Cells

EQ: What are the structures and functions of the different types of

cells and cell parts?

Discovery of Cells

• First cells were discovered by Robert Hooke– Looked at cork cells – No organelles were visible

• Van Leeuwenhoek looked a living cellular life in pond water– “EEWW this is in the water we drink”

• Advancement in microscopes lead to the visualization of organelles

Prokaryotic Cells

• Simple cells• No nucleus or complex organelles• Mostly bacteria

Eukaryotic Cells

• Complex cells• Have a variety of

specialized organelles• Genetic information is

enclosed in a nucleus• Include plant and

animal cells

Nucleus

• Found only in eukaryotes

• Information center of the cell

• Contains DNA – genetic information

• Surrounded by a nuclear envelope which regulates what enters and leaves the nucleus

Nucleolus

• Assembles the ribosome

Chromatin

• Granular material within the nucleus

• Consists of tightly coiled DNA

Ribosomes

• Assembles proteins• Uses the information

from the DNA that comes to the ribosome in the form of RNA

Smooth Endoplasmic Reticulum

• Aka smooth ER• Transports material

through the cells• Can store special

enzymes and chemicals for the synthesis of membrane lipids and detoxification of drugs

Rough Endoplasmic Reticulum

• Aka rough ER• Chemically modify the

proteins that are exported from the cell made in the ribosome

• Studded with ribosomes

Golgi Apparatus

• Modifies, sorts, and packages proteins and other cellular materials for transport out of the cell or storage

Lysosomes

• Small organelles with enzymes that breakdown lipids, carbohydrates and proteins for use by the cell

• Also breaks down non-functioning organelles

• Some human diseases are caused when lysosomes fail

Vacuole

• Store material like water, salts, proteins, and carbohydrates

• Single large vacuole in plant cells provide some support for the cell

Mitochondria

• Convert chemical energy stored in food into compounds that the cell can use

• The folds increase the surface area which increases the efficiency

• May have been an independent cell at one time

• Inherited through the maternal line

Chloroplasts

• Found only in plant cells

• Convert the sun’s energy into a type that the cell can use

• Appear green due to pigments for light absorption

• May have been an independent cell

Cytoskeleton

• Protein filaments that support the cell and give the cell shape

• Used to move chromosomes during mitosis

Cell Membrane

• Regulates what enters and leaves the cell• Provides protection and support for the cell• Composed of a lipid bi-layer (two layers of fat)

Cell Wall

• Found only in plants• Porous to allow

material in and out• Provides support and

protection for the cell• Made of cellulose –

tough carbohydrates

Cytoplasm

• Cell filler• Found between all the

organelles

Endosymbiosis Theory• About 2 billion years

ago membrane bound nuclei appear

• Prokaryotes began forming symbiotic relationships

• Symbiosis– A partnership where

one or both participants benefit, or one potentially is harmed

• Eukaryotes came from living communities formed by symbiotic prokaryotes

• Evidence– membrane bound

organelles– Mitochondrial and

Chloroplastic DNA

Endosymbiosis Theory• Evidence Continued…

– Mitochondria and chloroplasts have ribosomes similar to bacterial ribosomes

– Mitochondria and chloroplasts reproduce by binary fission while the cell containing them undergoes mitosis