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Slide 1 of 31 Chemistry 24.3. © Copyright Pearson Prentice Hall Slide 2 of 31 24.3 Amino Acids and Their Polymers Many people are lactose intolerant.

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Presentation on theme: "Slide 1 of 31 Chemistry 24.3. © Copyright Pearson Prentice Hall Slide 2 of 31 24.3 Amino Acids and Their Polymers Many people are lactose intolerant."— Presentation transcript:

1 Slide 1 of 31 Chemistry 24.3

2 © Copyright Pearson Prentice Hall Slide 2 of Amino Acids and Their Polymers Many people are lactose intolerant. These people cannot digest milk products because their bodies do not produce enough of the enzyme lactase to digest lactose, the sugar found in milk. You will learn what enzymes are and what function they serve in the body.

3 © Copyright Pearson Prentice Hall Amino Acids and Their Polymers > Slide 3 of Amino Acids What is the general structure of an amino acid?

4 Slide 4 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Amino Acids An amino acid is any compound that contains an amino group (—NH 2 ) and a carboxyl group (—COOH) in the same molecule.

5 © Copyright Pearson Prentice Hall Slide 5 of 31 Amino Acids and Their Polymers > 24.3 Amino Acids Amino acids have a skeleton that consists of a carboxyl group and an amino group, both of which are covalently bonded to a central carbon atom. The remaining two groups on the central carbon atom are hydrogen and an R group that constitutes the amino acid side chain.

6 Slide 6 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Amino Acids

7 © Copyright Pearson Prentice Hall Amino Acids and Their Polymers > Slide 7 of Peptides Which functional groups are always involved in amide bonds between amino acids?

8 Slide 8 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Peptides A peptide is any combination of amino acids in which the amino group of one amino acid is united with the carboxyl group of another amino acid.

9 Slide 9 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Peptides The amide bond between the carboxyl group of one amino acid and the nitrogen in the amino group of the next amino acid in the peptide chain is called a peptide bond.

10 © Copyright Pearson Prentice Hall Slide 10 of 31 Amino Acids and Their Polymers > 24.3 Peptides The amide bonds between amino acids always involve the central amino and central carboxyl groups. The side chains are not involved in the bonding.

11 © Copyright Pearson Prentice Hall Amino Acids and Their Polymers > Slide 11 of Proteins What determines the differences in the chemical and physiological properties of peptides and proteins?

12 Slide 12 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Proteins A peptide with more than about 100 amino acids is called a protein. Your skin, hair, nails, and muscles are made of protein. Proteins are needed for almost all chemical reactions that take place in the body.

13 Slide 13 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Proteins Amino Acids in a Peptide Chain

14 Slide 14 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Proteins Sections of a peptide chain may coil into a regular spiral, known as a helix.

15 Slide 15 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Proteins Peptide chains may also be arranged side by side to form a pleated sheet.

16 © Copyright Pearson Prentice Hall Slide 16 of 31 Amino Acids and Their Polymers > 24.3 Proteins Differences in the chemical and physiological properties of peptides and proteins result from differences in the amino acid sequence.

17 Slide 17 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Proteins The Shape of Myoglobin

18 © Copyright Pearson Prentice Hall Amino Acids and Their Polymers > Slide 18 of Enzymes How do enzymes affect the rates of reactions in living things?

19 Slide 19 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Enzymes Enzymes are proteins that act as biological catalysts. Enzymes increase the rates of chemical reactions in living things.

20 Slide 20 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Enzymes The enzyme urease hydrolyzes urea, a constituent of urine, into ammonia and carbon dioxide.

21 Slide 21 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Enzymes How Enzymes Work Enzymes catalyze most of the chemical changes that occur in the cell. Substrates are the molecules on which an enzyme acts. The place on an enzyme where a substrate binds is called the active site.

22 Slide 22 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Enzymes In a typical enzymatic reaction, the substrate interacts with side chains of the amino acids on the enzyme. These interactions cause the making and breaking of bonds.

23 Slide 23 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Enzymes An HIV particle (red) infects a human white blood cell (orange). The diagram models the enzyme HIV protease.

24 Slide 24 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Enzymes The enzyme carbonic anhydrase catalyzes the reversible breakdown of carbonic acid to carbon dioxide and water.

25 Slide 25 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Enzymes Coenzymes Coenzymes are metal ions or small organic molecules that must be present for an enzyme- catalyzed reaction to occur.

26 Slide 26 of 31 © Copyright Pearson Prentice Hall 24.3 Amino Acids and Their Polymers > Enzymes The enzyme catalase includes an iron(III) ion in its structure. Catalase catalyzes the breakdown of hydrogen peroxide to water and oxygen.

27 © Copyright Pearson Prentice Hall Slide 27 of 31 Section Quiz -or- Continue to: Launch: Assess students’ understanding of the concepts in Section 24.3 Section Quiz

28 © Copyright Pearson Prentice Hall Slide 28 of Section Quiz. 1.Choose the correct words for the spaces. An amino acid is a compound having the ________ group and the _________ group bonded to a central carbon atom. a.carboxyl, amino b.carbonyl, amide c.amino, peptide d.carbohydrate, amide

29 © Copyright Pearson Prentice Hall Slide 29 of Section Quiz. 2.Choose the correct words for the space. A protein is a peptide with ___________ amino acids linked in a chain. a.more than about 100 b.less than about 100 c.two d.zero

30 © Copyright Pearson Prentice Hall Slide 30 of Section Quiz. 3.Enzymes affect biochemical reactions by a.changing the equilibrium position of the system. b.acting as catalysts to speed up the reaction. c.being consumed as the reaction progresses. d.decreasing the size of competing substrates.

31 © Copyright Pearson Prentice Hall Slide 31 of Section Quiz. 4.Some vitamins participate in biological processes as a.peptides. b.amino acids. c.enzymes. d.coenzymes.

32 END OF SHOW


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