Thursday Opening Question: What are at least five things that you know about cells? Agenda:...

Thursday

Opening Question:What are at least five things that you know about cells?

Agenda:• Prokaryote/Eukaryote

foldable•Community Cells

Cells-R-Us

• Cell Theory- The cell theory consists of three components listed below:

• 1.) all organisms are made up of one or more cells,

• 2.) cells are the basic units of structure and function in all organisms, and

• 3.) all cells come from cells that already exist.

Eukaryotes and Prokaryotes• Nucleus (plants and

animals)• No nucleus (bacteria)

Prokaryote Eukaryote

Prokaryote versus Eukaryote

Plant Cells Animal Cells

Plant Versus Animal

Cell Membrane• Nickname: “the

fence”• Function: boundary

separating the cell from surrounding cells and invaders

• Controls what enters and exits the cell

Cytoplasm

• Nickname: “the air”

• Function: jelly-like material inside the cell membrane. Surrounds the nucleus and organelles.

Ribosomes

• Function: makes proteins

• Found in all cells, prokaryotic and eukaryotic

Endoplasmic Reticulum (ER)

• Nickname: “Roads”

• Function: The internal delivery system of the cell

Golgi Apparatus • Nickname: The

shippers• Function: packages,

modifies, and transports materials to different location inside/outside of the cell

• Appearance: stack of pancakes

LysosomesLysosomes: circular, but bigger than ribosomes)

• Nickname: “Clean-up Crews”

• Function: to break down food into particles the rest of the cell can use and to destroy old cells

Mitochondria

• Nickname: “The Powerhouse”

• Function: Energy formation• Breaks down food to make energy

VacuolesVacuolesNickname: The warehouse

• Function: stores water• This is what makes lettuce crisp

• When there is no water, the plant wilts

In Plants Only:• Cell Wall

• Located on the outside of the cell membrane.

• Acts as an extra fence.

• Supports and protects the plant cell.

• Chloroplasts• Organelles that capture

energy from sunlight.

• Aids in photosynthesis.

Exit Slip

• 3-2-1 • 3 things you learned

• 2 ways you contributed

• 1 question you still have

• On flip side, tell me: • the difference between a

prokaryote and a eukaryote

Agenda• Review

• Cells project

• Project presentation

• Exit slip

Nucleus• Nickname: The Brain

• Function: Contains the DNA and controls all functions within the cell.

CELLS!!!!Construct a model of an plant cell by adding

one organelle (cell part) at a time using construction paper. Create an organelle from the sheet given, color and add it to your drawing.

I will pass out to each group an organelle sheet. Clearly label & Recreate that organelle and cut it out and put it in your cell.

Be prepared to present an organelle to the class.

CELLS!!!!• The last organelle you receive will be the one

you present.

• One person from each group must present.

• The best Cell project picked and the best presenter will each get a 5 point bonus towards their cell book project.

Exit Slip

• 1 question you still have

• Below that: • Two differences between a

Ribosome and a Mitochondria

Wednesday

Opening Question:What do you know about a microscope?

Agenda:• Lab•Review•Quiz

Thursday

Opening Question:What do you know about Osmosis?

Agenda:• Plant and animal cell

foldable•Review•Osmosis

Review• Organelles

• Name

• Nickname

• Function

Plant Cells Animal Cells

Foldable

Diffusion

• Diffusion- the movement of molecules from an area where there are many to an area where there are few

• Movement of molecules from an area of high concentration to an area of low concentration.

Functions of Membranes

1. Protect cell

2. Control incoming and outgoing substances

3. Selectively permeable - allows some molecules in, others are kept out

Phospholipid Bilayer

Blood-Brain Barrier

• Allows some substances into the brain, but screens out toxins and bacteria

• Substances allowed to cross include: water, CO2, Glucose, O2, Amino Acids,

Alcohol, and antihistamines. HIV and bacterial meningitis can cross the barrier.

Methods of Transport Across Membranes

1. Diffusion -passive transport - no energy expended

2. Osmosis - Passive transport of water across membrane

3. Facilitated Diffusion - Use of proteins to carry polar molecules or ions across

4. Active Transport - requires energy to transport molecules against a concentration gradient – energy is in the form of ATP

Diffusion

Osmosis

Facilitated Diffusion

Active Transport

Osmosis• Osmosis- the diffusion of water through a cell membrane

Osmosis is a special case of diffusion

Osmosis involves the diffusion of water through a membrane

The membrane may be artificial and non-living e.g. Cellophane

In biology, the important membrane is the cell membrane

2

If a concentrated solution is separated from a dilute solution by a suitable membrane, water will pass from the dilute to the concentrated solution.

The membrane must allow water molecules to diffuse through. It is permeable to water.

In fact, water passes both ways but faster from the dilute to the concentrated solution.

Permeability3

Osmosiswater ordilute solution

concentratedsolution

membrane

More water passes fromdilute to concentrated ...

...until concentrationsbecome equal

level riseslevel falls

4

There are microscopic pores in the membrane.

Molecules below a certain size can diffusethrough the pores.

Water molecules can easily diffuse throughthe pores.

In the next slides represents a water molecule

and represents a sugar molecule

5

membranewater sugar solution

There are as many water molecules on the right as there are on the left but many of them are attached to sugar molecules and are not free to move.

6

Because the membrane allows only molecules of a certain size to diffuse through it, it is called selectively permeable.

The cell membrane functions as a selectivelypermeable membrane.

9

There is a greater concentration of free water molecules outside the cell than inside

so water diffuses into the cellby osmosis

and the cell swells up

Osmosis in animal cells 11

If osmosis continued the animal cell would burst

This would be bad news for animals

Consequently there are processes in the animal’s body which control osmosis

Mainly, this is done by keeping the concentration of body fluids outside the cellthe same as it is inside. This is called homeostasis.

12

In fresh water fish, the blood is more concentrated than the surrounding water

As a result the fish takes in water by osmosis

Not so much through the skin, which is thick,but through the gills which have a very thin membrane

Trout

Fresh water fish 14

The fish gets rid of the excess water by means of its kidneys

Perch

gills absorb water by osmosis

blood carries waterto kidneys

kidneys expel excess water ...

...in the form of dilute urine

heart

14

Sea water is a more concentrated solution than the fish’s blood. What will be the osmotic effect ?

A sea water fish will lose water by osmosis through its gills.

The fish drinks sea water and the gills expel the excess salt from the blood, so keeping itsconcentration constant

Herring

Sea water fish 15

In a plant cell, the cell membrane acts as a selectively permeable membrane

If there is water outside the cell, it will diffuseby osmosis into the vacuole

The cell wall is freely permeable to water

16

The cellulose cell wall cannot stretch, so the vacuole cannot continue to expand

But the pressure of the vacuole against the cell wall makes the cell very firm and the plant stands upright

17

cell wall cytoplasm and cell membrane

vacuole

The cell absorbs waterby osmosis ....

....but the cell wall stops the cell expanding any more

Plant cells 18

These cells are short of water; the tissue is limp and the plant is wilting

The cells have taken upwater by osmosis; thecells are turgid and thetissue is firm

Limp and turgid tissue 21

Exit Slip

• 1. Materials are moved into and out of the cell through which organelle?• a. cell membrane

• b. mitochondria

• c. ribosomes

• d. nucleus

• 2. What process allows water to move into and out of the cell?• a. Diffusion

• b. Meiosis

• c. Osmosis

• d. Pinocytosis

56 56

Wednesday, March 3, 2010

Opening Question:

Mitosis is the process in which the nucleus divides to form two new nuclei. How might mitosis differ in plants and animals?

Also, please put the “mitosis” definition in your binder glossary.

Agenda: • Mitosis Notes

How do little elephants grow up to be BIG elephants?

The process of sexual reproduction begins

after a sperm fertilizes an egg.

Skin cancer - the abnormal growth of skin cells - most often develops on skin exposed to the sun.

Cell that reproduce by asexual reproduction reproduce constantly.

Animated Mitosis Cyclehttp://www.cellsalive.com/mitosis.htm

• Interphase

• Prophase

• Metaphase

• Anaphase

• Telophase & Cytokinesis

• Chromosomes are copied (# doubles)• Chromosomes appear as threadlike coils

(chromatin) at the start, but each chromosome and its copy(sister chromosome) change to sister chromatids at end of this phase

CELL MEMBRANENucleus

Cytoplasm

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

• Mitosis begins (cell begins to divide)• Centrioles (or poles) appear and begin

to move to opposite end of the cell. • Spindle fibers form between the poles.

CentriolesSister chromatids

Spindle fibers



Spindle fibers

Centrioles

• Chromatids (or pairs of chromosomes) attach to the spindle fibers.

Centrioles

Spindle fibers

• Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell.

Centrioles

Spindle fibers

• Two new nuclei form. • Chromosomes appear as chromatin

(threads rather than rods).• Mitosis ends.

NucleiNuclei

Chromatin

• Cell membrane moves inward to create two daughter cells – each with its own nucleus with identical chromosomes.

Animal Mitosis -- Review

Interphase

Prophase

Metaphase

Anaphase

Telophase

Interphase

Plant Mitosis -- ReviewInterphase

Prophase

Metaphase

Anaphase

Telophase

Interphase

77

- Cell Division

77

http://www.cellsalive.com/mitosis.htm

Thursday Opening Question: What are at least five things that you know about cells? Agenda:...

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