Science 10 Review: The Cell

Quiz on Friday, September 4 on pages 154-159 of your textbook. You are responsible for all material on those pages.

Remembering the Cell• A cell is the smallest unit of life. All living things

are made of one or more cells.

• A cell can perform all functions necessary for living organisms.

• A cell contains many small structures called organelles, each of which has a special role to play.

Challenge Questions (Answer as a group)

A B

1. Which cell above is an animal cell? Plant cell?

2. What are the main differences in a plant and animal cell?

3. Label as many organelles as you can:

A

B

C

DE

F

G H

Nucleus

Cell Membrane

Endoplasmic reticulum

Ribosomes

Mitochondria

Golgi Apparatus

Vacuole

Lysosome

4. Label as many organelles as you can:

A

B

C

Cell Wall

Chloroplast

Central Vacuole

A

B

C

5. Match the organelle with its primary function:

Nucleus

Cell Membrane

Endoplasmic reticulum

Ribosomes

Mitochondria

Golgi Apparatus

Vacuole

Lysosome

A. Command center. Contains DNA.

B. Modifies proteins and lipids and packages them into vesicles for transport to cell membrane.

C. Small structures that build proteins.

D. Powerhouse. Carbohydrates are broken down to release energy.

E. Separates cell from environment and controls movement of molecules in and out of cell.

F. System of flattened sacs that build protein or lipids. Can be rough or smooth.

G. Fluid filled sac for storing food and water.

H. Vesicle that contains digestive enzymes.

6. Match the organelle with its primary function:

Chloroplast

Cell Wall

Central Vacuole

A. Rigid structure that provides support & protection.

B. Converts sunlight into chemical energy in the form of carbohydrates (sugar).

C. Fluid-filled storage sac that also provides support to a plant cell.

Closer Look At Cell Membranes• Separates cell from environment or inside of an organelle from the cytoplasm.

• Controls what crosses it.

• Made up of 3 things: phospholipids, proteins, & carbohydrates.

• Phospholipids form a bilayer with a hydrophillic outer shell and a hydrophobic core.

• Proteins are embedded in the bilayer and act as a passageway for water-soluble molecules & ions.

Fluid-Mosaic Model

What lives longer, a brain cell or a stomach cell?

BRAIN CELLS!!!!!!

(The average life span for a stomach cell is two days, but a brain cell can last a lifetime!)

So what’s the diff?

“Did You Know” Trivia

True or False: All cells in your body have a nucleus?

FALSE!!!!!!

(A red blood cell has no nucleus)

Why doesn’t it have a nucleus?

“Did You Know” Trivia

Science 10 Review: Cell Transport

Quiz on Thursday, September 4 on pages 154-159

of your textbook. You are responsible for all material on those pages.

Cell Transport• Most cells in plants and animals are surrounded

by extracellular fluid (ECF), a solution of dissolved chemicals.

• Cells take chemicals in from the ECF and release chemicals into the ECF.

• Because only certain molecules can pass through, cell membranes are called selectively permeable.

• The passage of molecules across a membrane can be passive or active.

Passive Transport• Molecules have a tendency to move from an area

of higher concentration to lower concentration (“down the concentration gradient”).

• This movement requires no energy from the cell, so it is called passive transport.

• Passive transport includes the following: Diffusion

OsmosisFacilitated diffusion

1. Diffusion

Only molecules that are soluble in lipids or small enough to pass through the pores of the cell membrane can enter via diffusion.

Examples include oxygen and carbon dioxide.

2. Osmosis

If there is a concentration gradient across the cell membrane and solute molecules are not able to diffuse across, then water will travel across the membrane in a process called osmosis.

Water will also travel from high concentration to low concentration until it is equal on both sides of the membrane.

Three terms to remember when discussing osmosis:

ISOTONIC

Concentration of water equal on both sides.

Water moves in both directions equally.

HYPOTONIC

Concentration of water greater outside when ECF is hypotonic.

Water moves in.

HYPERTONIC

Concentration of water greater inside when ECF is hypertonic.

Water moves out.

NOTE:

Water will always move from a HYPOTONIC solution to a

HYPERTONIC solution.

Hypo to Hyper

http://www.nclark.net/Cells

Challenge Question

Does a freshwater fish live in a hypotonic or hypertonic environment? Explain your choice.

Freshwater fish have to battle water intake because they live in a hypotonic environment.

One method to do this is to excrete urine with a very high salt content to lower the tonicity of the

blood.

3. Facilitated Diffusion

Large molecules such as glucose can still move passively across a membrane via facilitated diffusion.

The molecules pass through the protein embedded in the cell membrane from an area of high concentration to low concentration.

Active Transport

• Active transport is the process that moves molecules against the concentration gradient (from low concentration to high concentration)

• This transport creates a build up of certain molecules on one side of the membrane.

• Molecules must be moved through membrane proteins (channel or carrier).

• The proteins require energy to move the molecules against the concentration gradient. The energy often comes from adenosine triphosphate (ATP).

Endocytosis & Exocytosis• Sometimes molecules are too big to cross the

membrane, even through protein carriers.

• In this case, the membrane actually moves around the molecule to shuttle it into or out of the cell.

• Moving molecules into the cell = Endocytosis

• Moving molecules out of the cell = Exocytosis

• These processes also require ATP (energy).

Endocytosis• Membrane engulfs substance and draws it into

the cell in a membrane-bound vesicle.

• Pinocytosis = intake of small amount of ECF and molecules dissolved in it.

• Phagocytosis = intake of large amount of ECF with large material (cell, organic matter).

Exocytosis• Membrane bound vesicle fuses with cell

membrane, releasing contents into the ECF.

• Exocytosis is used during waste removal or release of hormones.

Your Challenge 1• Complete the following task:

Describe a model you could make using everyday items to demonstrate the processes of diffusion, active transport, and exocytosis. Be very specific in your description:

List of materials and amount of each material

Description of how materials are arranged (diagram would be helpful!)

Description of how materials move in the model

Your Challenge 2 • Complete the following task:

Use the following terms to create a concept map.

Transport Phagocytosis

Active Transport Pinocytosis

Passive Transport Diffusion

Endocytosis Facilitated diffusion

Exocytosis Osmosis

Your Challenge 3• Complete the following task:

Design an experiment that will prove or disprove OSMOSIS. You may use the following materials or anything else that you think you may need:

water dyes to color water

sugar sugar indicator

large beaker

dialysis tubing ( a semi permeable membrane)