Transcript 3.2 Looking Inside Cells

Section 2: Looking Inside Cells
7.1.b Students know the characteristics that distinguish
plant cells, including chloroplasts and cell walls.
7.1.c Students know that the nucleus is the repository for
genetic information in plant and animal cells.
Enter the Cell
• Organelles- carry out specific functions
within a cell
• Cell Wall- a stiff wall that surrounds the
membrane giving the cell a rigid boxlike
shape
• Key concept: “The cell wall helps to protect
and support the cell.”
• In plants the cell wall is made of cellulose
• Cell wall is tough but some things can
pass through like water and oxygen
• Animal cells DO NOT have cell walls
Enter the Cell
• Animal cells have cytoskeleton- a protein
“framework” inside the cell that gives the
cell its shape
• Cell Membrane- forms a protective barrier
between the cytoplasm and the
environment outside the cell because an
animal cell does not have a cell wall
• ALL cells have cell membranes
• Key concept: “The cell membrane controls
what substances come into and out of a
cell.”
• To survive a cell must get food, oxygen,
and as well as let out waste (like a window
screen)
Plant Cells
Animal Cell
Sail on to the Nucleus
• Nucleus is surrounded by the
nuclear envelope to protect
the nucleus
• Chromatin- thin strands
floating in the cell that
contains genetic material,
instructions for directing the
cells functions
• Nucleolus- where ribosomes
are made
Nucleus
• Key concept: “The
nucleus is the cell’s
control center,
directing all of the
cell’s activities.”
Organelles in the Cytoplasm
• Cytoplasm- a gel-like fluid that many
different organelles are found in
• Fluid in the cytoplasm is constantly moving
• Key concept: “In the cytoplasm are many
organelles, including mitochondria,
endoplasmic reticulum, ribosomes, Golgi
bodies, chloroplasts, vacuoles, and
lysosomes. Each of these organelles has
specific functions in the cell.”
Organelles in the Cytoplasm
• Mitochondria are
known as the
“powerhouses” of the
cell
• They convert energy in
food molecules to
energy the cell can use
to carry out its functions
Mitochondria
Endoplasmic
Reticulum
• Endoplasmic Reticulum is
similar to the system of
hallways in a building.
• Proteins and other materials
move throughout the cell
using the endoplasmic
reticulum.
• The spots on this organelle
are ribosomes, which
produce proteins.
Organelles in the Cytoplasm
Golgi Body
• Golgi Body- receive proteins
and other newly formed
materials from the
endoplasmic reticulum,
package, and distribute them
to other parts of the cell.
• Called the cells mailroom
• Flattened sacs and tubes
• Chloroplasts- capture energy from
the sunlight and use it to produce
food for the cell
• Only in plant cells (and some
other organisms)
• They are green in color giving the
plant a green color
Plant cells
Organelles in the Cytoplasm
• Vacuole- stores water, food,
waste, and other materials
• some animal cells have vacuoles
that store food, water, waste, and
other materials
• large water filled sacks
• most plant cells have one
• Ribosomes- small structures
that function like factories to
produce proteins
• they may float in the
cytoplasm or be attached to
the endoplasmic reticulum
Organelles in the Cytoplasm
• Lysosomes- small organelles that contain chemicals
that breaks down food particles and worn-out cell parts
• small round structures
• the “clean-up crew”
Nerve Cell
Cell Diversity
Blood Cell
• Key Concept: “The variety of structure in cells reflects
differences in cell function.”
• Some cells have certain organelles but not others
• Some cells have more of one type of organelles
• Cells come in different shapes
Looking Back
What role do the cell wall and cell
membrane play in the cell?
What is the role of the nucleus in the cell?
What organelles are found in the
cytoplasm and what are their functions?
How do cells differ?