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Learn about the history of cells, the cell theory, and the different types of cells. Discover the structure and function of organelles such as the nucleus, ribosomes, endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, mitochondria, chloroplasts, cytoskeleton, cell membrane, and cell wall. Observe and compare various cells under a microscope.
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Explore Cells • At your assigned lab table, draw the slide that you observe under the microscope. • Write down any interesting details you would use to describe the slide. • Be prepared to share your findings with the group.
What are some similarities and differences that you observed by looking at a variety of cells?
History of the cell • In 1665, RobertHooke was the first to view cells from cork (dead plant material). He called them “cells” because they looked like tiny rooms. • Anton van Leeuwenhoek saw tiny living organisms in water in 1675.
In 1838, Matthias Schleiden determined that plants are made up of cells. • In 1839, Theodor Schwann determined that animals are made up of cells. • In 1855, Rudolf Virchow concluded that new cells are produced from the division of existing cells.
The Cell Theory • All living things are composed of cells. • Cells are the basic units of structure and function in living things. • New cells are produced from existing cells.
Types of Cells • Two kinds of cells depending on whether they have a nucleus Eukaryote Prokaryote Genetic material
Prokaryotes • Usually small and simple • Genetic material (DNA) is notcontained in a nucleus • The ONLY prokaryotes in the world are BACTERIA.
Eukaryotes • Usually larger and more complex than prokaryotes. • May be unicellular like an amoeba or multicellular like a plant • Contain dozens of specialized structures called organelles. • Includes protists, fungi, plants and animals.
Eukaryotic cell structure • Two major parts: • Nucleus • Cytoplasm-portion of the cell outside the nucleus
Nucleus-The control center • Function: • Contains almost all of the cell’s DNA for coding proteins and other molecules. • DNA is found on chromosomes which contain genetic information.
Nucleus-The control center • Structure: • Surrounded by a double membrane called a nuclear envelope. It is dotted with many pores (holes) to allow materials (RNA, proteins, etc) in and out of the nucleus. • Small internal region called a nucleolus where ribosomes are made.
Ribosomes • Function: • Site of protein assembly. • Structure: • Small pieces of RNA and protein found throughout the cell.
Endoplasmic Reticulum • Function: • Site where lipid parts of cell membrane are made, along with proteins and other materials to export from the cell. • Structure: • Rough ER- has ribosomes on surface to assemble proteins • Smooth ER-NO ribosomes on surface
Golgi Apparatus • Function: • Modify, sort, and package proteins and other materials from the ER for storage in the cell or release from the cell. It puts the finishing touches on proteins. • Structure: • Stack of closely packed membranes
You have 3 minutes to compare your notes with a neighbor. Be sure to ask questions and fill in any blanks you may have in your notes at this time.
Lysosomes-The Clean Up Crew • Function: • Breakdown of lipids, carbohydrates and proteins into small molecules to be used by the rest of the cell • Breakdown used up organelles • Get rid of all “stuff” in the cell • Structure: • Small, filled with enzymes
Vacuoles - Storage • Function: • Stores water, salts, proteins and carbohydrates • Structure: • Sac-like • Plant cells have one large central vacuole • Animal cells have many small vacuoles
Mitochondria - Energy • Function: • Convert chemical energy in food into materials easier for the cell to use. • Structure: • Enclosed by two membranes with the inner membrane folded up. • Contains it’s own DNA (unlike other organelles) that is identical to your mother’s!
Chloroplasts – Energy in Plants • Function: • Captures energy from the sun (solar energy) and changes it into food (chemical energy) for plants (photosynthesis) • Structure: • Surrounded by two membranes • Contains own genetic information like mitochondria • Contains green pigment called chlorophyll • Not found in animal cells!
With your neighbor, list similarities and differences between mitochondria and chloroplasts. Be prepared to share with the class.
Cytoskeleton- structure and support • Function: • Helps maintain cell shape • Helps with movement of the cell (i.e. flagella and cilia) • Structure: • Two types: microfilaments and microtubules
Cell Membrane • Function: • Regulates what enters and leaves the cell • Provides protection and support • Structure: • Double membrane called a lipid bilayer • Flexible structure that forms a strong barrier between the cell and its surroundings
Cell Wall • Function: • Provides support and protection for the cell • Structure: • Lies outside the cell membrane • Found in plants, algae, fungi and many bacteria • NOT FOUND IN ANIMAL CELLS!
Individually, write down 3 differences between plant and animal cells.
