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Biology. Unit 3 – Cell Structures. What are cells?. Cells are the smallest things that are able to carry out all of the characteristics of life. Discovery of Cells. - In 1665, Robert Hooke is the first person to see dead cells. He was looking at cork under a microscope.
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Biology Unit 3 – Cell Structures
What are cells? • Cells are the smallest things that are able to carry out all of the characteristics of life.
Discovery of Cells - In 1665, Robert Hooke is the first person to see dead cells. • He was looking at cork under a microscope. • They resembled a honeycomb, so he called them cells.
Anton van Leeuwenhoek • In 1673, he was the first person to see living cells. • He looked at pond water, saliva, urine, feces, vomit, and other fluids that we won’t mention at this time.
Further Discoveries • Through the years, better microscopes were developed and many scientists made new discoveries. • These discoveries were put together in what we now call the cell theory.
Cell Theory 1. All organisms have one or more cells (definite form, limited size). • Cells are the basic unit of life (have all 7 characteristics). • All cells come from pre-existing cells (reproduction).
Cell Diversity • Cells vary in size, shape and function. • The smallest are a few micrometers (ten-thousandths of a meter) to 2 meters.
Cell Structures • Most cells have organized structures that perform specialized functions for the cell. • These structures are called organelles.
Organelles • Cell (Plasma) Membrane – controls what goes in and out of the cell • Nucleus – control center of a cell • Cytoplasm – “jelly-like” substance that supports other organelles and gives cell its shape • Mitochondria – makes energy or ATP • Endoplasmic Reticulum – moves things throughout the cell
Organelles Continued • Vacuole – storage container • Golgi Body – makes and puts things in vacuoles • Ribosomes – make proteins • Nucleolus – controls protein making • Nuclear Envelope – controls what goes in and out of the nucleus • Lysosomes – contain digestive enzymes
Organelles Continued • Centrioles – only in animals, helps with cell division • Cell Wall – only in plants, gives strength and support • Plastids – only in plants, contain pigments • Central Vacuole – only in plants, stores water • Starch Grains – only in plants, stores energy
Organelles Continued • Cilia – short hair-like structures used for movement • Flagella – long hair-like structures used for movement
Prokaryotic Cells • Simple cells that lack a nucleus and most organelles. • Bacteria and Archaea are the only examples.
Eukaryotic Cells • These are more complex cells that have a nucleus and many other organelles. • Every organism that is not bacteria would be an example.
Prokaryotic and Eukaryotic Comparison • Although prokaryotic cells are much simpler and lack most of the structures of eukaryotic cells, they have a few things in common: • They both have cytoplasm and cell membranes.
Prokaryotic and Eukaryotic Comparison 2. They both can contain genetic information (DNA). • Prokaryotic cells have a single, small circular chromosomes and small “plasmids,” which contain a few genes. • Eukaryotic cells have multiple, large, complex chromosomes.
Eukaryotic Chromosomes Prokaryotic Chromosomes/ Plasitds Prokaryotic and Eukaryotic Comparison
Prokaryotic and Eukaryotic Comparison • Prokaryotic cells are much smaller than eukaryotic cells. • Eukaryotic cells have so many more organelles to fit inside, so they have to be much bigger.
