1. 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

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

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

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

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

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

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

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

9. 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

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

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

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

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

14. 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

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

16. 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

17. 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

18. 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

19. 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

20. 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

21. 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

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

23. 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

24. 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

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

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

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

28. 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

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

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

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

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

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

34. 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

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

36. 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