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MOLECULAR GENETICS. DNA- deoxyribonucleic acid 1953- James Watson and Francis Crick discover the structure of the DNA molecule DNA is a double helix (twisted.

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Presentation on theme: "MOLECULAR GENETICS. DNA- deoxyribonucleic acid 1953- James Watson and Francis Crick discover the structure of the DNA molecule DNA is a double helix (twisted."— Presentation transcript:

1 MOLECULAR GENETICS

2 DNA- deoxyribonucleic acid James Watson and Francis Crick discover the structure of the DNA molecule DNA is a double helix (twisted ladder)

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4 The sides of molecule are: 1. a sugar molecule called deoxyribose 2. a phosphate group

5 The middle molecules are called: Nitrogen bases

6 There are four nitrogen bases: Adenine Guanine Cytosine Thymine

7 Nucleotide- the building block molecule of DNA 1 sugar 1 phosphate group 1 nitrogen base

8 Nitrogen base pairs Adenine always pairs with Thymine Guanine always pairs with Cytosine (Often called Complimentary base pairs) The bases are held together with Hydrogen bonds

9 Functions of DNA: 1.Replication- so that genetic material and information is passed from one generation to another and to succeeding cells 2.Control of cellular activities: DNA carries the code for assembling enzymes and other proteins that cells need

10 Quiz: answer these questions on a piece of paper 1.Describe the basic structure of DNA. 2.Describe the parts of a nucleotide. 3.What are the complimentary base pairs? 4.What type of bond holds nucleotides together?

11 DNA Replication DNA makes a copy of itself just before the cell divides

12 Steps of replication: 1.DNA double helix molecule unwinds and unzips. 2. New DNA nucleotides find their complimentary base pair. 3. Results in two identical molecules of DNA

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16 The amount of Adenine is equal to the amount of Thymine and the amount of Cytosine is equal to the amount of Guanine

17 *********** REMEMBER A GENE IS A SECTION OF DNA THAT CODES FOR A PROTEIN! !!!!!!!!!!!!!!!!! Each chromosome has many genes!!!

18 Gene (DNA) RNA formation Protein formation Cell structureCell enzymes Cell function

19 CENTRAL DOGMA DNA RNA PROTEIN

20 RNA- ribonucleic acid 1.The sugar in RNA is ribose 2.RNA is single stranded 3.The nitrogen base uracil replaces thymine (what base is complimentary to Uracil)

21 RNA transcription- DNA is used as a template for producing an RNA molecule

22 How does RNA form? 1. DNA is used as a template (model) to make RNA 2. RNA has three forms: messenger RNA (mRNA) transfer RNA (tRNA) ribosomal RNA (rRNA)

23 3. The molecule of DNA unwinds and unzips 4. One side of DNA acts as a template for producing a complimentary RNA strand 5. RNA molecules strip away from DNA, leave the nucleus and enter the cytoplasm

24 RNA now has the instructions for how to make a specific protein.

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29 Triplet codon Every three bases on the RNA molecule code for the placement of a specific amino acid FOR EXAMPLE: UCG AAA CCU Tryptophanlysineproline

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31 RNA will travel to the ribosome, the site of protein synthesis

32 Transfer RNA- tRNA tRNA has an anticodon Anticodon- three nitrogen bases that are complimentary to the triplet codon of mRNA

33 Transfer RNA (tRNA) Function- to carry amino acids from the cytoplasm to the ribosome

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35 PROTEIN SYNTHESIS tRNA carries amino acids from the cytoplasm to the ribosome the anticodon on tRNA finds its complimentary triplet codon on mRNA

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37 When the amino acids are next to each other they form a bond, and as amino acids are added to the chain, a protein forms

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