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October 11 th , 2012. Cell Structures!. The Cell: The Basic Unit of Life. All living organisms on Earth are made up of small units called cells
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October 11th, 2012 Cell Structures!
The Cell: The Basic Unit of Life • All living organisms on Earth are made up of small units called cells • All of the macromolecules that we have studied about so far (proteins, lipids, carbohydrates and nucleic acids) are small molecules that are part of cells • There are many different kinds of cells. Humans may have more than a 100 different kinds!
When looking through his microscope, Matthias Schleidendiscovered that every part of the plant cell he was looking at was made up of small tiny cells. Theodor Schwann discovered that every part of an animal he looked at through his microscope was made of cells! Later, Rudolf Virchow (another scientist) added that all cells arise from other cells
The Cell Theory! • All living things are made of cells. • Cells are the basic units of structure and function in living things. • Living cells come only from other living cells.
Why are Cells so small? • Most plant and animal cells are very small! Ranging from 10 and a 100 micrometers • Cells must constantly interact with their environment, gases and food molecules must be absorbed and waste products must be eliminated. • Inside the cell, there are many small organelles. All of these organelles need access to the cell membrane (surface of the cell) to get food or other necessities. If a cell’s surface area gets larger, then so does the volume. It will come to a point where there just isn’t enough cell membrane to give service to the inside of the cell!
Eukaryotes Vs. Prokaryotes • Eukaryotic cells have a nucleus, organized organelles, they are larger than prokaryotic cells and are multi-cellular • Prokaryotic cells do not have a nucleus, no organelles and they are all unicellular
Prokaryotic Cells • Bacteria and Archaebacteria (ancient bacteria, that still exist today) are prokaryotic cells • No nucleus • No membrane bound organelles • Unicellular – single-celled organisms
What are Protists? • Protists are a diverse group of organisms that cannot be classified as animals, plants or fungi • They consist of multicellular or unicellular organisms such as amoebae, red algae, dinoflagellates, diatoms and euglena
Eukaryotic Cells – The “Classic” Cell • Most living organisms have eukaryotic cells (including humans, animals, fungi, protists and plants) • Membrane-bound nucleus and organelles • Usually multi-cellular – many cells! • Larger than prokaryotic cells • Eukaryotic cells are divided into compartments and each of these compartments have different functions and are called organelles
What are Organelles? • Organelles are specific compartments within a cell • There are many types of organelles in eukaryotic cells • Prokaryotic cells do not have organelles
What are Cytoplasmic Organelles? • Membrane-bound organelles within the cytoplasm of a cell • Organelles include: -Nucleus -Vacuole -Vesicles -Endoplasmic reticulum -Golgi Complex -Lysosomes -Mitochondria -Chloroplasts
What is a Vacuole? • Vacuoles are little pockets in the cytoplasm of a cell where a cell stores food • Found mainly in plants – they are smaller in animals • Plant cells store starch molecules and water in vacuoles • Vacuoles help keep plant cells rigid and full • Membrane surrounding vacuole is called tonoplast
Vesicles – Travel Cellular Highways • Vesicles are found in both plant and animal cells • Primary role is to transport materials throughout the cell and keep the different areas of the cell in contact
Ribosomes • Not considered to be classic organelles • Ribosomes are small particles that manufacture proteins • They connect one amino acid to another in order to create a long chain which will become a protein. This process is called protein synthesis • They are located on the endoplasmic reticulum or they are free-floating within the cytoplasm
Unit Test Tomorrow! Unit Test will cover: • All material on PowerPoints • All supplementary material in textbook • Chemical Fundamentals (acids/bases, isotopes, radioisotopes, bonding, etc;), Chemicals of Life (macromolecules), Enzymes, Cellular Respiration and Photosynthesis