Chapter 2 – Part 2 Cell Theory Cell Types

Chapter 2 – Part 2
Cell Theory
Cell Types
The Cell Theory
1. All living things
are made of one
or more cells
2. Cells are the
basic units of
structure and
function in all
3. All cells arise
from preexisting
Cell Size
There are many types of cells in our
body, each with a different shape
and function
 Some cells, like human egg cells,
can be seen with the naked eye
 Other cells are very small, like sperm
cells, and need a microscope to be
Cell Size
Cell Size
Humans have trillions of cells in the
Size of cells range from 5µm to 20µm
in size
Cell Size Continued…
Small cells function more efficiently
than large cells
 If surface area to volume ratio is too
low, substances cannot enter and
leave the cell well enough to meet
the cell’s needs
 Small cells have high surface area to
volume ratio
Surface Area-to-Volume
Types of Cells
Prokaryote – “Before nuclei”
Eukaryote – “True nuclei”
Consists of unicellular organisms
Ex: Bacteria and archea
Can live in many environments
Ex: extreme temperatures, pH,
and radiation
Some can make their
own food
Grow and divide
rapidly using asexual
Prokaryote Cells
-Lacks a nucleus and most organelles
-Much smaller than a eukaryote cell
-One single circular strand of DNA
found in the cytoplasm
Prokaryote Cells Continued…
Plasmid: Circular
strand of DNA
Flagella: Aids in
Pili: Helps bacteria
attach to surfaces
Capsule: a
barrier used for
Consists of unicellular and
multicellular organisms
Ex: Plants, animals, fungi, protists…
 Organisms can asexually and
sexually reproduce
Eukaryote Cells
Contains a nucleus with DNA and
membrane-bound organelles
Larger, more complex cells
May have evolved from a
prokaryotic cell
Types of Eukaryote Cells
Plant Cells and Animal Cells