Transcript The Cell cont.

The Cell cont.
Chapter 7
Sections 3 & 4
Cell Boundaries
Cell Membrane
 A thin flexible barrier that surrounds all cells.
 It contains pumps and channels made of
proteins.
 It regulates what enters & leaves the cell.
 It provides protection and support.
Cell Boundaries
Cell Wall
 A strong supporting layer around the cell
membrane that is usually made of tough
fibers.
 It provides protection for the cell.
 Plants, algae, fungi, & many prokaryotes
have cell walls.
Cell Boundaries
Cytoplasm
It contains a solution of many
different substances in water.
 A solution is a mixture of 2 or more
substances.
Homeostasis
 Ideal conditions; a balance (feedback system)
 Sweat, shiver, heart rate (to deliver more
Oxygen).
Particle Transport
Passive Transport
Diffusion
Osmosis
Facilitated Diffusion
Active Transport
Passive Transport
 Moves down a gradient; particles move from
Higher concentration to lower concentration
 Energy is not required
Diffusion
 A process that occurs because
molecules constantly move & collide
with one another.
Particles move from an area of high
concentration to an area of low
concentration.
 Energy is not used or required.

Diffusion

Equilibrium – when the concentration of the
solute is the same throughout a system. All
organisms move towards & maintain
equilibrium.
 When this is reached, particles of a solution
will continue to move across the membrane in
both directions.
 Done by Osmosis & Diffusion
Osmosis
 The diffusion of water through a
selectively permeable membrane.
Energy is not used or required.
 Isotonic- “same strength”- movement of water


in & water out. Equal concentration
Hypertonic- “above strength”- water out.

Hypotonic- “below strength”- water in. (soil
hypo to root hyper)
Osmosis

Osmotic Pressure- pressure that is caused
during osmosis on the hypertonic side of a
selectively permeable membrane.

The cell contains salts, sugars, proteins, and other
molecules and when put into fresh water, it will
almost always be hypertonic and cause the cell to
swell and possibly burst.
Facilitated Diffusion
 The process in which channels facilitate
or help make it easier for certain
molecules to cross the cell membrane.
Protein channels- they are made of protein
& help move materials from one side to
the other side.
 Energy is not used or required.

Active Transport
 A process in which cells must sometimes
move materials in the opposite direction –
against the concentration difference.



Energy is required. (ATP)
A pump is used to take large molecules and force
them through the membrane.
Against a gradient
Active Transport
 Endocytosis- wraps or absorbs; taking into
cell by infolding or pocketing.
 Phagocytosis- enguls it after surrounding it;
“cell eating”
 Pinocytosis- take up liquid.
 Exocytosis- discharge of large particles;
surrounding & fusing with cell membrane.
Diversity of Cellular Life
Unicellular organisms
Multicellular organisms

Unicellular Organisms
Consists of a single cell.
It carries out all of the essential
functions that a larger organism does
such as: grow, respond, react to
environment, reproduce, & transform
energy.
 Ex. – yeast, algae, bacteria.

Multicellular Organisms
 Are made up of many cells.
The cells are specialized to perform
different tasks.
 Ex. – muscle cells, blood cells, pancreatic
cells.
 Cell specialization – when cells have
different jobs in an organism. Ex- blood
cells transport oxygen, muscle cells
contract and relax muscles.

Levels of Organization
 Individual cells- the first level of organization.
 Tissues- similar cells grouped together to perform a
particular function. Ex.- muscle, epithelial, nervous,
connective.
 Organs- a group of tissues that work together. Ex.heart, stomach, lungs.
 Organ systems- a group of organs that work
together to perform a specific function. Ex.- nervous
system, digestive system, circulatory system.