Chapter 7 Flashcards
Cellular Respiration
Take in energy from the environment and convert it into a form that cells can use
Cellular respiration
Strip an electron from an atom in a compound
Oxidation
Add the electron to another compound
Reduction
The combined effects of concentration and electrical gradients across a semipermeable membrane
chemiosmosis
requires oxygen
aerobic
doesnt require oxygen
anaerobic
uses oxygen if present but can switch to fermentation if needed
facultative aerobe
when cells use an organic molecule other than oxygen as an electron acceptor to recycle NAD+
fermentation
The series of reactions that producers and consumers use to extract energy from the bonds of sugar molecules is called…?
Cellular respiration
What is a redox reaction?
Oxidation and reduction reactions occur together
How does the cell harness transfer energy through redox reactions?
The removal of an electron from a molecule results in a decrease in potential energy in that molecule; shifting the electron to a different compound increases the potential energy of the second compound
What happens to the potential chemical energy in a molecule when electrons are added or removed?
When an electron is removed, the potential energy decreases; when it is added, the energy increases
What are electron carriers? Name two examples.
Compounds that readily accept and donate electrons; NAD and FAD
From what group of molecules are most electron carriers derived?
B vitamin group
What is NAD? Where does it come from? What is its oxidized/reduced form?
Nicotinamide adenine dinucleotide; derived from Vitamin B3; oxidized=NAD+; reduced=NADH
What is FAD? Where does it come from? What is its oxidized/reduced form?
Flavin adenine dinucleotide; derived from Vitamin B2; oxidized-FAD+; Reduced=FADH2
What is a reducing agent? What is an oxidizing agent?
A compound that reduces another is called a reducing agent and a compound that oxidizes another is called an oxidizing agent
How does glucose enter a cell if it is to be used in cellular respiration?
Secondary active transport against a concentration gradient; integral proteins called GLUT proteins (glucose transport proteins) through a form of facilitated diffusion
What are the four major steps of cellular respiration?
Glycolysis, Oxidation of Pyruvate, Citric acid cycle, Oxidative phosphorylation
Which of the four steps require oxygen? Which do not?
Oxidative phosphorylation requires energy and the other three do not
–Where does glycolysis take place?
Cytoplasm in eukaryotic and prokaryotic cells
Gycolysis –What is the starting molecule(s)?
6-carbon glucose ring structue
Gycolysis–What is the end product(s)?
2 molecules of 3-carbon pyruvate sugars
Gycolysis–Where is energy required? How much is required?
Required in the first half; 2 ATP
Gycolysis–Where is energy produced? How much is produced?
Produced in the second half; 4 ATP
Gycolysis–How many electron carriers are reduced? What happens to them?
2 NADH, used as electron acceptors later on
Regarding the oxidation of pyruvate:–Where does this step take place?
mitochondria
Regarding the oxidation of pyruvate:–What is the starting molecule(s)?
3 carbon pyruvate that is changed into a 2 carbon molecule
Regarding the oxidation of pyruvate:–What is the end product(s)?
Acetyl CoA
Regarding the oxidation of pyruvate:–Where is energy required? How much is required?
No energy is required
Regarding the oxidation of pyruvate:–Where is energy produced? How much is produced?
No ATP is created
Regarding the oxidation of pyruvate:–How many electron carriers are reduced? What happens to them?
One NAD+ is reduced to NADH
Regarding the citric acid cycle:–Where does this step take place?
Matrix of the mitochondria
Regarding the citric acid cycle:–What is the starting molecule(s)?
Acetyl CoA
Regarding the citric acid cycle:–What is the end product(s)?
3 NADH, 1 FADH2, 1ATP for each turn
Regarding the citric acid cycle:–Where is energy required? How much is required?
No energy is required
Regarding the citric acid cycle:–Where is energy produced? How much is produced?
2 ATP is produced
Regarding the citric acid cycle:–How many electron carriers are reduced? What happens to them?
6 NADH, 2 FADH2
Regarding the citric acid cycle:–What is the benefit of having a cyclical step in cellular respiration?
It is continuous and will stop only when there is enough ATP in the cell
Regarding the electron transport chain:–Describe the complexes making up the ETC.
The complexes work together with high energy electron carriers to from the ETC and transport electrons through a series of redox reactions; Two electrons are passed from NADH to complex I and proceed down the chain to II, III, and IV…, Two electrons from FADH2 are passed to complex II (bypassing complex I) and proceed to complex III and IV.
Regarding the electron transport chain:–Where does this step take place?
Inner mitochondrial membrane of eukaryotes and the plasma membrane of prokaryotes
Regarding the electron transport chain:–What is the starting molecule(s)?
electrons
Regarding the electron transport chain:–What is the end product(s)?
Reduce molecular oxygen to produce water
Regarding the electron transport chain:–Where is energy required? How much is required?
none
Regarding the electron transport chain:–Where is energy produced? How much is produced?
34 ATP
Regarding the electron transport chain:–How do the different electron carrier molecules interact with the ETC?
NADH=3 ATP; FADH=2 ATP
Regarding the electron transport chain:–What direct role does oxygen play?
reduced to from water
What is the purpose of the reduction of all the electron carrier molecules? What happens to them after they have served their purpose?
They are able to accept more electrons
What is the energy from the electrons involved in all the redox reactions used to do?
Couple reactions to send protons to create a concentration gradient
What is chemiosmosis? How does it transfer energy? What ions are involved?
The combined effects of concentration and electrical gradients across the semi permeable membrane, the free energy generated from this series of redox reactions in the ETC is used to run integral proton protein pumps, the pumps transport hydrogen ions
Where does the chemiosmotic gradient occur in the cell?
ATP synthase in the mitochondrial matrix
How do the ions move back across the membrane?
They moved back into the matrix via the ATP synthase
How is the energy transferred to ATP?
The energy is then coupled to add phosphate groups
What is the theoretical energetic yield of cellular respiration? What is a more realistic estimate of energy yield?
The theoretical yield is 38 ATP molecules but a more realistic is about 30 to 32
Why is there such variation in the amount of energy actually made?
The number of hydrogen ions in the ETC complexes can vary between species and intermediate compounds and these pathways are used for other purposes
How are carbohydrates other than glucose, proteins, and lipids used as sources of energy?
Carbohydrates such as glycogen can be cleaved into glucose and other carbohydrates can be catabolized as well, proteins can be broken down into their amino acid parts and then used, lipids such as cholesterol and triglyceride can we broken down at various steps in the glucose metabolic pathway
What is the limiting factor in performing glycolysis in the absence of oxygen? How is this overcome?
The limiting factor is NAD+ for step six of glycolysis, this can be solved through anaerobic cellular respiration
Name and describe the two major types of fermentation.
The first type of fermentation is lactic acid fermentation this is when lactate dehydrogenase converts pyruvate molecules into lactic acid oxidizing NADH into NAD plus to produce to ATP, the second type of fermentation is alcohol fermentation which produces ethanol and CO2 gas while oxidizing NADH to NAD
How is NADH oxidized in each of the two types of fermentation?
energy coupling
What is the net ATP production in fermentation?
2
Name two reasons why cellular respiration should be regulated.
To provide balanced amounts of energy in the form of ATP without being wasteful, to generate a number of intermediate compounds that are used in the building of macromolecules
How is cellular respiration regulated?
GLUT proteins that transport glucose, number and specificity of enzymes, the use of coenzymes
Give two specific examples of feedback inhibition on the rate of cellular respiration.
Phosphofructokinase is the main enzyme controlling glycolysis where high levels of ATP or product decrease the enzymes activity and slowed glycolysis, the rate of electron transport through the ETC pathway is slowed by high levels of ATP and speed up by high levels of ADP
