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CHAPTER 2 – CELL STRUCTURE AND FUNCTION
LESSON 1 – CELLS AND LIFE
CHAPTER 2 – CELL STRUCTURE AND FUNCTION
LESSON 1 – CELLS AND LIFE
UNDERSTANDING CELLS
• English scientist Robert Hooke looked
at a slice of cork under a microscope
he built.
o Cork is the bark of the cork oak
tree.
o What Hooke saw reminded him of
the rooms of monks – cellula.
o He called the structures “cells.”
• Other scientists began to use better
microscopes to identify more
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structures in cells of plants and
animals.
Three Principles of Cell Theory
(p. 44)
 All living things are made of one or
more cells.
 The cell is the smallest unit of life.
 All new cells come from pre-existing
cells.
SOME SUBSTANCES IN CELLS
1. Water
H2O
H–O–H
 70% of a cell’s volume is water.
2. Lipids, Carbohydrates, Proteins,
and Nucleic Acids
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 Proteins, nucleic acids, and some
carbohydrates (the starches and
cellulose) are macromolecules.
 Lipids are called macromolecules,
but they are much smaller.
TYPES OF MOLECULES
Examples
Functions
Lipids 
Carbohydrates
Proteins 
Nucleic Acids
fats
sugars
enzymes 
DNA 
oils
starches 
insulin 
RNA 
cholesterol
cellulose 
keratin 
● sugars supply
energy
● regulate
● DNA carries
cell processes hereditary
information
● starches store
energy
● RNA is used
in making
proteins
● storage of
energy
● form cell
membranes
● cellulose gives ● give
structural
structural
support in plant support
cell walls
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The molecules marked with  are macromolecules.
A macromolecule is a very large molecule containing a large quantity of small
units joined by chemical bonds.
MACROMOLECULES

A macromolecule is a very large
molecule containing a large quantity
of small units joined by chemical
bonds.

Types of macromolecules in cells:
1. Proteins
 A protein is a macromolecule that
consists of a long chain of linked
amino acids.
 Some functions of proteins are:
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structural support, transport of
chemicals, communication,
breakdown of chemicals
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o Examples of proteins
 Amylase in saliva breaks down
starches.
 Keratin makes up hair, horns,
and feathers.
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2. Nucleic Acids: DNA and RNA
 DNA is deoxyribonucleic acid
 RNA is ribonucleic acid.
 A nucleic acid is a
macromolecule in which the
units are nucleotides.
 DNA is used to make RNA.
 RNA is used to make proteins.
3. Polysaccharides
 These are made from sugars.
 Examples: starches and cellulose
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LIPIDS
 Lipids are non-polar molecules
from plant or animal tissues.
 Lipids don’t dissolve in water.
 Lipids include fats, waxes,
cholesterol, and vitamin A.
 Some lipids are an important part
of cell membranes.
 Fats are used in cells for storing
energy.
 The examples of lipids here are
much smaller than proteins,
polysaccharides, and nucleic acids,
but they are called macromolecules.
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CARBOHYDRATES
 Carbohydrates are sugars and
polysaccharides.
 Sugars are NOT macromolecules.
 Polysaccharides ARE
macromolecules made from
sugars.
 Examples: starch and cellulose
 Plants make sugars and also turn
some sugars into starch and
cellulose.
 Starch stores energy for plants.
 Cellulose provides structural
support for cell walls of plant cells.
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REVIEW OF
MACROMOLECULES IN CELLS
1. Proteins
 Building blocks of proteins are amino
acids.
2. Nucleic Acids – DNA and RNA
 Building blocks of DNA and RNA
are nucleotides.
3. Polysaccharides – Starch & Cellulose
 Building blocks are sugars.
 Sugars and polysaccharides are
carbohydrates.
OTHER MOLECULES IN CELLS
water
sugars (glucose)
lipids