* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download File
Survey
Document related concepts
Cytoplasmic streaming wikipedia , lookup
Tissue engineering wikipedia , lookup
Biochemical switches in the cell cycle wikipedia , lookup
Signal transduction wikipedia , lookup
Extracellular matrix wikipedia , lookup
Cell nucleus wikipedia , lookup
Cell membrane wikipedia , lookup
Cell encapsulation wikipedia , lookup
Cellular differentiation wikipedia , lookup
Cell culture wikipedia , lookup
Cell growth wikipedia , lookup
Cytokinesis wikipedia , lookup
Organ-on-a-chip wikipedia , lookup
Transcript
Chapter 15 Lecture Conceptual Integrated Science Second Edition The Basic Unit of Life—The Cell © 2013 Pearson Education, Inc. This lecture will help you understand: • • • • • • • • • • • • • • • • Characteristics of Life Macromolecules Needed for Life Cell Types: Prokaryotic and Eukaryotic The Microscope Tour of a Eukaryotic Cell The Cell Membrane Transport into and out of Cells Cell Communication How Cells Reproduce How Cells Use Energy ATP and Chemical Reactions in Cells Photosynthesis Cellular Respiration and Fermentation History of Science: Cell Theory Math Connection: Why Does Diffusion Limit the Size of Cells? Science and Society: Stem Cells © 2013 Pearson Education, Inc. Characteristics of Life • All living things – use energy. – develop and grow. – maintain themselves. – have the capacity to reproduce. – are parts of populations that evolve. © 2013 Pearson Education, Inc. Characteristics of Life • All living things use energy. – Plants take electromagnetic energy from sunlight and convert it to chemical energy. – Animals convert energy from food into chemical energy. – Living things use this chemical energy to build structures and fuel their activities. – How living things use energy is consistent with the laws of physics. © 2013 Pearson Education, Inc. Characteristics of Life • All living things develop and grow, changing over time. • Living things maintain themselves. – They build structures (bones, stems). – They repair damage (heal wounds). – They maintain their internal environments (body temperature, water balance). © 2013 Pearson Education, Inc. Characteristics of Life • All living things have the capacity to reproduce. – Asexual reproduction occurs when an organism reproduces by itself. – Sexual reproduction occurs when organisms produce sperm and eggs that join to develop into new individuals. © 2013 Pearson Education, Inc. Characteristics of Life • All living things are parts of populations that evolve. – Populations do not remain constant. – Populations change over time, across generations. – Populations may evolve in response to their environments. © 2013 Pearson Education, Inc. Macromolecules Needed for Life • • • • Proteins Carbohydrates Lipids Nucleic acids © 2013 Pearson Education, Inc. Cell Types: Prokaryotic and Eukaryotic • Prokaryotic cells have no nucleus. • Prokaryotes are almost always single-celled, microscopic organisms. Their DNA is found in a single circular structure. They usually have an outer cell wall. © 2013 Pearson Education, Inc. Cell Types: Prokaryotic and Eukaryotic • Eukaryotic cells have a nucleus and may be single-celled or multicellular. They – have their DNA inside the nucleus. – have linear chromosomes. – have various organelles. – are larger than prokaryotic cells. © 2013 Pearson Education, Inc. The Microscope • Light microscopes allow people to view cells and make out the larger features within them. • Electron microscopes allow people to view even smaller structures within cells. © 2013 Pearson Education, Inc. The Microscope Light microscope © 2013 Pearson Education, Inc. The Microscope Electron microscope © 2013 Pearson Education, Inc. Tour of a Eukaryotic Cell • Eukaryotic cells contain many parts, including: – Cell membrane – Nucleus – Cytoplasm – Cytoskeleton – Organelles • All the parts of the cell have specific functions. © 2013 Pearson Education, Inc. Tour of a Eukaryotic Cell • Plant cells also contain – a cell wall to make the cell rigid. – chloroplasts that perform photosynthesis. © 2013 Pearson Education, Inc. Eukaryotic Cell Structures Eukaryotic Cell Structures Structures within a eukaryotic cell that perform important cellular functions are known as organelles. Cell biologists divide the eukaryotic cell into two major parts: the nucleus and the cytoplasm. The Cytoplasm is the portion of the cell outside the nucleus. Eukaryotic Cell Structures Plant Cell Nucleolus Nucleus Smooth endoplasmic reticulum Nuclear envelope Ribosome (free) Rough endoplasmic reticulum Ribosome (attached) Golgi apparatus Cell wall Cell membrane Chloroplast Mitochondrion Vacuole Eukaryotic Cell Structures Animal Cell Nucleolus Smooth endoplasmic reticulum Nucleus Nuclear envelope Rough endoplasmic reticulum Ribosome (free) Cell membrane Ribosome (attached) Centrioles Mitochondrion Golgi apparatus Nucleus What is the function of the nucleus? Nucleus Nucleus The nucleus is the control center of the cell. The nucleus contains nearly all the cell's DNA and with it the coded instructions for making proteins and other important molecules. Nucleus The Nucleus Chromatin Nucleolus Nuclear envelope Nuclear pores Ribosomes What is the function of the ribosomes? Ribosomes Ribosomes One of the most important jobs carried out in the cell is making proteins. Proteins are assembled on ribosomes. Ribosomes are small particles of RNA and protein found throughout the cytoplasm. Endoplasmic Reticulum What is the function of the endoplasmic reticulum? Endoplasmic Reticulum There are two types of ER—rough and smooth. Endoplasmic Reticulum Ribosomes Copyright Pearson Prentice Hall Golgi Apparatus What is the function of the Golgi apparatus? Golgi Apparatus The Golgi apparatus appears as a stack of closely apposed membranes. Golgi Apparatus What is the function of lysosomes? Vacuoles What is the function of vacuoles? Vacuoles In many plant cells there is a single, large central vacuole filled with liquid. Vacuole Vacuoles Vacuoles are also found in some unicellular organisms and in some animals. The paramecium contains a contractile vacuole that pumps excess water out of the cell. Contractile vacuole Mitochondria and Chloroplasts What is the function of the mitochondria? Mitochondria and Chloroplasts Mitochondria Nearly all eukaryotic cells contain mitochondria. Mitochondria convert the chemical energy stored in food into compounds that are more convenient for the cell to use. Mitochondrion Mitochondria and Chloroplasts What is the function of chloroplasts? Mitochondria and Chloroplasts Chloroplasts Chloroplast Plants and some other organisms contain chloroplasts. Chloroplasts capture energy from sunlight and convert it into chemical energy in a process called photosynthesis. Cytoskeleton What are the functions of the cytoskeleton? Cytoskeleton The cytoskeleton is a network of protein filaments that helps the cell to maintain its shape. The cytoskeleton is also involved in movement. The cytoskeleton is made up of: • microfilaments • microtubules Cytoskeleton Cytoskeleton Cell membrane Endoplasmic reticulum Microtubule Microfilament Ribosomes Mitochondrion Cytoskeleton Centrioles are located near the nucleus and help to organize cell division. The Cell Membrane • The cell membrane – defines a cell's boundary. – controls what moves into and out of the cell. – consists of a phospholipid bilayer, membrane proteins, and short carbohydrates. © 2013 Pearson Education, Inc. Cell Membrane Cell Membrane Outside of cell Proteins Carbohydrate chains Cell membrane Inside of cell (cytoplasm) Protein channel Lipid bilayer The Cell Membrane • The fluid mosaic model describes the structure of the cell membrane, a mosaic of proteins and phospholipids, almost all of which can move fluidly around the membrane. © 2013 Pearson Education, Inc. Transport into and out of cells • Cells take in many resources, including water, oxygen, and organic molecules. • Cells also discard wastes. • Transport occurs through: – Diffusion – Facilitated diffusion – Active transport – Endocytosis and exocytosis © 2013 Pearson Education, Inc. Transport into and out of cells • Diffusion is the tendency of molecules to move from an area of high concentration to an area of low concentration. – Molecules diffuse across the phospholipid bilayer of the cell membrane. – Diffusion requires no energy from the cell. It is a form of passive transport. © 2013 Pearson Education, Inc. Diffusion Through Cell Boundaries Diffusion Particles in a solution tend to move from an area where they are more concentrated to an area where they are less concentrated. This process is called diffusion. When the concentration of the solute is the same throughout a system, the system has reached equilibrium. Diffusion Through Cell Boundaries Osmosis Osmosis Osmosis is the diffusion of water through a selectively permeable membrane. Copyright Pearson Prentice Hall Osmosis How Osmosis Works Dilute sugar solution (Water more concentrated) Concentrated sugar solution (Water less concentrated) Sugar molecules Selectively permeable membrane Movement of water Osmosis Water tends to diffuse from a highly concentrated region to a less concentrated region. If you compare two solutions, three terms can be used to describe the concentrations: hypertonic (“above strength”). hypotonic (“below strength”). isotonic (”same strength”) Osmosis Osmotic Pressure Osmosis exerts a pressure known as osmotic pressure on the hypertonic side of a selectively permeable membrane. Transport into and out of cells • Facilitated diffusion occurs when a transport protein binds to a molecule and moves it down a concentration gradient. – Facilitated diffusion requires no energy from the cell. It is a form of passive transport. © 2013 Pearson Education, Inc. Facilitated Diffusion Glucose molecules Facilitated Diffusion Protein channel Copyright Pearson Prentice Hall Transport into and out of cells • Active transport occurs when a transport protein moves a molecule against its concentration gradient. – Active transport requires energy from the cell. © 2013 Pearson Education, Inc. Active Transport Active Transport Sometimes cells move materials in the opposite direction from which the materials would normally move—that is against a concentration difference. This process is known as active transport. Active transport requires energy. Active Transport Molecular Transport In active transport, small molecules and ions are carried across membranes by proteins in the membrane. Energy use in these systems enables cells to concentrate substances in a particular location, even when diffusion might move them in the opposite direction. Active Transport Molecular Transport Molecule to be carried Active Transport Transport into and out of cells • Larger amounts of material can be transported into and out of cells through endocytosis and exocytosis. – In endocytosis, a vesicle pinches off from the cell membrane. – In exocytosis, a vesicle fuses with the cell membrane. © 2013 Pearson Education, Inc. Active Transport Endocytosis and Exocytosis Endocytosis is the process of taking material into the cell. Two examples of endocytosis are: – phagocytosis – pinocytosis During exocytosis, materials are forced out of the cell. Cell Communication • Cells communicate with one another using special molecules. • Communication between adjacent cells occurs when molecules move from one cell to another through special "doorways." – Animal cells have gap junctions. – Plant cells have plasmodesmata. © 2013 Pearson Education, Inc. Cell Communication • Long-distance communication relies on message molecules traveling through the bloodstream. – Receptors are membrane proteins. – A receptor binds a message molecule with a lock-and-key fit. – The binding of the receptor to a message molecule initiates a series of chemical reactions that results in the target cell's response to the message. © 2013 Pearson Education, Inc. Cell Communication © 2013 Pearson Education, Inc. How Cells Reproduce • In mitosis, one parent cell divides into two daughter cells that have the same genetic information as the parent cell. © 2013 Pearson Education, Inc. How Cells Reproduce • A dividing cell goes through the stages of the cell cycle: gap 1, synthesis, gap 2, and mitosis and cytokinesis. © 2013 Pearson Education, Inc. The Cell Cycle Cell Cycle The cell cycle is the series of events that cells go through as they grow and divide. Interphase is the period of growth that occurs between cell divisions. The Cell Cycle During the cell cycle: • a cell grows • prepares for division • divides to form two daughter cells, each of which begins the cycle again The Cell Cycle The cell cycle consists of four phases: – – – – G1 (First Gap Phase) S Phase G2 (Second Gap Phase) M Phase Events of the Cell Cycle Events of the Cell Cycle During G1, the cell – increases in size – synthesizes new proteins and organelles Events of the Cell Cycle During the S phase, • chromosomes are replicated • DNA synthesis takes place Once a cell enters the S phase, it usually completes the rest of the cell cycle. Events of the Cell Cycle The G2 Phase (Second Gap Phase) • organelles and molecules required for cell division are produced • Once G2 is complete, the cell is ready to start the M phase—Mitosis Events of the Cell Cycle Cell Cycle How Cells Reproduce • The phases of mitosis: – Prophase: Chromosomes condense, and nuclear membranes break down. – Metaphase: Chromosomes line up along the equatorial plane. – Anaphase: Sister chromatids are pulled apart and move to opposite poles of the cell. – Telophase: New nuclear membranes form around each set of chromosomes. • After mitosis, cytokinesis occurs: The cytoplasm divides, completing cell division. © 2013 Pearson Education, Inc. How Cells Reproduce © 2013 Pearson Education, Inc. How Cells Use Energy • Two things are necessary for a chemical reaction to occur: – Must be consistent with the law of conservation of energy. • Exothermic (energy-releasing) reactions occur spontaneously. • For all other reactions, cells rely on usable energy stored in molecules of ATP. – Activation energy needed for initial breaking of bonds. © 2013 Pearson Education, Inc. How Cells Use Energy • ATP provides energy for chemical reactions in cells. • Cells obtain energy from ATP when one phosphate group is removed, leaving ADP. © 2013 Pearson Education, Inc. How Cells Use Energy • Cells eventually turn ADP back into ATP by adding a phosphate group during cellular respiration. © 2013 Pearson Education, Inc. How Cells Use Energy • The sodium-potassium pump uses active transport to control the levels of sodium ions (Na+) and potassium ions (K+) in cells. This process uses one molecule of ATP. © 2013 Pearson Education, Inc. How Cells Use Energy • Reacting molecules must collide with an activation energy that is needed for the initial breaking of bonds. • The activation energy for many essential chemical reactions is very high. • A catalyst is a substance that lowers the activation energy, allowing a reaction to happen more quickly. • The catalysts in cells are enzymes—large, complex proteins. © 2013 Pearson Education, Inc. How Cells Use Energy • An enzyme binds the reactants at its active site and releases the products. • In the process, the enzyme is not altered or destroyed; it can be used again and again. © 2013 Pearson Education, Inc. How Cells Use Energy • Cells regulate enzymes – Cells control the synthesis and degradation of enzymes. – Enzyme function depends on temperature, pH, and other features of the environment. – Inhibitors can block the function of enzymes. © 2013 Pearson Education, Inc. How Cells Use Energy • Two types of enzyme inhibition – In competitive inhibition, the inhibitor binds to the active site of an enzyme so that the enzyme cannot bind its substrate. – Noncompetitive inhibition occurs when an inhibitor binds to a different part of the enzyme, changing the active site so that the enzyme can no longer bind to its substrate. © 2013 Pearson Education, Inc. Photosynthesis • The process organisms use to convert light energy from the Sun into chemical energy. • Conducted in the chloroplasts of plants. • Occurs in two stages: the light-dependent reactions and the light-independent reactions. • Photosynthesis is the ultimate source of (practically) all organic molecules on Earth. © 2013 Pearson Education, Inc. The Photosynthesis Equation The Photosynthesis Equation The equation for photosynthesis is: 6CO2 + 6H2O C6H12O6 + 6O2 Light carbon dioxide + water sugars + oxygen Light Copyright Pearson Prentice Hall The Photosynthesis Equation Photosynthesis uses the energy of sunlight to convert water and carbon dioxide into highenergy sugars and oxygen. Copyright Pearson Prentice Hall The Photosynthesis Equation Light energy Light-Dependent Reactions (thylakoids) H2O ADP + NADP Sugar O2 ATP NADPH Calvin Cycle (stroma) Copyright Pearson Prentice Hall CO2 + H20 Light and Pigments What is the role of light and chlorophyll in photosynthesis? Copyright Pearson Prentice Hall Light and Pigments Light and Pigments How do plants capture the energy of sunlight? In addition to water and carbon dioxide, photosynthesis requires light and chlorophyll. Copyright Pearson Prentice Hall Light and Pigments Plants gather the sun's energy with light-absorbing molecules called pigments. The main pigment in plants is chlorophyll. There are two main types of chlorophyll: – chlorophyll a – chlorophyll b – Caratnoid Copyright Pearson Prentice Hall Light and Pigments Chlorophyll absorbs light well in the blue-violet and red regions of the visible spectrum. Estimated Absorption (%) 100 80 60 Chlorophyll b Chlorophyll a 40 20 0 (nm) 400 450 Wavelength 500 550 600 650 700 750 Wavelength (nm) Copyright Pearson Prentice Hall Light and Pigments Chlorophyll does not absorb light will in the green region of the spectrum. Green light is reflected by leaves, which is why plants look green. Estimated Absorption (%) 100 80 60 Chlorophyll b Chlorophyll a 40 20 0 400 450 500 550 600 650 700 750 Wavelength (nm) Copyright Pearson Prentice Hall Light and Pigments Light is a form of energy, so any compound that absorbs light also absorbs energy from that light. When chlorophyll absorbs light, much of the energy is transferred directly to electrons in the chlorophyll molecule, raising the energy levels of these electrons. These high-energy electrons are what make photosynthesis work. Copyright Pearson Prentice Hall Photosynthesis Light-dependent reactions © 2013 Pearson Education, Inc. Photosynthesis • Light-independent reactions – The light-independent reactions make use of stored energy from the light-dependent reactions. – Carbon is fixed, moved from atmospheric CO2 to the sugar glucose. – The molecules produced during photosynthesis are used as a starting point for building all of the macromolecules of life. © 2013 Pearson Education, Inc. Inside a Chloroplast H2O CO2 Light NADP+ ADP + P Lightdependent reactions Calvin Calvin cycle Cycle Chloroplast O2 Copyright Pearson Prentice Hall Sugars