Polymers. DNA is a polymer of nucleotides. What polymers (macromolecules) have we met so far? Proteins are polymers of amino acids

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1 Subatomic particles (parts of an atom) 1. Protons (+) 2. Neutrons 3. Electrons (-) H-H -Smallest unit of an element. -Parts are held together via electrostatic forces BIO101: a roadmap to the course Atoms Elements O C Molecules -a group of two or more atoms held together by covalent bonds -One molecule can be held close to another molecule by hydrogen bonding -a substance that can t be broken down to other substances Molecules of Life -H20 and -complex carbon containing molecules -monomers that form polymers (macromolecules) Monomers: (1) monosaccharides (2) components of a fat molecule (3) amino acid (4)nucleotide Compounds -Comprised of two or more elements in a fixed ratio. -Parts held together by chemical bonds (ionic or covalent). -One compound can be held close to another compound by hydrogen bonding. Cellular Organelles: parts of the cell Ch 4 Nucleus*, smooth and rough ER, golgi, lysosomes, vacuoles, peroxisomes,ribosomes cell membrane, cell wall mitochondria*, chloroplasts*, etc cell Cell Membranes: How a cell communicates with outside world Ch5 Cellular Energy: How can a cell actually do anything? Ch 5 Cell Processes: (things that cells do) Cellular Respiration Ch 6 (mitochondria) Photosynthesis Ch 7 (chloroplasts) Cellular Division (nucleus, etc) mitosis and meiosis Ch 8 cell Inheritance: (how a cell got the genes (DNA) it has) Ch 9 -genotype and phenotype -Punnet squares See Evolution -genetics Macromolecules: (what living things, like cells, are made of) Ch 3 1. Carbohydrates 2. Lipids 3. Proteins (amino acids) 4. Nucleic acids: (DNA, RNA) DNA Replication: How is DNA actually duplicated before mitosis? Ch 10 Protein Synthesis: How does a cell make proteins from DNA sequence? Ch 10 *DNA RNA protein* DNA Technology: Cool things that can be done with DNA Ch 12 -cloning, PCR, restriction digests DNA mutations: Ch 10 Viruses What polymers (macromolecules) have we met so far? Think of cellular components Polymers Cellulose and starch are polymers of glucose molecules Enzymes are proteins. Proteins are polymers of amino acids. What are the monomers of these different polymers? DNA and RNA (nucleic acids) are polymers of nucleotides. nucleotide nucleotide nucleotide nucleotide Proteins are polymers of amino acids DNA is a polymer of nucleotides 1

2 DNA and RNA are polymers of nucleotides Nucleotide A nucleotide Nitrogenous base Phosphate group Pentose sugar Eukaryotic Chromosomes Long, continuous strings of DNA Humans have 23 pairs of chromosomes that contain ~25,000 genes Chromosome 1 has 2,100 and 2,600 genes Chromosome 2 has between 1,300-1,800 genes along its length The Y chromosome contains ~70 genes Prokaryotes: E. Coli has one, circular chromosome with ~3000 genes cell DNA (nucleic acid) IN the nucleus Gene A Gene B Gene C Gene D Gene E Protein (histone) DNA or Protein as the genetic material?? Nuclei observed to divide when cells reproduced themselves Large amounts of both DNA & protein in the nucleus Many thought protein was most likely the molecule of heredity Protein! DNA! Linus Pauling, Francis Crick, Jim Watson Protein vs. DNA Proteins are polymers of amino acids. How many amino acids are there?? DNA and RNA (nucleic acids) are polymers of nucleotides. How many different nucleotides does DNA have? nucleotide nucleotide nucleotide nucleotide 2

3 DNA or Protein as the genetic material?? PROTEINS seemed the obvious choice as they re very DIVERSE, and highly SPECIFIC. Proteins made of 20 different amino acidscould have more variety than DNA (made of only 4 different bases) Data tipping the scale towards DNA as genetic material Also very little was known about nucleic acids DNA Protein DNA is likely the genetic material, WHAT IS ITS STRUCTURE?? Scientists used X-ray crystallography to look at the structure of DNA X-ray crystallography What did the data say? X-ray crystallography data suggested that DNA has a helical shape, and that the helix has regular spacing and a uniform width Rosalind Franklin In the laboratory of Maurice Wilkins, Rosalind Franklin used X-ray crystallography to study the structure of DNA 3

4 DNA is likely the genetic material, WHAT IS ITS STRUCTURE?? By looking at Rosalind Franklin s data.. Watson and Crick decipher the structure of DNA! (1953) Watson and Crick propose the doublehelix Double Helix DNA is a two-stranded, helical molecule Double Helix with sugar and phosphates on the outside, bases on the inside Watson and Crick also propose Complimentary Base Pairing Which is the stronger pairing? Pop quiz If you were given the DNA sequence of ONE strand of a DNA molecule A T AATCTGGAAGATCA G C Could you decipher what the other strand of DNA looks like? What is the complimentary sequence? 4

5 Once the structure of DNA was determined..the race was on to figure out how it worked to pass on the genetic material of life How does the cell make more DNA and how is it passed down to future generations? Watson and Crick It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material. Watson and Crick. Nature, 1953 How does replicate its DNA, and when would it want to do so? When would a cell need to replicate its DNA? Every cell from a cell. MITOSIS & CYTOKINESIS Cell division must distribute identical genetic material (DNA) into each of two daughter cells What if you are a single-celled organism? Who could you be, first of all? What would happen if you underwent cell division? 5

6 cell DNA Replication IN the nucleus, is our DNA In eukaryotes, DNA is linear, long strings. Humans have 46 chromosomes. Each one must be faithfully copied before a cell can reproduce, or divide. Different organisms have different chromosome numbers Goats 60 Chinchilla 64 Bat 44 Apple 34 Lettuce 18 King crab 208 Drosophila (fruit fly) 8 DNA is circular! Prokaryotic DNA The cells of all living organisms must COPY their DNA before they divide DNA polymerase is the enzyme that catalyzes this process 6