Cell Chemistry (III)

1. Cell Chemistry (III) Functional Groups Polysaccharides Lipids

2. KNOW & Be Able to Identify These Functional Groups

3. Polysaccharides • Examples of polysaccharides • Glycogen: In animal cells (meats) • Starch: In plant cells • Cellulose: In plant cells • Composition of polysaccharides • Glucoses (several) joined by covalent bonds • Polysaccharides are POLYMERS of Glucose • The bonds between the many glucose molecules are synthesized by a type of chemical reaction called --- ??? • These bonds can be broken by a type of chemical reaction called --- ???

4. Glycogen: A Polysaccharide

5. Significance of Polysaccharides in Physiology (I) • Polysaccharides function as stored fuel, in both plant cells and animal cells. • Any excess fuel that is not burned (or --- ?? is stored, first, in the form of glycogen, a polysaccharide, and then in the form of triglycerides (or neutral fats) in adipocytes. • In humans, the organs and tissues rich in glycogen are: Liver cells (Hepatocytes) and muscle cells • In animal cells, there is a limit to the amount of glycogen that can be stored by ---? and ---? When the glycogen storage capacity is filled, all additional fuels are metabolized to triglycerides and stored in fat cells, also called --- ?

6. Significance of Polysaccharides in Physiology (II) • What is the advantage of storing fuel? • When monosaccharides are not available (as in hours after a meal or during fasting), the cells can --- ?? the polysaccharides/oligosaccharides of the disaccharides to get the monosaccharides. • Fill-in blank spaces with correct term • Polysaccharide --??-- Monosaccharides • Glycogen --?? ??? • What happens to Cellulose consumed by humans and animals? Can cells burn or --- ?? polysaccharides?

7. LIPIDS • Fatty acids, triglycerides, phospholipids, steroids and eicosanoids are all examples of lipids. • Significance of lipids: • They function as fuels, stored fuel, structural components of cell membranes and hormones.

8. Fatty Acids • Chemistry • Contain even # of C atoms • Most contain 16 to 20 C atom • Examples: Palmitate (C16), Stearate (C18) Oleate (C18, 1db) • Contain a carboxyl group at one end • May be classified as: • 1) Saturated (meaning??) • 2) Unsaturated (meaning ??) • Property: • Characterized as amphipathic, meaning that one small region is ---? While the other region is ---??

9. Significance of Free Fatty Acids • Free fatty acids (FFAs) are, with Glycerol, building blocks of triglycerides (or fats) • Margarine is a significant dietary source of FFAs • Using dehydration synthesis reaction (or condensation reaction), cells covalently bind three free fatty acids (FFA), one to each C atom of glycerol. • Illustrated in next slide

10. Synthesis of Triglycerides

11. Triglyceride Composition & Synthesis • As illustrated in previous slide, a triglyceride consists of: • Three FFA covalently bonded to • One Glycerol • The FAs are covalently linked by a chemical reaction called ---? • Their chemical property: Hydrophobic

12. Significance of Triglycerides in Physiology • Triglycerides are “stored fuel”. When hepatocytes and muscle cells can no longer store glycogen, the excess fuel is stored as triglycerides in cells called adipocytes. • Adipocytes form a type of connective tissue called adipose tissue. • There is no limit to the amount of triglyceride that can be stored by this tissue

13. YOU Should be able to • Draw the chemical structure of a FFA • Be able to tell the difference between saturated and unsaturated FFA • Questions • Complete hydrolysis of a triglyceride yields what product/ or products? • Complete oxidation of a FFA by cellular respiration yields what product or products?

14. Triglycerides or triacylglycerols • They are commonly known as fats • In humans and other vertebrates triglycerides are stored in adipocytes. • Adipocytes are cells that form a type of connective tissue called adipose tissue • When ---?? storage capacity of --?? and --?? is reached, all excess fuel is stored as triglycerides

15. Remember that: • Preferred fuels: Monosaccharides • When not immediately available cells hydrolyze polys to get monos • When no more monos are available cells start using free fatty acids (FFA). • Fill-in the blank spaces with correct term • To get FFAs, cells must --- triglycerides to --- + ---??

16. Significance of phospholipids in physiology • They are structural components of all cell membranes • The plasma membrane (PM), the ER, the membranes around the mitochondria and the lysosomes are composed of a phopholipid bilayer (plus cholesterol and proteins) • Phospholipids are amphipathic

17. Phospholipids:Chemistry • Property: Amphipathic • Composition • Glycerol • 2 fatty acids • Phosphate group • “X” group attached to phosphate • Phospholipids are structurally closest to what other lipid ---??

18. Structure of a Phospholipid and a Steroid

19. Steroids Cholesterol Androgens (i.e., testosterone) Estrogens (i.e., Glucocorticoids (i.e., Mineralocorticoids (like Aldosterone) Vitamin D

20. Significance of Steroids in Physiology • Cholesterol is the classic example of a steroid • It is the starting material for synthesis of androgens-(male hormones), estrogens (female hormones), glucocorticoids, bile acids, bile salts and Vit. D • Chemical property: Amphipathic

21. Some Questions ?? • Assume that this is a gene: ….-5’-ATGCAATCAGTC-…. • What is the sequence of the complementary strand? • These two strands would be joined by what bonds …Assume that the 3-’strand is the gene. • What is the sequence of the mRNA from that gene? • How many codons are there in that mRNA? • Write each codon on a separate line in your notes • What would be the corresponding seqence of the anticodons? • Which RNA has anticodons? • According to the genetic code, what is the AAS of the peptide from that gene?

22. The end Functional groups Polysaccharides Lipids