From Gene to Protein. Making Sense of DNA

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Jodie Beasley
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1 From Gene to Protein Making Sense of DNA

2 The 4 th Macromolecule DNA (deoxyribonucleic acid)

3 carbohydrates lipids The 4 major organic macromolecules nucleic acids proteins

the building blocks of organisms MONOMER amino acid nucleotide Monosaccharide (sugar) SIMPLE POLYMER peptide disaccharide COMPLEX POLYMER polypeptide (protein)

4 the building blocks of organisms MONOMER amino acid nucleotide Monosaccharide (sugar) SIMPLE POLYMER peptide disaccharide COMPLEX POLYMER polypeptide (protein) nucleic acid Polysaccharide (carbohydrate) The large molecules (macromolecules OR polymers) are formed when smaller building block molecules (monomers) bond covalently.

5 The blueprint for protein synthesis A CLOSER LOOK AT DNA

6 DNA The molecule Deoxyribonucleic acid Carries the genetic code of all living organisms

7 DNA exists as loose chromatin the material that makes chromosomes for most of the cell s cycle

8 Located inside the nucleus of eukaryotic cells and free floating in prokaryotes.

9 Franklin, Watson & Crick WHO DISCOVERED IT?

Photograph 51 Franklin died on April 16, 1958, of

10 Who Discovered DNA? Rosalind Franklin was the first to determine that DNA consisted of phosphate, sugar and nucleic acids and discovered its helical shape. Photograph 51 Franklin died on April 16, 1958, of ovarian cancer, possibly caused by her extensive exposure to radiation while doing X-ray crystallography work.

is a double helix with sugar-phosphate backbones on the outside

11 James Watson and Francis H.C. Crick constructed model of DNA in 1953 The model showed that DNA is a double helix with sugar-phosphate backbones on the outside and nucleotide bases on the inside Maurice Wilkins Watson & Crick and their model of DNA 1962 Nobel Prize

13 DNA Structure DNA consists of nucleotide monomers that are arranged into a ladder-like structure called a Double Helix. Unlike an actual polymer that has the same monomers linked, DNA has slightly different nucleotides that are linked

14 Nucleotide monomer of DNA Phosphate house pool Pentose Sugar Nitrogenous Base A, C, T, G garage Each nucleotide consists of: 1. Phosphate group 2. Pentose sugar 3. Nitrogenous base

15 4 Nitrogenous Bases Two Groups: 1. Purines (two rings) Adenine and Guanine 2. Pyrimidines (one ring) Thymine and Cytosine

16 Nitrogenous Bases Each base will only bond with one other specific base, called complementary base pairing. Adenine (A) Thymine (T) Form a base pair. Cytosine (C) Guanine (G) Form a base pair.

17 Nucleotides A Adenine T Thymine C Cytosine G Guanine

18 Nucleic acids

19 DNA Structure Because of this complementary base pairing, the order of the bases in one strand determines the order of the bases in the other strand.

20 DNA Structure the Ladder Backbone Sugar/Phosphate Rungs Nitrogenous Bases

21 A C T C T G A G A G T C T A

22 Hydrogen Bonds Hydrogen bonds are weak and easily broken with little energy used to break bond Bonds are constantly breaking Hydrogen bond is only 5-10% as strong as a covalent bond 5/23/

23 Practice Pairing TEMPLATE STRAND A C G G T A T G C C A T COMPLIMENTARY STRAND

24 Bonding TEMPLATE STRAND A C G G T A T G C C A T Weak HYDROGEN bonds form between the Nitrogen Base Pairs.

25 The backbone of it all TEMPLATE STRAND A C G G T A T G C C A T The backbone is made of alternating sugars and phosphates. - Remember: Sugar ALWAYS attaches to the Nitrogen base

27 DNA and the genetic code Cracking the Genetic Code Amoeba sisters

28 DNA and histones HOW DOES ALL THAT DNA FIT INTO ONE TINY NUCLEUS?

29 When a cell is not actively dividing (interphase), its DNA is loosely laid out in the nucleus wound around proteins called histones.

30 The histone/dna packets form units called nucleosomes. As the cell prepares for division and the DNA makes a copy of itself. The nucleosomes continue to coil up tightly into the classic X shaped chromosomes form.

31 Coiling animation

32 How to Make an Exact Copy DNA REPLICATION

33 DNA review what we know Where is DNA found? What is chromatin? What are histones? What do we call DNA wrapped in histones? nucleosome What is formed when chromatin condenses? CHROMOSOMES!

34 So Remember: DNA Chromatin Nucleosomes Chromosomes

35 Chromosome Nucleosome DNA double helix s Histones

36 DNA What we know Remember Mitosis? When a cell divides, each daughter cell gets one complete copy of the DNA. What phase of the cell cycle does the cell copy its DNA?

37 DNA What we know During the S-phase of mitosis the cell copies its DNA Process is called DNA REPLICATION Now that we know something about DNA s structure, how do you think it copies itself?

39 When a cell prepares to divide, the DNA makes an exact copy and coils tightly

40 To maintain genetic continuity chromosomes need to replicate to maintain diploid # Each chromatid is an exact copy of the other (replication)

41 Semiconservative replication

42 Every cell has full set of chromosomes. diploid Enzymes recognize the small number of active genes in a cell and ignore the rest.

Nucleic Acids. Biotechnology

Nucleic Acids. Biotechnology Nucleic Acids Biotechnology DNA Deoxyribonucleic acid Forms the Genetic Code 1953 The work of four people identify the structure of DNA. This knowledge opens the floodgates of scientific discovery that