Chapter 5, 6, 7 Flashcards
Selective Permeability
Allows some substances to move across more easily than others
Amphipathic
Has both a hydrophobic region and hydrophilic region
Fluid Mosaic Model
Membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids
The membrane remains fluid at lower temperature if it is rich in _________
Phospholipids with unsaturated hydrocarbon tails
Kinks in the tails where the double bonds are located make it impossible to pack closely together
Integral Proteins
Penetrate the hydrophobic interior of the lipid bilayer.
Transmembrane Protein
Span the entire membrane
Peripheral Protein
Are not embedded in the lipid bilayer at all; they are loosely bound to the surface of the membrane.
6 major functions of membrane proteins
Transport Enzymatic Activity Signal Transduction Cell-Cell Recognition Intercellular Joining Attachment to the cytoskeleton and extracellular matrix
The Elephant Shits Cranberries In Alabama
Cell Cell Recognition
A cells ability to distinguish one type of neighboring cell from another
Glycolipids
Membrane carbohydrates that are short branched chains of fewer than 15 sugar units covalently bonded to lipids
Glycoproteins
Membrane carbohydrates bonded to proteins
Nonpolar molecules such as hydrocarbons, CO2, and O2 are _________and dissolve in the ___________ of the membrane and cross it easily.
Hydrophobic, lipid bilayer
Transport proteins
Span the membrane and aid in the movement of specific ions and polar molecules
Channel Proteins
Function by having a hydrophilic channel that certain molecules or atomic ions use as a tunnel
Aquaporins
A channel protein that facilitates the passage of water molecules through the plasma membrane of certain cells.
Carrier Proteins
Hold onto their passengers and change shape in a way that shuttles them across the membrane.
Passive transport
Diffusion of a substance across a membrane with no energy investment
Diffusion
The movement of particles of any substance so that they tend to spread out into the available space.
Osmosis
The diffusion of free water across a selectively permeable membrane
Tonicity
The ability of a surrounding solution to cause a cell to gain or lose water.
Isotonic Solution
No net movement of water across plasma membrane
Hypertonic
Cell shrivels as water leaves due to more no penetrating solute
Hypotonic
Water will enter the cell and bursts or lyse
Plant cells are ________ and generally healthiest in a __________environment
Turgid, hypotonic
Plants are flaccid in a ________ solution
Isotonic
Plants become _____________ in a hypertonic solution
Plasmolyzed
Plasmolysis- plasma membrane pulls away from cell wall.
Osmoregulation
The control of solute concentrations and water balance
Facilitated Diffusion
Passive diffusion with the help of transport proteins that span the membrane
Ion channels
Channel proteins that transport ions
Gated channels
Ion channels which open or close in response to a stimulus
Active transport
Expending energy to move something across membrane
Hydrophobic and small uncharged polar molecules can pass through the lipid bilayer through
Passive diffusion
Hydrophilic substances diffuse through membranes with the assistance of
Transport proteins, either channel or carrier proteins
Energy for active transport is usually supplied by
ATP
Membrane potential
Voltage across a membrane
Electrochemical gradient
The combination of electrical and chemical forces acting on an ion
Electrogenic pump
A transport protein that generates voltage across a membrane
Proton pump
The main electrogenic pump of plants, fungi, and bacteria
Cotransport
A transport protein can couple the downhill diffusion of a solution to the uphill transport is a second substance against its own concentration gradient
Exocytosis
The process in which the cell secretes certain biological molecules by the fusion of vesicles with the plasma membrane
Endocutosis
The process where a cell takes in molecules and particulate matter by forming new vesicles from the plasma membrane
3 types of endocytosis
Phagocytosis-cell engulfs a particle by extending pseudopodia around it and packaging it within a food vacuole
Pinocytosis-a cell continually gulps droplets of extracellular fluid into tiny vesicles
Receptor mediated endocytosis-specialized type of pinocytosis where specific substances are acquired
3 stages on the receiving cell
Reception
Transduction
Response
Ligand
A molecule that specifically bonds to another molecule
Plasma membrane is built by the
ER and Golgi apparatus
Two types of facilitated diffusion
Channel proteins and carrier proteins
Two types of channel proteins
Aquaporins and ion channels
Paracrine signaling
Local signaling in animal cells where messenger molecules are secreted by a signaling cell
Synaptic signaling
Consists of an electrical signal moving along a nerve cell that triggers secretion of neurotransmitter molecules
In long distance signaling, plants and animals use chemicals called
Hormones
Ligand binding generally causes a shape change in the
Receptor
Two types of membrane receptors
G protein coupled receptors
Ligand Gated ion channels
Examples of hydrophobic messengers
Steroid and thyroid hormones of animals and nitric oxide in both plants and animals
Protein Kinases
Transfer phosphates from ATP to protein in a process called phosphorylation
A signaling pathway involving phosphorylation and dephosphorylation can be referred to as a
Phosphorylation cascade
Metabolism
The totality of an organisms chemical reactions
A metabolic pathway begins with a specific ________ and ends with a ________
Molecule, product
Catabolic pathways
Release energy by breaking down complex molecules into simpler compounds
Example: cellular respiration
Anabolic pathways
Consume energy to build complex molecules from simpler onesies
Example:synthesis of proteins from amino acids
Bioenergetics
Study of how energy flows through living organisms
Heat is
Thermal energy in transfer from one object to another
Chemical energy
Potential energy available for release in a chemical reaction
Thermodynamics
Study of energy transformation
1st law of thermodynamics
Energy of the universe is constant and can be transferred but not created or destroyed
2nd law of thermodynamics
Every energy transfer increases the entropy, disorder, of the universe
For a process to occur spontaneously it must
Increase the entropy of the universe
A living systems free energy is
Energy that can do work when temperature and pressure are uniform as in a living cell
Change in free energy=
Gfinal-Ginitial
Only process with negative G are spontaneous
A process is spontaneous and can perform work only when it is moving towards
Equilibrium
Exergonic reaction
Proceeds with a net release of free energy and is spontaneous
Endergonic reaction
Absorbs free energy from surroundings and is non spontaneous
Cells are not in ___________: they are open systems experiencing a constant flow of materials
Equilibrium
Three main kinds of work a cell does
Chemical
Transport
Mechanical
Energy Coupling
The use of an exergonic process to drive an endergonic one
ATP is composed of
Ribose, adenine, and three phosphate groups
Bonds of the phosphate groups can be broken by
Hydrolysis-energy is released when the terminal phosphate bond is broken
Phosphorylated Intermediate
Recipient of a phosphate group
ATP hydrolysis leads to a change in a proteins __________ and often it’s ability to bond to another molecule
Shape
ATP is a renewable resource that is regenerated by the addition of a phosphate groups to
ADP
Catalyst
A chemical agent that speeds up a reaction without being consumed by the reaction
Enzyme
A catalytic protein
The initial energy needed to start a chemical reaction is called the
Activation energy
A catalyst can speed up a reaction by lowering the _________ without itself being consumed
Ea- enzymes do not affect the change in free energy
The reactant that an enzyme acts on is called the enzymes_______
Substrate
The enzyme binds to a substrate forming a
Enzyme substrate complex
The active site is the
Region on the enzyme where the substrate binds
Enzyme specificity results from the complementary fit between the shape of the enzymes active site and the shape of the
Substrate
The active site can lower an Ea barrier by:
Orienting substrate correctly
Straining substrate bonds
Providing a favorable micro environment
Covalently bonding to the substrate
When all enzyme molecules in a solution are bonded with substrate, the enzyme is
Saturated
At enzyme saturation, reaction speed can only be increased by adding more enzyme
Cofactors are
Non protein enzyme helpers, may be inorganic or organic
Example: most vitamins act as coenzymes
Organic cofactors is called
Coenzyme
Competitive Inhibitors
Bind to the active site of an enzyme, competing with the substrate
Noncompetitive Inhibitors
Bind to another part of an enzyme causing it to change shape and making the active site less effective
Allosteric Regulation
May either inhibit or stimulate an enzymes activity
Cooperativity
A form of allosteric regulation that can amplify enzyme activity
In feedback inhibition the end product of a metabolic pathway shuts down the
Pathway
Fermentation
Partial degradation of sugars that occurs without oxygen
Aerobic Respiration
Consumed organic molecules and oxygen and yields ATP
Chemical reactions that transfer electrons between reactants are called
Oxidation-reduction reactions
Oxidation
Substance loses electrons
Reduction
Substance gains electrons
Electron donor is called the
Reducing agent
The electron receptor is called the
Oxidizing agent
During cellular respiration _______ is oxidized and _______ is reduced
Fuel, oxygen
Stages of cellular respiration
Glycolysis
Pyrivate Oxidation and the Citric Acid Cycle
Oxidative Phosphorylation
Electrons are passed to increasingly ____________ carrier molecules down the chain through a series of redox reactions
Electronegative
Glycolysis
Breaks down glucose into two molecules of pyruvate in the cytosol
Pyruvate oxidation and the __________ completes the breakdown of of glucose in the mitochondrial matrix
Citric acid cycle
Oxidative phosphorylation
Accounts for most of the ATP synthesis and occurs in the inner membrane of the mitochondrion
Oxidative phosphorylation accounts for nearly _________ percent of ATP generated
90
A smaller amount of ATP is formed in glycolysis and the citric acid cycle by
Substrate level phosphorylation
For each molecule of glucose degraded to CO2 and water by respiration the cell makes up to ______ molecules of ATP
32
Glycolysis occurs in the
Cytoplasm
Net yield of Glycolysis is
2 ATP plus 2 NADH per glucose molecule
Glycolysis occurs whether or not _________ is present or not
Oxygen
Glucose uses ______ ATP I’m glucose energy investment phase
2
Before the citric acid cycle can begin, pyruvate must be converted to _______ which links glycolysis to the citric acid cycle
Coenzyme A (acetyl CoA)
The electron transport chain is located in the
Inner membrane of the mitochondria
Electrons are transferred from NADH or FADH2 to the
Electron transport chain
Electron transfer in the electron transport chain causes proteins to pump ________ from the mitochondrial matrix to the intermembrane space
H+
H+ then moves back across the membrane passing through the protein complex, ATP synthase
ATP synthase uses the exergonic flow of H+ to drive phosphorylation of ATP
Chemiosmosis
The use of energy in a H+ gradient to drive cellular work
The H+ gradient is referred to as a
Proton motive force
During cellular respiration, most energy flows in the following sequence
Glucose to NADH to electron transport chain to proton motive force to ATP
Without oxygen the __________ will cease to operate
Electron transport chain
In the absence of oxygen, glucose will couple with
Fermentation to produce ATP
Fermentation uses
Substrate level phosphorylation instead of electron transport chain to generate ATP
In alcohol fermentation
Pyruvate is converted to ethanol in two steps
Fermentation produces about _______ATP per glucose molecule
2
Facultative Anaerobes
Can survive using either ferment or respiration
Substrate level phosphorylation
Direct phosphorylation of ADP
Oxidative phosphorylation
When ATP is generated from the oxidation of NADH and FADH2
How many steps in Krebs cycle
8
Beta oxidation breaks down
Fatty acids
