Air is a mixture of gases, including oxygen and nitrogen Chapter 1 - section 3: Chemical Compounds in cells What is air made up of? Air is a mixture of gases, including oxygen and nitrogen Oxygen and nitrogen are elements

What is an Element? An element is any substance that cannot be broken down into simpler substances

What is the smallest unit of an element? An atom An element is made up of only one kind of atom

What are the most common elements in living things? Carbon, oxygen, hydrogen, and nitrogen

What is formed when elements combine? A compound Example: Water is a compound made up of the elements hydrogen and oxygen

What is the smallest unit of most compounds? A molecule A water molecule is made up of two hydrogen atoms and one oxygen atom

Most living things contain which element? Carbon Compounds that contain carbon are called organic compounds

What are the most important groups of organic compounds? Carbohydrates, lipids, proteins, and nucleic acids Many of these are found in food

What are compounds that don’t contain the element carbon? Inorganic Compounds Exception: Carbon dioxide is classified as inorganic even though it contains carbon Examples: Water, and sodium chloride

What are carbohydrates? An energy-rich organic compound made up of the elements carbon, hydrogen, and oxygen Example: sugars and starches

When are starches produced? During the food-making process that takes place in plants Sugar molecules combine forming large molecules called starches

Why do plants contain starch? Plant cells store excess energy in molecules of starch Examples of starchy foods: potatoes, noodles, rice, and bread

How do we get energy from plants? Our body breaks down the starch into glucose (a sugar) which our cells use to produce energy

What are Proteins? Large organic molecules made of carbon, hydrogen, oxygen, nitrogen, and in some cases sulfur Proteins make up our fingernails and spider webs Examples of food high in protein: meat, eggs, fish, nuts, and beans

What are protein molecules made up of? Smaller molecules called amino acids

How do amino acids form proteins? Cells combine the 20 common amino acids to form thousands of different proteins The type of protein formed depends on the kind of amino acid and the order with which they form, very much like how letters in the alphabet make different words; rice also spells mice Alanine Arginine Asparagine Aspartic Acid Cysteine Glutamic Acid Glutamine Glycine Histidine Isoleucine Leucine Lysine Methionine Phenylalanine Proline Serine Threonine Tryptophan Tyrosine Valine

What is an enzyme? A type of protein that speeds up a chemical reaction in a living thing Example: Enzymes in your saliva speed up digestion by breaking down starches into sugar

What are lipids? Fats, oils, and waxes are all lipids Like carbohydrates, lipids are energy-rich organic compounds made of carbon, hydrogen, and oxygen Lipids contain more energy than carbohydrates

What is cholesterol? Cholesterol is a lipid that our bodies need – our liver produces enough Excess cholesterol collects along blood vessels and blocks the flow of blood Meat, cheese, and eggs are high in cholesterol

What are nucleic acids? Very large organic molecules made of carbon, oxygen, hydrogen, nitrogen, and phosphorus These contain the instructions that cells need to carry out all the functions of life There are two kinds: DNA and RNA

Deoxyribonucleic acid What is DNA? Deoxyribonucleic acid The genetic material that carries information about an organism that is passes from parent to offspring – directs all of the cell’s functions Most of the DNA is found in the chromatin in the nucleus

What is RNA? Ribonucleic Acid Plays a role in the production of proteins Found in the cytoplasm, as well as in the nucleus

What substance makes up about 2/3 of our bodies? Water Without water, most chemical reactions could not take place Water helps the cells keep their size and shape and carries substances into and out of the cell

Chapter 1-section 4: The Cell in its Environment How is the cell membrane like a gatekeeper? The cell membrane is selectively permeable – some substances can pass through while others cannot

Diffusion Osmosis Active Transport What are the three methods by which substances move into and out of the cell? Diffusion Osmosis Active Transport

What is Diffusion? The process by which molecules tend to move from an area of higher concentration to an area of lower concentration

The amount of the substance in a given volume What is concentration? The amount of the substance in a given volume

What causes diffusion? Molecules are always moving, bumping into each other as they do The more molecules in an area the more collisions – these collisions cause them to spread out eventually spreading evenly across an area

What is osmosis? The diffusion of water molecules through a selectively permeable membrane

What is passive transport? The movement of materials through a cell membrane without using energy

What is active transport? The movement of materials through a cell membrane using energy

What is the difference between passive and active transport? Active transport requires the cell to use energy while passive transport does not

What two ways allows cells to move materials by active transport? Transport proteins Transport by engulfing

How do transport proteins work? Transport proteins in the cell membrane “pick up” molecules outside and inside the cell to move them These substances include calcium, potassium, and sodium

How does transport by engulfing work? The cell membrane engulfs (or surrounds) a particle

Why are cells small? It would take much longer for a molecule to reach the center of a very large cell than it would in a small cell When a cell reaches a certain size it divides into two new cells