CHAPTER 2:INTRODUCTION TO CELLS

WHAT IS A CELL?• A cell is the smallest unit that is capable of

performing life functions.• Most cells cannot be seen by the naked

eye.• All living things are made of cells. Some

living things are made of one cell, and others are made of millions, billions, trillions of cells.

WHAT ARE SOME TYPES OF CELLS?

WHAT DO CELLS HAVE IN COMMON?• All cells have an outer covering, called a cell

membrane.• All cells have an internal, Jello-like material called

cytoplasm.

HOW ARE CELLS DIFFERENT?• When comparing cells, size and shape relate

to function. • 2 Cell Types:• Prokaryotic Cells: lack membrane-bound

internal structures. (NO NUCLEUS)• Eukaryotic Cells: contain membrane-

bound internal structures. (YES NUCLEUS)

PROKARYOTIC CELLS

EUKARYOTIC CELLS

HOW ARE LIVING THINGS ORGANIZED?• Cells are the smallest unit in living things

• Groups of similar cells that work together to perform a job are known as tissues

• Groups of tissues are known as organs• Groups of organs are known as an organ system

• Construct a FLOW CHART to help you remember the organization of living things.

HOW DO WE VIEW CELLS?Early Microscopes• Lenses made images larger,

but not always clear.• Antonie van Leeuwenhoek:

a Dutch fabric merchant, who made a simple microscope in the mid 1600s using a tiny glass bead as a lens.

HOW DO WE VIEW CELLS?Modern Microscopes• Use lenses to bend light• A simple microscope has one lens, while a

compound microscope (what we use in lab) has two sets of lenses.

• A stereomicroscope, which as 2 eyepieces, creates a three-dimensional image.

• Powers of the eyepiece multiplied by the objective lenses determine the total magnification.

WHAT IS AN ELECTRON MICROSCOPE?• Electron microscopes are more powerful than other

microscopes

• They use a magnetic field in a vacuum to bend electronic beams

• Images come out in black and white, and specimens cannot be living

WHAT IS THE CELL THEORY?• The cell theory is the result of many

scientists’ observations and conclusions• 1. All organisms are made up of one or more

cells.• 2. The cell is the basic unit of organization

in organisms.• 3. All cells come from other cells.