Objectives List scientists who contributed to the cell theory List the components of the cell theory Compare prokaryote and eukaryote cells Label a plant and an animal cell Know the functions of cell organelles

Early Contributions Robert Hooke - First person to see cells, he was looking at cork and noted that he saw "a great many boxes. (1665) Anton van Leeuwenhoek - Observed living cells in pond water, which he called "animalcules" (1673)

Theodore Schwann - zoologist who observed tissues of animals had cells (1839) Mattias Schleiden - botanist, observed tissues of plants contained cells ( 1845) Rudolf Virchow - also reported that every living thing is made of up vital units, known as cells. He predicted that cells come from other cells. (1850 )

The Cell Theory 1. Every living organism is made of one or more cells. 2. The cell is the basic unit of structure and function. It is the smallest unit that can perform life functions. 3. All cells arise from pre-existing cells. *Why is the Cell Theory called a Theory and not a Fact?

Cell Features ALL cell have these parts Ribosomes – make protein for use by the organism Cytoplasm – fluid material within  cell DNA – genetic material Cytoskeleton – internal framework of cell Cell Membrane – outer boundary, some things can cross the cell membrane

Comprehension Checkpoint Answer true or false Robert Hooke was the first person to see cells. Bacteria cells have a cell membrane. The Cell Theory was developed by a single scientist. Plant cells have cytoplasm. Cells taken from fungi do not have DNA. Cells can only come from pre-existing cells. It only took five years to develop the Cell Theory.

Prokaryote Cells The first cells to inhabit the earth Simple cells Bacteria These cells do NOT have a nucleus, their DNA is circular and floats in the cytoplasm Some bacteria have a tail-like structure called a flagella, that helps it to move. A capsule surrounds some bacteria and helps them avoid the body’s immune system

Bacteria Images Bacteria that causes Anthrax

Eukaryotic Cells Cells found in plants, animals, protists, and fungi   The cell is composed of 4 main parts: Cell membrane Cytoplasm Nucleus – “control center” of cell, houses DNA Organelles – small structures that carry out specific functions (“little organs”)

Nucleus Usually found at center of cell Has a nuclear membrane & nuclear pores  Contains cell’s DNA in one of 2 forms chromatin - DNA bound to protein (non-dividing cell) chromosomes - condesed structures seen in dividing cell  Also contains an organelle called nucleolus - which makes the cell’s ribosomes

Cell Organelles Mitochondria – this is the cell’s energy center. It turns food into a chemical energy called ATP The mitochondria is sometimes called the “powerhouse” of the cell

Cell Organelles Golgi Apparatus – processes, packages and secretes proteins. It is comparable to a factory or a post office. *A vesicle forms with Golgi to transport substances outside cell.  

Cell Organelles Lysosome – Contains digestive enzymes, breaks things down, "suicide sac” Endoplasmic Reticulum – Transport, "intracellular highway".  -Rough ER contains many ribosomes & is involved in protein synthesis  -Smooth ER ribosomes not found on surface

Cytoskeleton – Helps cell maintain support & shape; movement a. microtubules-hollow structures; also help build cilia and flagella b.  microfilaments-threadlike c.  centrioles-only in animal cells; used during cell division (paired) 

Vacuole – storage area for water and other substaces, plant cells usually have a large central vacuole

Protein Production The cell is like a factory. Its product is protein which goes to body to serve different functions. DNA has instructions to build protein These instructions are sent to ribosomes The ribosomes build protein and send it through ER The proteins are delivered to golgi where they are completed and “tagged” for export outside cell

THE ANIMAL CELL

Cheek Cells Seen Through Microscope

Plant Cells Have additional structures CELL WALL – surrounds membrane & provides additional support CHLOROPLASTS – contain green pigment, function in photosynthesis CENTRAL VACUOLE – large water container in center of cell

PLANT CELL Can you identify the parts?

Anacharis Cells Viewed With a Microscope

Animal Cell vs Plant Cell

Organelles With DNA Mitochondria and chloroplasts have their own DNA (separate from the nucleus) This supports the ENDOSYMBIOSIS THEORY which states that eukaryotic cells evolved when prokaryote cells engulfed or absorbed other cells.

CELL MEMBRANE Selectively permeable ; it regulates what comes into the cell and what leaves the cell It is composed of a double layer of phospholipids with proteins embedded throughout