3. Understanding Cells
Once a long, long time ago (300 years ago) in a far away place
(England) a scientist named Robert Hooke made a microscope to
look at some cork.
He looked in and saw this:
He decided to call the empty spaces he saw cells or “cellula”
5. The Cell Theory
Written in 3 parts:
1. All living things are made of one or more cells
2. The cell is the smallest unit of life.
3. All new cells come from preexisting (older)
cells.
7. Water
More than 70% of a cells volume is water.
Water is essential for life.
Functions:
◦Inside our cells
◦Surrounding our cells
◦Insulating our bodies (keeping us warm)
◦Maintain homeostasis
8. Water
Water is ideal for dissolving
substances allowing different
substances to pass between cells
◦Water is good at dissolving substances
because it is a polar molecule
◦The positive and negative ends of a water
molecule attract the positive and negative
ends of other substances.
◦Similar to a magnet
10. Nucleic Acids
Both DNA (deoxyribonucleic acid) and RNA
(ribonucleic acid) and nucleic acids.
Definition: Nucleic acids are macromolecules
that form when long chains of molecules called
nucleotides join together.
The order of DNA and RNA is important and
work as codes and instructions.
These instructions tell the cell how to grow, how
to reproduce, how to respond to environmental
changes, and how to make proteins.
13. Proteins
RNA is the code of
building proteins.
Proteins are long
strings of amino acid
molecules.
Each protein has a
particular function to
help us survive.
◦ They are like the commands in
computer programs or the
machinery in a car.
15. Proteins
Different functions:
◦Enzymes that break down
nutrients in food
◦Give structure and support
◦Keratin in found in hair, horns,
and feathers
◦Help cells communicate
◦Transport substances
between cells
17. Lipids
Definition: A lipid is a large macromolecule that does not dissolve in water.
They play an important role as protective barriers in the cell.
Other functions:
◦Energy storage
◦Cell communication
Examples:
◦Cholesterol
◦Phospholipids
◦Vitamin A
20. Carbohydrates
Definition: One sugar molecule, two sugar molecules, or a long chain
of sugar molecules make up carbohydrates.
Function:
◦Store energy
◦Give structure and support
◦Communication between cells
Examples:
◦Sugars and starches – store energy
◦Cellulose – makes cell walls in plants