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Transcript
Biology 1- Chapter 7 Notes Prentice Hall (pg. 168-193) • 7–1 Life Is Cellular • A. The Discovery of the Cell 1. Early Microscopes 2. The Cell Theory B. Exploring the Cell C. Prokaryotes and Eukaryotes 1. Prokaryotes 2. Eukaryotes • 7–2 A. B. C. D. E. F. G. H. Cell Boundaries A. Cell Membrane B. Cell Walls C. Diffusion Through Cell Boundaries 1. Measuring Concentration 2. Diffusion D. Osmosis 1. How Osmosis Works 2. Osmotic Pressure E. Facilitated Diffusion F. Active Transport 1. Molecular Transport 2. Endocytosis and Exocytosis Eukaryotic Cell Structure Comparing the Cell to a Factory Nucleus Ribosomes Endoplasmic Reticulum Golgi Apparatus Lysosomes Vacuoles Mitochondria and Chloroplasts 1. Mitochondria 2. Chloroplasts 3. Organelle DNA I. Cytoskeleton 7–3 • 7–4 The Diversity of Cellular Life A. Unicellular Organisms B. Multicellular Organisms 1. Specialized Animal Cells 2. Specialized Plant Cells C. Levels of Organization 1. Tissues 2. Organs 3. Organ Systems 7.1: The History of the Cell Theory • Before microscopes were invented, people believed that diseases were caused by curses and supernatural spirits. • As scientists began using microscopes, they quickly realized they were entering a new world–one of microorganisms. • Microscopes enabled scientists to view and study cells, the basic units of living organisms. Development of Light Microscopes • The first person to record looking at water under a microscope was Anton van Leeuwenhoek. • The microscope van Leeuwenhoek used is considered a simple light microscope because it contained one lens and used natural light to view objects. • Compound light microscopes use a series of lenses to magnify objects in steps. • These microscopes can magnify objects up to 1500 times. The Cell Theory • Robert Hooke was an English scientist who lived at the same time as van Leeuwenhoek. • Hooke used a compound light microscope to study cork, the dead cells of oak bark. • He thought the structures he observed resembled the one room “cells” • Hooke is credited with giving cells their name • Cells are the basic building blocks of all living things. The cell theory is made up of three main ideas: 1. All organisms are composed of one or more cells. 2. The cell is the basic unit of structure and function of organisms. 3. All cells come from preexisting cells. Three Scientists contributed to the Cell Theory: • 1838- Schleiden: plants are made of cells • 1839- Schwann: animals are made of cells • 1855- Virchow: New cells are produced from the division of old cells Development of Electron Microscopes • The electron microscope was invented in the 1940s. • This microscope uses a beam of electrons to magnify structures up to 500,000 times their actual size. There are two basic types of electron microscopes. • The scanning electron microscope scans the surface of cells to learn their three dimensional shape. • The transmission electron microscope allows scientists to study the structures contained within a cell. Scanning Probe Microscope • Discovered in the 1990’s • Produces images by tracing the surfaces of samples with a fine probe • Can observe single atoms in the air or in solution SEM Picture of Neuron Condensed DNA by Scanning probe Two Basic Cell Types Cell membrane Cytoplasm Prokaryotic Cell Cell membrane Cytoplasm Nucleus Eukaryotic Cell Organelles Prokaryotic and Eukaryotic Cells Prokaryotic Cells • Cells that do not contain internal membrane-bound structures and do not have a nucleus are called prokaryotic cells. Prokaryotic Cell • Unicellular organisms such as bacteria are very simple. • They still carry out all of life’s activities such as respiration, cell reproduction, growth, etc. Eukaryotic Cells • Cells containing membrane-bound structures and a nucleus are called eukaryotic cells. • Most of the multicellular plants and animals are made up of cells that are very specialized and diverse in their structures and functions Eukaryotic Cell 7.2 Eukaryotic Cell Structure Organelles • The membrane-bound structures within eukaryotic cells are called organelles. • Each “little organ” has a specific function that contributes to cell survival. • Separation of organelles into distinct compartments benefits the eukaryotic cells. • Lysosomes • Nucleus • Plasma Membrane • Endoplasmic Reticulum • Mitochondrion Biologists divide the cell into two major parts • The nucleus is the central membrane-bound organelle that manages cellular functions. • Everything between the cell membrane and the nucleus is called the cytoplasm. Nucleus - Nuclear envelope – double layered membrane surrounding nucleus; contains small pores - Nuclear pores- allow transport of materials in and out of nucleus - Chromatin-granular material visible within the nucleus; consists of DNA tightly coiled around proteins - Chromosomes – threadlike Nucleolus Chromatin structure within the nucleus containing the genetic information that is passed from one generation of cells to the next (chromosomes are formed when chromatin condenses during cell division) Nuclear - Nucleolus – dense material Envelope in nucleus; makes ribosomes which make proteins Nuclear Pore Ribosomes • Ribosomes are made in the nucleolus. • They travel in and out of the nucleus through the nuclear pores. Ribosomes • Ribosomes are small particles within the cell on which proteins are assembled; made of RNA and protein • They can be free (in the cytoplasm) • They are also attached to the rough endoplasm reticulum Endoplasmic reticulum • The endoplasmic reticulum (ER) is responsible for assembly, transport, and storage of molecules within cell. • There are two types • Rough ER- contains ribosomes and makes proteins • Smooth ER- lacks ribosomes; has enzymes that make membrane lipids and detoxifies drugs • Liver cells contain many smooth ER for detoxification Golgi Apparatus • Stacks of membranes in the cell that modifies, sorts, and packages proteins from the endoplasmic reticulum • The Golgi apparatus is like a customization shop where finishing touches are added to proteins. Lysosomes • Lysosomes are organelles that contain digestive enzymes. They digest excess or worn out organelles, food particles, and engulfed viruses or bacteria. • The lysosomes are the clean-up crew of the cell • Tay-Sachs disease is caused by excess lipid accumulation on the brain. The cause of this disease has been traced to lysosomes that failed to function properly Vacuoles • Vacuoles are membrane-bound spaces used for temporary storage of materials (such as water, salts, proteins, and carbohydrates) • Notice the difference between vacuoles in plant and animal cells. Plant Vacuole Animal Cell Cell • Paramecium have a contractile vacuole that pumps excess water out of the cell, which aids with homeostasis Mitochondria • Mitochondria are • Cellular respiration is the membrane-bound process that converts organelles in plant and chemical energy stored in animal cells that transform food into ATP energy for energy for the cell. cells to use. • A mitochondria, like the • Muscles cells (needed for endoplasmic reticulum, has a highly folded inner movement) contain a large membrane. number of mitochondria for • The folds increase the energy production surface area of the mitochondrion in order to make more energy (ATP) • Cellular Respiration takes place in the mitochondria of cells Chloroplasts • Chloroplasts are found in cells of plants and some other organisms • Chloroplasts are organelles that capture light energy and produce food to store for a later time. • Photosynthesis takes place in the chloroplasts • Chloroplasts contain green pigment called chlorophyll. • Chlorophyll traps light energy and gives leaves and stems their green color. • Chloroplasts acts like a solar power plant Organelle DNA • Lynn Margulis - described mitochondria and chloroplasts as free-living aerobic prokaryotes which developed a partnership with host cell; endosymbiosis hypothesis • chloroplasts and mitochondria have their own circular DNA & ribosomes, make their own proteins, reproduce on their own Cytoskeleton • Cells have a support structure called the cytoskeleton within the cytoplasm. • It is a network of proteins that help maintain cellular shape and movement • The cytoskeleton is composed of microtubules and microfilaments. Cell membrane Endoplasmic reticulum Microtubule Microfilament Ribosomes Mitochondrion • Microtubules are thin, hollow cylinders made of protein that maintain cell shape • Microfilaments are thin solid protein fibers that help cells move (amoeba) Centrioles • Made of microtubules and cytoskeleton • one of two tiny structures located in the cytoplasm of animal cells near the nuclear envelope • help to organize cell division (helps cells split into two) • only found in animal cells Cilia and Flagella Cilia • Some cell surfaces have cilia and flagella, which are structures aid in locomotion or feeding. • Made of microtubules from the cytoskeleton • Cilia and flagella can be distinguished by their structure and by the nature of their action. • Cilia are short, numerous, hair-like projections that move in a wavelike motion. • Flagella are long projections that move in a whip-like motion. • Flagella and cilia are the major means of locomotion in unicellular organisms. Flagella Microscope Lab • Purpose :To compare the basic structures and shape of plant and animals cells by looking at onion (epidermal) cells and cheek (epithelial) cells – epidermal cells- cells that make up the protective outer covering of plants; tissue that covers the human body – epithelial cells- cells that make up tissues that cover bodies or organs • To review basic microscope parts and lab techniques like staining cells and preparing a wet mount for microscope slides • • Shape Components Plant Cells Rectangular Cell wall Cell Membrane Nucleus Animal Cells Circular Cell Membrane Nucleus Plant cells have structures not found in animal cells • Cell wall - help give plants shape, support and protection • Chloroplast-site of photosynthesis • Large central vacuole contains water which helps keep plant from wilting; when the vacuole is full it presses against the cell wall to give the plants rigidity (turgid pressure) Animal cells have structures not found in plant cells • Cytoskeleton- animal cells use the cytoskeleton to help with support and aid in movement • Centrioles-aid in cell division Differences between Plant/Animal Cells Animal Cells Centrioles Plant Cells Cell membrane Ribosomes Nucleus Endoplasmic reticulum Golgi apparatus Lysosomes Vacuoles Mitochondria Cytoskeleton Cell Wall Chloroplasts Animal Cell Nucleolus Nucleus Ribosome (attached) Nuclear envelope Ribosome (free) Cell Membrane Mitochondrion Smooth endoplasmic reticulum Rough endoplasmic reticulum Centrioles Golgi apparatus Animal Cell Plant Cell Smooth endoplasmic reticulum Vacuole Ribosome (free) Chloroplast Ribosome (attached) Cell Membrane Nuclear envelope Cell wall Nucleolus Golgi apparatus Nucleus Mitochondrion Rough endoplasmic reticulum Plant Cell Cell Specialization • • • • Animal cells Red Blood Cells- carries oxygen; small and round to fit through vessels Pancreatic Cells- produce enzymes to break down food; contains many ribosomes and rough ER to aid in this process Muscle Cells- long and threadlike to aid in movement; contain many mitochondria for energy production Plant Cells Guard cells- in the pores of leaves; aids in water exchange Cell Shape is Related to Function Levels of Organization Muscle cell Smooth muscle tissue Stomach Digestive system • Many multicellular organisms have structures called organs that have a specific function and work with other organs. • Working together, these organs carry out the life processes of the entire organism. • Multicellular organisms contains cells, tissues, organs and organ systems Microscopes • What is a microscope and its parts? • How do I properly use a microscope? The Compound Microscope 1. Eyepiece (ocular lens) 2. Arm 3. Stage 4. Opening of the stage 5. Fine adjustment knob 6. Coarse adjustment knob 7. Base 8. Illuminator 9. Diaphragm 10.Diaphragm lever 11.Stage clips 12.Low-power objective 13.High-power objective 14.Nosepiece 15.Body tube Parts of the Microscope and their Function 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. Eyepiece Contains a magnifying lens Arm Supports the body tube Stage Supports the slide being observed Opening of the stage Permits light to pass up to the eyepiece Fine adjustment knob Moves the body tube slightly to sharpen the image Coarse adjustment knob Moves the body tube to focus the image Base Supports the microscope Illuminator Produces light or reflects light up toward the eyepiece Diaphragm Regulates the amount of light passing up toward the eyepiece Diaphragm lever Opens and closes the diaphragm Stage clips Hold the slide in place Low-power objective Provides a magnification of 10× and is the shortest objective High-power objective Provides a magnification of 40× and is the longest objective Nosepiece Holds the objectives and can be rotated to change the magnification Body tube Maintains the proper distance between the eyepiece M. A. L. B. C. (10x) K. D. (40x) E. J. F. I. H. G.