Exploring Life Chapter 4+ 5 Study Guide 4.1 Life Requires about 25 chemical elements 4.2 Skip

1. Exploring Life Chapter 4+ 5 Study Guide 4.1 Life Requires about 25 chemical elements 4.2 Skip 4.3 skip 4.4 Life Depends on the unique properties of water

2. 4.1 Life Requires about 25 chemical elements • Why is there chemistry in a biology textbook? • The answer is that all of biology involves chemistry. • All living things share the same chemical building blocks and depend on chemical processes for survival.

3. 4.1 Life Requires about 25 chemical elements • Elements- About 25 elements are essential to life . • of these elements oxygen (O), carbon (C), hydrogen (H), and nitrogen (N)— make up about 96 percent of your body.

4. 4.4 Life Depends on the unique properties of water • All living things are dependent on water. • Inside your body, your cells are surrounded by a fluid that is mostly water, and your cells themselves are 70 to 95 percent water

5. 4.4 Life Depends on the unique properties of water • The tendency of molecules of the same kind to stick to one another is called cohesion. • Cohesion is much stronger for water than for most other liquids. • Water molecules are also attracted to certain other molecules. This is called adhesion

6. 4.4 Life Depends on the unique properties of water • Trees depend on cohesion and adhesion to help transport water from their roots to their leaves • This effect is known as surface tension.

7. 4.4 Life Depends on the unique properties of water • You've witnessed another example of cohesion if you've ever seen an insect "skating" across the surface of a pond. • This effect is an example of surface tension, also

8. 4.4 Life Depends on the unique properties of water • Temperature Moderation If you have ever burned your finger on a metal pot while waiting for the water in it to boil, you know that water heats up much more slowly than metal. In fact, because of hydrogen bonding, water has a better ability to resist temperature change than most other substances

9. 4.4 Life Depends on the unique properties of water • One result of this property (temperature moderation) is that it causes oceans and large lakes to moderate the temperatures of nearby land areas • Water also moderates • temperature through evaporation, • such as when you sweat.

10. 4.4 Life Depends on the unique properties of water • Ice floats because its molecules are less densely packed than those in liquid water.

11. 4.4 Life Depends on the unique properties of water • How is the fact that ice floats important to living things? • If ice sank, it would form on the bottom of a body of water as the water was cooling. • Ponds and lakes would freeze from the bottom up, trapping the fish and other organisms in a shrinking layer of water without access to the nutrients from the muddy bottom. • Instead, when a deep body of water cools, • the floating ice insulates the liquid water below, allowing life to persist under the frozen surface.

12. 4.4 Life Depends on the unique properties of water • Water is the main solvent inside all cells, • in blood, • and in plant sap. • Water dissolves an enormous variety of solutes necessary for life.

13. 4.4 Life Depends on the unique properties of water • Acids, Bases, and pH pH of 7 is neither acidic nor basic. The pH of the solution inside most living cells is close to 7. Which is the most acidic? Which is the most basic?

14. 4.4 Life Depends on the unique properties of water • Buffers • Because the molecules in cells are very sensitive to concentrations of H+ and OH- ions, even a slight change in pH can be harmful to organisms. • Many biological fluids contain buffers, substances that cause a solution to resist changes in pH. • Blood contains buffers (like a sponge or barrier) so cells stay at pH 7.4

15. 4.4 Life Depends on the unique properties of water • Earth is perfect planet for Life • Contains water • Just far enough and close enough to sun • Just enough energy and heat • Ozone shields harmful radiation • Essential elements in rock, soil, air • H, O, C are recycled

16. Chapter 5 • 5.1 Organic compounds • 5.2 Carbohydrates • 5.3 Lipids • 5.4 Proteins • 5.5 Enzymes

17. 5.1 Organic Compounds • Carbon • Carbon can form bonds with one or more other carbon atoms, producing an endless variety of carbon skeletons. • Most carbon-based molecules are classified as organic molecules

18. Building Organic Compounds To build compounds A water molecule is released This is called a dehydration reaction because it involves removing (de-)water (hydro-).

19. Breaking Down Compounds • In a Hydrolysis reaction, water (hydro-) is used to break down (-lysis) compounds. • To summarize, water is removed to build a compound, and water is added to break it down.

20. 5.2 Carbohydrates A carbohydrate is an organic compound made up of sugar molecules. Sugars contain the elements carbon, hydrogen, and oxygen in the ratio of 1 carbon: 2 hydrogen: 1 oxygen (CH2O) Monosaccharides –simple sugar (Glucose, fructose, and galactose ) Disaccharides -2 sugars (sucrose) Polysaccharides--chain of sugars (Glycogen, cellulose, and starch )

21. 5.3 Lipids • Oil's inability to mix with water is typical of the class of water-avoiding compounds called lipids • A fat consists of a three-carbon backbone saturated fat unsaturated fat Steroids-hormones and cholesterol

22. 5.4 Proteins • A protein is a polymer constructed from a set of just 20 kinds of amino acids • Made up of C, H, O, N-Put this in your notes • Cells create proteins by linking amino acids together into a chain called a polypeptide

23. 5.5 Enzymes • To start a chemical reaction, it is first necessary to weaken chemical bonds. This activation process requires that the molecules absorb energy. This "start-up" energy is called activation energy • The main catalysts of chemical reactions in organisms are specialized proteins called enzymes • Enzymes provide a way for reactions to occur at the cell's normal temperature

24. The enzyme sucrase, which catalyzes the hydrolysis (breakdown) of sucrose (the substrate). • pH and temperature can affect how an enzyme works or if it can work at all • Enzymes are specific • Enzymes can be re-used

25. Organic compound and Function Chart

26. Video (Chemistry of Life 18 min)