Guanine (G)
DNA Replication • Before a cell can divide the DNA must replicate (make a copy of itself)
DNA Replication • Making a new strand of DNA is actually quite easy. • Replication occurs in 3 easy steps…
1. DNA Unzips • An enzyme unzips the molecule • The enzymes breaks the hydrogen bonds that hold the nitrogen bases together.
T A C G C G DNA Replication DNA Unzips
T A C G C G DNA Replication DNA Unzips
T A C G C G DNA Replication DNA Unzips
T A C G C G DNA Replication DNA Unzips
T A C G C G DNA Replication DNA Unzips
T A C G C G DNA Replication DNA Unzips Left Strand of Original DNA Right Strand of Original DNA
2. Base Pairing • Complementary bases match with each DNA strand in the open helix
DNA Replication Base Pairing T A C G G C Left Strand Original DNA Right Strand Original DNA
DNA Replication Base Pairing T T A C G G C Left Strand Original DNA Right Strand Original DNA New Right DNA Strand
DNA Replication Base Pairing T T A C C G G C Left Strand Original DNA Right Strand Original DNA New Right DNA Strand
DNA Replication Base Pairing T T A C C G G C C Left Strand Original DNA Right Strand Original DNA New Right DNA Strand
DNA Replication Base Pairing T T A A C C C C G G Left Strand Original DNA Right Strand Original DNA New Right DNA Strand New Left DNA Strand
DNA Replication Base Pairing T T A C C G G C C A G Left Strand Original DNA Right Strand Original DNA New Right DNA Strand New Left DNA Strand
DNA Replication Base Pairing T T A C C G G G C C A G Left Strand Original DNA Right Strand Original DNA New Right DNA Strand New Left DNA Strand
3. DNA Zips Up • An enzyme zips the new molecules back up.
T T T A A A C C C G G G C C C G G G DNA Replication • Voila! • Two identical strands of DNA!
DNA Replication Review Step 3 Step 2 Step 1
Remember - All this takes place in the S phase of INTERPHASE
T T A A C C G G C C G G Now that DNA has replicated, we are ready to begin Mitosis (nucleus of the cell divides)
It’s all about the chromosomes! • There are 46 in human body cells • The number of chromosomes remain constant during Mitosis Sister chromatids
Parent Cell MITOSIS DNA condenses into chromosomes. The centrioles separate, and the spindle form. The nuclear envelope disappears. Prophase Chromosomes align on the equator. Each chromosome is connected to a spindle fiber at its centromere. Metaphase
Sister Chromatids separate into individual chromosomes Anaphase Chromosomes gather at opposite ends. DNA uncoils and two new nuclear envelopes form. Telophase
Cytokinesis • Cleavage (indention in cell membrane) or cell plate formation occurs. • Cell divides. Plant Cell Animal Cell
Which Cells Go Through Mitosis? Cells which help the body in: Growth Repair Work The cells are called autosomes
What happens if cell division gets out of control? • CANCER • The body doesn’t respond normally to the body’s control mechanisms • p. 127, 138-139
Bone Cancer X-ray Ovarian Cancer Cell Dividing
Mitosis Review 1. Is the beginning parent cell diploid or haploid (2n or n)? 2. Are the daughter cells diploid or haploid (2n or n)?
More Mitosis Review 3. How many daughter cells are produced? 4. Are the resulting daughter cells different from the parent cell?
More Mitosis Review 5. Are the resulting daughter cells different from each other? 6. How many chromosomes are in a human parent cell? 7. How many chromosomes are in a human daughter cell?
More Mitosis Review 8.What types of cells are produced by mitosis? 9. Why (when) does a cell go through mitosis?