Download Cell Structures

Cell Structures- 7.2
Animal Cell
Plant Cell
The Outer Cell
Cell membrane- a thin, flexible barrier
around the cell. Cell membranes are
semi-permeable, meaning that they allow
certain materials in and out of the cell
Cell Wall- Thick, outer covering of plant
cells, bacteria cells, fungi cells and algae
cells. Cell walls provide support and
protection for the cell. Made of cellulose
(plants) and chitin (fungi)
Picture It!
Cell Membrane
Cell Wall
The Nucleus
Scottish botanist Robert Brown first identified the
nucleus in 1831
The nucleus controls much of the cell’s activity
and contains the cell’s hereditary information in
the form of DNA (Deoxyribonucleic Acid)
Almost all eukaryotic cells including plant and
animal cells contain a nucleus
Prokaryotic cells like bacteria have no nucleus
The Nucleus, Cont.
An Actual
Nucleus
Model of a Nucleus
“Matrix”
Nucleus
Inside the Nucleus
Chromatin- the granular material inside the
nucleus. It is made of DNA bound to protein, and
carries the hereditary information in the cell
Chromosomes- chromatin condenses to form
chromosomes during cell division
Nucleolus- Small dense region inside the
nucleus that is responsible for the assembly of
ribosomes, which make proteins
Nuclear membrane- outer covering of the
nucleus, allows a steady stream of RNA in and
out.
Nucleolus
Chromatin
Chromosomes
Cytoskeleton
Network of protein
filaments that helps the
cell maintain its shape
Also involved in many
forms of cellular
movement
Microtubules are hollow
protein tubes that
maintain cellular shape
and serve as “tracks” on
which organelles can
travel
Microfilaments- protein
filaments that provide
structure for the cell
Organelles in the Cytoplasm
The cytoplasm is the liquid
“goo” like material inside
the cell. It is made of water
and salts, and contains all
the cell organelles (little
organs)
Ribosomes are made of
RNA and protein. They
assemble proteins following
the coded information
stored in the nucleus.
Electron Microscope
image of Ribosomes
Endoplasmic Reticulum
Internal membrane
system in which cell
membrane
components are
made and proteins
are modified
Smooth ER- does not
contain ribosomes
Rough ER- “studded”
with ribosomes
Smooth ER
Rough ER
More Cytoplasmic Organelles
Golgi Apparatus- packages and ships
materials, attachs necessary
carbohydrates and lipids to proteins. This
organelle is a stack of sac-like membranes
Lysosomes- breaks down carbohydrates
and lipids, also “eats” dead organellescleans up the cell
Vacuoles- store food and water for cells to
use, plant cells have huge organelles
Can you find the vacuole?
Energy! Energy! Energy!
Mitochondria- Found in
both animal and plant
cells. Breaks down
glucose (food) to release
energy
Chloroplasts- Found in
plant, algae and some
bacteria cells.
Autotrophic, the organelle
that converts sunlight into
glucose
Putting it All Together
An Amazing Journey
Tiny little cells are so very complex! Imagine taking a magic
journey inside one of your cells… what would you see????
Section 7.3
Movement Through the
Membrane
Cell Membrane
The cell membrane is the flexible outer
covering found on the outside of cells
It regulates what enters and leaves the cell
and also provides protection and support
Cell membranes allow food and water in
and gases and wastes out
They are semi-permeable, which means
that some things are allowed through, and
others are not
Cell Membrane, Cont.
The core of the cell
membrane is a lipid
bi-layer (a double
layer of lipids)
Proteins act as
channels through the
membrane
Carbohydrate chains
are there for cell
identification
Diffusion
Every cell is in a liquid environment– with a
liquid interior and surrounded by liquid. The cell
membrane separates these two liquid
environments.
Concentration of a solution is the mass of the
solute that is dissolved in a certain volume of
solvent
In a solution, molecules move constantly.
Across a membrane, they move from a high to a
low concentration. This is called diffusion
Diffusion, Cont.
Diffusion causes many substances to
move across the cell membrane, but it
does not require energy
Diffusion happens automatically, when
there is a concentration difference or the
solutions are in equilibrium (equal
concentrations on both sides)
In equilibrium, however, the molecules
move rapidly in both directions
Osmosis
Osmosis is diffusion, but not all diffusion is
osmosis.
Osmosis is the movement of water across
a semi-permeable membrane
Water moves from an area of high water to
an area of low water concentrations
When equilibrium is reached, it moves in
both directions
Osmotic Pressure
Osmosis exerts pressure on a certain side
of the cell membrane
HyPERtonic- Area of high concentrations
of particles such as salt or sugar (high
PERticles)
HypOtonic- Area of high concentration of
water (high H2O-- hypOtonic)
Isotonic- concentrations of particles and
water are equal
Solution Types
If you place a cell (like an egg) in a highparticle solution (Hypertonic) then water
will rush out of the egg and the egg will
shrivel
In a Hypotonic (High water) solution, water
will rush into the egg and the egg will swell
In a Isotonic solution, no change will be
noticed because the water will move in
both directions, in and out of the egg
Facilitated Diffusion
The word facilitate means to “assist” or to
“help”
In facilitated diffusion, proteins that are
embedded in the membrane help bigger
molecules go through by acting as a channel
There must be a concentration difference,
meaning this will not take place in equilibrium
Extra energy is not needed
Active Transport
“Active” implies that you need energy
This is transport that needs energy in
order to take place
Endocytosis- food is taken into a cell–
Phagocytosis is a type of this, it is literally
“cell eating”
Exocytosis is the exit of materials out of a
cell– usually waste
Homework
Define Vocabulary 7.3 and 7.4 on page
196
Due Tuesday
Also: Progress Report