Chapter 2The Chemistry of Life

Life depends on chemistry.

Millions of chemical reactions occur in living organisms every day. Organisms rely on chemical reactions in order to function. Food must be broken down, gases must be exchanged, molecules

must be built.

Levels of Organization

Levels of Organization

http://micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/

Section 2-1The Nature of Matter

Atoms Atom - Basic unit of matter.

All matter - including living things - is made up of groups of atoms “stuck” (bonded) together.

Elements Element – a kind or “species” of atom. There are

>100 elements or kinds of atoms. Living things are mostly made of six elements:

C, H, O, N, P, S (in order of most to least common)

1. Carbon2. Hydrogen3. Oxygen4. Nitrogen5. Phosphorus6. Sulfur

Elements

What element is…N?C?S?P?H?O?

Chemical Compounds Compound – a substance formed by the

chemical bonding of two or more elements Written as chemical formulas. Letter = element,

small number = how many atoms of the element Example: Water or H2O = 2 hydrogen atoms and 1

oxygen atom Example: Glucose or C6H12O6 = 6 carbon atoms, 12

hydrogen atoms, and 6 oxygen atoms

Chemical Compounds How many atoms of each element are in

these compounds?

(Nitric acid) HNO3

(Salt or Sodium Chloride) NaCl (Potassium Phosphate) KPO4

(Carbon dioxide) CO2

(Sulfur dioxide) SO2

(Glycerol) C3H8O3

CHECKPOINT A living thing is made up of cells, which are

made up of ___________, which are made up of ___________, which are different kinds of ___________.

Chemical Reactions Chemical reaction – atoms break and/or make bonds to

form different compoundsReactants – elements or compounds that enter into a

reactionProducts – elements or compounds that are

produced by the reaction

Example: 2H2O2 2H2O + O2 (reactant) (products)

Example: 2K + Cl2 2KCl (reactants) (product)

Chemical Reactions

Identify the products and reactants in each of these reactions.

8 Fe + S8 -> 8 FeS 2 H2O -> 2H2 + O2

Zn + 2 HCl -> ZnCl2 + H2

NaCl + AgNO3 -> NaNO3 + AgCl C10H8 + 12O2 -> 10CO2 + 4H2O

Section 2-3 Organic Molecules -Carbon Compounds

The Chemistry of Carbon Organic molecules - carbon based molecules that make up

living organisms Carbon forms the backbone or basic structure of all large

organic molecules, because it is abundant and flexible. Can bond with up to 4 other atoms at once. Can form single, double or triple bonds. Bonds easily with other carbon atoms to form the backbone of

large organic molecules. Can bond with many different elements

such as H, O, P, S, N.

Four Groups of Organic Molecules Most molecules in cells are so large they

are called macromolecules or “giant molecules.” Most macromolecules = polymers, which are

chains of repeating smaller molecules called monomers.

Polymerization – Joining monomers together to make a polymer

Organic molecules are classified into 4 groups:

1. Carbohydrates 2. Lipids 3. Nucleic acids 4. Proteins

Carbohydrates Elements: C, H, O Examples: Sugars and starches Functions:

Main source of energy for living things Used for structure in plants and some animals

Monomer – monosaccharide (simple sugar, like glucose), Polymer – polysaccharide (complex carbohydrate, like starch)

Nucleic Acids Composition: C, H, O, N, P Examples: DNA and RNA Function: Store and transmit genetic information Monomer – nucleotide / Polymer – nucleic acid

Proteins Composition: C, H, N, O Examples: enzymes, cell membrane

proteins, muscle proteins Functions:

Control rate of chemical reactions Regulate cell processes Structure Transport other substances

Monomer – amino acid / Polymer – polypeptide or protein

Structure or shape of a protein is extremely important to its function.

Lipids Composition: mostly C and H and some O Examples: Fats, oils, waxes Functions:

Energy storage Compose parts of biological membranes and waterproof

coverings Generally not

soluble in water No monomers or

polymers.

Section 2-4:Chemical Reactions and Enzymes

Energy in Reactions Chemical reactions don’t

happen automatically. (see graphs)

Activation energy – the energy needed to get a reaction started

Enzymes Some reactions are too

slow or require too much energy to happen in cells… unless they have help.

Enzymes = proteins that speed up chemical reactions that take place in cells

Enzymes work by lowering the activation energy of the reaction, making it easier which makes it faster.

Activation energy without enzyme

Activation energy with enzyme

Course of Reaction

Enzymes and Reactions

Think cars:Which car finishes the race first, the one that

took MORE gas before it would start, or the one that took LESS?

Enzyme Action Catalyst = A chemical that speeds up a

reaction without being used up or altered.

Enzymes are biological catalysts.

Each enzyme = unique shape = only binds to a specific reactant = only catalyzes one kind of reaction.

Active site

SubstratesProducts

Products are released. Enzyme is available again.

Chemical reaction occurs andsubstrates are changed to products.

Substrates bind to enzyme at active site.

Enzyme

Enzyme Action

Reactants bindto the enzyme atthe active site.

Chemical reaction changes reactants

to products.

Product is released. Enzyme is available again.

Enzyme Action

Enzyme Animations

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work.html

http://www.lpscience.fatcow.com/jwanamaker/animations/Enzyme%20activity.html

http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter25/animation__enzyme_action_and_the_hydrolysis_of_sucrose.html

http://www.kscience.co.uk/animations/model.swf

http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter2/animation__protein_denaturation.html

A change in the enzyme prevents reactants from

binding. Shapes don’t match.

Chemical reaction can’t occur. Reactants don’t get

changed to products.

Effects of Altered pH or Temperature on Enzyme Action

Summary: An enzyme outside of its OPTIMAL environment does not function as well, which means it will not make the reaction proceed as QUICKLY.

pH and Buffers pH scale – measurement system of

how acidic or basic something is / ranges from 0 –14

pH 7 = neutral (pure water) pH < 7 = acid (tomatoes, lemons) pH > 7 = base (soaps, cleaners)

pH in human cells must be kept between 6.5 and 7.5 or chemical reactions will be affected.

pH and temperature affect how well enzymes work because they change the shape of the protein.

Enzyme Thought Problems 1. Two plants live in a 35 degree environment. Which

one is more likely to survive and reproduce: the one whose enzymes work best at 30 degrees, or the one whose enzymes work best at 20 degrees? Why?

2. Your body temperature is 98.6 degrees, and your body’s pH is close to 7. At what temperature and pH do you think most human enzymes probably work?

3. Your cells can live at 90 degrees. The cells of bacteria from Antarctic ice, however, die at 70 degrees. Why?

4. Your body must maintain homeostasis: you must keep your body at a constant temperature and pH. Why is this essential to your survival?

Enzyme Thought Problems

5. At which pH do each of these enzymes perform optimally (best)? At which pH do these enzymes become denatured?

6. Which enzyme is probably found in a human stomach?