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130 Cards in this Set
- Front
- Back
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proteins have direction orientation. Explain the two protein terminals
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N terminus is outside the cell - ECM
C terminus is inside the cell - cytoplasm c for cyto |
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where is the plasma membrane built?
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Endoplasmic Reticulum
Golgi Complex |
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what type of molecules dissolve in Pl. Mem.
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non-polar molecules
CO2 O2 hydrocarbons |
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how do polar and ionic substances pass through pl. mem.
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using transport proteins
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name the transport channel for water
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aquaporins
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describe a carrier protein
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transport protein
"holds" onto passenger changes shape to facilitate transport high specificity |
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explain osmosis
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diffusion -passive- of free water molecules across a permeable membrane
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most common form of passive transport
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Diffusion
down concentration gradient |
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explain a hypertonic environment
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there is more non-penetrating solute outside of the cell
causes cell to shrivel in a hypertonic solution |
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explain a hypotonic environment
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there is less non-penetrating solute outside the cell
causes cell to burst in hypotonic solution |
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what is Tugor pressure
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when a cell is Turgid - firm
cells swell with water by osmosis expansion is limited to force applied by cell wall |
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name two facilitated transport mechanisms. Are these active or passive
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channel proteins
carrier proteins |
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name two passive transport mechanisms
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diffusion
osmosis channel proteins carrier proteins |
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describe a channel protein
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passive - no E required
Protein forming an aqueous pore spanning the lipid bilayer of the cell membrane which when open allows certain solutes to traverse the membrane. Hydrophilic passage |
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describe a carrier protein
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proteins involved in the movement of ions, small molecules, or macromolecules, across a biological membrane
by facilitated diffusion or active transport specific to one type or family of molecules alternate between two shapes |
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define active transport
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Active transport is the movement of a substance across a MEMBRANE, AGAINST its concentration GRADIENT.
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define primary and secondary active transport
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the use of chemical energy, such as ATP is called primary active transport.
Secondary active transport involves the use of an electrochemical gradient, involves channel proteins as opposed to carrier proteins, and does not use energy produced in the cell. |
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Define electrochemical gradient and give the most common example
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An electrochemical gradient is a spatial variation of both ELECTRICAL POTENTIAL and chemical concentration across a membrane
Proton concentration - H+ Potential Energy |
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what happens if solvent can diffuse but solute cant?
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If water is the solvent, it will move by Osmosis TOWARDS the high SOLUTE concentration and therefor increase pressure
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define metabolism
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all of the chemical reaction, in a living organism, necessary to maintain life
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two facts of catabolism
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yields E
occurs spontaneously breaks down order |
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Three Energy carriers
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ATP
NADH NADPH |
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Three types of regulation
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Genetic
Allosteric Covalent Proteolytic activation |
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what structure lies inside transmembrane proteins and allows passage of polar molecules
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alpha helices
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6 functions of membrane proteins
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Transport
Emzymatic activety Signal Transduction = g protein-coupled Cell to Cell recognition = connexins Intercellular joining = desmosomes Attachment to Cytoskeleton and ECM = hemidesmosome |
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what ions have a high concentration outside of a mammal cell
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Na+
Cl- Ca++ |
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what ions have a high concentration inside of a mammal cell
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K+
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isotonic def
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adjusting internal SOLUTE concentrations to match that outside.
A form of osmo regulation |
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what is the tonicity of plant cell walls
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slightly hypertonic to outside
more solutes so solution move in by osmosis, give the cell rigidity and shape |
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what is an ion channel
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pore-forming proteins = present in biological membranes - that help establish and control the small voltage gradient across the plasma membrane of cells by allowing the flow of ions down their electrochemical gradient
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types of gates for ion channels?
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Voltage gated Na+ K+ Ca++
Ligand gated second messengers - from the inside of the cell membrane, rather as from outside |
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how do ligand gates work
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causes a CONFORMATIONAL change in the structure of the channel protein that ultimately leads to the OPENING of the channel GATE
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explain second messengers
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molecules that RELAY SIGNALS from receptors on the cell surface to target molecules INSIDE the cell
Greatly AMPLIFY the strength of the signal Are a component of signal transduction cascades. |
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what is the primary transfer ion in plants and animals and where is the concentration highest
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H+ in plants
Na+ in animals (3Na+ out, 2 K+ in) both outside both generate charge and concentration gradient - electrochemical |
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Voltage-gated ion channels
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are a class of transmembrane ion channels that are activated by changes in ELECTRICAL POTENTIAL DIFFERENCE near the channel; these types of ion channels are especially critical in neurons, but are common in many types of cells.
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explain a sodium potasium pump
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3 Na+ mplecules are pumped to the outside of the cell where concentrations are higher
At the same time 2 K= molc are pumped inside. The next change is to make the outside of the cell more positive |
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two forms of bulk transport
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exocytosis
endocytosis |
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exocytosis? give example
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A process by which the contents of a cell vacuole (transport vesicle) are released to the exterior through fusion of the vacuole membrane with the cell membrane.
budded from Golgi Neurons releasing neurotransmitters Carb deliver to outside of cell |
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delta G for cellular respiration
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-686 kcal/mol
spontaneous |
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shape of a free Pi
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HOPO3,2-
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delta G for ATP hydrolysis
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-7.3 kcal mol-1
spontaneous |
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Explain Ea in terms of spontaneous biological compounds
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Proteins, DNA and other complex molecules are rich in free E and have potential to decompose spontaneously. They don't make it over the Ea however without enzymes.
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what does dehydrogenase do
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removes a pair of H atoms and delivers 2 electrons and one H+ to the coenzyme NAD+
reduces NAD to reduce you need to de hygonen ate |
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why do NADH and FADH represent stored E
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because each electron can fall down an E gradient towards water
E released is coupled to H+ pumps |
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what is the amount of enery transfers from NADH to O2 (H2O)
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Delta G = -53 kcal / mol
exergonis spontaneous used to power H+ pumps |
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name four major steps of the e- transfer in respiration
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glucose
NADH ETC O2 make H20 |
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4 steps of respiration
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Glycolysis - produces Pyruvate
Pyruvate Oxidation - produces Acetyl CoA Citric acid cycle - produces 3 NADH and 1FADH ETC and Chemiosmosis pyruvate dehygrogenase complex |
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what levels is ATP produced
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Substate level phosphorylation
glycolysis & TCA Cycle oxidative phosphorlation ETC |
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name the enzyme that phosphorylates glucose
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hexokinase
hexagon = 6 Kinase = attaches Pi cost one ATP |
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name the enzyme that phosphorylates fructose
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phosphofructokinase
phospho= already has a Pi group Fructo= sugar Kinase= adds Pi Cost 1ATP |
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what steps of glycolysis does substate level phosphorylation occur?
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7 & 10
2ATP created at each step |
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where in glycolysis is NADH created, and by what?
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step 6
triosephosphate (3C sugar with a Pi) dehydrogenase (de hygogenates the sugar and attaches 2e- and H+ onto NAD+) 2 step process Uses E from Pi group on sugar |
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where during glycolysis does regulation occur and what is the type
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step 3
AMP stimulates glycolysis by binding to Phosophofructokinase Citrate or ATP inhibits when E is sufficient - allosteric control |
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name the second step in oxidative respiration
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Pyruvate Dehydrogenase Complex
3 enzymes, 3 reactants From cytosol to matrix Produces Acetyl CoA |
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explain substrate level phosphorylation
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results in the formation and creation of ATP or GTP
by the direct transfer and donation of a phosphoryl (PO3) group to ADP or GDP from a phosphorylated reactive intermediate. |
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Is Substrate-level phosphorylation endergonic
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No, its exogonic
creates ATP using phosphorylated substrate and an enzyme |
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Payoff from Citric acid cycle?
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3NADH
1FADH 1ATP per pyruvate molecule |
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Number of reactions in the Citric acid cycle?
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8 reactions
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explain chemiosmosis and where it occurs
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is the movement of ions across a selectively-permeable membrane, down their electrochemical gradient
ATP synthase is the enzyme that makes ATP by chemiosmosis |
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where are H+ pumped during oxidative phosphorylation
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ETC pumps H+ into IM space
ATP synthase uses this gradient to move H+ back into the Mcd matrix, creating ATP |
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three types of work?
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Movement
Transport chemical synthesis |
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how the E carriers differ
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ATP has charged triphosphate tail - high Ep
NADH, NADPH and FADH2 use elecron energy in the ETC |
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in a solution how many charges does ATP have
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four
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what is the natural reaction of ATP in water
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to hydrolyse, becoming ADP + Pi + Energy
-7.3 kcal/mol |
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different E results from ATP in vitro cf in vivo
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In vivo, its couple to endogonic reactions
In vitro the E is released as heat |
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explain phosphorylation
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E released from ATP hydrolysis is used to attach the released Pi group to another entity
covalently |
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beside phosphorylation, how does ATP promote reactions?
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It physically binds - non covalently -to proteins where it is later hydrolysed
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enzyme substate complex
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substrate binds with the enzyme active site, and an enzyme-substrate complex is formed. The substrate is transformed into one or more products, which are then released from the active site.
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what type of interaction hold substate to active site
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weak
ionic or H Bonds |
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4 ways enzymes catalyse reactions
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Orientate 2 substances to encourage reaction
Bind to rearrange e-'s in the substrate Strain the bound substrate Covalently bond with substrate |
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effect of Temp on reactions
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produces more collisions
if temp is too high it will denature the enzyme and reduce enzymatic activety |
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effect of pH on reactions
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will either protonate or deprotonate the enzyme
depending on optimal pH |
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what is a cofactor
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NON PROTEIN chemical compound that is bound to a PROTEIN & is required for the proteins biological transformations.
a side kick |
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2 groups of cofactors and examples
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Organic (coenzymes) such as vitamins or heme
Inorganic such as metail ions Mg++, Cu+, Mn++ |
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what are coenzymes
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organic cofactors
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2 types of inhibition and their properties
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Irreversible - bind covalently and often change the enzme chemically e.g.drugs like penecillin and nerve gas. Dangerous.
Reversible - competitive or non competitive |
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2 types reversible inhibition
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competitive - binds to ACTIVE site and blocks substrate
non competitive- binds elsewhere to effect substrate binding |
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allosteric REGULATION
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regulation of an enzyme or other protein by binding an EFFECTOR MOLECULE at the protein's allosteric site (that is, a site other than the protein's active site).
Effectors that enhance the protein's activity are referred to as allosteric activators, whereas those that decrease the protein's activity are called allosteric inhibitors. |
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enzyme that removes PO4 group
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phosphatase
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enzyme that attaches PO4 group
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Kinase
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how does nerve gas work
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Irreversible inhibition
prevents breakdown of neurotransmitters which prevents transmission of nerve impulses |
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2 types of metabolism regulation
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controlling whether or not a gene that encodes a protein gets transcribed
controlling enzyme activety |
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3 ways to control enzymes
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Allosteric regulation
covalent control Proteolytic activation |
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explain covalent control of enzymes
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phosphorylation
attachment of phosphate group activates or inactivates |
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explain Proteolytic activation
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inactive precursor enzymes are activated by hydrolysis of peptide bonds
Proenzymes or zymogens |
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what are RNA enzymes called
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Ribozymes
A few reactions can be catalysed by RNA molecules (nucleic acids) |
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explain induced fit
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when the substrate enters the active site the enzyme will change its shape slightly such that the active site will embrace the substrate.
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third type of ATP creation
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ATP PC
Phosphogen System |
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6O2 is _____ in cellular respiration
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Reduced, forming 6H2O
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what happens to Ep of an electron as it moves towards a more electronegative atom?
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electrons lose Ep
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what is produced during glycolysis
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2NADH
2ATP 2 Pyruvate |
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what produces just 1 NADH
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Pyruvate Dehydrogenate Complex
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What are the products of the citric acid cycle
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3NADH
1FADH2 1ATP from ADP CO2 |
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where do the 10 NADH that are used in the ETC come from
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2 from Glycolysis - triosephosphate dehydrogenase
2 from Pyruvate Dehydrogenase Complex 6 from TCA cycle |
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how many ATP are created in cellular respiration and where do they come from
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32 in total
Net 2 from Glycolysis - steps 7 & 10 substrate level phosphorylation 2 from TCA cycle - 1 per pyruvate - sub level phos. 28 from Oxidative Phosp. and the ETC |
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explain fermentation
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no O2 present
Involves Pyruvate NADH and ATP - all from Glycolysis ELECTRONS passed back from NADH to Pyruvate creating Lactate or Ethenol, Net 2 ATP and a Oxidised NAD+ which is recycled |
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name an 2 inhibitors of Glycolysis, where they come from and what they do
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Citrate
from TCA cycle ATP from Glycolysis/TCA Cycle or Oxidative Phosphorylation Inhibits Phosphofructokinase |
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name a stimulate of Glycolysis
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AMP
stimulates PhosphoFructoKinase Step 3 |
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Name two fats that are involved in Oxidative Phos. and where they enter the process
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Glycerol = enter during Glycolysis
Fatty acids = Enter at Pyruvate Dehydrogenase Complex |
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Where do amino acids enter cellular respiration and what is the waste product?
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Waste is NH2
Enter in Glycolysis, Pyruvate Dehydrogenase Complex and TCA Cycle |
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what do brown fat cells do?
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uncouple ETC from ATP synthase
Hybernation |
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how many ATP from Triacylglycerol
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300
broken down to Aceyle unit, which is equivalent to Acetyl CoA |
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why is the actual cost of ATP 4H=
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ATP needs to be exported to outside of the matrix and into the cytosol.
ADP needs to be moved into the matrix to be phosphorylated into ATP. Transport cost is net one H+ 3 to get ATP out and 2 to get ADP in |
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Name the enzyme that transports ATP out of, and ADP into the Mcd Matrix
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ATP/ADP Translocase
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describe the essential steps in light reaction
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Photon E is used to reduce NADP+ to NADPH
H2O is split to provide electrons for NADPH Some ATP is produced from cyclic and non cyclic phosphorylation |
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where do light reactions take place
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in the thylakiod membrane
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where does the calvin cycle take place
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in the stroma
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what is reduced during Photosynthesis
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6CO2 to C6H12O6
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what is oxidised during photosynthesis
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H2O to O2
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chlorophylls and carotenoids are examples of what
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antenna complexes
or light harvesting complexes |
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which photosystem contains the water splitting complex
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PS2
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four outcomes of an excited electron
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release heat
release light resonate E to neighbour these three involve electron falling to its ground state Transduction+ passing e- to and e- carrier |
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which part of photosynthesis releases O2
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when H2O is split to give P680 and electron, H2O is oxidised into O2 and release
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what photosystem has a P680 reaction center chlorophyll
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PS2
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two key pigments in PS2
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Reaction centre Chlorophyll
antenna (light harvesting) chlorophyll |
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what is Pq
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Plasoquinone
lipid soluble protein passes e- to Cytochrome complex |
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what is Pc
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Plastocyanin
receives e- from Cytochrome complex outside of membrane, in Thylakiod space |
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name of e- carrier to NADP+ Reductase
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ferredoxin
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name the 5 proteins involved in the ETC for plants
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Pq plastoquinone
Cytochrome complex Pc plastocyanin Fe Ferredoxin NADPH+ Reductase |
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where does NADPH+ get its H+ from
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The solution in the stroma
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name three e- carriers in plants and their relative places
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Pq plastoquinone is inside the membrane - lipid soluble
Pc is inside the Thylakiod space Fe Ferredoxin is in the stroma |
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where does the higher H+ concentation exist in plants?
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Inside the thylakiod space
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where are ATP created in plants
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In stroma
from pumping H=+ from thylakiod space to the strome |
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three stages of calvin cycle
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Carbon fixation: Rubisco fixes CO2 to Rubulose Bisphosphate
Reduction: NADPH and ATP (phosposylation) are used to reduce 6CO2 to C6H12O6 Regeneration: ATP needed to regenerate RuBP |
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decribe cyclic photophosphorylation
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Fe ferredoxin recycles e- back to cytochrome complex
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two effects of open stromata
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O2 out CO2 in
Lose H2O due to transpiration |
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what happens in alternative carbon fixing
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Stromata is closed so CO2 O2 ratio need to controlled for Rubisco
Using C4 pathways or CAM |
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explain CAM
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stromata close during day and open at night
CO2 fixation and calvin cycle SEPARATED FIXATION AT NIGHT |
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Explain C4 pathway
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higher CO2 to O2 ratio is acheived by fixing CO2 to PEP in Mesophyll
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delta G of photosynthesis
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-118kcal/mol
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