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Uncover the wonders of cells, the basic unit of life, and delve into the fascinating realm of cell structures and functions in this educational unit on Biology. Understand the diversity of cells, their organelles, and the contrast between prokaryotic and eukaryotic cell types.
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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.
