BIOL 20A Tamkun (Week 3 Macromolecules: Lipids & Nucleic Acids)
BIOL 20A Tamkun (Week 3 Macromolecules: Lipids & Nucleic Acids) BIO 20A
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This 3 page Class Notes was uploaded by Holly Chen on Thursday October 6, 2016. The Class Notes belongs to BIO 20A at University of California - Santa Cruz taught by John Tamkun in Fall 2016. Since its upload, it has received 6 views.
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Date Created: 10/06/16
Unit 3 - Macromolecules: Lipids & NucleicAcids Macromolecules: Lipids • Lipids - large molecules (not truly polymers) that don’t mix well with water. • Most heterogenous class of molecules. • Major component of cell membranes. • 3 major classes of lipids: fats, phospholipids, steroids Lipids: Fats • Fat - made from glycerol and fatty acids. Hydrophobic due to the non polar C and H bonds in the hydrocarbon chain, water molecules don’t bond with fat. • Glycerol: an alcohol with 3 carbons with a hydroxyl group each. • Fatty acids: made of a long carbon skeleton with a carboxyl group at one end with the rest being a hydrocarbon chain. • To make a fat, 3 fatty acid molecules (can be same or different) are joined to glycerol through ester linkage, creating triacylglycerol, which is non polar. • Functions: • Energy storage. • 1 gram of fat is twice as much energy as 1 gram of a polysaccharide like starch. Saturated v.s unsaturated fat • Saturated or unsaturated refers to the fatty acid’s hydrocarbon chain structure. • Saturated fat - saturated with hydrogen, no double bonds between carbon atoms to allow maximum flexibility of the molecule. • Most animal fats are saturated (e.g lard, butter) • The lack of double bonds allow the molecules to pack together. • Usually solid at room temperature. • Unsaturated fat - has double bonds with less hydrogen, often creating a “bend” or kink in the hydrocarbon chain. • Fats of plants, fish. • Referred to as oils (e.g olive oil, fish oil). • Built with more than one type of unsaturated fatty acids. • Usually liquid at room temperature because the bends and the double bonds prevent tight packing, so it doesn’t solidify. Lipids: Phospholipids • Phospholipids - 1 glycerol molecule + 2 fatty acids + a modified phosphate group. • Major component of cell membranes due to the phosphate group, which is a negatively charged polar head (hydrophilic). Fatty acid chain remains the same with non polar tails (hydrophobic). • Phospholipid’s two different ends behave differently in water. • Phosphate group forms and hydrophilic head that interacts with water. • Hydrocarbon are hydrophobic and don’t interact with water. • When phospholipids as a whole is added to water, double layers called bilayers are formed (hydrophilic on the outside, hydrophobic on the inside). • This forms a boundary between the cell and the outside environment. Lipids: Steroids • Steroids - a carbon skeleton with four rings, different steroids will have specific functional groups attached to the ring. • Example: cholesterol, common component of animal cell membranes. • Precursor to synthesize other steroids. Macromolecules: NucleicAcids (DNA/RNA) • Nucleic acids - macromolecules of polymers of polynucleotides made from monomers of nucleotides. • Nucleoside - nitrogenous base, a five carbon sugar (pentose) without a phosphate group. • Nucleotides - nitrogenous base, a five carbon sugar (pentose) and one or more phosphate group. Provide energy that drives many chemical reaction in cells. • Purines (adenine and guanine): larger, double ring structure. • Pyrimidines (thymine, uracil and cytosine): single ring structure. T&C for DNA, U&C for RNA. • Polynucleotides - nucleotides are joined together by phosphodiester linkage, making a backbone of repeating patterns of sugar phosphate units. • Central component of molecular biology and life in general (no shit). • DNA- deoxyribonucleic acid. • Blueprint of a cell. • The genetic material inherited from parents. • During cell replication, DNAmolecules are copied and passed along. • DNAis not directly responsible for the day to day operations of the cell. • RNA: ribonucleic acid. • Genes along a DNAmolecule directs the synthesis of RNAor messenger RNA (mRNA), which control a cell’s protein synthesizing mechanisms. • Site of protein synthesis: ribosomes. • General formula: transcription of DNAmakes RNA, translation of mRNAyields protein. Transfer and ribosomal RNAs (mRNAand tRNA) are involved in the process of translation. 5 Carbon Sugar = DNA/RNA • Carbon is numbered 1’through 5’ • Nucleic acids have 3’ends and 5’ends. • 5’end has a phosphate group. • 3’end has a hydroxyl group. • Anucleotide monomer would be added to the 3’end of the polymer.
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