The Cell cont.

1
The Cell cont.

• Chapter 7
• Sections 3 4

2
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.

3
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.

4
Cell Boundaries

• Cytoplasm
• It contains a solution of many different
  substances in water.
• A solution is a mixture of 2 or more substances.

5
Homeostasis

• Ideal conditions a balance (feedback system)
• Sweat, shiver, heart rate (to deliver more
  Oxygen).

6
Particle Transport

• Passive Transport
• Diffusion
• Osmosis
• Facilitated Diffusion
• Active Transport

7
Passive Transport

• Moves down a gradient particles move from Higher
  concentration to lower concentration
• Energy is not required

8
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.

9
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

10
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)

11
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.

12
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.

13
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

14
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.

15
Diversity of Cellular Life

• Unicellular organisms
• Multicellular organisms

16
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.

17
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.

18
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.