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Cells and Cell Theory
Life – How can it be defined(video)?
What are the Characteristics of life?
• Have a life span
• Grow in size, reproduce and are able repair
themselves
• Can sense and respond to changes in their
environment
• Require energy (nutrition or photosynthesis)
• Produce waste
• Movement
• Respiration (exchange gasses with environment)
• Made up of cells
Life simplified?
All living things must have three general properties
• Metabolism
– All chemical process that occur within a living
organism, resulting in energy production and waste
products
• Growth and Movement
– The act or process of increasing in size
– Changing ones position
• Reproduction
– The sexual or asexual process by which organism
generate others of the same kind
The Cell Theory States:
• The cell is the basic unit of life
– The cell can perform all the characteristic of living things
• All living are made up of one or more cells
• All cells come from preexisting cells
• The overall health of the organism depends on the
health of its individual cells
The First Cell
What came first the Chicken or the egg?
Recall that all cells come from preexisting cells, which means you
need a cell to make a cell–So where did the first cell come from?
• The first cell likely formed through
symbiosis –
– A close relationship between two types
of organisms that helped them to
survive and prosper together better
then apart.
• The world is filled with trillions of
bacteria. It is possible that many
parts of the cell were once individual
bacteria, that discovered it was easier
to survive together, then a part
3.5 Billion Years Ago
• Prokaryote (without a nucleus)
• Only form as single cells
Examples
Bacteria
– E. coli
Some Algae – Blue-Green
Viruses
– Flu
Red Blood Cells
20 000 different kinds
today
1.5 billion years of evolution….
life develops a “brain”
• Eukaryote (with a nucleus)
• Form single to trillion celled organisms
Examples
Fungi
– mushrooms
Protozoa – amoeba
(single celled)
Plants
– rose
Animal – humans
Organelles’ video
ORGANELLES
• Cells are the smallest unit of life,
but like atoms, they are made
up of smaller objects. In atoms
we call them subatomic
particles, in cells we call them
organelles.
• Organelles are small specialized
structures that perform specific
functions within a cell
All cells have the following organelles
Organelles
Cell Membrane
Many organelles
have membranes
like the vacuole
and the nucleus
Letter
Location/Structure
Function
The “outer part” or Acts like a gate keeper.
perimeter of a cell or
eg. Controls what gets in
organelle.
and out
DNA – genetic
material
Chromatin
Ridden or hair like
structures found in
the nucleus
The nucleus is guided by
the DNA, which contains all
of the bodies instructions
for life
Chromosomes
look like butterflies,
only occur during cell Eg. Instruction booklet
division (mitosis)
Cytoplasm
A mixture of chemicals Carries the organelles. It is
and water flowing
the area where cell work is
around the cell
done
eg. The cell’s environment
The following organelles are found in many
cells
Nucleus
found in eukaryote cells
Cells with a nucleus
Regulates all cell
activity.
eg. It is the boss
Nucleolus
Dark sphere found Makes ribosomes
inside the nucleus note: Disappears during
cell division (mitosis)
Ribosomes
Very smaller spheres
attached to the
Endoplasmic Reticulum
Makes proteins for
cell growth and
reproduction
Endoplasmic
Reticulum
(ER)
Smooth and Rough
A series of canals with
ribosomes (rough and
attached to the nucleus)
or without ribosomes
(smooth and closer to the
cell membrane)
1. acts like a
conveyor belt or road
inside the cell
2. Provides a site for
chemical reactions to
occur
Mitochondria
Tiny, maze like
structures
Uses food and oxygen to
make energy – ATP
molecules
eg. Site of cellular
respiration
Golgi Body
also called
G. Apparatus
G. Complex
stacks of flattened
sacs
Prepares and packs
proteins and protein
combinations for use
inside or outside of the cell
Vacuoles
very large in plant cells stores water, food and
and helps to support waste for later use
the cell wall of a plant
eg. It is a warehouse
of goods
The following are some unique organelles
found in different cells
Cell Wall
found only in plants
Protects and supports a
plant cell
Centrioles
multi-tubular
structure found
mostly in animals
only used on cell division
Used to split the nuclear
material
Chloroplast
Contains different
colours of
chlorophyll
Green chlorophyll is the
site of photosynthesis
Makes food
Lysosome
spherical “balls” filled
with digestive enzymes
Recycles worn out
products