CELL BIOLOGY
Complete High School Biology
Study Guide
10th Grade / Sophomore Biology
Cell Theory • Prokaryotic & Eukaryotic Cells • Animal &
Plant Cells • Organelles • Cell Membrane • Diffusion •
Osmosis • Active Transport • Cell Cycle • Mitosis
Study Notes / Key Vocabulary / Quick Checks /
Practice Questions
, INTRODUCTION TO CELLS
What Is a Cell?
A cell is the smallest unit of life.
Every living organism is made of one or more cells.
Some organisms, such as many bacteria, consist of only one cell. These are called
unicellular organisms.
Other organisms, including humans, animals and plants, consist of many cells working
together. These are called multicellular organisms.
Cells carry out the essential processes needed for life, including obtaining and using
energy, producing proteins, removing waste, growing and reproducing.
Cell Theory
Cell theory contains three fundamental principles:
1. All living organisms are made of one or more cells.
Every living organism has a cellular structure.
2. The cell is the basic unit of structure and function in living things.
A cell is the smallest structure capable of performing the processes associated
with life.
3. All cells come from pre-existing cells.
New cells are produced when existing cells divide.
Key Vocabulary
Cell: The smallest unit capable of carrying out the processes of life.
Unicellular: Consisting of a single cell.
Multicellular: Consisting of multiple cells.
Organelle: A specialized structure within a cell that performs a particular function.
Cell division: The process by which a parent cell produces new cells.
QUICK CHECK
1. What is the smallest unit of life?
A cell.
2. What are the three main principles of cell theory?
All living organisms consist of cells, cells are the basic unit of life, and new
cells come from existing cells.
, PROKARYOTIC VS. EUKARYOTIC CELLS
There are two broad types of cells: prokaryotic cells and eukaryotic cells.
Prokaryotic Cells
Prokaryotic cells are generally small and relatively simple.
They do not have a membrane-bound nucleus. Instead, their DNA is
located in an area of the cytoplasm called the nucleoid.
Prokaryotic cells also lack membrane-bound organelles such as
mitochondria and the Golgi apparatus.
Bacteria and archaea are prokaryotes.
Eukaryotic Cells
Eukaryotic cells are generally larger and more complex.
Their DNA is primarily contained within a membrane-bound nucleus.
They also contain membrane-bound organelles that perform specialized
functions.
Animals, plants, fungi and protists are eukaryotes.
Comparison
NUCLEUS
Prokaryotic: No membrane-bound nucleus
Eukaryotic: Present
DNA LOCATION
Prokaryotic: Nucleoid region
Eukaryotic: Primarily nucleus
MEMBRANE-BOUND ORGANELLES
Prokaryotic: Generally absent
Eukaryotic: Present
TYPICAL SIZE
Prokaryotic: Smaller
Eukaryotic: Larger
EXAMPLES
Prokaryotic: Bacteria and archaea
Eukaryotic: Animals, plants, fungi and protists
MEMORY TIP
Prokaryote = no membrane-bound nucleus
Eukaryote = membrane-bound nucleus
Complete High School Biology
Study Guide
10th Grade / Sophomore Biology
Cell Theory • Prokaryotic & Eukaryotic Cells • Animal &
Plant Cells • Organelles • Cell Membrane • Diffusion •
Osmosis • Active Transport • Cell Cycle • Mitosis
Study Notes / Key Vocabulary / Quick Checks /
Practice Questions
, INTRODUCTION TO CELLS
What Is a Cell?
A cell is the smallest unit of life.
Every living organism is made of one or more cells.
Some organisms, such as many bacteria, consist of only one cell. These are called
unicellular organisms.
Other organisms, including humans, animals and plants, consist of many cells working
together. These are called multicellular organisms.
Cells carry out the essential processes needed for life, including obtaining and using
energy, producing proteins, removing waste, growing and reproducing.
Cell Theory
Cell theory contains three fundamental principles:
1. All living organisms are made of one or more cells.
Every living organism has a cellular structure.
2. The cell is the basic unit of structure and function in living things.
A cell is the smallest structure capable of performing the processes associated
with life.
3. All cells come from pre-existing cells.
New cells are produced when existing cells divide.
Key Vocabulary
Cell: The smallest unit capable of carrying out the processes of life.
Unicellular: Consisting of a single cell.
Multicellular: Consisting of multiple cells.
Organelle: A specialized structure within a cell that performs a particular function.
Cell division: The process by which a parent cell produces new cells.
QUICK CHECK
1. What is the smallest unit of life?
A cell.
2. What are the three main principles of cell theory?
All living organisms consist of cells, cells are the basic unit of life, and new
cells come from existing cells.
, PROKARYOTIC VS. EUKARYOTIC CELLS
There are two broad types of cells: prokaryotic cells and eukaryotic cells.
Prokaryotic Cells
Prokaryotic cells are generally small and relatively simple.
They do not have a membrane-bound nucleus. Instead, their DNA is
located in an area of the cytoplasm called the nucleoid.
Prokaryotic cells also lack membrane-bound organelles such as
mitochondria and the Golgi apparatus.
Bacteria and archaea are prokaryotes.
Eukaryotic Cells
Eukaryotic cells are generally larger and more complex.
Their DNA is primarily contained within a membrane-bound nucleus.
They also contain membrane-bound organelles that perform specialized
functions.
Animals, plants, fungi and protists are eukaryotes.
Comparison
NUCLEUS
Prokaryotic: No membrane-bound nucleus
Eukaryotic: Present
DNA LOCATION
Prokaryotic: Nucleoid region
Eukaryotic: Primarily nucleus
MEMBRANE-BOUND ORGANELLES
Prokaryotic: Generally absent
Eukaryotic: Present
TYPICAL SIZE
Prokaryotic: Smaller
Eukaryotic: Larger
EXAMPLES
Prokaryotic: Bacteria and archaea
Eukaryotic: Animals, plants, fungi and protists
MEMORY TIP
Prokaryote = no membrane-bound nucleus
Eukaryote = membrane-bound nucleus
