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What can you tell me about this compound? pyridoxine CH2OH HO OH N H+ What can you tell me about this compound? P O O OH OH OH IP3 O P P What can you tell me about this compound? H3C NH H2C OH CH epinephrine OH OH What can you tell me about this compound? beta-carotene Chapter 2 Apply Problem #5 If an aqueous (water) extract does not work but one using benzene as the solvent does have an effect, what might you conclude about the chemical nature of the hormone? explain. Hormone is lipophilic or nonpolar. Explain: Hormone dissolves in benzene, an organic solvent (nonpolar) but doesn’t dissolve in polar solvent (water). Proteins The other main component of the cell membrane. Functions of Protein Transport channels pumps carriers Communication receptors signaling molecules hormones “flags” Enzymes Structure Collagen, keratin, bone matrix, intracellular microtubules Antibodies Movement Muscle cells are 20% actin (protein) Amino Acid Structure O O + H3N H2N CH CH OH R R group can be • polar or nonpolar • big or small • charged – acidic or basic R O- Amino acids – R groups lysine O O H2N CH CH2 CH2 CH2 CH2 NH2 C OH H2N CH C OH CH2 cysteine SH Amino acids – R groups O H2N CH CH2 C aspartic acid O OH tryptophan H2N CH C CH2 C HN OH O OH Amino acids O H3C H2N CH C OH CH2 NH H2C OH CH epinephrine OH tryosine OH OH Peptides – dipetide formation Formation from amino acids: FOX fig 2.25 O O H2N cysteine CH C H2N OH CH C OH H CH2 glycine SH O H2N dipeptide CH CH2 SH C NH2 CH H COOH + H 2O Tripeptide - glutathione • glycine • cysteine • glutamic acid Peptides O O H2N CH C OH + H2N CH CH2 CH2 CH2 SH C C NH2 CH COOH H dipeptide O OH glutamic acid OH O O C CH H2 C H2 C C NH2 O H2N CH CH2 glutathione SH C NH2 CH H COOH Protein Four levels of structural organization Primary structure Amino acid sequence gly-cys-ala-trp-glu-asp-gly-tyr-cys-ala Secondary structure Sections of peptide chain coil or fold into either: Alpha helix Beta sheet Tertiary structure Whole peptide chain (protein) folds/coils around itself H bonding, sulfide bridges, non-polar/non-polar interactions Quaternary structure More than one peptide chain associated with each other Proteins (FOX fig 2.26) Tertiary Structure (FOX fig 2.27) Protein Synthesis within the context of homeostasis. Objectives Review how proteins are synthesized Give an example of an effector action Review key organelles Preview regulation of ions Preview endocrine signaling Protein Synthesis within the context of homeostasis. Negative Feedback: Sensor detects a change parameter’s level Control unit activates an effector Effect is to return parameter to normal level Typical effector action is to make a protein Another effect is to activate a protein protein activation can lead to the release of hormone or neurotransmitter protein activated is often an enzyme Protein Synthesis Example: Aldosterone What is aldosterone? Steroid hormone produced by adrenal cortex It is a mineralocorticoid Promotes the retention of Na+ and loss of K+ What induces the release of aldosterone? Low Na+ and high K+ Target organ? Kidney – epithelial cells of distal tubule carrier protein (albumin) aldosterone target cell plasma membrane Aldosterone on carrier approaches the cell membrane Aldosterone diffuses readily into the lipophilic membrane. Aldosterone receptor picks up aldosterone and moves it into the cell. aldosterone receptor Aldosterone receptor complex heads towards the nucleus. know cell structures Translation (FOX fig 3.24) Microtubules aid movement of vesicles to cell membrane Pumps/channels are degraded in lysosomes when no longer needed Carbohydrates Contain CH2O 6 carbon sugars – C6H12O6 glucose (glu) fructose (fru) galactose (gal) 5 carbon sugars – C5H10O5 ribose DNA RNA Carbohydrates If glucose and galactose have the same formula (C6H12O6) what is the difference? structural isomers (FOX fig 2.13) CHO CH2OH H O HO OH OH OH OH glucose OH H H OH H OH CH2OH glucose reversed in galactose Ribose Found in DNA and RNA (FOX fig 2.29) Found in ATP (FOX fig 4.15) Found in NADH and FADH2 (FOX fig 4.17) OH HOH2C O HO OH ribose removed in DNA Disaccharides (FOX fig 2.15) Disaccharide short hand Sucrose = glu-fru Lactose = glu-gal Maltose = glu-glu What’s this? glu-glu-glu-glu-glu-glu-glu-glu-glu- Polysaccharide glu-glu-glu-glu-glu-glu-glu-glu-glu Starch Glycogen linear chains of glucose found in plants densely branched chains of glucose found in humans Cellulose chains of glucose (tend to stack into sheets) found in plants Why can’t we digest cellulose? First how do we digest starch? Amylase (enzyme) takes long chains of glucose and breaks off disaccharide pieces. What are the characteristics of enzymes? Enzymes Biological catalysts either make reactions happen or make reactions happen faster Names end in –ase starch (aka amylose) is digested with amylase Can be classified according to activity phosphatase – removes phosphate groups kinase – adds phosphate groups Proteins Characteristics of Protein Interactions Such as enzyme/substrate or receptor/hormone Binding site that is specific The substrate/hormone is called the ligand (The ligand is the thing that binds to the protein) What is the ligand for the aldosterone receptor? What is the ligand for amylase? The rate of reaction or activity is dependent on binding characteristics. Binding characteristics Specificity – binding site designed for one type of ligand Affinity – strength of bond between ligand and binding site Competition – two or more ligands competing for one binding site Saturation – occupation of binding sites thousands of enzymes/receptors per cell graph (FOX fig 4.6) Saturation (FOX fig 4.6) Why can’t we digest cellulose? starch has alpha linkages cellulose has beta linkages Example of ENZYME SPECIFICITY!! Functions of Carbohydrates Fuel Signaling Molecule Ribose is component of: DNA RNA ATP NAD/FADH Digestive Regulation Fiber normalize transit time Fiber decreases cholesterol, TAG and LDL