TOPIC: CELLSAIM: How do we describe cells?

How do we know that cells

exist?

The discovery of the microscope

RobertHooke

•Observed slices of cork with a comp. microscope (1600’s)

Anton van Leeuwenhoek

1600’sUsed a simple microscope

First to look at living cells

Observed one- celled organisms like bacteria

Rain pond water, the mouth, intestines

MatthiasSchleidan

Observed plant cells

All plants are made of cells

TheodorSchwann

Observed animal cells

All animals are made of cells

RobertVirchow

All cells are made from pre-existing cells.

(Cells divide more cells)

CellTheory

1. Cells are the basic unit of structure in all living things.

(Living things are made of cells)

2. Cells are the basic unit of function of all living things

(They carry out life processes)

3. All cells come from pre-existing cells.

Exceptionsto the CellTheory

1. Viruses are NOT cells, and are NOT made of cells.

Virus do not reproduce by division because they are not

cells.

2. Mitochondria & Chloroplasts

cell parts that have their own DNA and reproduce on their own.

(Don’t need the nucleus to reproduce)

3. The first cell could not have come from a pre-existing cell.

Cells •Microscopic•Found in living

things•There are

different types•Smallest living

thing on earth

EXAMPLES OF CELLS

Skin cells

Bone cells

MORE CELLS

Brain cells

Blood cells

If there are so

many cells how do we

classify them? 2.Based on the type of

organism it belongs to• Plant cell• Animal cell

1.Based on location or function of the cell

• blood cell• muscle cell

Organism • Any living thing

• Examples:–Shark -Tree-Bacteria–Human -Bird

Nucleus or No Nucleus or No Nucleus??Nucleus??

Some cells have a nucleus, they are called

EUKARYOTES(Hey, you!! Do you have a nucleus?)

• Animal and Plant cells are eukaryotes.

Some cells don’t have a nucleus, they are called PROKARYOTES

• Bacteria are prokaryotic cells.

Cells work (perform life activities) because

they contain organelles

Organelles• Structures

that are found in the cell that perform all cell activities

• a.k.a cell parts

Examples of

organellesNucleus

• Located in the center of the cell

• Appears as a circle• Sometimes solid in

color

The function is to be the control center for the cell and contains chromosomes. Contains a Nucleolus – helps in protein production.

Chromosomes - contain hereditary genetic information

Cell Membrane

• Located around the entire cell

• Appears as a thin line• Similar to the walls

of the classroom

• The function is to be a barrier (wall) between the outside of the cell and the inside. AND……

• Allows materials to transport in and out of the cell

Cytoplasm • Located inside the cell membrane and outside the nucleus

• Appears as the “liquid” between all the organelles

• The function is to support all the organelles AND…

• Transport materials around the cell

• Similar to the ______in our bodies

Vacuole• Location is

scattered around the cytoplasm

• Appears as an empty circle

• The function is to be the storage site for wastes and other cellular materials

• Similar to the garbage pails in each room

Endoplasmic Reticulum

• Located around the nucleus

• Appears as canals • A.k.a. – ER

• The function of the ER is to transport materials within the cell

AND….Sometimes contains

ribosomes

Ribosomes • Located on the ER and scattered around the cytoplasm

• Appears as dots

• The function is protein formation (synthesis)

• RIBosomes---Baby-back ribs give you protein

What do cells need to do all this work?

Mitochondria

• Located within the cytoplasm

• Appear as bean shaped structures

• The function is the production of energy

• A.k.a – the powerhouse

More OrganellesGolgi Bodies • Located in the

cytoplasm• Appear as a

structure with many folds

• The function is to package all the wastes for removal

Lysosome • Located in the cytoplasm

• Appear as small circular structures with particles inside

• The function is to digest (break down) cellular materials

Centriole• Located in the

cytoplasm• Often near the nucleus• Appears in a set of two• ONLY IN ANIMAL CELLS

• The function is to help the cell with cellular division of the chromosomes

Chloroplasts• Located around the edge

of the cell• Appear as oval structures

with lines • ONLY IN PLANT CELLS• Contain Chlorophyll

• The function is to perform photosynthesis

Photosynthesisprocess in which plants produce their own food

Cell wall• Located outside

the cell membrane• ONLY IN PLANT

CELLS

• The function is to provide support and structure for the cell

Organelle Challenge