BIOLOGY 151 1st Edition Lecture 8 Outline of Last Lecture 1. Dissolved molecules can...2. Permeability of lipid bilayer3. Concentration of dissolved solutes outside cells can be...4. Cells in fresh (hypotonic) water5. What if the cell wants something else inside or outside?6. Exocytosis and endocytosis Outline of Current Lecture 1. Electrochemical effects2. Nucleic acids3. Active transport with transporters (pumps) work against the diffusion gradient4. Heredity, genes, and DNA5. Darwin, Evolution, and Heredity (1859)6. Why did we take so long to figure out heredity?7. Is all life "pre-formed?"8. Inheritance of traits "acquired" by parents from experience, environment?9. Mid-1800s10. Mendel's (1861) rules for sexual inheritance of "genes"11. What is a gene?Current Lecture - 2/6/15- facilitated diffusion - can couple the two; use a pump to get the concentration difference that is used for cotransport. - movement of K+ would create voltage difference across membrane.- the cytosol has a much higher concentration of potassium ions and impermeable anions relative to the extracellular fluid- as K+ ions diffuse out of the cell, the impermeable anions are left behind, creating a membrane potential- The magnitude of the membrane potential increases until an equilibrium is reached Electrochemical effects: - What if an ion moves across a membrane?- if one ion moves without allowing movement of ions of opposite charge it creates a voltage difference between inside and outside of cell- that will attract/repel other ions- forces on ion: sum of concentration difference and electrical attractionThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Common sources electrochemical gradients --ion channels facilitate selective diffusion of ion from high to low conc. - voltage difference can eventually counteract the concentration difference.-H+ pumps use chemical energy to move H+ ions outside the cell-Na+/K+ pumps move 3 Na+ outside for every 2 K+ moved inside the cellNucleic acids:- nucleotide monomers make polymers- nitrogenous base (5 different kinds)- phosphates (1-3)- monosaccharide (sugar) - ribose or deoxyribose1) Use nucleotides to supply chemical energy-Adenoside Triphosphate (ATP) to Adenosine Diphosphate (ADP) + phosphate + energy-bond between 2nd and 3rd phosphate groups (Pi)Active transport with transporters (pumps) work against the diffusion gradient:- the energy to make ATP comes from catabolic reactions that are exergonic- ATP hydrolysis provides the energy for cellular processes that are exergonic- Ex. C6H12O2 becomes 6CO2 + 6H2O + energy - use the energy to make ATP from ADP + Pi2) Nucleic acid polymers via C-phosphate-C bonds:-RNA - any of four ribose nucleotides: bases = adenine (A), cytosine (C), guanine (G), uracil (U)-DNA - any of four deoxyribose nucleotides: bases = A, C, G, or thymine (T) instead of U.Heredity, Genes, and DNA:- What kind of info. is being passed from parent to offspring? Cell to cell?- How stable is it and why does it vary between individuals and species?Darwin, Evolution, and Heredity (1859):- Natural Selection1) There is variation of traits within population of individuals that make up a species.2)Those traits are heritable.3) Certain traits allow better survival of individuals.- Darwin didn't know...1) Why there was variation 2) How inheritance worked- Soup Problems:-making complex enzymes, etc. Not random?-keeping it all over time: heredity-solved in cells with nucleic acids- Answer = DNA- polymer of deoxyribonucleic acid- sequence of nucleotides in DNA code for making sequence of amino acids in proteinsWhy did we take so long to figure out heredity?:- Many ideas conflicted with stable heredity1) Spontaneous generation of organisms2) Preformation3) Inheritance of acquired traitsIs all life pre-formed?:- are organisms too complex to build?- alternative: organisms "preformed" during the Biblical creation- Preformationism (1700s) --complete (and very small) version of organisms in sperm or eggs-Problems:-Russian doll problem?-no characteristics from mom?-single-celled life?-variation of traits?-changes during development?Inheritance of trait "acquired" by parents from experience, environment?:- Hippocrates (5th century B.C.) - sperm acquires info. from all parts of adult, passes info. on to offspring- Aristotle: no way1) Injured man does not produce injured offspring2) Child gets traits (grey hair) not present in parents-But idea persisted; ex. folklore, Lamarck (1809), Darwin (1859)-no experimental support?Mid-1800s:- no spontaneous generation or preformation, not sure about acquired traits- What are the rules for passing info. to offspring (especially in sexual reproduction)?- What are the physical bases of those rules?Mendel's (1861) rules for sexual inheritance of "genes":- picked simple traits, easily-bred organism, used large numbers and probabilities- different traits controlled by "units" = genes- the only structure in cells that acted like they obeyed Mendel's rules during sexual reproduction were chromosomes (late 1800s-early 1900s)- mapping of genes on chromosomeWhat is a gene?:- genes on chromosomes- chromosomes contain DNA + proteins- most thought genes were proteins. Why?1) Many different proteins with different activities2) DNA had about equal conc. of 4 nucleotides (A,C,G,T)- Old (wrong) "tetranucleotide" model of DNA structure - bit 2 experiments in 1940-50s suggestedDNA was the basis of stable inheritance1) Bacteria growing in dish (bacterial "culture") can be transformed (Griffith 1920-30s)-Smooth (S) pneumonia bacteria kill mice, rough (R) do not-colonies in dish look different-growing R cells with ground up (dead) S cells transforms R to S-After transformation, S is inherited-take S cell extract, remove proteins (add proteinase), RNA (add RNase), lipids, or carbohydrates-extract still transformed R to S (Avery, 1944)-only DNA left?-negative result!-Why not small amounts of protein, lipid, RNA, or something else?-1949 (5 years later) - treat with enzyme that removes DNA (DNase), transformation is