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Transcript
3.1 Cell Theory KEY CONCEPT Cells are the Basic unit of life. TEKS 3F, 4A 3.1 Cell Theory TEKS 3F, 4A The cell theory grew out of the work of many scientists and improvements in the microscope. • Many scientists contributed to the cell theory. First to see cells (cork cells) in a microscope. First to see tiny organisms moving in pond water he placed under the microscope 1838Concluded all plants were made of cells 1839Concluded all animals were made of cells 1855- New cells can only be produced from the division of existing cells. This completed the 3rd statement of the new “Cell Theory” of life 3.1 Cell Theory TEKS 3F, 4A The cell theory grew out of the work of many scientists and improvements in the microscope. • Many scientists contributed to the cell theory. • More was learned about cells as microscopes improved. • The cell theory is a unifying concept of biology. 3.1 Cell Theory TEKS 3F, 4A Early studies led to the development of the cell theory. • The Cell theory has three principles. – All organisms are made of cells. 3.1 Cell Theory TEKS 3F, 4A Early studies led to the development of the cell theory. • The Cell theory has three principles. – All organisms are made of cells. – All existing cells are produced by other living cells. – The cell is the most basic unit of life. 3.1 Cell Theory TEKS 3F, 4A Prokaryotic cells lack a nucleus and most internal structures of eukaryotic cells. • All cells share certain characteristics. – Cells tend to be microscopic. – All cells are enclosed cell membrane by a membrane. – All cells are filled with cytoplasm. cytoplasm Bacterium (colored SEM; magnification 8800x) 3.1 Cell Theory TEKS 3F, 4A There are two cell types: eukaryotic cells and prokaryotic cells. • Prokaryotic cells do not have a nucleus. nucleus • Prokaryotic cells do not have membrane-bound organelles. organelles cell membrane cytoplasm 3.1 Cell Theory 3.2 Cell Organelles Cells have an internal structure. • The cytoskeleton has many functions. – supports and shapes cell – helps position and transport organelles – provides strength – assists in cell division – aids in cell movement TEKS 3F, 4A 3.1 Cell Theory 3.2 Cell Organelles TEKS 3F, 4A Several organelles are involved in making and processing proteins. • The nucleus stores genetic information. • Many processes occur in the endoplasmic reticulum. 3.1 Cell Theory 3.2 Cell Organelles TEKS 3F, 4A Several organelles are involved in making and processing proteins. • Manufacturing and transport processes occur in the endoplasmic reticulum. • There are two types of endoplasmic reticulum. – rough endoplasmic reticulum – smooth endoplasmic reticulum 3.1 Cell Theory 3.2 Cell Organelles Several organelles are involved in making and processing proteins. (continued) • Ribosomes link amino acids to make proteins. TEKS 3F, 4A 3.1 Cell Theory 3.2 Cell Organelles TEKS 3F, 4A Several organelles are involved in making and processing proteins. (continued) • Ribosomes link amino acids to form proteins. • Vesicles are membrane-bound sacs that hold materials (like the newly made proteins). 3.1 Cell Theory 3.2 Cell Organelles Other organelles have various functions. • Mitochondria supply energy to the cell. TEKS 3F, 4A 3.1 Cell Theory 3.2 Cell Organelles TEKS 3F, 4A Other organelles have various functions. • Vacuoles are fluid-filled sacs that hold materials. • Larger in plants cells to help maintain water pressure. 3.1 Cell Theory 3.2 Cell Organelles Other organelles have various functions. • Lysosomes contain enzymes to digest material. TEKS 3F, 4A 3.1 Cell Theory 3.2 Cell Organelles TEKS 3F, 4A Other organelles have various functions. • Centrioles are tubes found in the centrosomes. Centrioles help divide DNA during mitosis. Centrioles form cilia and flagella. 3.1 Cell Theory 3.2 Cell Organelles TEKS 3F, 4A Other organelles have various functions. • Mitochondria supply energy to the cell. • Vacuoles are fluid-filled sacs that hold materials. • Lysosomes contain enzymes to digest material. • Centrioles are tubes found in the centrosomes. – Centrioles help divide DNA. – Centrioles form cilia and flagella. 3.1 Cell Theory 3.2 Cell Organelles Plant cells have cell walls and chloroplasts. • A cell wall provides rigid support. TEKS 3F, 4A 3.1 Cell Theory 3.2 Cell Organelles TEKS 3F, 4A Plant cells have cell walls and chloroplasts. • Chloroplasts convert solar energy to chemical energy during photosynthesis. 3.1 Cell Theory 3.3 Cell Membrane KEY CONCEPT The cell membrane is a barrier that separates a cell from the external environment. TEKS 3F, 4A 3.1 Cell Theory 3.3 Cell Membrane TEKS 3F, 4A Cell membranes are composed of two phospholipid layers. water Hydrophillic Hydrophobic water 3.1 Cell Theory 3.3 Cell Membrane TEKS 3F, 4A Cell membranes are composed of two phospholipid layers. • The cell membrane has two major functions. – forms a boundary between inside and outside of the cell – controls passage of materials cell membrane inside cell outside cell 3.1 Cell Theory 3.3 Cell Membrane TEKS 3F, 4A Cell membranes are composed of two phospholipid layers. • The cell membrane is made of a phospholipid bilayer. • There are other molecules embedded in the membrane. • The fluid mosaic model describes the membrane. cell membrane carbohydrate chain cholesterol protein protein channel protein 3.1 Cell Theory 3.3 Cell Membrane TEKS 3F, 4A Cell membranes are composed of two phospholipid layers. • The cell membrane is selectively permeable. Some molecules can cross the membrane while others cannot. 3.1 Cell Theory 3.3 Cell Membrane TEKS 3F, 4A Chemical signals are transmitted across the cell membrane. • • Receptors bind with ligands (chemical messengers) and change shape. There are two types of receptors. – intracellular receptor – lipid-based (testosterone, estrogen) – membrane receptor – usually proteins intracellular receptor membrane receptor 3.1 Cell 3.4 Osmosis andTheory Diffusion TEKS 3F, 4A Diffusion and Osmosis are types of passive transport. • Passive transport does not require energy input from a cell. • Molecules can move across the cell membrane through passive transport. • Requires a gradient – molecules move from higher concentrations to lower concentrations. • There are two types of passive transport. • diffusion • osmosis 3.1 Cell 3.4 Osmosis andTheory Diffusion Diffusion and osmosis are types of passive transport. Diffusion • Diffusion is when molecules move down a concentration gradient. • Movement is from a region of higher concentration to a region of lower concentration. • Osmosis is the diffusion of water molecules across a semipermeable membrane. TEKS 3F, 4A 3.1 Cell 3.4 Osmosis andTheory Diffusion TEKS 3F, 4A The mixture of solutes and solvents are called solutions. NOTE: The following terms are based on the concentration of solute which will then determine the movement of water. Hypertonic- “high” levels of solute/Low H20 Hypotonic-”low” levels of solute/high H2O Isotonic-“equal” levels on both sides of membrane – ”tonic” 3.1 Cell 3.4 Osmosis andTheory Diffusion TEKS 3F, 4A Fresh water flows to salt water as rivers flow to the sea… 3.1 Cell 3.4 Osmosis andTheory Diffusion TEKS 3F, 4A This is the shrinking of the cell due to water leaving the cell… 95% water plasmolysis. 5% solute 93% water 7% solute This is the bursting of the cell due to water entering the cell… cytolysis. 93% water 7% solute 95% water 5% solute 3.1 Cell 3.4 Osmosis andTheory Diffusion Some molecules can only diffuse through transport proteins. • Some molecules cannot easily diffuse across the cell membrane. • Facilitated diffusion is diffusion through transport proteins. TEKS 3F, 4A 3.1 Theory 3.5 ActiveCell Transport, Endocytosis, and Exocytosis TEKS 3F, 4A KEY CONCEPT Cells use energy to transport materials that cannot diffuse across a membrane. ATP Cells also use energy to transport materials against a concentration gradient! …from a low concentration to a higher concentration.. 3.1 Theory 3.5 ActiveCell Transport, Endocytosis, and Exocytosis • Passive transport requires no energy from the cell. • Active transport is powered by chemical energy (ATP). • Active transport occurs through transport protein pumps. • Cells use active transport to maintain homeostasis. TEKS 3F, 4A 3.1 Theory 3.5 ActiveCell Transport, Endocytosis, and Exocytosis TEKS 3F, 4A A cell can import and export large materials or large amounts of material in vesicles during the processes of endocytosis and exocytosis. • Cells use energy to transport material in vesicles. • Endocytosis is the process of taking material into the cell. • Phagocytosis is a type of endocytosis. 3.1 Theory 3.5 ActiveCell Transport, Endocytosis, and Exocytosis TEKS 3F, 4A A cell can import and export large materials or large amounts of material in vesicles during the processes of endocytosis and exocytosis. • Cells use energy to transport material in vesicles. • Exocytosis is the process of expelling material from the cell.