Same except they have vesicles that form cell plates

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Same except they have vesicles that form cell plates instead or centromeres  Meiosis 1. Used to make gametes 2. Chromosome number is halved (haploid) 3. Zygote is a diploid after fertilization  Meiosis 1 and 2 *Meiosis 1 is the same as mitosis, and reduces the number of chromosomes, 2 diploid daughter cells form. *Meiosis 2 achieves the segregation of sister chromatides, 4 haploid daughter cells form.  Crossing over Exchange of genetic material between homologue chromosomes. Product: recombiant chromosomes containing some DNA from each parent  LECTURE#10 What is DNA? LECTURE#10 What is DNA?
 Early geneticists... didn't know what carried genes, but knew the substance needed to: 1. Contain inforrmation 2. Be easy to copy 3. Be variable, to account for diversity  DNA or protein? 3. So, which is the genetic material?
 Griffith Experiment (1928) Transformation of one strain of bacteria by another. 2 strains: 1. R-harmless 2. S-deadly Heat-killed S is harmless, but when added to R, the strain becomes deadly  Hershey and Chase (1952) Labeled viruses with radioactive material. When they labeled sulfur, the labeled protein did not get transferred to the cell. When they labeled phosphorus, only in DNA, the labeled material was transferred, proving that DNA carried genetic material.  Watson and Crick (1953)
1. Determined the ED structure of DNA 2. Structure revealed its function 3. X-ray crystallographic studies 4. Ladder twisted into a spiral coil 5. Double helix  Double helix nucleotide ladder containing 2 strands of paired bases with phosphorous backbones held together by hydrogen bonds.  Base pairing rules... A to T, G to C make copying sequences possible  DNA structure explains function 1. Easily copied a) Each strand is a tamplate for the other 2. Sequence is information a) contained in the order of the four bases b) A,C,G,T c) millions of bases in length 2. Accounts for diversity a) Alleles have different DNA sequences  Variation and Diversity Individuals have slight differences in sequence, different species have greater differences. Chimps are 98% homologous to humans 
DNA replication 1. Hydrogen bonds broken 2. Strands unwind and separate 3. Each strand is a template for the other 4. New bases observe base-pairing rules 5. Result is two identical copies  DNA Polymerase Main enzyme involved in replication  Many proteins are involved in DNA replication 1. Initiate replication 2. Unwind DNA 3. Stabilize the open strands 4. Connect bases to form a backbone  Mistakes DNA Polymerase may insert incorrect bases.

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