The Building Blocks of Life



A cell is defined as
the basic structural
and functional unit of
all organisms.
It is the smallest living
building block of all
organisms

Some cells are single
organisms
Some cells group
together to form living
tissues of a larger,
more complex
organism

The first person to name the cell
was Robert Hooke in 1665
He used an early version of a microscope
to look at cork and described the little
boxes as cells (as in a jail cell)
 From:
He believed only plants had “cells”

http://www.ucmp.berkeley.edu/history/hooke.
html
A Dutch inventor who created the
microscope that we recognize today
 In 1678, he was the first person to discover
a single celled protozoa
 He called these “Little Animals”
 He also looked at blood cells

 All
organisms
are made of one
or more cells
 The cell is the
basic unit of all
living things
 All cells come
from existing
cells
From :
http://www.answers.com/to
pic/cell-theory-1

Cell theory refers to the
idea that cells are the basic
unit of structure in every
living thing. Development of
this theory during the Mid
1600s was made possible
by advances in microscopy.
This theory is one of the
foundations of biology. The
theory says that new cells
are formed from other
existing cells and the cell is
a fundamental unit of
structure, function and
organization in all living
organisms.
Prokaryotes
Think
Pro
Means
NO!
No
nucleus
Eukaryotes
Think “Eu” = You
You have eukaryotic cells
just like all animals and
most
plants.
Think
Pro
Means
NO!
No nucleus
Cells that DO NOT have a nucleus.
 These single cells are molecules
surrounded by a membrane and cell wall.
 Prokaryotic cells lack typical
“organelles”, but may contain
a membrane system inside a
cell wall.
 Examples include simple
bacteria

Think “Eu” =You
You have eukaryotic cells
just like all animals and most
plants.
Eukaryotic Cell
Cells that have a nucleus and usually have
organelles that perform specific jobs for
the cell.
 Example – Plant and Animal Cells are
Eukaryotic
 Eukaryotic cells usually are 10
times larger
than Prokaryote cells.

See the visible nucleus (dark spot)
Eukaryotic Cell
Organelles are the structures (PARTS)
inside of a cell that perform the functions
necessary for the cell to survive.
 Example: Think about your heart, lungs
and liver… They are all organs inside of
your body. The cell has parts like this
inside of its cell that are called
organelles.

The cell membrane is the protective layer
that covers the cell’s surface.
 It acts like the fence around a yard. It is
like the skin on your body. It keeps some
things out and lets other things in.

Support
 Protection
 Controls movement of materials in/out of
cell
 Barrier between cell and its environment
 Maintains homeostasis

Cell Wall: not found in animal cells
 Gives support to the cell
 Is a second layer or “fence” like the cell
membrane.

not found in animal cells


Found in : plant,
fungi, and some
bacteria, but not
animal cells
Description :
 Outer
layer that is rigid
& strong
 Made of cellulose

Function –Support
and protection of cell
Nucleus: An organelle inside of the cell
that directs the activity in the cell.
 It holds the DNA (chromosomes)

 This
is the blue print material (directions) for
the cell.
 It tells how to reproduce and perform all of the
cells jobs.
nucleus
The nucleus
tells all the
other cell
parts what to
do.
Mitochondria The organelle that releases
energy in the cell. (The powerhouse of the
cell)
 Breaks down sugar (glucose) molecules to
release energy


Chloroplasts Organelle that produces
chlorophyll. ( The chemical of
photosynthesis) to power the plant cell.
 Chlorophyll
traps the energy of sunlight, which
is then used by the plant cell to make sugar
for energy.

Only found in PLANT cells.
Uses energy from sun to make food
(glucose) for the plant
 Process called photosynthesis
 Responsible for the
conversion of
Carbon dioxide to
Carbohydrates
 Similar to the
mitochondria of the animal cells

Cytoplasm The gel-like material inside of
the cell membrane.
 Found in all cells
 Keeps organelles in place



1.
2.
3.
Some single celled
organisms must move
about to search for
food.
They can move by:
Cilia
Flagella (whip-like
tails)
Pseudopods (false
feet)
1
2
3
Pseudopod
movement
The cells in your body function similar to
the way your entire body works
 The nucleus (brain) tells the cell what to do
 The organelles each perform a specific
task to help the body survive
 All living things are made up of cells.

Responsible for intracellular digestion
and the release of cellular waste
products.
 In animal cells, vacuoles are generally
small.
 Large in plant cells and play a role in
turgor pressure.

Ribosomes

Site of protein synthesis, it may be free in the cytoplasm
or attached to membranes.
Lysosomes
Contains digestive enzymes, if it breaks it will kill the cell
Endoplasmic Reticulum
Interconnection channels that store and transport
materials around the cell.
Why are cells considered the most basic
level of life?
 Why are Eukaryotes considered more
advanced than Prokaryotes?
 Name some cells in your body. Are they
all alike or different?
 How would our bodies work differently if
we had chloroplasts in our body cells?

Aliens are often shown as
being
green creatures?
Can you guess why?

Many scientists believe if there is life on other planets
that it would have evolved differently than life on Earth.
One belief is that life forms would be a cross between
animals and plants and, therefore, aliens would have the
ability to use sunlight as a source of food. Cool!

http://www.williamsclass.com/SeventhScie
nceWork/CellTheoryParts.htm