Chapter 5 The Working Cell

Fireflies use ___________ to send signals to potential mates Intro: Cool “Fires” Attract Mates and Meals Fireflies use ___________ to send signals to potential mates Instead of using _________ signals like most other insects The light comes from a set of chemical reactions, that occur in light-producing organs at the rear of the insect.

Energy is the _________________________________ ENERGY AND THE CELL Energy is the _________________________________ All organisms require ___________ ! (“ability to obtain and use energy” was a defining characteristic of living things!) What is Energy?

___________ energy is the energy of motion ___________energy is stored energy, which can be converted to kinetic energy. Rollercoaster animation Figure 5.1A–C

Two laws govern energy transformations ___________________ : the study of energy transformations The _______ Law of Thermodynamics Energy can be changed from ______________________________, but energy ________ be ___________ or ____________. Figure 5.2A

Energy for cellular work The _____________ Law of Thermodynamics Energy transformations ___________ __________or entropy, and some _________________ __________________ Heat Chemical reactions Carbon dioxide Glucose + + ATP ATP water Oxygen Figure 5.2B Energy for cellular work

Chemical reactions either _________ or ___________ energy

______________ reactions - ________________ and yield products rich in _________ energy. Potential energy of molecules Reactants Energy required Products Amount of energy required Figure 5.3A

______________ reactions - _________ energy and yield products that contain _______ ____________ energy than their _____________ Reactants Energy released Products Amount of energy released Potential energy of molecules Figure 5.3B

__________________ - Uses _____________ reactions to fuel ____________ reactions. This is how cells carry out thousands of chemical reactions! (cellular metabolism) Endergonic and exergonic

Currency of the cells Energy is like a __________ __________ , with ________ being the “currency” for the cells. You either save $ or you withdraw $! You cells can either _________ (save $) _________ by ________ bonds OR __________ (withdraw $) __________ by __________ bonds! Can only do one or the other at any given time!

________ (adenosine triphosphate) powers nearly all forms of _________ __________ The energy in an ATP molecule lies in the _________ between its __________ groups. Phosphate groups ATP Energy P Hydrolysis Adenine Ribose H2O Adenosine diphosphate Adenosine Triphosphate + ADP Figure 5.4A

____________ a phosphate; breaks the bond = __________ of energy. ________________ = adding a _________ group to make molecules more reactive by _________ energy. ATP Chemical work Mechanical work Transport work P Molecule formed Protein moved Solute transported ADP + Product Reactants Motor protein Membrane protein Solute ____________ a phosphate; breaks the bond = __________ of energy. ______ a phosphate; builds a bond = _________________ energy. Animation Figure 5.4B

Cellular work can be sustained because ATP is a ___________ resource that cells constantly ___________________! ATP ADP + P Energy for endergonic reactions Energy from exergonic reactions Phosphorylation Hydrolysis Figure 5.4C

HOW ENZYMES FUNCTION Enzymes __________ ______ the cell’s chemical reactions by _______________________________________ For a chemical reaction to begin reactants must absorb some energy, called the _______________________________________ (energy needed to get the reaction going) EA barrier Reactants Products 1 2 Enzyme Figure 5.5A

Progress of the reaction A ___________ speeds up a reaction, by ___________ the energy of _________ needed to _______ a reaction. Reactants EA without enzyme EA with enzyme Net change in energy Products Energy Progress of the reaction Figure 5.5B

THEREFORE, ALL ____________ are catalysts!

An enzymes _______________ ________ determines which chemical reactions it will catalyze. 1 Enzyme available with empty active site Active site Substrate (sucrose) 2 Substrate binds to enzyme with induced fit Enzyme (sucrase) Glucose Fructose H2O 4 Products are released 3 Substrate is converted to products Animation 2 Animation 1 Figure 5.6

How?? What affects enzyme activity?? ___________________ , ___________ concentration, and ________ influence enzyme activity and can affect its function. How?? Some enzymes require nonprotein cofactors such as metal ions or organic molecules called ______________. Ex. _________________

Normal binding of substrate Enzyme _________ can ________ enzyme action _________________ inhibitors- take the place of a substrate in the active site ____________ inhibitors alters an enzyme’s function by changing its shape Substrate Enzyme Active site Normal binding of substrate Enzyme inhibition Noncompetitive inhibitor Competitive inhibitor Many poisons, pesticides, and drugs are enzyme inhibitors. Figure 5.8

Phospholipids have a _________ head and 2 __________ tails. The plasma membrane of the cell is ________________ ____________ controlling the flow of substances into or out of the cell Phospholipids have a _________ head and 2 __________ tails. Phospholipid bilayer, with the heads facing outward and the tails facing inward CH2 CH3 CH N + O O– P C Phosphate group Symbol Hydrophilic head Hydrophobic tails Water Hydrophilic heads Hydrophobic tails Figure 5.11A

A membrane is a ________________ with ___________ , _________ and _________________ embedded in a phospholipid bilayer or along each side. Fibers of the extracellular matrix Carbohydrate (of glycoprotein) Glycoprotein Microfilaments Phospholipid Cholesterol Proteins Plasma membrane Glycolipid Cytoplasm Figure 5.12

Membrane proteins can function as: ____________ - they help speed up chemical reactions for the cell. ____________ – bind and transmit chemical messages from other cells _____________- moving substances across the membrane ATP Messenger molecule Receptor Activated molecule Receptor site animation Figure 5.13A

TYPES OF TRANSPORT ACROSS A MEMBRANE

NO ENERGY REQUIRED! 1) __________ transport- substances diffuse through membranes _____________________ ; spread from areas of __________ concentration to areas of ________ concentration Small nonpolar molecules such as O2 and CO2 Diffuse easily across the phospholipid bilayer of a membrane (Diffusion animation) Equilibrium Membrane Molecules of dye Figure 5.14A Figure 5.14B

Many kinds of molecules DO NOT diffuse freely across membranes NO ENERGY REQUIRED! Many kinds of molecules DO NOT diffuse freely across membranes For these molecules, transport proteins MUST provide passage across membranes through a process called _______________ __________. Solute molecule Transport protein Facilitated diffusion animation Figure 5.15

NO ENERGY REQUIRED! ____________ is the diffusion of ______________ across a membrane In osmosis water travels from a solution of _________ _____________ concentration to one of __________ ________ concentration (higher water conc. to lower water conc.) Lower concentration of solute Higher concentration of solute Equal concentration of solute H2O Solute molecule Selectively permeable membrane Water molecule Solute molecule with cluster of water molecules Net flow of water Osmosis animation Figure 5.16

Shrink in _________________ solutions The control of water balance is called __________________ Shrink in _________________ solutions Swell in ________________ solutions Equal movement of particles in _____________ solutions (Animal cells are normal, but plant cells are limp) Plant cell H2O Plasma membrane (1) Normal (2) Lysed (3) Shriveled (4) Flaccid (5) Turgid (6) Shriveled (plasmolyzed) Isotonic solution Hypotonic solution Hypertonic solution Animal cell . Figure 5.17

Active transport- ENERGY REQUIRED! __________ ___________ can move solutes _______ a concentration gradient through active transport, which requires ________ (One example of active transport is the sodium-potassium pump used in nerve impulses) P Protein changes shape Phosphate detaches ATP ADP Solute Transport protein Solute binding 1 Phosphorylation 2 Transport 3 Protein reversion 4 Figure 5.18

ENERGY REQUIRED! To move large molecules or particles through a membrane, a vesicle may fuse with the membrane and expel its contents (_________________) Membranes may fold inward enclosing material from the outside (_________________) Fluid outside cell Cytoplasm Protein Vesicle Vesicle forming Figure 5.19A

Endocytosis can occur in 3 ways: ________________– cellular eating (animation) _______________ – cellular drinking Receptor-mediated endocytosis Pseudopodium of amoeba Food being ingested Phagocytosis Pinocytosis Receptor-mediated endocytosis Material bound to receptor proteins PIT Cytoplasm Plasma membrane TEM 54,000 TEM 96,500  LM 230 Figure 5.19C

Enzymes are central to the processes that make energy available to the cell __________- carry out photosynthesis using solar energy to produce glucose and oxygen from carbon dioxide and water _____________ - consume oxygen in cellular respiration, using the energy stored in glucose to make ATP. Overview animation (We’ll go. into more detail on each process in the upcoming chapters!)