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Transcript
Core Biology Overview Cells Features of Life and the Cell Living Things and Their Parts The word living is not easy to define. Biologists recognize that all living things share certain features. Features of Living Things Reproduce Grow Develop Need Food Use Energy Made of Cells Respond Adapt to Environment Reproduce Reproduce means to form offspring similar to the parents. Grow Living things grow by using materials and energy from their environment to increase their size. Development Development is all the changes that occur as a living thing grows. Need Food All things that are living need food. Living thing can either make their own for or not. Producers make their own food. Consumers eat producers and consumers. Producers Producers are living things that make or produce their own food. Consumers Consumers are living things that eat, or consume, other living things. The Order of things Living Things use Energy Energy is the ability of do work. Moving and changing is the work that living things use energy for. Animals get their energy from the food that they eat. Plants get their energy from photosynthesis. What is a cell? The CELL is the smallest unit of matter that CAN Carry on ALL the PROCESSES OF LIFE. Who first used the microscope? One of the First Microscopes was made by the Dutch drapery store owner Anton von Leewenhoek. With his hand-held microscope, Leewenhoek became the FIRST person to OBSERVE and DESCRIBE MICROSCOPIC ORGANISMS and LIVING CELLS. Dead plant cells first? . In 1665, the English Scientist Robert Hooke used a microscope to examine a thin slice of cork and described it as consisting of "a great many little boxes". It was after his observation that Hook called what he saw "Cells". Three parts of Cell Theory Cell Theory Contributers In 1838, German Botanist Matthias Schleiden studied a variety of PLANTS and concluded that all PLANTS "ARE COMPOSED OF CELLS". The next year, German Zoologist Theodor Schwann reported that ANIMALS are also made of CELLS and proposed a cellular basis for all life. . In 1855, German Physician Rudolf Virchow induced that "THE ANIMAL ARISES ONLY FROM AN ANIMAL AND THE PLANT ONLY FROM A PLANT" OR " THAT CELLS ONLY COME FROM OTHER CELLS". Are Cells alike? CELL DIVERSITY Not all cells are alike. Even cells within the same organism show Enormous Diversity in Size, Shape, and Internal Organization. Your Body contains at least 200 Different Cell Types. Example of large cell CELL SIZE A few types of cells are large enough to be seen by the unaided eye. The Female Egg is the largest cell in the body, and can be seen without the aid of a microscope. Can cells be any size? MOST CELLS ARE SMALL FOR TWO REASONS: #1 Cells are limited in size by the RATIO between their Outer Surface Area and Their Volume. A SMALL CELL HAS MORE SURFACE AREA THAN A LARGE CELL FOR A GIVEN VOLUME OF CYTOPLASM. This is important because the nutrients, oxygen, and other materials a cell requires must enter through it surface. As a cell grows larger at some point its surface area becomes too Small to allow these materials to enter the cell quickly enough to meet the cell's need. Cell Size Cont. Cell Size cont. #2 THE CELL'S NUCLEUS (THE BRAIN) CAN ONLY CONTROL A CERTAIN AMOUNT OF LIVING, ACTIVE CYTOPLASM. Cell Shape CELL SHAPE 1. Cells come in a variety of Shapes. 2. Notice the neurons on the wall, the basic cell of our Nervous System. This diversity of form reflects a diversity of function. 3. Most Cells have a Specific Shape. Why a special shape? THE SHAPE OF A CELL DEPENDS ON IT'S FUNCTION. Examples: Cells of the Nervous System that carry information from your toes to your brain are long and threadlike. Blood Cells are shaped like round disk that can squeeze through tiny blood vessels. What is on the inside? INTERNAL ORGANIZATION 1. Cells contain a variety of Internal Structures called ORGANELLES. 2. An organelle is a Cell Component that PERFORMS SPECIFIC FUNCTIONS FOR THE CELL. 3. Just as the organs of a multicellular organism carry out the organism's life functions, the Organelles of a cell Maintain the Life of the Cell. On the inside cont. 4. There are many different cells; however, there are certain features common to all, or most Cells. What is on the outside? The entire cell is Surrounded by A THIN MEMBRANE, called the CELL MEMBRANE What does the Nucleus do? A Large Organelle near the Center of the Cell is the NUCLEUS. IT CONTAINS THE CELL'S GENETIC INFORMATION AND CONTROLS THE ACTIVITIES OF THE CELL. Layout of the Nucleus Why else is the nucleus important? The PRESENCE OR ABSENCE of a NUCLEUS is important for Classifying Cells. ORGANISMS WHOSE CELL CONTAIN A NUCLEUS AND OTHER MEMBRANE-BOUND ORGANELLES ARE CALLED EUKARYOTES. ORGANISMS WHOSE CELLS NEVER CONTAIN (OR LACK) A NUCLEUS AND OTHER MEMBRANE-BOUND ORGANELLES ARE CALLED PROKARYOTES. What type of cell is bacterium? UNICELLULAR ORGANISMS such as bacteria and their relatives are Prokaryotes. More on bacterium later… Where are these cells classified? The difference between Prokaryotes and Eukaryotes is such an important distinction that Prokaryotes are placed in Two Kingdoms, Separate from Eukaryotes. Need to know more?... More on the big difference. THE CELL MEMBRANE A Cell cannot survive if it is totally isolated from its environment. The Cell Membrane is a complex barrier separating the cell from it's external environment. Cell Membrane function The Cell Membrane Functions like a GATE, Controlling what ENTERS and LEAVES the Cell. This "Selectively Permeable" Membrane regulates what passes into and out of the cell. All cells, from all organisms, are surrounded by a CELL MEMBRANE. More Cell Membrane The Cell Membrane is a thin layer of Lipid and Protein that separates the cell's content from the world around it. SELECTIVELY PERMEABLE The Cell Membrane CONTROLS the ease with which substances pass into and out of the cell-some substances easily cross the membrane, while others cannot cross at all. For this reason, the Cell Membrane is said to be SELECTIVELY PERMEABLE. Cell Membrane makeup Cell Membranes are made mostly of PHOSPHOLIPID MOLECULES. Phosphate + Lipid. Every thing you wanted to know about PHOSPHOLIPID MOLECULES Phospholipids are a kind of Lipid that consists of TWO FATTY ACIDS (TAILS), and PHOSPHATE GROUP (HEADS). A Phospholipid Molecule has a POLAR "Head" and Two NONPOLAR "Tails". POLAR - The two ends of the Phospholipid Molecule have different properties in Water. Properties in water The Phosphate Head is HYDROPHILIC meaning "WATER LOVING". Because of its hydrophilic nature, the head of a Phospholipid will orient itself so that it is as close as possible to water molecules. The Lipid Tails are HYDROPHOBIC meaning "WATER-FEARING", the Hydrophobic tails will tend to orient themselves away from water. When dropped in WATER, PHOSPHOLIPIDS line up on the surface with their Phosphate Heads Sticking into the Water and Lipid Tails pointing up from the surface. Take a look… Passive transport Passive Transport Explained In passive transport substances literally transport themselves across the cell membrane without the cell expending energy. Active Transport Active Transport Explained Active Transport is the opposite of passive because it requires energy from the cell. Movement of a substance against a concentration difference. Diffusion Diffusion is a process by which substances spread through a liquid or gas. In diffusion things move from high to low concentration. Osmosis Explained Why bilayer? Cells are bathed in aqueous, or watery, environment. Since the inside of a cell is also an aqueous environment, both sides of the Cell Membrane are surrounded by Water Molecules. These Water Molecules cause the Phospholipids of the Cell Membrane to form TWO LAYERS. Lipid bilayer Cell Membranes CONSIST of TWO Phospholipid LAYERS Called a LIPID BILAYER. Heads face the watery fluids inside and outside the cell. Lipid Tails are sandwich inside the Bilayer. Peripheral proteins A Variety of PROTEIN MOLECULES are EMBEDDED in the Lipid Bilayer. Some Proteins are Attached to the surface of the cell membrane, these are called PERIPHERAL PROTEINS, Integral proteins The Proteins that are Embedded in the Lipid Bilayer are called INTEGRAL PROTEINS. Some Integral Proteins extend across the entire Cell Membrane and are exposed to both the inside of the cell and the exterior environment. Others extend only to the inside or only to the exterior surface. Lets take a look… Protein wrap up There are many kinds of Proteins in membranes; they HELP to MOVE Material INTO and OUT of the Cell. Some Integral Proteins form Channels or Pores through which certain substances can pass. Other Proteins bind to a substance on one side of the Membrane and carry it to the other side of the Membrane. Integral Proteins exposed to the Cell's External environment often have Carbohydrates attached to them serve as identification badges that allow cells to recognize each other and may act as Site where viruses or chemical messengers such as hormones can attach. FLUID MOSAIC MODEL OF CELL MEMBRANES Membranes are FLUID and have the consistency of vegetable oil. The Lipids and Proteins of the Cell Membrane are always in motion. Phospholipids are able to drift across the membrane, changing places with their neighbor. Proteins in and on the membrane Form PATTERNS, or MOSAICS. Because the Membrane is FLUID with a MOSAIC of Proteins, scientists call the modern view of Membrane Structure THE FLUID MOSAIC MODEL ORGANELLES Where are organelles found? 1. EVERYTHING BETWEEN THE CELL MEMBRANE AND THE NUCLEUS IS THE CELL'S CYTOPLASM. 2. CYTOPLASM consists of TWO MAIN COMPONENTS: CYTOSOL and ORGANELLES. 3. CYTOSOL is a jellylike mixture that consists MOSTLY OF WATER, along with PROTEINS, CARBOHYDRATES, SALTS, MINERALS and ORGANIC MOLECULES. 4. Suspended in the Cytosol are tiny ORGANELLES (ORGANS). 3 Organelles found in plant cells but not animals Cell wall Large plastids Vacule What is an organelle? Suspended in the Cytosol are tiny ORGANELLES (ORGANS). ORGANELLES ARE STRUCTURES THAT WORK LIKE MINIATURE ORGANS, THEY CARRY OUT SPECIFIC FUNCTIONS IN THE CELL. MITOCHONDRIA (MET-oh-KAHNdree-uh) THE "POWERHOUSE" OF THE CELL. Mitochondria are the sites of Chemical Reactions that transfer Energy from Organic Compounds to ATP. Energy contain in food is released. Converted to ATP. ATP is the molecule that most Cells use as their main Energy Currency. MITOCHONDRIA Mitochondria are Usually more numerous in Cells that have a High Energy Requirement Your muscle cells contain a large number of mitochondria. Mitochondria is surrounded by TWO Membranes. A. The smooth outer membrane serves as a boundary between the mitochondria and the cytosol. MITOCHONDRIA part 2 B. The inner membrane has many long folds, known as CRISTAE (KRIStee). The Cristae greatly increases the surface area of the inner membrane, providing more space for the Chemical Reactions to occur. RIBOSOMES (RIE-buhSOHMZ) Unlike most other organelles, Ribosomes Are Not Surrounded by a membrane. Ribosomes are the site of PROTEIN SYNTHESIS (Production or Construction) in a cell. ENDOPLASMIC RETICULUM (ER) (EN-doh-PLAZ-mik riTIK-yuh-luhm) . The ER is a system of membranous tubules and sacs. The ER functions Primarily as an Intracellular Highway, a path along which molecules move from one part of the cell to another. The amount of ER inside a cell fluctuates, depending on the Cell's Activity. Poisons, waste, and other toxic chemicals are made harmless. ER is an extensive network of membranes that connect the Nuclear Envelope to the Cell Membrane. Transports materials through the cell. ENDOPLASMIC RETICULUM (ER) Can be ROUGH OR SMOOTH. A. ROUGH ER is studded with RIBOSOMES and processes PROTEINS to be exported from the cell. B. SMOOTH ER IS NOT Covered with RIBOSOMES and processes LIPIDS and CARBOHYDRATES. The Smooth ER is involved in the synthesis of steroids in gland cells, the regulation of calcium levels in muscle cells, and the breakdown of toxic substances by liver cells. GOLGI APPARATUS (GOHLjee) 1. The Golgi Apparatus is the Processing, Packaging and Secreting Organelle of the Cell. 2. The Golgi Apparatus is a system of membranes. Made of Flattened SAC like Structures called CISTERNAE. 3. It works Closely with the ER, the Golgi Apparatus modifies proteins for export by the cell. LYSOSOMES (LIE-suhsohmez) 1. Lysosomes are small spherical organelles that enclose hydrolytic enzymes within a single membrane. 2. Lysosomes are the Site of Food Digestion in the Cell. 3. Lysosomes are formed from pieces of the GOLGI APPARATUS that break off. 4. Lysosomes are common in the Cells of Animals, Fungi, and Protists, But Rare in Plant Cells. Cytoskeleton Cytoskeleton is the supporting framework of the cell. Made of proteins called microtubules and microfilaments. MICROFILAMENTS MICROFILAMENTS 1. MICROFILAMENTS are NOT HALLOW and have a structure that resembles ROPE made of TWO TWISTED CHAINS OF PROTEIN called ACTIN. 2. MICROFILAMENTS can CONTRACT, causing movement. 3. Muscle Cells have many microfilaments. MICROTUBULES MICROTUBULES 1. Microtubules are HALLOW TUBES like plumbing pipes. They are the Largest Strands of the Cytoskeleton. 2. Microtubules are made of a PROTEIN called TUBULIN. 3. Microtubules have THREE FUNCTIONS: A. To maintain the shape of the cell. B. To serve as tracks for organelles to move along within the cell. C. When the Cell is about to divide, bundles of Microtubules known as SPINDLE FIBERS come together and extend across the cell to assist in the movement of Chromosomes during Cell Division. Vacuoles Storage, every good factory needs plenty of storage for materials. Vacuoles in plant cells can store water and other items. Overview of Animal Cell Overview of Plant Cell Summary of Animal cell and function