Chapter 3: Cells
Chapter 3 Learning objectives:
3.1 Cells Are the Units of Life
- Cells were not discovered until microscopes were invented
A. Simple Lenses Revealed the First Glimpses of Cells
Describe the contributions of the following people to the study of cells
● Robert Hooke: He was the first person to see the outlines of cells. His
discovery initiated a new field of science, now called cell biology.
● Antony van Leeuwenhoek: A largely self-taught man in science, he is
commonly known as "the Father of Microbiology", and one of the first
microscopists and microbiologists
B. The Cell Theory Emerges
● What are the three early components of Cell Theory? (Mathias J. Schleiden
and Theodor Schwann
1. All organisms are made of one or more cells
2. The cell is the fundamental unit of all life.
3. Rudolf Virchow: He proposed that all cells come from pre-existing cells
● Name three modern ideas that were added to Cell Theory
1. All cells have the same basic chemical composition
2. All cells use energy
3. Cells contain DNA that is duplicated and passed on as each cell divides
C. Microscopes Magnify Cell Structures
Microscopes allow us to see cells and structures within cells.
i. Light microscopes
● Light microscopes give true-color images of live or preserved cells. Their
main disadvantage is that many cell structures are too small to see using a
light microscope.
● The most powerful ones can magnify up to 1600 times and resolve
objects that are 200 nanometers apart.
ii. Transmission and Scanning Electron Microscopes
● Transmission electron microscopes (TEM) send a beam of electrons through a
very thin slice of a specimen. They produce black and white images at a
much higher magnification than possible with light microscopes, allowing a
better view of internal structures.
, ● Scanning electron microscopes (SEM) scan a beam of electrons over the
surface of a metal-coated, three-dimensional specimen. Their main
advantage is their ability to reveal texture on the specimen’s outer surface.
● TEMs can magnify up to 50 million times and resolve objects less than
1 angstrom (10–10 meters) apart.
D. All Cells Have Features in Common
Describe the following structures that are found in all cells:
● Ribosomes: These are the structures that manufacture proteins.
● Cell membrane: (also called the plasma membrane) That forms a boundary
between the cell and its environment
● Cytoplasm: This includes all cell contents (except the nucleus, in cells that
have one)
● Cytosol: Is the fluid portion of the cytoplasm.
Another feature common to nearly all cells is small size.
Explain the relationship between surface area and volume.
As an object grows, so does the volume.
What effect does increasing cell size have on cell function?
Folds on the outer surface of cells increase surface area relative to volume.
3.2 Different Cell Types Characterize Life’s Three Domains
Prokaryotes are the earliest and simplest life forms and do not have a nucleus.
Eukaryotes evolved later. Their cells have a nucleus and membrane-bound organelles.
Chapter 3 Learning objectives:
3.1 Cells Are the Units of Life
- Cells were not discovered until microscopes were invented
A. Simple Lenses Revealed the First Glimpses of Cells
Describe the contributions of the following people to the study of cells
● Robert Hooke: He was the first person to see the outlines of cells. His
discovery initiated a new field of science, now called cell biology.
● Antony van Leeuwenhoek: A largely self-taught man in science, he is
commonly known as "the Father of Microbiology", and one of the first
microscopists and microbiologists
B. The Cell Theory Emerges
● What are the three early components of Cell Theory? (Mathias J. Schleiden
and Theodor Schwann
1. All organisms are made of one or more cells
2. The cell is the fundamental unit of all life.
3. Rudolf Virchow: He proposed that all cells come from pre-existing cells
● Name three modern ideas that were added to Cell Theory
1. All cells have the same basic chemical composition
2. All cells use energy
3. Cells contain DNA that is duplicated and passed on as each cell divides
C. Microscopes Magnify Cell Structures
Microscopes allow us to see cells and structures within cells.
i. Light microscopes
● Light microscopes give true-color images of live or preserved cells. Their
main disadvantage is that many cell structures are too small to see using a
light microscope.
● The most powerful ones can magnify up to 1600 times and resolve
objects that are 200 nanometers apart.
ii. Transmission and Scanning Electron Microscopes
● Transmission electron microscopes (TEM) send a beam of electrons through a
very thin slice of a specimen. They produce black and white images at a
much higher magnification than possible with light microscopes, allowing a
better view of internal structures.
, ● Scanning electron microscopes (SEM) scan a beam of electrons over the
surface of a metal-coated, three-dimensional specimen. Their main
advantage is their ability to reveal texture on the specimen’s outer surface.
● TEMs can magnify up to 50 million times and resolve objects less than
1 angstrom (10–10 meters) apart.
D. All Cells Have Features in Common
Describe the following structures that are found in all cells:
● Ribosomes: These are the structures that manufacture proteins.
● Cell membrane: (also called the plasma membrane) That forms a boundary
between the cell and its environment
● Cytoplasm: This includes all cell contents (except the nucleus, in cells that
have one)
● Cytosol: Is the fluid portion of the cytoplasm.
Another feature common to nearly all cells is small size.
Explain the relationship between surface area and volume.
As an object grows, so does the volume.
What effect does increasing cell size have on cell function?
Folds on the outer surface of cells increase surface area relative to volume.
3.2 Different Cell Types Characterize Life’s Three Domains
Prokaryotes are the earliest and simplest life forms and do not have a nucleus.
Eukaryotes evolved later. Their cells have a nucleus and membrane-bound organelles.
