1. Chapter 2: How Cells Function
2.1: Chemical reactions take place inside cells
2.2: Cells capture and release energy
2.3: Materials move across the cell’s membranes
Will learn:
-About the types of elements found in all cells
-the functions of the large molecules in the cell
-Why water is important to the activities of the cell
Have already learned:
-All living things are made of cells
-Cells need energy to sustain life
-Plant and animal cells have similarities and differences

2. Warm-up Questions True for animal cells, plant cells, or both?
They need energy to sustain life
They have organelles
They have cell walls

3. All cells are made of the same elements
The matter that makes up the cell itself is too small for a light microscope
All matter broken down into elements, each with own characteristics
Example:
Oxygen, on Earth, found as colorless odorless gas
25 elements (of ~100 on Earth ) are essential for life
6 elements account for about 99% of the mass of our bodies!
Oxygen: 65%, Carbon: 18.5%, Hydrogen: 9.5%, Calcium: 1.5%, Phosphorus: 1.0%, all other 19: 1.2%

4. Elements Smallest unit of an element: atom In our body:
RANK- simple to complex:
cell, atom, molecule
Smallest unit of an element: atom
In our body:
mostly in the form of compounds – atoms of two or more elements chemically bonded
O + O = O C + O + O = CO2
Most cellular activities: atoms and molecules interacting via chemical reactions (bonds broken and formed to make new molecules)
Need and release energy! Chemical energy!

5. Large molecules for cell function
1) Carbohydrates
2) Lipids
3) Proteins
4) Nucleic Acids
ALL have carbon atoms
Work together in a cell

6. Carbohydrates Provide the cell with energy
Also structure
Breaking the bonds within the cell releases energy
Simple carbohydrates – carbon, oxygen, hydrogen
Complex carbohydrates – simple linked into chains: starch, cellulose, glycogen
Plants: energy not used makes starches and cellulose (cell wall)
Animals eat plants and get energy

7. Lipids Fats, oils, and waxes
Similar to carbohydrates, also made of carbon, oxygen, and hydrogen
Cells use lipids for energy and making structures
Atoms arranged differently than carbohydrates
Do not dissolve in water!
Cannot mix with water
(important for cell membranes…)

8. Proteins Made of amino acids
Carbon, oxygen, hydrogen, nitrogen, and sometimes phosphorus and sulfur
Linked into long chains, folded into 3-D shapes
Structure and function determined by type, number, and order of the amino acids
We get amino acids from food:
meats, eggs, cheese, beans, or created by body
Different types: enzymes (control chemical reactions in cells), others support growth and repair, muscle movement, fight infections, deliver oxygen, form part of the cell membranes

9. Nucleic Acids
Hold instructions for the maintenance, growth , and reproduction of a cell
DNA – Deoxyribonucleic acid
RNA – Ribonucleic acid
Both made of carbon, oxygen, hydrogen, nitrogen, and phosphorus.
Subunits called nucleotides
DNA: information used by the cell for making all the protein the cell needs
Nucleotide pattern in DNA is copied to RNA, which delivers information into the cytoplasm…where it controls chemical reactions and form structures.

10. Two thirds of all cells is water
All chemical reactions inside the cell take place in water
Water makes up:
46% of body’s mass inside cells
23% outside cells in body fluids
Polar: slight positive charge near hydrogen atoms, slight negative near oxygen
Attract opposite charges, repel like
Many substances dissolve in water

11. Water & Cells Most lipids do NOT dissolve in water
Cell membrane is made of a double layer of lipids
Head is polar, tail is not polar
Cell membrane is a boundary, keeping the inside of a cell separate from the outside
Water-hating tails repel water