* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Osmosis/Diffusion
Survey
Document related concepts
Tissue engineering wikipedia , lookup
Cell nucleus wikipedia , lookup
Signal transduction wikipedia , lookup
Cell growth wikipedia , lookup
Extracellular matrix wikipedia , lookup
Cell encapsulation wikipedia , lookup
Cellular differentiation wikipedia , lookup
Cell culture wikipedia , lookup
Cell membrane wikipedia , lookup
Cytokinesis wikipedia , lookup
Organ-on-a-chip wikipedia , lookup
Transcript
Cell Structure & Function http://koning.ecsu.ctstateu.edu/cell/cell.html Learning Targets I can… - Discuss the parts of the Cell Theory - Explain the function of the nucleus - Explain the function of the cell membrane Discovery of the Cell • Mid-1600s scientists began using microscopes to observe living things • 1665, Robert Hooke looked at cork with early compound microscope • Thousands of tiny empty chambers called “cells” • 1674 Anton van Leeuwenhoek used singlelens scope to look at pond water • What did he see? The Cell Theory • More observations confirmed that CELLS were the basic units of life • 1838, Matthias Schleiden-all plants made of cells (pg. 170, Fig. 7-2) • 1839, Theodore Schwann, all animals made of cells • 1855, Rudolf Virchow, new cells produced only from division of existing cells Discoveries Summarized in The Cell Theory 1. All living things are made up of cells 2. Cells are the smallest working units of all living things. 3. All cells come from preexisting cells through process of cell division. Definition of Cell A cell is the smallest unit that is capable of performing life functions. Exploring the Cell • • • • • • • Fluorescent labels Light microscopy Confocal light microscopy High-resolution video technology TEM SEM Scanning probe microscope Examples of Cells amoeba Plant Bacteria Nerve cell Red Blood cell Definition of Cell A cell is the smallest unit that is capable of performing life functions. Cells are composed of … • key chemical elements -carbon -hydrogen -oxygen -nitrogen -phosphorus -sulfur Cells carry out life functions • • • • • Grow/reproduce Homeostasis Energy transformation Dispose of wastes Make new molecules Two Categories of Cells •Prokaryotic •Eukaryotic Prokaryotic • One-celled organisms, EX: bacteria • Smaller/simpler (some exceptions) • Few internal structures • No nucleus for DNA • Carry out all life funtions -grow -reproduce -respond to environment Eukaryotic • • • • Contain organelles surrounded by membranes Most living organisms are eukaryotic DNA contained in nucleus Bigger and more variety “Typical” Animal Cell “Typical” Plant Cell 7.2 Eukaryotic Cell Structure • The eukaryotic cell is like a factory • Many structures in the cell act like specialized organs…ORGANELLES • Eukaryotic cell divided into 2 parts: 1. nucleus 2. cytoplasm (outside the nucleus) They work together Nucleus • Control center of cell, “main office, boss” • Contains nearly all the cell’s DNA and coded instructions for making proteins and other important molecules • Surrounded by nuclear envelope (made up of 2 membranes) • Membrane separates it from cytoplasm • Nuclear pores so material can move in and out of nucleus (ex. Proteins, RNA) Nucleus (cont.) • Chromatin- granular material made of DNA bound to protein • Most of time it is spread throughout nucleus • During division it condenses and forms CHROMOSOMES (threadlike, contain genetic info that’s passed to next generation) Nucleolus • Inside nucleus • Contains RNA to build proteins • ribosome assembly begins Nuclear Membrane (envelope) • Surrounds nucleus • Made of TWO layers • Openings allow material to enter and leave nucleus Ribosomes • **PROTEINS are put together on the ribosomes (cell is “protein-making machine”) • Small particles of RNA and protein found throughout the cytoplasm • They follow coded instructions from the nucleus • Many ribosomes in cells which are active in protein synthesis • Free ribosomes can make proteins Just a reminder… • • • • • • Proteins are macromolecules They contain N, C, H, O They are made up of amino acids Some control rate of reactions Some regulate cell processes Some carry substances into/out of cells • Some help fight disease Endoplasmic Reticulum, ER • Moves materials around in cell (transportation) • Smooth type: no ribosomes • Rough type (pictured): ribosomes embedded in surface (involved in making proteins) ER (cont.) • Lipid components of the cell membrane are assembled • Proteins and other materials exported from cell are also assembled here • New proteins leave the ribosomes • Some are inserted into the rough ER and are chemically modified Smooth ER • No ribosomes on surface • Can hold collections of enzymes that carry out certain jobs: -synthesis of membrane lipids -detox of drugs **liver cells contain a lot of smooth ER Golgi Apparatus • Protein “packaging plant” • Move materials within the cell • Move materials out of the cell • Receives the proteins produced in rough ER Golgi Apparatus (cont.) Modifies, sorts, and packages proteins and other materials from the ER for storage in the cell or secretion out of cell “customization shop”, finishing touches are put on proteins before they are “shipped” to other places in or outside the cell Material for membranes of the cell is packaged and distributed by Golgi Lysosomes are products of the Golgi Lysosomes • “Digestive plant” for proteins, lipids, and carbohydrates • Filled with enzymes • Transports undigested material to cell membrane for removal • Cell breaks down if lysosome explodes Lysosomes (cont.) • Clean-up crew • They remove junk (organelles that are no longer useful) • Tay-Sachs disease and lysosomes not working properly • Paramecia digest food by surrounding it in a vacuole. Lysosomes fuse with vacuole and release acids Vacuoles • Sac-like structures, storage area • Store water, salts, proteins, CHOs • Plants can have one large Central Vacuole filled with liquid • Allows plants to support leaves, flowers • Contractile vacuole in paramecium pumps water out of cell (homeostasis) Mitochondria • Convert the chemical energy stored in food into compounds that the cell can use “Powerhouse of the cell” • Most of the chemical reactions involved in cellular respiration happen in the mitochondria • The inner membrane folds are where chem. rxns. happen • Folding increases the surface area inside the mitochondria which allows the small organelle to do as much work as possible. Chloroplasts • Found in plant cells • Capture the energy from sunlight and convert it into chemical energy during photosynthesis • “Solar power plants” • Inside are large stacks of other membranes, which contain the green pigment chlorophyll. Cytoskeleton • Network of protein filaments • Give structure and support, maintain shape of cell • Movement cytoskeleton microfilaments microtubules Microfilaments • Threadlike • Made of actin • Tough, flexible framework that gives support • movement Microtubules Hollow, made of proteins Maintain cell shape In cell division, they form a mitotic spindle which helps separate chromosomes In animal cells, form centrioles that help organize cell division Centrioles are NOT found in plant cells Microtubules (cont.) •Help build cilia and flagella •Enable cells to swim through liquids •Like oars of a boat Surrounding the Cell Cell Membrane • Outer membrane of cell that controls movement in and out of cell • nearly all cell membranes made of double-layered sheet called a lipid bilayer • flexible structure and strong barrier between the cell and its surroundings. Cell Membrane (cont.) • two layers of lipids • protein molecules embedded in the lipid bilayer • Carbohydrate molecules attached to many of the proteins • Structure of cell membrane Osmotic Pressure • Cells need a way to balance the intake and loss of water • Osmosis exerts a pressure (osmotic pressure) on the hypertonic side of a selectively permeable membrane • Osmotic pressure can cause serious problems for a cell. Functions of proteins and CHOs • Some of the proteins form channels and pumps that help to move material across the cell membrane • Many of the CHOs act like chemical identification cards and allow individual cells to identify each another Cell Wall • provide support and protection for the cell. • plants, algae, fungi, and many prokaryotes • outside the cell membrane • porous enough to allow water, oxygen, carbon dioxide, and certain other substances to pass through easily. Cell Wall (cont.) • made from fibers of carbohydrate and protein • Plant cell walls are composed mostly of cellulose (a tough CHO fiber) • Wood and paper (cellulose) Diffusion • Particles move from high concentration to low concentration • Equilibrium- when the concentration of the solute is the same throughout a system • diffusion depends on random particle movements, so substances diffuse across membranes without using energy living cells exist in a liquid environment (adult body=50-65% water) One of the most important functions of the cell membraneregulate movement of dissolved molecules on one side of the membrane to the other side • If a substance can diffuse across a membrane, the membrane is permeable • Impermeable to substances that cannot cross it • Most biological membranes are selectively permeable • Cytoplasm contains a solution of different substances in water • A solution is a mixture of two or more substances • Solute is dissolved in solvent • The concentration of a solution = mass of solute in a given volume of solution (mass/volume) • Ex. 12 g of salt dissolved in 3 liters of water Osmosis • Osmosis is the diffusion of water through a selectively permeable membrane • cells contain salts, sugars, proteins, and other molecules making them hypertonic to fresh water • Osmotic pressure produces a net movement of water into a typical cell that is surrounded by fresh water • If that happens, volume of a cell will increase until the cell becomes swollen…eventually, the cell may burst • Most cells in large organisms do not come in contact with fresh water • Cells are in fluids like blood that are isotonic • Isotonic fluids have concentrations of dissolved materials roughly equal to those in the cells themselves • plant cells and bacteria do come into contact with fresh water but have tough cell walls • Cell walls prevent the cells from expanding • Increased osmotic pressure makes the cells more likely to experience injuries to their cell walls Facilitated Diffusion • cell membranes have protein channels • make it easy for certain molecules to cross the membrane • Red blood cells have a cell membrane protein with an internal channel that allows only glucose to pass through it • It facilitates, or helps, the diffusion of glucose across the membrane -facilitated diffusion Active Transport • Requires energy to move cells against a concentration gradient • Small molecules, ions can be moved using transport proteins or pumps in the membrane • Larger molecules can be moved across membrane by endocytosis and exocytosis Molecular Transport • Ca, K, Na moved across membrane by proteins that act like pumps Endo/Exocytosis • Larger molecules, solid clumps of material • Endocytosis-materials taken into the cell by infoldings, pockets, of cell membrane Phagocytosis • “cell eating” • Extensions of cytoplasm surround particle and package it in a food vacuole • Cell engulfs it • Ex. Amoebas • Uses a lot of energy Pinocytosis • Cells take up liquid from environment • Pockets form along cell membrane and fill with liquid • Then pinch off and form vacuoles in the cell Exocytosis • Release material from the cell • Membrane of vacuole surrounding the material fuses with the cell membrane and forces contents out of cell • Ex. Contractile vacuole removes water 7.4 Diversity of Cellular Life • Multicellular-organisms made up of many cells • all multicellular organisms depend on communication and cooperation among specialized cells • Cells within an organism can develop in different ways to perform different tasks in a process called cell specialization Specialized Animal Cells • Red blood cells-specialized to transport oxygen • contain a protein that binds to oxygen in the lungs and transports the oxygen throughout the body where it is released • Cells specialized to produce proteins are found in the pancreas • Pancreas- a gland that produces enzymes that make it possible to digest food • Pancreatic cells are packed with ribosomes and rough ER • Pancreatic cells also have a well-developed Golgi apparatus and clusters of storage vacuoles loaded with enzymes • human ability to move is due to specialized structures of muscle cells • They generate force by using an overdeveloped cytoskeleton • Skeletal muscle cells are packed with fibers arranged in a tight, regular pattern • The fibers are actin microfilaments and a cytoskeletal protein called myosin Specialized Plant Cells • exchange carbon dioxide, oxygen, water vapor, and other gases through tiny openingsstomata (on the undersides of leaves) • Specialized cells called guard cells regulate the exchange • Guard cells monitor the plant's internal conditions and change their shape according to the conditions • When the plant can benefit from gas exchange, the stomata open • The stomata close tightly when the plant's internal conditions change Levels of Organization • in a multicellular organism individual cells tissues organs organ systems. • Similar cells are grouped into units called tissues • Tissue is a group of similar cells that perform a certain function • The collection of cells that produce digestive enzymes in the pancreas makes up one kind of tissue • Most animals have four main types of tissue: muscle, epithelial, nervous, and connective tissue • Many groups of tissues work together as an organ • Each muscle in your body is an individual organ • Within a muscle there are nerve tissues and connective tissues • Each type of tissue performs an important task to help the organ function • A group of organs that work together to perform a specific function is called an organ system • Example: Digestive system • Muscle cells make up smooth muscle tissue and along with other tissues makes up the stomach (organ). The stomach is part of digestive system (organ system) pg. 193 Inside the Cell Chromosomes • In nucleus • Made of DNA • Contain instructions for traits & characteristics http://library.thinkquest.org/12413/structures.html Cytoplasm • Gel-like mixture • Surrounded by cell membrane • Contains hereditary material Mitochondria • Produces energy through chemical reactions – breaking down fats & carbohydrates • Controls level of water and other materials in cell • Recycles and decomposes proteins, fats, and carbohydrates http://library.thinkquest.org/12413/structures.html Vacuoles • Membrane-bound sacs for storage, digestion, and waste removal • Contains water solution • Help plants maintain shape http://library.thinkquest.org/12413/structures.html Chloroplast • Usually found in plant cells • Contains green chlorophyll • Where photosynthesis takes place http://library.thinkquest.org/12413/structures.html