Return to chapter outlines menu
Chapter 1
Cell Structure and
Function
I. Discovering Cells
The basic unit of structure and function in living things
is the cell.
The invention of the microscope made it possible for people to study cells.
Microscopes with more than one lens are called compound
microscopes.
Cell Theory states:
- All living things are made of cells
- cells are the basic unit of structure and function in living things
- all cells are made from living cells
How a light microscope works:
-the lenses magnify an object by bending the light that passes through them
- Since a compound microscope has two lenses, it bends the light twice and
magnifies the object more than a single lens can.
Total magnification = magnification of objective lens x magnification of eyepiece lens
examples:
eyepiece lens = 5x
objective lens = 40x
magnification = 5 x 40 = 200x
- the ability to clearly distinguish individual parts of an object
is resolution
II. Looking inside cells
plant cells (left) and animal cells (right)
How are they alike?
How are they different?
Parts of a cell:
-cell wall - found only in plant cells
-a stiff layer of nonliving material
that surrounds the cell
- helps to support and protect the cell
- cell membrane- found in all cells
- located just inside cell wall in plant cells
- forms the outside boundary of other cells
- controls what goes into and out of the cell
-nucleus - the cell’s control center
- it directs the cell’s activities
- cytoplasm- the region between the cell membrane and
the nucleus
- it is a jello-like substance
- contains the organelles
Organelles-
- mitochondria produce energy
also called the powerhouse of the cell
-endoplasmic reticulum (also called
the ER) - it is a series of passageways that carry
materials around inside a cell.
- ribosomes - attached to the endoplasmic reticulum (ER). They are factories that
produce proteins
-Golgi body - work like a mail room to package
proteins and distribute them to other parts of the cell
-chloroplasts
- found only in plant cells
They capture energy from the sun and use it to produce
food for the cell.
-vacuole - a storage area for the cell
- may contain food ,water , or wastes
- lysosome
- contain chemicals that recycle
a cell’s waste
III. Chemical compounds in cells
Any substance that cannot be broken down into simpler substances is an
element
example:
oxygen, iron, carbon
An element is made up of only one kind of atom
The most common elements in living things are carbon, hydrogen,
oxygen, and nitrogen
When two or more elements combine chemically they form
compound
example:
O2 + 2H2 ------------> 2H2O
The smallest unit of most compounds is called a
molecule
example:
H2O
CO2
C 6H12O6
Compounds that do NOT contain the element carbon are called
inorganic compounds.
Compounds that DO contain the element carbon are called
organic compounds. Many of these are found in living things. These include
carbohydrates, proteins,
nucleic acids, and lipids (fats).
carbohydrate - contains carbon, hydrogen
and oxygen
- rich in energy
examples: sugars, starches
protein - contains carbon,
hydrogen, oxygen, nitrogen, sulfur
- cells use proteins to build body parts
- one type of protein are enzymes which
speed up chemical reactions
lipid-contains carbon, hydrogen, oxygen
- rich in energy
- examples are fats, oils, waxes
IV. The Cell in its Environment
The cell membrane is selectively permeable which means that it
lets only certain molecules in or out. It is like a
gate keeper.
Molecules move through a cell membrane by either diffusion, or
osmosis, or active transport
Diffusion is the process by which molecules move through a
cell membrane from an area of
high concentration to an area of
low concentration. It is also called
passive transport because it does not
require energy
Osmosis is the diffusion of water molecules.
Active Transport is the movement of molecules through a cell membrane
using energy. The molecules move from an
area of low concentration to an area of high
concentration.
