How do we define what it
means to be alive?
Defining Life
There is no universal definition of life. To define life in terms is still a
challenge for scientists.
Conventional definition: must exhibit the following criteria:
1. Homeostasis: Regulation of the internal environment to maintain a constant
state; for example, sweating to reduce temperature.
2. Organization: Being composed of one or more cells, which are the
basic units of life.
3. Metabolism: Consumption of energy
4. Growth: A growing organism increases in size in all of its parts, rather than
simply accumulating matter.
5. Adaptation: The ability to change over a period of time in response to the
environment
6. Response to stimuli: A response can take many forms, from the contraction
of a unicellular organism when touched to complex reactions involving all
the senses of higher animals. A response is often expressed by motion, for
example, the leaves of a plant turning toward the sun or an animal chasing
its prey.
7. Reproduction: The ability to produce new organisms.
Cell Theory - Review
1. All living things are made of cells
2. Cells are the basic units of
structure (form) and function
(purpose) in living things.
3. Living cells come only from other
living cells
Brainpop: Cells
What technology was created that
allowed cells to be discovered?
• Hint: you could not SEE
a cell without this piece
of equipment.
• Another hint: we used
this piece of equipment
during our last unit of
study.
What are cells?
• Cells are the basic unit of structure and
function in living things.
• All living things are made up of cells
• Cell are the building blocks of life
• Cells are specialized to do certain jobs in
different regions of your body.
• There are about 200 different types of cells in
your body.
• Cells are so tiny you could fit more than a
million of them on a period at the end of a
sentence.
• Cells were named by Robert Hooke.
• 1st scientist to call spaces in cork cells he
observed under the microscope “cells.”
• Comes from the Latin word cella which means
“little rooms”.
• Unicellular: one cell – bacteria.
• Multicellular: many cells –humans have over
200 different types of cells (blood, bone, skin)
and an estimated 100 trillion total cells.
Cells
• Each cell is an amazing world unto itself: it can
take in nutrients, convert these nutrients into
energy, carry out specialized functions, and
reproduce as necessary.
• Each cell stores its own set of instructions for
carrying out each of these activities.
• Organelles: small structures, or “organs” within
cells that perform a specific function
PLANT AND ANIMAL
CELLS
Cell Theory:
• All organisms are
made up of one or
more cells.
• The cell is the
basic unit of
organization of all
organisms.
• All cells come from
other cells already
in existence.
CELL WALL:
PLANT
• Function:
Gives the cell most
of its support and
structure
• A thick, rigid
membrane that
surrounds a plant
cell
• Bonds with other
cell walls to form
the structure of
the plant
Plant
Cell
Cell Wall
CELL MEMBRANE
Plant and Animal
•
•
Function:
Semi permeable,
allowing some
substances to pass
into the cell and
blocking others.
Thin layer of
protein and fat that
surrounds the cell
Animal Cell
Cell
Membrane
Plant
Cell
Cell Membrane
• Function:
Where the
organelles are
located.
• The jellylike material
located inside the
cell.
• In Both Plant and
Animal Cell
Cytoplasm
Animal Cell
Cytoplasm
Plant
Cell
Cytoplasm
ENDOPLASMIC RETICULUM
• Function:
transports
materials through
the cell
• Rough ER is
covered with
ribosome's that
give it a rough
appearance
• In both Plant and
Animal Cell
Animal Cell
Smooth
ER
Rough
Endoplasmic
Reticulum
Plant
Cell
Smooth
ER
Rough
Endoplasmic
Reticulum
Chloroplast
• Function:
Manufactures food
through
photosynthesis. Uses
energy from sunlight
to make sugar.
• An elongated or discshaped organelle
containing chlorophyll
• Only in Plant Cell
Plant
Cell
Chloroplast
Golgi Bodies
• Function:
Golgi bodies are the
packaging and
secreting organelles
of the cell.
• Are stacks of
membrane-covered
sacs that package
and move proteins
to the outside of the
cell.
• In Both Plant and
Animal Cell
Animal Cell
Golgi
Body
Plant
Cell
Golgi
Body
Lysosome
• Function:
Where the digestion of
cell nutrients takes
place
• Also called cell vesicles
• Spherical organelles
surrounded by a
membrane
• They contain digestive
enzymes
• In Both Plant and
Animal Cell
Animal Cell
Lysosome
Plant
Cell
Lysosome
Mitochondria
•
•
•
•
Functions:
Where energy is
released.
Rod-shaped
organelles with
a double
membrane
Membrane is
infolded many
times, forming a
series of
projections
(called cristae)
In Both Plant
and Animal Cell
Animal Cell
Mitochondria
Plant
Cell
Mitochondria
Nucleus:
The Manager
• Function:
Controls many of
the functions of
the cell
• Spherical body
containing many
organelles,
including the
nucleolus
• Contains DNA (in
chromosomes)
• Surrounded by
the nuclear
membrane
• In Both Plant and
Animal Cell
Nucleus
Animal Cell
Nucleus
Plant
Cell
Ribosomes
• Function:
Small structures in
the cytoplasm that
create proteins.
• Ribosome's are
either free floating
in the cytoplasm of
a cell or attached
to endoplasmic
reticulum in a cell.
• In both Plant and
Animal Cell
Animal Cell
Ribosomes
Plant
Cell
Ribosomes
Vacuole
•
•
•
•
Function:
Like your suitcase, a
vacuole is a
temporary storage
space for the cell.
Fluid-filled,
membranesurrounded cavities
inside a cell
Filled with food
being digested and
waste material that
is on its way out of
the cell
Many in Animal, One
large in Plant
Animal Cell
Vacuole
Plant
Cell
Vacuole
Nuclear Membrane
• Protects and guards the nucleus
• Controls movement of materials in and out of
the nucleus
• Keeps the DNA inside the nucleus
• Allows other materials to pass in and out of
the nucleus
• In Both Plant and Animal Cell
Animal Cell
Nuclear Membrane
Nuclear Plant
Membrane Cell
Nucleolus
• Controls the cells activity… The Brain
• Inside the nucleus
• The nucleolus is the part of the nucleus
which contains most of the genes that
code for the synthesis of ribosomal RNA
• In both Plant and Animal Cell
Nucleolus
Animal Cell
Nucleolus
Plant
Cell
Chromosomes
• Contains the DNA
• Located in the nucleus
• In Both Plant and Animal Cell
Animal Cell
Chromosomes
Chromosomes
Plant
Cell
Animal Cell
Nucleolus
Nucleus
Nuclear Membrane
Chromosomes
Mitochondria
Cytoplasm
Smooth
ER
Lysosome
Golgi
Body
Vacuole
Ribosomes
Cell
Membrane
Rough
Endoplasmic
Reticulum
Nucleolus
Chromosomes
Cytoplasm
Smooth
ER
Nucleus
Nuclear Plant
Membrane Cell
Lysosome
Golgi
Body
Vacuole
Chloroplast
Mitochondria
Cell Wall
Cell Membrane
Rough
Endoplasmic
Reticulum
Ribosomes
Edible Plant and Animal Cells
Animal Cell
________
________
_________
Plant
Cell
Animal Cell Parts
Plant Cell Parts
Nuclear membrane
Chromosomes
Nuclear membrane
Chromosomes
Mitochondria
Nucleus
Mitochondria
Nucleus
Smooth ER
Nucleolus
Smooth ER
Nucleolus
Rough ER
Rough ER
Chloroplast
Golgi Body
Golgi Body
Cell Wall
Cell Membrane
Cell Membrane
Ribosomes
Ribosomes
Vacuole
Vacuole
Lysosome
Lysosome
Cytoplasm
Cytoplasm