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Explore the fascinating world of cells, from their discovery through the microscope to their classification and functions within living organisms. This detailed guide delves into the Cell Theory, different cell types, organelles, and more, providing insights into the building blocks of life.
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TOPIC: CELLS AIM: How do we describe cells?
How do we know that cells exist? The discovery of the microscope
Observed slices of cork with a comp. microscope (1600’s) Robert Hooke
1600’s Used a simple microscope First to look at living cells Anton van Leeuwenhoek
Observed one- celled organisms like bacteria Rain pond water, the mouth, intestines
Observed plant cells All plants are made of cells Matthias Schleidan
Observed animal cells All animals are made of cells Theodor Schwann
All cells are made from pre-existing cells. (Cells divide more cells) Rudolph Virchow
Cell Theory 1. Cells are the basic unit of structure in all living things. (Living things are made of cells)
2. Cells are the basic unit of function of all living things (They carry out life processes) 3. All cells come from pre-existing cells.
Exceptions to the Cell Theory 1. Viruses are NOT cells, and are NOT made of cells.
Virus do not reproduce by division because they are not cells.
2. Mitochondria & Chloroplasts cell parts that have their own DNA and reproduce on their own. (Don’t need the nucleus to reproduce)
3. The first cell could not have come from a pre-existing cell.
Microscopic Found in living things There are different types Smallest living thing on earth Cells
EXAMPLES OF CELLS Skin cells Bone cells
MORE CELLS Brain cells Blood cells
If there are so many cells how do we classify them? 2.Based on the type of organism it belongs to • Plant cell • Animal cell • Based on location or function of the cell • blood cell • muscle cell
Organism • Any living thing • Examples: • Shark -Tree -Bacteria • Human -Bird
Nucleus or No Nucleus?? Some cells have a nucleus, they are called EUKARYOTES (Hey, you!! Do you have a nucleus?) • Animal and Plant cells are eukaryotes. Some cells don’t have a nucleus, they are called PROKARYOTES • Bacteria are prokaryotic cells.
Cells work (perform life activities) because they contain organelles Organelles Structures that are found in the cell that perform all cell activities a.k.a cell parts
Examples of organelles Nucleus • Located in the center of the cell • Appears as a circle • Sometimes solid in color The function is to be the control center for the cell and contains chromosomes. Contains a Nucleolus –helps in protein production. Chromosomes -contain hereditary genetic information
Cell Membrane Located around the entire cell Made of lipids and proteins embedded within. The function is to be a barrier between the outside of the cell and the inside. AND…… Allows materials to transport in and out of the cell: SEMIPERMEABLE or Selectively Permeable
Cytoplasm Located inside the cell membrane and outside the nucleus Appears as the “liquid” between all the organelles The function is to support all the organelles AND… Transport materials around the cell: Called Cyclosis Similar to the ______in our bodies
Vacuole Location is scattered around the cytoplasm Appears as an empty circle The function is to be the storage site for wastes and other cellular materials Similar to the garbage pails in each room
Endoplasmic Reticulum Located around the nucleus Appears as canals A.k.a. – ER • The function of the ER is to transport materials within the cell AND…. Sometimes contains ribosomes
Ribosomes Located on the ER and scattered around the cytoplasm Appears as dots The function is protein formation (synthesis) RIBosomes---Baby-back ribs give you protein
What do cells need to do all this work? Mitochondria Located within the cytoplasm The function is the production of energy (ATP)by the process of cellular respiration!! A.k.a – the powerhouse
More Organelles Golgi Bodies Stack of membranes in the cytoplasm. The function is to package and ship materials
Lysosome Located in the cytoplasm Appear as small circular structures with particles insideThey contain Digestive Enzymes. • The function is to digest (break down) cellular materials
Centriole Located in the cytoplasm Often near the nucleus Appears in a set of two ONLY IN ANIMAL CELLS The function is to help the cell with cellular division of the chromosomes
Chloroplasts Located around the edge of the cell Appear as oval structures with lines ONLY IN PLANT CELLS Contain Chlorophyll • The function is to perform photosynthesis Photosynthesis process in which plants produce their own food
Cell wall Located outside the cell membrane ONLY IN PLANT CELLS The function is to provide support and structure for the cell