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How are the ingredients for life put together?

• Most molecules that make up living things Carbon Compounds and Cells are very large and complex. • Now let’s learn abou t their s tru ctur e an d All living organisms are composed function. of cells, from just one to many trillions.

Carbon compounds Carbon is unique among the elements.

• Life as we know it is carbon based. • A carbon atom can • This means that most of the compounds form chemical bonds with other carbon you are made of contain the element atoms in long chains carbon. or rings. • Some carbon compounds contain several thousand carbon atoms.

You use carbon compounds every day. The carbon compounds in living things are classified into four groups: • Carbon compounds are not only found in living things. 1. carbohydrates, • Plastic, rubber, and gasoline are carbon compounds. 2. lipids, • In fact, there are over 12 3. proteins, and million known carbon 4. nucleic acids. compounds!

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Compounds in a Person

CARBOHYDRATES

Is water a carbon compound?

Plants and animals use carbohydrates. Carbohydrates are energy-rich compounds made from carbon, • Cells use carbohydrates to get and hyygdrogen, and ox ygen. store energy. • Plants conta in ce llu lose, a carbohydrate, which gives them a rigid structure.

Glucose Carbohydrates are classified as sugars and starches. • Glucose is a simple sugar made of 6 • Sugars are simple carbon, 12 hydrogen, molecules which are and 6 oxygen atoms. smaller than starches.

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The sugar you use to sweeten food is called sucrose. Starch molecules are very large. • They consist of many sugar molecules • A sucrose molecule is combined. made from two glucose molecules.

Plant cells store energy as starch.

• Rice, potatoes, and wheat are plant starches.

LIPIDS

Lipids

• Lipids include fats, oils, and waxes.

Can you think of examples of lipids in plants or animals?

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Lipids are made by cells to store energy for long periods of time. • Animals that hibernate live off of the fat stored in their cells.

Polar bears have a layer of fat beneath their skin to insulate them from very cold temperatures.

Cholesterol is a lipid. Too much cholesterol in some people’s diet may cause fat deposits on their • Like fat, cholesterol is listed on food labels. blood vessels. • Cholesterol is a lipid that makes up part of •This may lead to the outer membrane of cells. coronary artery • YliYour liver normall lldy produces enough disease. cholesterol for your cells to use.

Foods that come from animals are often high in cholesterol.

PROTEINS

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Hemoglobin is a protein in your blood Proteins that carries oxygen to your cells. • Proteins are very large molecules made of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur. • Many animal parts like hair, fingernails, muscle, and skin, contain proteins.

Foods high in protein include meats, Enzymes are proteins. dairy products, and beans. • An enzyme is a type of protein that cells use to speed up chemical reactions. • Digestive enzymes are made by the pancreas. • These enzymes help break down the foods you eat into smaller molecules that can be absorbed by your cells.

Proteins are made of amino acids Amino Acid Comparison

• Your cells combine • You can compare amino acids to letters in different amino acids in the alphabet. various ways to make • Just as you can spell thousands of words different proteins. with just 26 letters , you can make • There are 20 amino thousands of different proteins from just acids used by cells to 20 amino acids. make proteins.

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Nucleic acids • Nucleic acids are compounds made of long, repeating chains called nucleotides. • Nucleotides are made from carbon, hyygdrogen, ox ygen, nitro gen, and phosphorus. • Each nucleotide contains a sugar molecule, NUCLEIC ACIDS a phosphate molecule, and a base molecule.

DNA A DNA molecule can be compared to a book that contains “recipes” for making • DNA is a nucleic acid that contains the all of the proteins that you are made of. information cells need to make all of their proteins. Some scientists refer to DNA as the “blueprints” for life.

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