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Chapter 3 Biochemistry. LIPIDS AND NUCLEIC ACIDS Contemporary Biology Monkemeier. Lipids . Lipids are also known as fats. There are five categories of lipids listed in our text book. Fatty acids Triglycerides Phospholipids Waxes Steroids. What do all Lipids have in common?.
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Chapter 3 Biochemistry LIPIDS AND NUCLEIC ACIDS Contemporary Biology Monkemeier
Lipids • Lipids are also known as fats. • There are five categories of lipids listed in our text book. • Fatty acids • Triglycerides • Phospholipids • Waxes • Steroids
What do all Lipids have in common? • The ONLY thing that ALL lipids have in common is that they do NOT DISSOLVE in water! • Another way of stating that is that lipids are NOT SOLUBLE in water.
Lipids and Energy • Lipids contain MORE carbon to hydrogen bonds (C-H) bonds than proteins and carbohydrates! • The Carbon to Hydrogen (C-H) bond is VERY high in energy! • Lipids contain MORE energy per gram than carbohydrates and proteins because lipids contain more C-H BONDS!
Lipids are Nonpolar • Some lipids contain LONG carbon chains. • While other lipids contain carbon rings. • The LONG carbon chains and carbon rings are NONPOLAR.
NONPOLAR Substances • Lipids are NONPOLAR. • NONPOLAR substances such as lipids do not dissolve in water because water is POLAR. • Remember that “like dissolves like” so polar substances dissolve in polar substances and nonpolar substances dissolve in nonpolar substances.
Monomers of Lipids • There are so many different kinds of lipids and they vary in structure. • The lipids do not have one “monomer” or subunit to put together to make all lipids, BUT some kinds of lipids contain LONG carbon chains known as FATTY ACIDS.
Fatty Acids • Fatty Acids are LONG carbon chains. • Fatty Acids can be used to build some of the kinds of lipids mentioned in the chapter. • Fatty acids contain a carboxyl group at one end of the chain and a methyl group at the other end of the chain.
Saturated vs. Unsaturated • Fatty acids that contain single bonds between the atoms of the carbon chain are known as saturated fatty acids. • Fatty acids that contain double bonds between the atoms of the carbon chain are known as unsaturated fatty acids.
Saturated vs. Unsaturated • Animal fats are usually saturated and are solids at room temperature. • Plant fats are usually unsaturated and are liquids at room temperature.
Triglycerides • Triglycerides store energy for organisms. • Triglycerides contain three fatty acid chains and one glycerol molecule.
Phospholipids • Phospholipids contain two fatty acid chains, one glycerol molecule and a phosphate. • Phospholipids compose cell membranes,
Phospholipids • Phospholipids have a water –loving end (hydrophilic) and a water-fearing end (hydrophobic) • Phospholipids form a bilayer and compose the cell membrane.
Waxes • Waxes are structural lipids consisting of a long fatty acid chain joined to a long alcohol chain. • Waxes are lipids so they do not dissolve in water and this makes them waterproof. • Plants produces waxes as protective coatings on their outer surfaces.
Steroids • Steroids consist of FOUR, fused carbon rings. • Steroids can act as chemical signals or messengers in the body like testosterone. • Steroids can also help support cell membranes such as cholesterol.
Nucleic Acids • Nucleic acids are large polymers composed of subunits called nucleotides. • Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are examples of nucleic acids.
Nucleotides • The monomers of nucleic acids are known as nucleotides. • A nucleotide consists of a nitrogen base (nitrogenous base), a sugar and a phosphate.
Building Nucleic Acids • Nucleotides are put together using the chemical reaction known as dehydration synthesis (aka condensation) to build nucleic acids. • The sugar of one nucleotide gets bonded to the phosphate of a neighboring nucleotide.
DNA • DNA codes for all of the proteins within an organism. • DNA is a double helix (twisted ladder) • DNA is found in the nucleus in eukaryotic cells. • DNA is the hereditary molecule that organisms pass from one generation to another.
RNA • RNA assists during the making of proteins. • RNA is a single helix • RNA is found in both the nucleus and the cytoplasm. • RNA can also act as an enzyme.
Quiz • A quiz on Lipids and nucleic acids is scheduled for Thursday, October 28, 2010. • Be sure to review this ppt again. • Be sure to complete the worksheet entitled Lipids and Nucleic Acids. • Be sure to reread the sections in your text book relating to lipids and proteins.
