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“Cell Processes”

Chapter 3

Learning Target l  I can…. l  1)Explain the

difference between diffusion and osmosis.

l  2)Predict the movement of particles into and out of a cell.

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“MOVING CELLULAR MATERIAL”

Section 3.2

”All” cells must obtain and use materials for energy”…..

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ATP " Stands for “Adenosine triphosphate” " Also known as “energy”. " It’s the fuel for cells. " How do cells get energy?........... " Cells break down sugar and fats to help

release energy. " This energy is transferred to ATP which

the cell can use. " The energy must be transferred to ATP

before the cells can use it. 5

Quickcheck:

l Which organelle in a cell is responsible for the production of ATP?

l MITOCHONDRIA

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Remember me: “The Cell Membrane”

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Cell Membrane

The cell membrane is made of 2 layers of phospholipids called the lipid bilayer

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Close that window!!! l  There are many reasons we open and shut

the windows in our house. l  Do you want to let all of the bugs and leaves

in? l  A window screen provides the protection to

keep unwanted things outside . But it also allows some things to pass into and out of the room like air, unpleasant odors, or smoke.

l  How does the cell membrane carry out similar functions to that of a window screen?

The cell membrane

l A cell membrane, like a screen, will let some things through more easily than others.

l  Ex: Air gets through a screen, but insects are kept out.

l A cell’s membrane is “selectively permeable”. In other words it allows some things to enter or leave the cell while keeping other things outside or inside of the cell.

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Solubility l Materials that are soluble in lipids can pass through the cell membrane easily

What determines how particles move in and out of the cell?

l  Which way particles moves depends on the

l  a) size of the molecule or particle,

l  B) the path taken through the membrane,

c) whether or not energy is used.

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Small molecules move through the cell membrane very easily. e.g. (O2, CO2, H2O)

Semipermeable Membrane

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Molecules larger than water (such as proteins) do not move through the membrane on their own.

Semipermeable Membrane

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Types of Transport Across Cell Membranes

Moving things “without energy”

l The movement of substances through the cell membrane “without using energy” is called passive transport.

l The cell membrane can move things into and out of the cell without using energy either by:

l  Simple Diffusion l  Osmosis

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Diffusion Simple Diffusion

v  Doesn’t require energy

v  Moves materials from high to low concentration v  Example: Oxygen and/or water diffusing into a cell and carbon dioxide diffusing out.

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Simple Diffusion l  In other words l  Molecules move

from crowded to less crowded areas of concentration.

l  This can occur in solids, liquids, and gases.

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Diffusion “in action”…..

l  You might smell perfume when you sit near or walk past someone wearing it. This is because the perfume molecules are randomly moving throughout the air .

l  The molecules are going from an areas that is crowded (such as inside the bottle) to a less crowded

l  area (such as the air itself). l  There’s more space for the molecules to spread out

and move in the air. l  Diffusion stops once there is an equal number of

molecules in both areas. l  The molecules are in equilibrium.

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DIFFUSION

Diffusion is a PASSIVE process which means no energy is used to make the molecules move, they have a natural KINETIC ENERGY

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Diffusion of Liquids

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Diffusion through a Membrane

Cell membrane

Solute moves DOWN concentration gradient (HIGH to LOW)

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Remember there are three factors that determine how particles move in

and out of the cell: l  Which way particles

moves depends on the l  a) size of the molecule

or particle, l  B) the path taken

through the membrane,

c) whether or not energy is used.

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Diffusion Simple Diffusion

v  Doesn’t require energy

v  Moves materials from high to low concentration v  Example: Oxygen and/or water diffusing into a cell and carbon dioxide diffusing out.

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Diffusion Because they are so

small, molecules such as Oxygen, water, and

carbon dioxide diffuse in and out of a cell at “any

point” of entry.

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Osmosis l  Diffusion of

“water” across a membrane

l  Moves from HIGH water potential (low solute) to LOW water potential (high solute)

Diffusion across a membrane

sem-i-permeable membrane

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Molecules that are “not so small”….

Such as Glucose (sugar) or amino acids (--a chain of proteins)

Find transport proteins to provide “doorways” to help move material from high to low concentration

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This is an example of how it works…

Molecules will spontaneously move through the pores of the cell membrane with the help of “Channel Proteins” that provide a “doorway”

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Another example of how larger molecules can get across the cell

membrane l  Carrier proteins do

not extend through the membrane.

l  They bond and drag molecules through the lipid bilayer and release them on the opposite side.

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Sample problem….

CELL

10% NaCL 90% H2O

10% NaCL 90% H2O

What is the direction of water movement? The cell is at _______________. equilibrium

ENVIRONMENT

No net movement

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Practice:Sample 1

CELL

10% NaCL 90% H2O

20% NaCL 80% H2O

What is the direction of water movement?

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Practice: sample 2

CELL

15% NaCL 85% H2O

5% NaCL 95% H2O

What is the direction of water movement?

ENVIRONMENT

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Practice 3

What is the direction of salt (NaCl) movement?

40% NaCl 60% H2O

CELL

ENVIRONMENT

20% NaCl 80% H2O

Practice 4

What is the direction of salt (NaCl) movement?

20% NaCl 80% H2O

CELL

ENVIRONMENT

90% NaCl 10% H2O

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Just a little more practice… Draw the illustration…

CELL

25% NaCl 65% H2O

35% NaCl 35% H2O

What is the direction of water movement?

What is the direction of the salt (NaCl)?

Explain your answers.

Outside Environment

Answer……

CELL

25% NaCl 65% H2O

35% NaCl 35% H2O

What is the direction of water movement?

What is the direction of the salt (NaCl)?

Explain your answer. Molecules move from areas of high concentration to lower concentration

Outside Environment

Into the cell

Out of the cell

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A simple rule to remember is: salt sucks Salt is a solute. When it is concentrated inside or outside the cell, it will draw the water in its direction. This is also why you get thirsty after eating something salty!

100% water 0% salt

30% salt 70% water

“Flower”

“container” The addition of salt in the container lowers the concentration of water. The water concentration is higher in the cells of the flower.

What happens when you put salt on a snail?

l  They will shrivel up!!! l  Why? l  The bodies of snails and slugs contain much

water in them.  Due to the process of osmosis, in the scenario of salt and snails, the snails act as the area with high water concentration. On the other hand, the salt that you add to the snails has a low water concentration.

l  The snails really do not melt when we add salt.  They dry up because too much water in their bodies is sucked out of them and into the salt.  The poor snails shrivel up and die as a result.

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What do you think?

A fish that is accustomed to living in salt water is placed in fresh water. What do you predict might happen to the cells of the fish? A. They might shrink up and cause the fish to die. B. They would become healthier because the water is so fresh. C. They might swell and burst and cause the fish to die.

The process of osmosis would explain the net movement of water into a cell if the percentage of A.  water was 90% inside the cell and 95% outside the

cell B.  water was 95% inside the cell and 90% outside the

cell C.  protein was 30% inside the cell and 35% outside

the cell D.  water and protein was equal inside and outside the

cell

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Active Transport

v DOES Require energy (ATP)

v Moves materials from LOW to HIGH concentration. It goes

v AGAINST the concentration gradient

Types of Active Transport

Some transport proteins require energy to do work

Sodium Potassium Pumps (Active Transport using proteins)

These “Protein Pumps” change shape to move molecules: this requires energy!

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2 Ways to Move the “Big Stuff” 1) Large molecules move materials into the cell

by endocytosis.

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Endocytosis

. It takes in dissolved molecules as a “vesicle” is being formed. This is sometimes called “Cell eating”.

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Now Watch it Work! J Endocytosis: taking bulky material into a cell

•  Uses energy •  Cell membrane surrounds

the food particle •  Called “cell eating”

because it forms a food vacuole & digests food

•  This is how white blood cells eat bacteria!

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Another Way to Move the “Big Stuff”

Large molecules are moved out of the cell by vesicles that fuse with the cell membrane through exocytosis.

2) Exocytosis- moving large things out.

Exocytosis is how many hormones are secreted and how nerve cells communicate with one another.

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Now Watch it work! J Exocytosis: a process that

forces material out of cell “in bulk” •  Membrane surrounds the

material and fuses with the cell membrane

•  Cell changes shape – requires energy

•  EX: Hormones or wastes released from cell

Endocytosis & Exocytosis animations

Active vs Passive transport

l Is similar to riding a bike…It takes no energy to ride the bike and carry things downhill… (passive transport)

l But it takes energy to ride a bike to carry you uphill…(active transport)

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Types of Cellular Transport

•  Passive Transport cell doesn’t use energy 1.  Diffusion 2.  Facilitated Diffusion 3.  Osmosis

•  Active Transport cell does use energy 1.  Protein Pumps 2.  Endocytosis 3.  Exocytosis

high

low

This is gonna be hard work!!

high

low

Weeee!!!

• Animations of Active Transport & Passive

Transport

SECTION 3.3

“CELL ENERGY”

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Here are your Target Goals:

l  I can: l  ---describe

photosynthesis and cellular respiration.

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It Begins with Sunlight!

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The sun’s energy!

Mostly all the earth’s energy comes from the sun. Plants and some other types of organisms that contain chlorophyll are able to use the light energy from the sun to produce food.

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Photosynthesis l Involves the Use Of Light Energy to convert Water (H20) and Carbon Dioxide (CO2) into Oxygen (O2) and High Energy Sugar(C6H12O6 or Glucose).

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The Photosynthesis Equation

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Pigments •  In addition to water, carbon dioxide, and light energy, photosynthesis requires “pigments”.

•  Chlorophyll is the primary pigment that traps the sunlight and it is found inside the organelle called chloroplasts.

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All organisms need energy…. Animals and other organisms “can not ” make their own food. l  Instead they consume plants and other organisms

as their source of food. l  The food you eat has to be broken down so that the

energy it contains can be converted into a form your cells can use.

l  Do you remember what that form of energy is?

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How do we get our energy??.. l organisms “break down food” and

release energy…. through a process called

l Cellular respiration --- it involves the use of oxygen….. It is also called “aerobic respiration”.

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Chemical Equation for Cellular Respiration…

l Study this and tell me… How is it similar to the equation for photosynthesis?

Cellular respiration

In most Eukaryotes… l Cellular

respiration takes place in the mitochondria of plants and animals.

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Releasing Energy From ATP l Energy is released in your body in the form of ATP. It is constantly being used and remade by cells.

l ATP provides all of the energy for cell activities.

l Most of the energy “released” is in the form of heat (which your body uses to maintain body temperature).

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A little senseless humor…