Cells

Discovery of Cells 1665: Robert Hooke looking at cork under

crude microscope

In 1673, van Leeuwenhoek saw unicellular organisms in pond scum

First to see bacteria and yeast

Two centuries pass; Schleiden (1838) proposes all plants are made of cells

Schwann makes same claim for animals Wrote first Cell Theory:

1. All organisms are made of one or more cells. 2. Cell is basic unit of life.

All plants are made of cells!

Wow! So are all animals! Let’s make up a “cell

theory”!

Who wrote the first two parts of the cell theory?

A. Hooke B. van Leeuwenhoek C. Schleiden D. Schwann E. Both C and D

20 years later, Virchow saw that all cells come from other cells

Added 3rd part of cell theory: 3. All cells come from existing cells.

All cells come from other cells!!

All cells have…

Lots of different kinds of cells, but all have: Cell Membrane DNA Cytoplasm Organelles Small Size

Which of the following is NOT something that ALL cells have in common?

A. Cell Membrane

B. DNA

C. Chloroplasts

D. Cytoplasm

E. Organelles

F. Small Size

Cell Membrane

Also called plasma membrane Surrounds all cells Has holes to allow things in and out

Which of the following is NOT true of the cell membrane?

a. Also called plasma membrane

b. Surrounds all cells

c. Only found in animal cells

d. Has holes to allow things in and out

DNA Hereditary material Controls all of the cell’s activities Has info needed to make new cells

Which of the following is NOT true of DNA?

a. It is the hereditary material

b. It makes fats for the cell

c. It controls all of the cell’s activities

d. It has the info needed to make new cells

Cytoplasm

Fluid that fills the cell

Organelles

Structures inside that perform special jobs for the cell (example: ribosomes=make protein, etc.)

Small Size

Almost all require use of microscope Large organisms have more cells, not bigger

ones!!

Two types of Cells

Prokaryotic Bacteria! No nucleus Organelles are not

covered with a membrane

DNA is a circle

Eukaryotic All other cells Has a nucleus Organelles are covered

with a membrane (skin) DNA is linear (in a line)

Identify which cell is prokaryotic.

A B

Eukaryotic Cells

Very complex! Inside parts (organelles) are difficult to see

Cell Membrane Double layer Has pores (holes) which allow things in and

out Selectively permeable = “choosy” about what

enters and leaves the cell.

Cell Wall Plants, algae and fungi only Made of cellulose Strength and support

Which of the following is NOT true of cell walls?

A. Plant cells and fungi cells have them. B. Animal cells have them. C. They are made of cellulose. D. They provide strength and support for the

cell.

Nucleus Nucleus means “kernel” or “nut” Membrane covered, with holes so things can

pass through Control center: stores DNA (instructions for

making protein and reproduction)

Ribosomes

Cells are made of proteins. Amino acids link together to make proteins at

ribosomes

= Protein

Endoplasmic reticulum Also called ER Makes lipids (fats) Breaks down drugs and other dangerous

chemicals Also delivery system

of cell Rough and Smooth

Which of the following is not true of endoplasmic reticulum?

A. Also called ER B. Makes lipids (fats) C. Breaks down drugs and other dangerous

chemicals D. Delivery system of cell E. Comes in only one type: rough ER

Mitochondria

Cells need energy. Where do they get it? Food is broken down for energy at the

mitochondria Needs oxygen to function

ATPADENOSINE TRI-

PHOSPHATE

Chloroplasts

In plants and algae Organelle which converts

light energy, water, and carbon dioxide into sugar (FOOD!)

Contain chlorophyll, the pigment that does this

Golgi Complex

Packages and ships materials out of the cell

Looks like ER, but closer to cell membrane

Little pieces can pinch off and leave the cell

Lysosomes

Filled with enzymes (chemicals which sometimes break things down)

Destroy waste and old cell parts, as well as invaders

Storage Centers Vesicles: membrane

covered “bubbles” that form when part of the cell membrane surrounds something and pinches off

Vacuoles: huge storage areas for water and other liquids, especially in plants

The Cytoskeleton The cytoskeleton is similar to the skeletons in

animals. They provide strength and structure. They help hold organelles in place. They can also help move things around

inside a cell.

Answer the following questions. Restart the PowerPoint to find them. DON’T GUESS! (True or False) Elephants have bigger cells

than mice do. ___________ (True or False) To be selectively permeable

means that you are not “choosy” about what materials you allow to enter and leave the cell. ___________

(True or False) Lysosomes digest waste and invaders through the use of enzymes (special chemicals). __________

(True or False) Oxygen is not needed when energy is made at the mitochondria. ______

(True or False) Amino acids are chemicals which link together to make carbohydrates. _______

(True or False) Proteins are assembled at ribosomes. __________

(True or False) There are three main types of cells: prokaryotic, eukaryotic, and protokaryotic. ________

(True or False) The Golgi Complex is similar to a post office; it packages materials for shipment out of the cell. ___________

Which of the following is NOT true of chloroplasts?

A. Found in plants and algae. B. Changes sunlight and water into food. C. Found in some animal cells D. Contain the pigment chlorophyll.

Which of the following is not true of the nucleus?

A. Its name means “kernel” or “nut”. B. It has holes in it. C. It is only found in plant cells. D. It is the control center of the cell,

containing the DNA.