The Chemistry of Life!

Why are we talking about chemistry????

Well….., because everything you do-from walking, to thinking, to digesting your lunch- is a series of chemical reactions! We have to understand basic chemistry in order to understand cell biology and genetics.

So, let the fun begin!!!!!

Levels of Biological Organization

Matter Matter – anything that has weight

and takes up space. Includes solids, liquids, and gases

All matter is composed of elements. There are 112 known elements

Ex. Iron, copper, silver, aluminum, carbon, hydrogen, oxygen

Matter and Living Organisms Living organisms require about 20

elements. Of these, oxygen, carbon,

hydrogen and nitrogen make up more than 95% of the human body.

Elements and Atoms Elements are composed of tiny

particles called atoms. Atoms are the smallest complete

units of elements. Atoms vary in size, weight, and the

ways they interact with each other.

Atomic Structure

Nucleus Protons (+

charge) Neutron (neutral)

Electron cloud Electrons (-

charge)

Chemical Bonds

A bond is formed when electrons from two atoms interact with each other and their atoms become joined.

Molecules and Compounds Molecule – when two or more atoms

bond. CO2 , O2 , H2 and H2O are all molecules.

Compound – when different elements combine. CO2 and H2O are molecules, but they are also compounds because they are molecules containing more than one element.

Molecules and Compounds Molecules Compounds

Calm Down!!

I know this is all very exciting! Let’s take a minute for you to chill out-we don’t want you to get over excited!

Carbon is essential to life!! All living things are composed mostly of

carbon. All life on Earth is carbon based. There are four basic types of organic

(carbon based) molecules. Carbohydrates Lipids Nucleic Acids Proteins

Carbohydrates Provide energy for

cells Supply materials to

build cell structures and are stored as reserve energy supplies

Carbohydrates include sugars and starches.

Lipids Lipids are

insoluble (do not dissolve) in water.

Lipids are fats and are used by your body to store energy. Lipids store more energy than carbs.

Lipids

Steroids are also lipids.

Examples: Cholesterol, estrogen, progesterone, testosterone…

Nucleic Acids

Nucleic Acids contain the genetic instructions for all living things.

Two types of nucleic acids RNA DNA

Proteins

Proteins serve as:

Structural materials

Energy sources Hormones Receptors on cell surfaces Antibodies Enzymes

Enzymes

Enzymes are important proteins because they speed up chemical reactions.

Without enzymes, the chemical processes carried out by your cells would happen too slowly to keep you alive!

Enzymes Your body requires enzymes to

digest food and to convert fats and carbohydrates to energy.

Some examples of enzymes are pepsin, lipase, and lactase.

Enzymes

Lactose intolerance is an example of the trouble that can be caused by an enzyme deficiency. People who are lactose intolerant lack the enzyme lactase. Lactase breaks down the sugar lactose. If a lactose intolerant person consumes dairy products, they can feel really sick. Fortunately, lactase supplements are available to allow lactose-intolerant people to safely consume dairy products.

More about enzymes! Each enzyme has a specific

chemical reaction it speeds up. Pepsin breaks down proteins and

is found in your digestive tract. Lactase breaks down lactose (a

sugar found in milk). Lipase breaks down lipids (fats).

The Enzyme-Substrate Complex

Substrates are the reactant(s) upon which the enzyme acts

Enzymes form a complex with their substrates called the enzyme-substrate complex (ES complex) at the active site

When the ES complex breaks up it releases product

This link shows how enzymes work

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

This link shows how enzymes work under various conditions!

http://www.kscience.co.uk/animations/anim_2.htm

Enzymes Are Picky About Their Working Conditions!

As we saw in the animation, enzymes need the correct temperature or pH in order to work.

If the temperature is too cold, or too hot, the enzymes may not work.

Generally, chemical reactions happen more quickly in warmer temperatures. But too much heat can destroy an enzyme.

Enzymes are Very Sensitive

Each enzyme has an optimal temperature, pH, and ionic strength

Human enzymes are optimized to work at body temperature (37OC)

Certain body enzymes are most active at the pH of a given body compartment:

Pepsin’s optimum pH matches that of the stomach (acidic)

Trypsin’s optimum pH is basic, like the upper intestine

What does heat do to an enzyme?

View animation of how heat affects the structure of a protein.

Remember, enzymes are proteins!!!

Frying eggs

What the heck is pH?? pH is the measure of the acidity of

a substance. Acids release hydrogen ions (H+)

when they are mixed with water. The pH scale is a measure of how acidic a substance is.

More on pH! The pH scale

ranges from 0-14. 7 is neutral. Substances with a pH of 7 or below are acidic (acids). Substances with a pH above 7 are alkaline (bases).

Picky enzymes! Some enzymes need acidic

conditions in which to work, like the enzymes in your digestive tract.

If an enzyme doesn’t have the right conditions, it cannot do its job!

What factors affect enzyme function?

We will be conducting a laboratory investigation in order to answer the question above.

For help in getting started, go to the link below

Liver lab

Answer the following questions on your own

paper.1. What is the difference between a

molecule and a compound?2. What are four types of organic

compounds? Describe how each is important to living things.

3. What does an enzyme do? What type of organic compound is an enzyme?

4. List two conditions that can affect the ability of an enzyme to function.