2. Mr. Malinkovich OFFICE: Room 321 -before school -by appointment

3. Honors Biology 2/7/14 Objective: – SBBAT: Describe the structure and function of DNA -Agenda: -Go over last week’s quiz -Notebook self-check -Take quiz over: -Meiosis, genetic variation, genetic complexity -Discuss yesterday’s activity -Take notes -BR: Update TOC: DNA class notes -HW: NONE

4. Genetic Variation Genetic variation among individuals is caused by differences in genes or other DNA segments Natural selection can only act on variation with a genetic component (does not act on acquired traits) Sources of Variation – Mutations Random changes that alters the expression of a trait – Chromosomal rearrangements Combinations of chromosomes during gamete formation – Rapid Reproduction Quick reproductive cycles = increased chance for mutations – Sexual reproduction Mixing of genes from individuals

5. Genetic Variation Mutations can result in favorable traits – Altered continuous or discrete traits Increase chance of survival/ reproduction Increase diversity Mutations can result in disease – Decrease chance of survival/ reproduction Recombination can – Increase diversity by creating new combinations of existing alleles – Lead to disease if there are errors in meiosis Nondisjunction:

6. Genetic Complexity Sometimes knowing individual’s genotype is not enough to predict phenotype – Complex Traits Behavior Intelligence Personality – There is direct evidence that complex traits are affected by genotype and environmental factors Maze-bright vs maze-dull Hippocampus development and maternal touch – involved in memory and spatial navigation

7. Genetic Complexity Sometimes the genotype for a trait involves several genes that are all expressed – Skin color – Incomplete dominance Partial expression of dominant allele – Blending of dominant and recessive phenotypes – Sickle cell trait vs disease – Codominance Expression of multiple dominant alleles – Blood types » A, B, AB, O

8. A A A A T C G C G T G C T

9. Macromolecules: Nucleic Acids Examples: – RNA (ribonucleic acid) single helix – DNA (deoxyribonucleic acid) double helix Structure: – monomers = nucleotides RNADNA

10. 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!

11. 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!

12. 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?

13. 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?

14. DNA molecule Double helix – H bonds between bases join the 2 strands A :: T C :: G H bonds? Why is this important?