AP Biology AP Biology John D. O’Bryant School of Mathematics and Science September 17, 2012

AP Biology Agenda  Do Now (Quiz)  Macromolecules (review)  Qualitative Tests of Biological Macromolecules  Case Study: “A Can of Bull”

AP Biology Do Now (Quiz)  1. Beta pleated sheets are characterized by  A) disulfide bridges between cysteine amino acids.  B) parallel regions of the polypeptide chain held together by hydrophobic interactions.  C) folds stabilized by hydrogen bonds between segments of the polypeptide backbone.  D) membrane sheets composed of phospholipids  E) hydrogen bonds between adjacent cellulose molecules

AP Biology Do Now (Quiz)  2. Which of these molecules would provide the most energy (kcal/g) when eaten  A) glucose  B) starch  C) glycogen  D) fat  E) protein

AP Biology Do Now (Quiz)  3. The alpha helix of proteins is  A) part of the tertiary structure and is stabilized by disulfide bridges  B) a double helix  C) stabilized by hydrogen bonds and commonly found in fibrous proteins  D) found in some regions of globular proteins and stabilized by hydrophobic interactions  E) a complementary sequence to messenger RNA

AP Biology Do Now (Quiz)  4. Cows can derive nutrients from cellulose because  A) they can produce enzymes that break the beta linkages between glucose molecules  B) they chew and rechew their cud so that cellulose fibers are finally broken down  C) One of their stomachs contains bacteria that can hydrolyze the bonds of cellulose  D) their intestinal tract contains termites, which produce enzymes to hydrolyze cellulose  E) they can convert cellulose to starch and then hydrolyze starch to glucose

AP Biology Do Now (Quiz)  5. Dehydration reactions are used in forming which of the following compounds?  A) triacylglycerides  B) polysaccharides  C) proteins  D) A and C only  E) A, B, and C

AP Biology Proteins Multipurpose molecules

AP Biology Protein denaturation  Unfolding a protein  conditions that disrupt H bonds, ionic bonds, disulfide bridges  temperature  pH  salinity  alter 2° & 3° structure  alter 3-D shape  destroys functionality  some proteins can return to their functional shape after denaturation, many cannot In Biology, size doesn’t matter, SHAPE matters!

AP Biology Let’s build some Proteins! EAT X

AP Biology Chaperonin proteins  Guide protein folding  provide shelter for folding polypeptides  keep the new protein segregated from cytoplasmic influences

AP Biology Protein models  Protein structure visualized by  X-ray crystallography  extrapolating from amino acid sequence  computer modelling lysozyme

AP Biology Nucleic acids

AP Biology Nucleic Acids Information storage

AP Biology proteins DNA Nucleic Acids  Function:  genetic material  stores information  genes  blueprint for building proteins DNA  RNA  proteins  transfers information  blueprint for new cells  blueprint for next generation

AP Biology A A A A T C G C G T G C T

Nucleic Acids  Examples:  RNA (ribonucleic acid)  single helix  DNA (deoxyribonucleic acid)  double helix  Structure:  monomers = nucleotides RNADNA

AP Biology Nucleotides  3 parts  nitrogen base (C-N ring)  pentose sugar (5C)  ribose in RNA  deoxyribose in DNA  phosphate (PO 4 ) group Are nucleic acids charged molecules? Nitrogen base I’m the A,T,C,G or U part!

AP Biology Types of nucleotides  2 types of nucleotides  different nitrogen bases  purines  double ring N base  adenine (A)  guanine (G)  pyrimidines  single ring N base  cytosine (C)  thymine (T)  uracil (U) Purine = AG Pure silver!

AP Biology Nucleic polymer  Backbone  sugar to PO 4 bond  phosphodiester bond  new base added to sugar of previous base  polymer grows in one direction  N bases hang off the sugar-phosphate backbone Dangling bases? Why is this important?

AP Biology Pairing of nucleotides  Nucleotides bond between DNA strands  H bonds  purine :: pyrimidine  A :: T  2 H bonds  G :: C  3 H bonds Matching bases? Why is this important?

AP Biology DNA molecule  Double helix  H bonds between bases join the 2 strands  A :: T  C :: G H bonds? Why is this important?

AP Biology Copying DNA  Replication  2 strands of DNA helix are complementary  have one, can build other  have one, can rebuild the whole Matching halves? Why is this a good system?

AP Biology When does a cell copy DNA?  When in the life of a cell does DNA have to be copied?  cell reproduction  mitosis  gamete production  meiosis

AP Biology DNA replication “It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material.” James Watson Francis Crick 1953

AP Biology Watson and Crick … and others… 1953 | 1962

AP Biology Maurice Wilkins… and… 1953 | 1962

AP Biology Rosalind Franklin ( )

AP Biology Interesting note…  Ratio of A-T::G-C affects stability of DNA molecule  2 H bonds vs. 3 H bonds  biotech procedures  more G-C = need higher T° to separate strands  high T° organisms  many G-C  parasites  many A-T (don’t know why)

AP Biology Another interesting note…  ATP Adenosine triphosphate ++  modified nucleotide  adenine (AMP) + P i + P i

AP Biology HELIXHELIX

AP Biology Macromolecule Review

AP Biology Carbohydrates  Structure / monomer  monosaccharide  Function  energy  raw materials  energy storage  structural compounds  Examples  glucose, starch, cellulose, glycogen glycosidic bond

AP Biology Lipids  Structure / building block  glycerol, fatty acid, cholesterol, H-C chains  Function  energy storage  membranes  hormones  Examples  fat, phospholipids, steroids ester bond (in a fat)

AP Biology Proteins  Structure / monomer  amino acids  levels of structure  Function  enzymes u defense  transport u structure  signals u receptors  Examples  digestive enzymes, membrane channels, insulin hormone, actin peptide bond

AP Biology Nucleic acids  Structure / monomer  nucleotide  Function  information storage & transfer  Examples  DNA, RNA phosphodiester bond

AP Biology Let’s build some DNA, baby!

AP Biology Ghosts of Lectures Past (storage)

AP Biology Building the polymer

AP Biology RNA & DNA  RNA  single nucleotide chain  DNA  double nucleotide chain  N bases bond in pairs across chains  spiraled in a double helix  double helix 1 st proposed as structure of DNA in 1953 by James Watson & Francis Crick (just celebrated 50th anniversary in 2003!)

AP Biology Information polymer  Function  series of bases encodes information  like the letters of a book  stored information is passed from parent to offspring  need to copy accurately  stored information = genes  genetic information Passing on information? Why is this important?