Chapters 4 & 22partA Flashcards
There are 2 basic types of reactions in cells. By definition those that release energy are called what? Those that require the input of energy are called what?
exergonic reaction - releases energy
endergonic reaction - require the input of energy
Define kinetic energy.
energy of motion
Define potential energy.
stored energy (chemical bonds)
Nearly all enzymes are what type of molecule?
proteins
The location on an enzyme where the reactants (substrates) interact is called the what?
active site
Generally speaking can an enzyme catalyze a diversity of reactions or only catalyze 1 specific reaction?
1 specific reaction
When an ATP molecule is “used” to power a chemical reaction it is converted into: (list the products)
ATP —> ADP + Pi + energy
Define the term catabolism as it applies to metabolism.
Reactions that release energy through the breakdown of large biomolecules.
Define the term anabolism as it applies to metabolism.
Energy-utilizing reactions that result in the synthesis of large biomolecules.
Define metabolism as it applies to a person or a cell.
All chemical reactions that take place in an organism.
What do metabolic reactions do?
- Extract energy from nutrient biomolecules (such as proteins, carbohydrates, and lipids)
- Either synthesize or break down molecules.
Write out the complete chemical equation that describes the oxidation of glucose.
C6H12O6 + 6O2 —–> 6CO2 + 6H2O + 30ATP
List the starting substrate of glycolysis.
Starting substrate - glucose
Where in the cell does glycolysis take place? Is this and advantage or disadvantage?
Cytoplasm
Advantage because it’s fast since it is made where it is used.
What is the total net yield of ATP from glycolysis?
2 ATP
Is glycolysis an aerobic or anaerobic process?
Anaerobic because it does not require oxygen.
Describe the fate of pyruvate in a cell when oxygen levels are low. Be sure to include all the molecules involved (including the enzyme).
The pyruvate will be converted to lactate by the enzyme lactate dehydrogenase. It is then used by the myocardial cells and the liver. If it builds up it is exported to the blood which drops the pH. (acidosis)
Define anaerobic as it applies to cellular reactions.
A reaction that does not require oxygen
Glycolysis (all by itself) produces what? (include numbers)
2 pyruvate
What is the starting substrate of the citric acid cycle?
Acetyl CoA
How many ATP molecules are generated by “1 turn” of the citric acid cycle? What other molecules are generated (include numbers)
1 ATP
3 NADH
1 FADH2
Where exactly does the citric acid cycle occur?
in the mitochondria matrix
Where exactly does electron transport and oxidative phosphorylation take place?
mitochondria on innermembrane and intermembrane space
What powers the hydrogen pumps in electron transport? List the molecules.
high energy electrons from NADH and FADH2 to power hydrogen pumps.
The enzyme that actually produces ATP during oxidative phosphorylation is called what? For a glucose molecules about how many ATP does it produce?
ATP Synthase
For a glucose molecule it produces about 30 ATP
What is the fate of the electrons during electron transport?
each pair of electrons released combines with two H+ (hydrogen atom) and an O2 (oxygen atom) creating a molecule of water. H2O
2H + O2 + H2O
Where is oxygen used in electron transport?
final e- acceptor
Roughly how many ATP’s can be generated from a triglyceride?
about 300
Define glycolysis and list the specific substrates and products. Classify as either anabolic or catabolic.
glycolysis - the breakdown of glucose by enzymes, releasing energy and pyruvic acid.
Substrate - Glucose
Product - Pyruvate
Catabolic
Define gluconeogenesis and list the specific substrates and products. Classify as either anabolic or catabolic.
gluconeogenesis - the synthesis of glucose from noncarbonate sources, such as amino acids and glycerol.
Substrates - glycerol, pyruvate, amino acids, lactic acid
Product - glucose
Anabolic
Define ketogenesis and list the specific substrates and products. Classify as either anabolic or catabolic.
ketogenesis - formation of ketone bodies, an alternative energy source, from acetyl-CoA.
Substrates - acetyl-CoA
Product - Ketone bodies
Anabolic
Define beta-oxidation and list the specific substrates and products. Classify as either anabolic or catabolic.
beta-oxidation - breakdown of fatty acids to acetyl-CoA
Substrates - fatty acids
Product - acetyl-CoA
Catabolic
Define lipogenesis and list the specific substrates and products. Classify as either anabolic or catabolic.
lipogenesis - synthesis of fatty acids and triglycerides
Substrate - glucose
Product - triglycerides
Anabolic
Define lipolysis and list the specific substrates and products. Classify as either anabolic or catabolic.
lipolysis - the breakdown of triglycerides to fatty acids and glycerol.
Substrate - triglycerides
Product - fatty acids and glycerol
Catabolic
Define glycogenolysis and list the specific substrates and products. Classify as either anabolic or catabolic.
glycogenolysis - the breakdown of glycogen for glucose production.
Substrate - glycogen
Product - glucose
Catabolic
Define glycogenesis and list the specific substrates and products. Classify as either anabolic or catabolic.
glycogenesis - the conversion of glucose to glycogen for storage in the liver
Substrate - glucose
Product - glycogen
Anabolic
Which body cells/organs are especially good at lipogenesis?
liver and adipocytes
Which body cells/organs are especially good at glycogenesis?
liver and skeletal muscles
Define the “fed state”. Which metabolic pathways would be most active during this state? Describe the fate of carbohydrates, proteins, and lipids during the fed state.
The period of time following a meal, when the products of digestion are being absorbed, used, and stored. “Use it! Store it!”
glycolysis, glycogenesis, lipogenesis,
Fate: used or stored
Describe the 2 major ways that cells store “energy” for later. Be sure to describe the substrates and products of the metabolic pathways. (exclude ATP)
- Glucose is converted into glycogen for storage in the liver and skeletal muscles through glycogenesis
- Glucose is converted to triglycerides to be stored in adipocytes through lipogenesis
Define the “fasted state”. Which metabolic pathways would be most active during this state? Describe the fate of carbohydrates, proteins, and lipids during the fasted state.
The period once nutrients from a recent meal are no longer in the bloodstream and available for use by the tissues (about 12-14 hours past absorptive)
glycogenolysis, gluconeogenesis, lipolysis, beta-oxidation
Fate: Carbs = glucose, proteins = ATP, lipids = glycerol, fatty acids -> blood “moblize!”
Describe how amino acids are catabolized. How are they used for ATP synthesis?
First used to produce protein in cells,
Then for ATP production by either deamination in the liver or used to make glucose through gluconeogenesis
During the fasted state the liver has a number metabolic pathways that are active and CRITICAL to homeostasis. Describe each in detail. Be sure to list the substrates and products for each, and describe the importance each.
glucagon stimulates glycogenolysis and gluconeogenesis.
glycogenolysis - the breakdown of glycogen for glucose production. (Substrate - glycogen, Product - glucose)
gluconeogenesis - the synthesis of glucose from noncarbonate sources, such as amino acids and glycerol.
(Substrates - glycerol, pyruvate, amino acids, lactic acid; Product - glucose)
maintains plasma glucose homeostasis for the brain.
During the fasted state proteins can be used for energy. Where do these proteins come from?
Muscles
Explain what a very dark band means when interpreting the results of our gel electrophoresis experiment.
That protein is in abundance
Based on the results of our gel electrophoresis experiment, which proteins were most numerous?
Albumin
Where is albumin produced in the body - which cells/organ makes it?
the liver
Where are gamma globulins produced in the body - which cells makes it? Where are those cells found?
they are made in the lymphocytes and plasma cells of the immune system.
What are gamma globulins?
a protein fraction of blood rich in antibodies
Compared to other serum proteins comment on the size of gamma globulins.
they are the largest
If gamma globulins were apparent in our electrophoresis gel, where would they be located?
at the bottom
What exactly does a spectrophotometer measure?
concentrations of substances in solutions by measuring the amount of light that passes through it.
State Beers Law. Explain how this law is useful in a laboratory setting.
The amount of absorbed light is directly proportional to the molar concentration of the molecule(s) in solution.
*We can use absorbance to determine molar concentration of an unknown if we first measure the absorbance of a standard of known molar concentration.
Write out the complete chemical equation for the oxidation of glucose.
C6H12O6 + 6O2 —> 6CO2 + 6H2O + 30ATP
Define metabolism.
All chemical reactions in the body.
What does BMR stand for? Explain what BMR is.
Basal Metabolic Rate - The rate required for normal body maintenance at rest.
Describe two ways metabolic rate can be measured. Explain how each method estimates metabolic rate.
Directly by enclosing an animal or human in a chamber and measuring the heating of water, (MB = gram calories/hour/cm2) or by using an indirect method such as measuring the oxygen consumption of an animal or human in a closed container (4.8 gram calories of energy are released/ mL oxygen consumed).
Describe 4 ways that a person’s metabolic rate could be increased above BMR.
- activity
- digestion due to recently eating
- sickness
- temperature - hot
Describe 4 ways that a person’s metabolic rate could be decreased below BMR.
- sleeping
- fasting
- depressant drugs
- temperature - cold
The primary hormone (s) that determine BMR is/are what?
thyroxine (T4) and triiodothyronine (T3)
What was the effect of lowered body temperature on MR? Explain.
It lowers the metabolic rate because the kinetic energy is low so there are fewer collisions
Energy is defined as what?
The capacity to do work
The general term that describes energy stored in chemical bonds is what?
Potential energy
Chemical reactions in a living system function to do what?
transfer energy from one molecule to another or use energy stored in a molecule.
Describe three categories of work that require energy.
- Chemical work - making/breaking chemical bonds
- Transport work - moving molecules
- Mechanical work - movement of cilia (ex. muscle - actin/myosin heads)
Explain the first and second laws of thermodynamics and how they apply to the human body.
- First law of thermodynamics - (aka the law of conservation of energy) states that the total amount of energy in the universe is constant. This law explains human metabolism: the conversion of food into energy that is used by the body to perform activities.
- Second law of thermodynamics states that natural spontaneous processes move from a state of order to a condition of randomness or disorder, also known as entropy. This law explains how creating and maintaining order in an open system such as the body requires the input of energy.
Describe four common types of chemical reactions.
- combination (A+B=C)
- Decomposition (C=A+B)
- Single displacement (A+Bx=Ax+B)*
- Double displacement (Ax+My=Ay+Mx)*
* x and y represent atoms, ions, or chemical groups
Explain the relationships between free energy, activation energy, and endergonic and exergonic reactions.
Free energy - potential energy stored in the chemical bonds of a molecule
Activation energy - the initial input of energy required to bring reactants into a position that allows them to react with one another.
Endergonic reaction - reactions that require a net input of energy
Exergonic reaction - reaction that releases energy
Apply the concepts of free energy and activation energy to reversible and irreversible reactions.
the net free energy change of a reaction plays an important role in determining whether that reaction can be reversed, because the net free energy change of the forward reaction contributes to the activation energy of the reverse reaction.
Explain what enzymes are and how they facilitate biological reactions.
Enzymes are almost always proteins.
Enzymes have an active site where molecules interact and where the reaction takes place. They grab molecules that are bonded and bends them straining the bond so that the surrounding H2O doesn’t need as much Kinetic energy to seperate them.
How does the term isozyme apply to enzymes?
Isozymes are enzymes that catalyze the same reaction but under different conditions or in different tissues.
How does the term coenzyme apply to enzymes?
Organic cofactors for enzymes are called coenzymes.
How do the term proenzyme and zymogen apply to enzymes?
They are enzymes that are synthesized as inactive molecules and activated on demand by proteolytic activation.
How does the terms cofactor apply to enzymes?
They are “helper molecules” that assist in biochemical transformations.
Name and explain the four major categories of enzymatic reactions.
- Oxidation-Reduction reactions - Add or subtract electrons
- Hydrolysis-Dehydration reactions - Add or subract a water molecule
- Addition-Subtraction-Exchange reactions - Exchange groups between molecules
- ligation reactions - Join two substrates using energy from ATP
List five ways cells control the flow of molecules through metabolic pathways.
- by controlling enzyme concentrations
- by producing modulators that change reaction rates
- by using two different enzymes to catalyze reversible reactions
- By compartmentalizing enzymes within intercellular organelles
- by maintaining an optimum ratio of ATP to ADP.
Explain the roles of the following molecules in biological energy transfer and storage: ADP, ATP, NADH, FADH2, NADPH.
ADP + Pi —> ATP (ADP is attached to one of the three phosphate groups of the ATP by a covalent bond. The energy stored in this high-energy phosphate bond is released when the bond is broken during the removal of the phosphate group.
NADH and FADH2 transfers the electrons to the electron transport system (ETS) in the mitochondria. The ETS uses energy from the electrons to make the high-energy phosphate bond of ATP.
Both NADPH and ATP are primarily responsible for most of the biological energy storage that is derived from sunlight.
Outline the pathways for aerobic and anaerobic metabolism of glucose and compare the energy yields of the two pathways.
Aerobic: Glycolysis - Glucose produces pyruvate Pyruvate-acetyl step - Pyruvate produces Acetyl CoA Citric Acid Cycle Produces about 30 ATP
Anaerobic:
Glycolysis - Glucose produces pyruvate
Without O2 the pyruvate is converted to Lactic Acid
Produces 2 ATP
Write two equations for aerobic metabolism of one glucose molecule: one using only words and a second using the chemical formula for glucose.
- Glucose (sugar) + Oxygen → Carbon dioxide + Water + Energy (as ATP)
- C6H12O6 + 6O2 —> 6CO2 + 6 H2O + 30 ATP
Explain how the electron transport system creates the high-energy bond of ATP.
The ETS uses unergy from NADH and FADH2 to make the high-energy phophate bond of ATP
Describe how the genetic code of DNA is transcribed and translated to create proteins.
The enzyme RNA Polymerase binds to DNA creating a single strand of mRNA. mRNA and RNA polymerase detach from DNA and the mRNA goes to the cytosol after processing. Then the ribosomes attach to the mRNA acting as an enzyme and provide the code for the order of amino acids.
Explain the roles of transcription factors, alternative splicing, and post- translational modification in protein synthesis.
Transcription factors - bind to DNA and activate the promoter.
Alternative splicing - enzymes clip segments out of the middle or off the ends of the mRNA strand. Other enzymes then splice the remaining pieces of the strand back together.
Post-translational Modification - the pricess by which the nwly made proteins form different types of covalent and noncovalent bonds.
