Download Section 2: Chemistry of Life

Section 2: Chemistry of Life
What are atoms and molecules?
• All cells are made from the same materials
• The materials in cells are made up of atoms that can join together to form molecules
Atoms are the building blocks of matter
• Just six elements make up most of the human body
• These and other elements are important for cell processes n all living things
What are some important types of molecules in cells?
• Organisms need certain types of molecules for growth, repair, and other life processes
• Organisms use nutrients for energy and as building materials
• These nutrients come from the food you eat
Lipids
• Lipid – fat molecule or a molecule that has similar properties
• Do not mix with water
• Storing energy
• Fats and oils are lipids that store energy that organisms can use when they need it
• Cells get lipids from foods such as olive oil and fish
• Waxes and steroids are other types of lipids
Proteins
• Protein is a molecule made up of smaller molecules called amino acids
• Foods high in proteins, such as peanut butter and meat, proteins are broken down into amino acids
• Amino acids are used to make new proteins
• Proteins are used to build and repair body structures and to regulate body processes
o Enzymes help chemical processes happen in cells
Carbohydrates
• Molecules that include sugars, starches, and fiber are called carbohydrates
• Cells use carbohydrates as a source of energy and for energy storage
• Cells break down carbohydrates to release the energy stored in them
• Contain carbon, hydrogen, and oxygen atoms
• Simple carbohydrates: table sugar
• Complex carbohydrates: starch (pasta)
Nucleic Acids
• Nucleic acid is a molecule that carries information in cells
• Made up of smaller molecules called nucleotides
• Deoxyribonucleic acid, DNA, is one type of nucleic acid that is found in all cells
• DNA contains the information that cells need to make molecules
What are phospholipids?
• Cell membrane helps protect the cell and keep the internal conditions of the cell stable
• A lipid that contains phosphorus is called a phospholipid
• Phospholipids form much of the cell membrane
• The head of a phospholipid molecule is attracted to water
• The tail repels water
• Because there is water inside and outside the cell, the phospholipids form a double layer
o The tails in both layers face each other
• Molecules, such as water, are regulated into and out of a cell through the cell membrane
Why is water important?
• Water makes up nearly two-thirds of the mass of the cell
• Water moves through the cell membrane by a process called osmosis
o Osmosis depends on the concentration of the water inside and outside of the cell
• If the water concentration inside the cell is lower than the water concentration outside the cell then water will
move into the cell
• If the environment outside a cell has a low concentration of water, water will move out of the cell
o Losing too much water can cause a cell to shrivel and die
o The right balance of water allows a cell to function normally
o If too much water enters a cell, it may swell up and burst