Chapter 4 Chapter 5, Chapter 6
Terms in this set (74)
ability to do work
stored energy that (if harvested) is available to do work
actual energy used to perform an action (work)
chemical reax. that need energy input, usually anabolic, and the products contain more potential energy than the reactants
chemical reax. that DO NOT need energy input (energy is released) usually catabolic, products have less potential energy than the reactants
when forward and reverse reax. are occurring at the same rate
driving force in a chemical reaction
the material or substance on which an enzyme acts
the part of an enzyme where substrates bind
substances that must be present for an enzyme to catalyze a chemical reax.
small organic non-protein molecules that carry chemical groups between enzymes
a chemical that dissolves in a solvent forming a solution
a chemical in which other substances dissolve, forming a solution
difference in concentration (solute in solvent) from one location to the next
the spontaneous mov't of a substance from a region of high concentration to low concentration
the simple diffusion of water across a selectively permeable mebrane
less solute on the outside of the cell than inside (burst)
more solute on outside than inside of cell (shrinking)
the force of water pressing against the cell wall
transport substance INTO cell
transport substance OUT of cell
What is the difference between an endergonic reax. and an exergonic reax?
Energonice reax. NEED energy while exergonic reax. DO NOT need energy (energy is released)
What happens when reactants in a chemical reax. accumulate? Also when products in a chemical reax. accumulate?
When reactants accumulate the reax. is more likely to go forward.
When products accumulate the reax. will proceed in reverse/go backwards.
Why does the "disappearance" of a product prevent chemical equilibrium?
Cells must remain far from chemical equilibrium for their metabolic processes to happen.This is done by preventing the accumulation of products. Products aren't allowed to accumulate since they are quickly consumed in another reaction.
The disappearance prevents this equilibrium which keeps the reactions moving in the appropriate direction.
How does ATP releases energy for a cell?
ATP hydrolysis releases energy. Removing the endmost P (phosphate) group of AT produces ADP and a free phosphate group.
The possible effects of using ATP as an energy source for phosphorylating another molecule are?
The presence of the phosphate may energize the target molecule, making it more likely to bond with other molecules is one effect.
A change in the shape of the target molecule is another possible effect.
How does negative feedback (feedback inhibition) regulate a metabolic pathway?
The product of a reaction inhibits the enzyme that controls its formation.
Describe noncompetitive inhibition
In noncompetitive inhibition, product molecules bind to the enzyme at a location other than the active sit, in a way that alters the enzyme's shape that it can no longer bind substrate.
Describe competitive inhibition.
Competitive inhibition the product of a reaction binds to the enzyme's active site, preventing it from binding substrate. It is "competitive" because the product competes with the substrate to occupy the active site.
Explain how positive feedback regulates a metabolic pathway.
A product activates the pathway leading to its own production.
List conditions that can affect enzyme activity or cause an enzyme to become non-functional.
a. pH concentration
b. Salt concentration
d. Pharmaceutical drugs
Explain what is meant by the phrase "moving down" or "following" the concentration gradient
The moving from a high to a low concentration (does not require energy)
Describe passive transport and recognize examples of it.
Passive transport requires no energy (ATP) to transport molecule across the cell membrane.
Describe active transport across a cell membrane and recognize examples of it.
Active transport requires energy (ATP) to move molecule across the membrane.
List the forms of passive transport
Simple Diffusion (Osmosis)
Describe the difference between simple diffusion and facilitated diffusion
Both move molecules down its concentration gradient, but in facilitated diffusion transport protein is needed. Also facilitated diffusion moves molecules that are not semipermeable.
List the types of molecules that can cross a cell membrane by simple diffusion
Lipids and small nonpolar molecules (oxygen and carbon dioxide)
Explain how a cell can use simple diffusion to acquire essential substances (such as oxygen) or get rid of cellular wastes (such as carbon dioxide) (be sure to consider why equilibrium is not achieved)
The mitochondria consumes oxygen as soon as it diffuses into the cell, maintaining the oxygen gradient that drives diffusion.
Respiration produces carbon dioxide which diffuses out because its concentration always remains higher in the cell than outside.
Describe what happens to a cell placed in either a) an isotonic solution to the cell, b) a hypotonic solution compared to the cell or c) a hypertonic solution compared to the cell. Be sure to include information regarding what physically happens to the cell (does it shrink, does it swell) and why this physical change is observed (what is responsible for the cell shrinking or swelling?)
Isotonic - Cell maintains its shape, equal water coming in and out
Cell will swell, more water coming in than water going out
Cell will shrink, more water going out than coming in
The sodium-potassium pump is a membrane transport system that expels 3 Na+ ions out of the cell for each 2 K+ ions it brings into the cell. Explain why this pump requires energy (it is an example of an active transport mechanism)
Pump requires energy because it is moving both ions against the concentration gradient
List the function of vesicular transport
Endocytosis: transport substance into cell
Exocytosis: transport substance out of cell
Transcytosis:transport into, across, and then out of cell
Substance (vesicular) trafficking: transport from one area or organelle in cell to another
substrate level phosphorylation
occurs in the Krebs Cycle & Glycolysis, a high-energy "donor" molecule physically transfers a P group to ADP, forming ATP
occurs in Electron Transport Chain, H+ (protons) move down their gradient through ATP synthase channels back into the matrix, and ADP is phosphorylated to ATP
electrons from NADH produce pyruvate. This process regenerates NAD+ so that glycolysis can continue, but generates no additional ATP. Also this process does not require oxygen and uses glucose to start
ATP synthase enzyme
forms a channel in the membrane, releasing the protons and using their potential energy to add P to ADP. Also generates ATP in the light reactions of photosynthesis
occurs in the cytoplasm, and oxygen not required. Six carbon glucose splits into two 3 carbon pyruvates
This process harvests energy in two forms.
- First, some of the electrons from glucose are transferred to NADH
- Second, glycolysis generates two molecules of ATP
complete oxidation of glucose to carbon dioxide, also uses oxygen which then produces ATP
cellular respiration using an electron acceptor other than oxygen
oxidize the pyruvate and release carbon dioxide (CO2)
when organisms (often plants) convert the suns energy into food
Explain why no cell can survive without ATP (why is ATP essential to life)
It powers nearly every activity that requires energy input in the cell
List the 3 categories of pathways that generate ATP from food
Write the overall balanced equation of aerobic respiration
Glucose + oxygen→carbon dioxide + water + ATP
Explain how plants both produce (by photosynthesis) and consume (by aerobic respiration) oxygen in the process of generating energy and explain why we consider plants to be oxygen producers overall
Plants incorporate much of the remaining glucose into cellulose, starch, and other stored organic molecules
Plants are considered oxygen producers overall because more oxygen is produced by photosynthesis than the plant consumes in cellular respiration.
Explain how plants both consume (by photosynthesis) and produce (by aerobic respiration) carbon dioxide in the process of generating energy and explain why we consider plants to be carbon dioxide consumers overall
They absorb much more carbon dioxide in photosynthesis than they release in respiration, and they release more oxygen than they consume
Explain why there are multiple steps in the pathway of aerobic respiration rather than a single step (why doesn't the cell release all potential energy in glucose's chemical bonds in one step)?
One step would be too great of a release of energy and cell would be destroyed
List the 3 main processes of aerobic respiration
Electron Transport Chain
Explain why, organisms in domains Bacteria and Archaea; the enzymes of the Krebs Cycle are in the cytoplasm and the electron transport proteins are embedded in the cell membrane rather than the mitochondria
Domains Bacteria and Archaea are prokaryotic
List where glycolysis takes place
In the cytoplasm
List where (be specific) the Krebs cycle and the electron transport chain takes place in a eukaryotic cell mitochondria
The matrix of a mitochondria
Describe the pathway of glycolysis. Be sure to include what is required for the pathway to take place, as well is what is not required
Occurs in the cytoplasm; glucose is required for the pathway to take place. Does not require oxygen.
1st 5 steps devoted to activating glucose by adding phosphate to produce to 3 carbons called PGAL.
2nd 5 steps is devoted to extracting the energy & adding phosphate to ADP to get ATP/to make 2 pyruvate molecules
List the net products of the glycolysis pathway (how many total molecules of ATP are made for every glucose molecule that enters glycolysis minus how many molecules of ATP are consumed for every glucose molecule that enters glycolysis)
2 net ATP, also pyruvate to enter Krebs cycle and electron carrier molecules
Describe the Krebs cycle. Be sure to include what is required for the pathway to take place and what is produced from the pathway
Occurs in the matrix of the mitochondria in eukaryotes & cytoplasm in prokaryotes. Many electron carrier molecules are made (NADH + FADH2). Oxygen not required.
2 pyruvates are needed to start the pathway.
2 Acetyl CoA is produced from the first reaction
Describe the electron transport chain. Be sure to include what is required for the pathway and what is produced from the pathway
Occurs in eukaryotes mitochondria (inner membrane) and prokaryotes cell membrane. Requires oxygen and uses chemiosmotic phosphorylation.
Protein completes transport protons (H+) across inner membrane and will use energy in electron carrier molecules to do this because it is transporting against the concentration gradient.
Produces 34 ATP/A LOT of ATP
Compare the energy production of the 3 processes (glycolysis, Krebs cycle and electron transport chain) of aerobic respiration
Electron Transport Chain yields the most ATP. Krebs Cycle & Glycolysis yield a net of two ATP (separately yield this)
Describe how other sources of food, such as proteins and lipids, can enter into aerobic cellular respiration to generate energy
Proteins - broken down into amino acid polymers
Lipids/Fats - broken down into glycerol and fatty acids
Both proteins and lipids are broken down to acetyl CoA accompanied by production of limited ATP and NADH
Describe the difference between aerobic respiration and anaerobic respiration
Aerobic respiration requires oxygen while anaerobic respiration does not
Describe the difference between aerobic respiration and fermentation
Does not require oxygen and does not yield much ATP (only used short term)
Describe alcoholic fermentation.
Alcoholic fermentation first converts pyruvate to acetaldehyde and carbon dioxide, and then NADH reduces the acetaldehyde to produce NAD+ and ethanol.
Describe lactic acid fermentation.
Lactic acid fermentation occurs in a cell by it using NADH to reduce pyruvate, but the products are NAD+ and the three carbon compound lactic acid.