2 Phospholipids Phosphate head hydrophilic Fatty acid tails hydrophobic Arranged as a bilayer Phosphate attracted to water Fatty acid repelled by water Aaaah, one of those structure function examples
3 Arranged as a Phospholipid bilayer Serves as a cellular barrier / border polar hydrophilic heads sugar H 2 O salt nonpolar hydrophobic tails impermeable to polar molecules polar hydrophilic heads waste lipids
4 Membrane fat composition varies Fat composition affects flexibility membrane must be fluid & flexible about as fluid as thick salad oil % unsaturated fatty acids in phospholipids keep membrane less viscous cold-adapted organisms, like winter wheat increase % in autumn cholesterol in membrane
5 Cell membrane defines cell Cell membrane separates living cell from aqueous environment thin barrier = 8nm thick Controls traffic in & out of the cell allows some substances to cross more easily than others hydrophobic (nonpolar) vs. hydrophilic (polar)
6 Permeability to polar molecules? Membrane becomes semi-permeable via protein channels specific channels allow specific material across cell membrane inside cell H 2 O aa sugar NH 3 salt outside cell
7 Cell membrane is more than lipids Transmembrane proteins embedded in phospholipid bilayer create semi-permeabe channels lipid bilayer membrane protein channels in lipid bilyer membrane
8 Cell membrane must be more than lipids In 1972, S.J. Singer & G. Nicolson proposed that membrane proteins are inserted into the phospholipid bilayer It s like a fluid It s like a mosaic It s the Fluid Mosaic Model!
9 Membrane is a collage of proteins & other molecules embedded in the fluid matrix of the lipid bilayer Glycoprotein Extracellular fluid Glycolipid Phospholipids Peripheral protein Cholesterol Cytoplasm Transmembrane proteins Filaments of cytoskeleton 1972, S.J. Singer & G. Nicolson proposed Fluid Mosaic Model
10 Why are proteins the perfect molecule to build structures in the cell membrane?
11 Classes of amino acids What do these amino acids have in common? nonpolar & hydrophobic
12 Classes of amino acids What do these amino acids have in common? I like the polar ones the best! polar & hydrophilic
13 Proteins domains anchor molecule Within membrane nonpolar amino acids hydrophobic anchors protein into membrane On outer surfaces of membrane in fluid polar amino acids hydrophilic extend into extracellular fluid & into cytosol Polar areas of protein Nonpolar areas of protein
14 Examples Retinal chromophore H + H + NH 2 aquaporin = water channel in bacteria Porin monomer H 2 O H 2 O b-pleated sheets Bacterial outer membrane Nonpolar (hydrophobic) COOH a-helices in the cell membrane H + proton pump channel in photosynthetic bacteria function through conformational change = protein changes shape Cytoplasm
15 Many Functions of Membrane Proteins Outside Plasma membrane Channel Inside Transporter Enzyme activity Cell surface receptor Antigen Cell surface identity marker Cell adhesion Attachment to the cytoskeleton
16 Membrane Proteins Proteins determine membrane s specific functions cell membrane & organelle membranes each have unique collections of proteins Classes of membrane proteins: peripheral proteins loosely bound to surface of membrane ex: cell surface identity marker (antigens) integral proteins penetrate lipid bilayer, usually across whole membrane transmembrane protein ex: transport proteins channels, permeases (pumps)
17 Membrane carbohydrates- Oligosaccharides Play a key role in cell-cell recognition ability of a cell to distinguish one cell from another antigens important in organ & tissue development basis for rejection of foreign cells by immune system
18 The Role of Membrane Carbohydrates in Cell-Cell Recognition Cells recognize each other by binding to surface molecules, often containing carbohydrates, on the extracellular surface of the plasma membrane Membrane carbohydrates may be covalently bonded to lipids (forming glycolipids) or more commonly to proteins (forming glycoproteins) Carbohydrates on the external side of the plasma membrane vary among species, individuals, and even cell types in an 2011 Pearson Education, Inc.
19 Figure 7.11 HIV Receptor (CD4) Co-receptor (CCR5) Receptor (CD4) but no CCR5 Plasma membrane HIV can infect a cell that has CCR5 on its surface, as in most people. HIV cannot infect a cell lacking CCR5 on its surface, as in resistant individuals.
20 Synthesis and Sidedness of Membranes Membranes have distinct inside and outside faces The asymmetrical distribution of proteins, lipids, and associated carbohydrates in the plasma membrane is determined when the membrane is built by the ER and Golgi apparatus 2011 Pearson Education, Inc.
21 Movement across the Cell Membrane
22 Diffusion 2nd Law of Thermodynamics governs biological systems universe tends towards disorder (entropy) Diffusion movement from HIGH LOW concentration
23 Simple Diffusion Move from HIGH to LOW concentration passive transport molecules are usually small and hydrophobic no energy needed movement of water diffusion osmosis
24 Diffusion through phospholipid bilayer What molecules can get through directly? fats & other lipids inside cell NH 3 lipid salt What molecules can NOT get through directly? polar molecules H 2 O ions (charged) outside cell sugar aa H 2 O salts, ammonia large molecules starches, proteins
25 Facilitated Diffusion Diffusion through protein channels channels move specific molecules across cell membrane no energy needed open channel = fast transport HIGH facilitated = with help LOW The Bouncer
26 Active Transport Integral proteins exhibit a specificity for a particular type of molecule Cells may need to move molecules against concentration gradient conformational shape change transports solute from one side of membrane to other protein pump costs energy = ATP LOW conformational change ATP HIGH The Doorman
27 Active transport Many models & mechanisms The sodium-potassium pump is an electrogenic pump it contributes to the membrane potential (voltage). ATP ATP antiport symport
28 Getting through cell membrane Passive Transport Simple diffusion diffusion of nonpolar, hydrophobic molecules lipids HIGH LOW concentration gradient Facilitated transport diffusion of polar, hydrophilic molecules through a protein channel HIGH LOW concentration gradient Active transport diffusion against concentration gradient LOW HIGH uses a protein pump requires ATP ATP
29 Transport summary simple diffusion facilitated diffusion active transport ATP
30 How about large molecules? Moving large molecules into & out of cell through vesicles & vacuoles endocytosis phagocytosis = cellular eating pinocytosis = cellular drinking exocytosis exocytosis
31 Endocytosis phagocytosis fuse with lysosome for digestion pinocytosis non-specific process receptor-mediated endocytosis triggered by molecular signal
32 The Special Case of Water Movement of water across the cell membrane
33 Osmosis is just diffusion of water Water is very important to life, so we talk about water separately Diffusion of water from HIGH concentration of water to LOW concentration of water across a semi-permeable membrane
34 Concentration of water Direction of osmosis is determined by comparing total solute concentrations Hypertonic - more solute, less water Hypotonic - less solute, more water Isotonic - equal solute, equal water water hypotonic hypertonic net movement of water
35 Managing water balance Cell survival depends on balancing water uptake & loss freshwater balanced saltwater
36 1 Managing water balance Hypotonic ATP a cell in fresh water high concentration of water around cell problem: cell gains water, swells & can burst example: Paramecium ex: water continually enters Paramecium cell solution: contractile vacuole pumps water out of cell ATP plant cells turgid = full cell wall protects from bursting KABOOM! No problem, here freshwater
37 Pumping water out Contractile vacuole in Paramecium ATP
38 2 Managing water balance Hypertonic a cell in salt water low concentration of water around cell problem: cell loses water & can die example: shellfish solution: take up water or pump out salt plant cells plasmolysis = wilt can recover I m shrinking, I m shrinking! I will survive! saltwater
39 3 Managing water balance Isotonic animal cell immersed in mild salt solution no difference in concentration of water between cell & environment problem: none no net movement of water flows across membrane equally, in both directions cell in equilibrium volume of cell is stable example: blood cells in blood plasma slightly salty IV solution in hospital That s perfect! I could be better balanced
40 Aquaporins Water moves rapidly into & out of cells evidence that there were water channels protein channels allowing flow of water across cell membrane Peter Agre John Hopkins Roderick MacKinnon Rockefeller
41 Do you understand Osmosis.05 M.03 M Cell (compared to beaker) hypertonic or hypotonic Beaker (compared to cell) hypertonic or hypotonic Which way does the water flow? in or out of cell
42 Any Questions??
43 Ghosts of Lectures Past (storage)
44 Diffusion across cell membrane Cell membrane is the boundary between inside & outside separates cell from its environment Can it be an impenetrable boundary? NO! IN food carbohydrates sugars, proteins amino acids lipids salts, O 2, H 2 O IN OUT OUT waste ammonia salts CO 2 H 2 O products cell needs materials in & products or waste out
CH 7 Membranes Cellular Membranes Phospholipids are the most abundant lipid in the plasma membrane. Phospholipids are amphipathic molecules, containing hydrophobic and hydrophilic regions. The fluid mosaic
Membrane Structure and Function -plasma membrane acts as a barrier between cells and the surrounding. -plasma membrane is selective permeable -consist of lipids, proteins and carbohydrates -major lipids
thebiotutor AS Biology OCR Unit F211: Cells, Exchange & Transport Module 1.2 Cell Membranes Notes & Questions Andy Todd 1 Outline the roles of membranes within cells and at the surface of cells. The main
Unit 2: Cells, Membranes and Signaling CELL MEMBRANE Chapter 5 Hillis Textbook HOW DOES THE LAB RELATE TO THE NEXT CHAPTER? SURFACE AREA: the entire outer covering of a cell that enables materials pass.
CHAPTER 5.1 5.2: Plasma Membrane Structure 1. Describe the structure of a phospholipid molecule. Be sure to describe their behavior in relationship to water. 2. What happens when a collection of phospholipids
Name Period Concept 7.1 Cellular membranes are fluid mosaics of lipids and proteins 1. The large molecules of all living things fall into just four main classes. Name them. 2. Explain what is meant when
Cell Membrane Coloring Worksheet Composition of the Cell Membrane & Functions The cell membrane is also called the plasma membrane and is made of a phospholipid bilayer. The phospholipids have a hydrophilic
BSC 2010 - Exam I Lectures and Text Pages I. Intro to Biology (2-29) II. Chemistry of Life Chemistry review (30-46) Water (47-57) Carbon (58-67) Macromolecules (68-91) III. Cells and Membranes Cell structure
The Lipid Bilayer Is a Two-Dimensional Fluid The aqueous environment inside and outside a cell prevents membrane lipids from escaping from bilayer, but nothing stops these molecules from moving about and
Osmosis, Diffusion and Cell Transport Types of Transport There are 3 types of transport in cells: 1. Passive Transport: does not use the cell s energy in bringing materials in & out of the cell 2. Active
Modes of Membrane Transport Transmembrane Transport movement of small substances through a cellular membrane (plasma, ER, mitochondrial..) ions, fatty acids, H 2 O, monosaccharides, steroids, amino acids
AP * BIOLOGY CELL MEMBRANES, TRANSPORT, and COMMUNICATION Teacher Packet AP* is a trademark of the College Entrance Examination Board. The College Entrance Examination Board was not involved in the production
Cell Biology - Part 2 Membranes The organization of cells is made possible by membranes. Membranes isolate, partition, and compartmentalize cells. 1 Membranes isolate the inside of the cell from the outside
Homeostasis and Transport Module A Anchor 4 Key Concepts: - Buffers play an important role in maintaining homeostasis in organisms. - To maintain homeostasis, unicellular organisms grow, respond to the
4. Biology of the Cell Our primary focus in this chapter will be the plasma membrane and movement of materials across the plasma membrane. You should already be familiar with the basic structures and roles
Note: For the past several years, I ve been puzzling how to integrate new discoveries on the nature of water movement through cell membranes into Chapter 7. The Section below is a draft of my first efforts
BIOLOGICAL MEMBRANES: FUNCTIONS, STRUCTURES & TRANSPORT UNIVERSITY OF PNG SCHOOL OF MEDICINE AND HEALTH SCIENCES DISCIPLINE OF BIOCHEMISTRY AND MOLECULAR BIOLOGY BMLS II / B Pharm II / BDS II VJ Temple
PLASMA MEMBRANE 1. The plasma membrane is the outermost part of a cell. 2. The main component of the plasma membrane is phospholipids. FIGURE 2.18 A. The phosphate end of the molecule is polar (charged)
CHAPTER 2 GETTING IN & OUT OF CELLS PASSIVE TRANSPORT Cell membranes help organisms maintain homeostasis by controlling what substances may enter or leave cells. Some substances can cross the cell membrane
There have been many magnificent boats built to try to reach 50 knots. This was the creation of an Australian team that held the record for more than a decade, from 1993 till 2005, at 46.5 knots with their
DO NOT WRITE ON THIS TEST- USE ANSWER DOCUMENT AP Biology-Chapter #6 & 7 Review Multiple Choice Identify the choice that best completes the statement or answers the question. 1. All of the following are
Name: Period: CELL MEMBRANE & CELL TRANSPORT (PASSIVE and ACTIVE) Webquest PART I: CELL MEMBRANES WEBSITE #1: http://www.wisc-online.com/objects/index_tj.asp?objid=ap1101 1. What is the BASIC UNIT of LIFE?
Chapter 3 Cellular Structure and Function Worksheets (Opening image copyright by Sebastian Kaulitzki, 2010. Used under license from Shutterstock.com.) Lesson 3.1: Introduction to Cells Lesson 3.2: Cell
Transmembrane proteins span the bilayer α-helix transmembrane domain Hydrophobic R groups of a.a. interact with fatty acid chains Multiple transmembrane helices in one polypeptide Polar a.a. Hydrophilic
Keystone Review Practice Test Module A Cells and Cell Processes 1. Which characteristic is shared by all prokaryotes and eukaryotes? a. Ability to store hereditary information b. Use of organelles to control
Use the following graph to answer questions 1 and 2. Rate of diffusion of X into the cell 1. Which of the following processes is represented by the above graph? c. Active transport 2. Molecule X is most
Human Anatomy & Physiology I with Dr. Hubley Practice Exam 1 1. Which definition is the best definition of the term gross anatomy? a. The study of cells. b. The study of tissues. c. The study of structures
Bio 100 - Cells 1 Cell Structure and Function Tenets of Cell Theory 1. All living things are made up of one or more cells 2. Cells are the basic living units within organisms, and the chemical reactions
PART I: Neurons and the Nerve Impulse Identify each of the labeled structures of the neuron below. A. B. C. D. E. F. G. Identify each of the labeled structures of the neuron below. A. dendrites B. nucleus
Mammalian Physiology Cellular Membranes Membrane Transport UNLV 1 UNIVERSITY OF NEVADA LAS VEGAS PHYSIOLOGY, Chapter 1 Berne, Levy, Koeppen, Stanton Objectives Describe the structure of the cell membrane
Name: ate: 1. Which structure is outside the nucleus of a cell and contains N?. chromosome. gene. mitochondrion. vacuole 2. potato core was placed in a beaker of water as shown in the figure below. Which
Please print Full name clearly: Introduction BIOL 305L Laboratory Two Osmosis, because it is different in plants! Osmosis is the movement of solvent molecules through a selectively permeable membrane into
6 Membranes Concept Outline 6.1 Biological membranes are fluid layers of lipid. The Phospholipid Bilayer. Cells are encased by membranes composed of a bilayer of phospholipid. The Lipid Bilayer Is Fluid.
CHAPTER 8 MEMBRANE STRUCTURE AND FUNCTION OUTLINE I. Membrane models have evolved to fit new data: science as a process II. III. IV. A membrane is a fluid mosaic of lipids, proteins and carbohydrates A.
Lecture 4 Cell Membranes & Organelles Structure of Animal Cells The Phospholipid Structure Phospholipid structure Encases all living cells Its basic structure is represented by the fluidmosaic model Phospholipid
Membrane Structure, Transport, and Cell Junctions 5 A model for the structure of aquaporin. This protein, found in the plasma membrane of many cell types, such as red blood cells and plant cells, forms
Cell membranes and transport Content Fluid mosaic model of membrane structure Movement of substances into and out of cells Learning Objective: a. Describe and explain the fluid mosaic model of membrane
Chapter 5 THE FUNDAMENTAL UNIT OF LIFE Multiple Choice Questions 1. Which of the following can be made into crystal? (a) A Bacterium (b) An Amoeba (c) A Virus (d) A Sperm 2. A cell will swell up if (a)
Chapter Test A CHAPTER 7 Cellular Structure and Function Part A: Multiple Choice In the space at the left, write the letter of the term or phrase that best answers each question. 1. Which defines a cell?
UNIT 1: Biochemistry Chapter 2: Cell Structure and Function pg. 70-107 Organelles are internal structures that carry out specialized functions, interacting and complementing each other. Animal and plant
The Parts of the Cell 3 main parts in ALL cells: plasma membrane, cytoplasm, genetic material this is about the parts of a generic eukaryotic cell Plasma Membrane -is a fluid mosaic model membrane is fluid
7.2 Cell Structure Lesson Objectives Describe the structure and function of the cell nucleus. Describe the role of vacuoles, lysosomes, and the cytoskeleton. Identify the role of ribosomes, endoplasmic
Chapter 4: A Tour of the Cell 1. Cell Basics 2. Prokaryotic Cells 3. Eukaryotic Cells 1. Cell Basics Limits to Cell Size There are 2 main reasons why cells are so small: If cells get too large: 1) there
2007 7.013 Problem Set 1 KEY Due before 5 PM on FRIDAY, February 16, 2007. Turn answers in to the box outside of 68-120. PLEASE WRITE YOUR ANSWERS ON THIS PRINTOUT. 1. Where in a eukaryotic cell do you
Ions cannot cross membranes Membranes are lipid bilayers Nonpolar tails Polar head Fig 3-1 Because of the charged nature of ions, they cannot cross a lipid bilayer. The ion and its cloud of polarized water
BCOR 11 Exam 1, 2004 MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1. When applying the process of science, which of these is tested? a. an observation
Carbohydrates, proteins and lipids Chapter 3 MACROMOLECULES Macromolecules: polymers with molecular weights >1,000 Functional groups THE FOUR MACROMOLECULES IN LIFE Molecules in living organisms: proteins,
Connexions module: m46021 1 The Cell Membrane OpenStax College This work is produced by The Connexions Project and licensed under the Creative Commons Attribution License 3.0 By the end of this section,
http://www.bristol.ac.uk/phys-pharm/teaching/staffteaching/sergeykasparov.htmlpharm/teaching/staffteaching/sergeykasparov.html Physiology of the Cell Membrane Membrane proteins and their roles (channels,
Quick Hit Activity Using UIL Science Contests For Formative and Summative Assessments of Pre-AP and AP Biology Students Activity Title: Quick Hit Goal of Activity: To perform formative and summative assessments
ell Unit Practice Test #1 Name: ate: 1. Which organelle is primarily concerned with the conversion of potential energy of organic compounds into suitable form for immediate use by the cell?. mitochondria.
RAD 223 Radiography physiology Lecture Notes First lecture: Cell and Tissue Physiology: the word physiology derived from a Greek word for study of nature. It is the study of how the body and its part work
Name Period Concept 5.1 Macromolecules are polymers, built from monomers 1. The large molecules of all living things fall into just four main classes. Name them. 2. Circle the three classes that are called
Cells Structure, Function and Homeostasis Characteristics of Cells Basic unit of life anything alive is made of cells Plasma membrane (skin) that separates them from the environment. Skeletonsfor protection
Bio 100 Molecules of cells 1 Chapter 3 Molecules of Cells Compounds containing carbon are called organic compounds Molecules such as methane that are only composed of carbon and hydrogen are called hydrocarbons
Lab 4: Osmosis and Diffusion The plasma membrane enclosing every cell is the boundary that separates the cell from its external environment. It is not an impermeable barrier, but like all biological membranes,
CH 6 The Cell Microscopy Scientists use microscopes to visualize cells too small to see with the naked eye. In a light microscope (LM), visible light is passed through a specimen and then through glass
SECTION 4-1 REVIEW THE HISTORY OF CELL BIOLOGY Define the following terms. 1. cell 2. cell theory Write the correct letter in the blank. 1. One early piece of evidence supporting the cell theory was the
1. Membrane transport. A. (4 pts) What ion couples primary and secondary active transport in animal cells? What ion serves the same function in plant cells? Na+, H+ 2. (4 pts) What is the terminal electron
Protein Trafficking/Targeting (8.1) Lecture 8 Protein Trafficking/Targeting Protein targeting is necessary for proteins that are destined to work outside the cytoplasm. Protein targeting is more complex
Biology I Chapter 7 Interest Grabber NOTEBOOK #1 Are All Cells Alike? All living things are made up of cells. Some organisms are composed of only one cell. Other organisms are made up of many cells. 1.
Eukaryotes The Eukaryotic Cell Classwork 1. Identify two characteristics that are shared by all cells. 2. Suppose you are investigating a cell that contains a nucleus. Would you categorize this cell as
Cell Structure & Function! Chapter 3! The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka!' but 'That's funny.! -- Isaac Asimov Animal Cell Plant Cell Cell
The Structure and Function of Macromolecules: Carbohydrates, Lipids & Phospholipids The FOUR Classes of Large Biomolecules All living things are made up of four classes of large biological molecules: Carbohydrates
Organelles and Their Functions The study of cell organelles and their functions is a fascinating part of biology. The current article provides a brief description of the structure of organelles and their
Membranes What are the purposes of membranes? Physical barriers/compartmentalization Gatekeepers exclusion of toxic molecules Energy and signal transduction Aid in cell locomotion Cell-cell interactions
CELLS: PLANT CELLS 20 FEBRUARY 2013 Lesson Description In this lesson we will discuss the following: The Cell Theory Terminology Parts of Plant Cells: Organelles Difference between plant and animal cells
Week 1 EOC Review Cell Theory, Cell Structure, Cell Transport Benchmarks: SC.912.L.14.1 Describe the scientific theory of cells (cell theory) and relate the history of its discovery to the processes of
Background Bubbles make a great stand in for cell membranes. They re fluid, flexible, and can self-repair. Bubbles and cell membranes are alike because their parts are so similar. If you could zoom down
The Cell: Organelle Diagrams Fig 7-4. A prokaryotic cell. Lacking a true nucleus and the other membrane-enclosed organelles of the eukaryotic cell, the prokaryotic cell is much simpler in structure. Only
Biol 205 Exam 1 TEST FORM A Spring 2008 NAME Fill out both sides of the Scantron Sheet. On Side 2 be sure to indicate that you have TEST FORM A The answers to Part I should be placed on the SCANTRON SHEET.
BACKGROUND (continued) A cell must exchange materials with its surroundings, a process controlled by the plasma membrane. Plasma membranes are selectively permeable, regulating the cell s molecular traffic:
Biology Chapter 7 Practice Test Multiple Choice Write the letter that best answers the question or completes the statement on the line provided. 1. The work of Schleiden and Schwann can be summarized by
The Cell Interior and Function 5 5.0 CHAPTER PREVIEW Investigate and understand the organization and function of the cell interior. Deﬁne the differences between eukaryotic and prokaryotic cell structure.
The Molecules of Cells I. Introduction A. Most of the world s population cannot digest milk-based foods. 1. These people are lactose intolerant because they lack the enzyme lactase. 2. This illustrates
Cell Transport across the cell membrane Kathy Jardine and Brian Evans July 17, 2014 INFORMATION ABOUT THE LESSON Grade Level and Subject Area 10 (9-11): Biology Time Frame 4-45 min class periods Objectives:
CYTOLOGY Cytology Living organisms are made up of cells. Either PROKARYOTIC or EUKARYOTIC cells. A. two major cell types B. distinguished by structural organization See table on handout for differences.
CHAPTER 3 THE CHEMISTRY OF ORGANIC MOLECULES 3.1 Organic Molecules The chemistry of carbon accounts for the diversity of organic molecules found in living things. Carbon has six electrons, four of which
Introduction to the Cell: Plant and Animal Cells Tissues, Organs, and Systems of Living Things Cells, Cell Division, and Animal Systems and Plant Systems Cell Specialization Human Systems All organisms
Compartmentalization of the Cell Professor Alfred Cuschieri Department of Anatomy University of Malta Objectives By the end of this session the student should be able to: 1. Identify the different organelles