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what is the role of oxygen in cellular respiration
it accepts electrons from the electron transport chain
when the poison cyanide blocks the electron transport chain, glycolysis and the citric acid cycle soon grind to a halt as well. Why do you think they stop?
they run out of NAD and FAD;NAD+ and FAD, which are recycled by electron transport, are limited)
A biochemist wanted to study how various substances were used in cellular respiration. In one experiment, he allowed a mouse to breathe air containing O2 "labeled" by a particular isotope. In the mouse, the labeled oxygen first showed up in
Which of the following is the most immediate source of energy for making most of the ATP in your cells?
THE MOVEMENT OF h+ ACROSS A MEMBRANE DOWN ITS CONCENTRATION GRADIENT
In which of the following is the first molecule becoming reduced to the second molecule
pyruvate; lactate---at the same time NADH is oxidized to NAD+)
what is the distinction between cellular respiration and fermentation?
NADH is oxidized by the electron transport chain in respiration only
Which of the three stages of cellular respiration is considered the most ancient? explain
Glycolysis is considered the most ancient because it occurs in all living cells and doesnt require oxygen or membrane enclosed organelles
Explain in terms of cellular respiration why we need oxygen and why we exhale carbon dioxide
Oxygen picks up electrons from the oxidation of glucose at the end of the electron transport chain. Carbon dioxide results from the oxidation of glucose. It is released in the grooming of pyruvate and the citric acid cycle
compare and contrast fermentation as it occurs in human muscle cells and as it occurs in yeast cells
In lactic acid fermentation (in muscle cells), pyruvate is reduced by NADH to form lactate, and NAD+ is recycled. In alcohol fermentation, pyruvate is broken down to CO2 and and ethanol as NADH is oxidized to NAD+. Both types of fermentation allow glycolysis to continue to produce 2 ATP/glu7cose by recycling NAD+
Explain how your body can convert excess carbohydrates in the diet to fats. Can excess carbohydrates be converted to protein? what else must be supplied?
As carbohydrates are broken down in glycolysis and the grooming of pyruvate, glycerol can be made from G3P and fatty acids from acetyl CoA. Amino groups, containing N atoms, must be supplied to varous intermediates of glycolysis and the citric acid cycle to produce amino acids
an average adult human requires 2200 kcal of energy per day. Suppose your diet provides an average of 2300 kcal per day. How many hours per week would you have to walk to burn off the extra calories? Swim? Run?
100 kcal per day is 700 kcal per week.
Walking 3 mph would require 700/245=about 2.8 hr; swimming 1.7 ; running .7 hr
your body makes NAD+ and FAD from two B vitamins, nacin and riboflavin. The recommended dietary allowance for niacin is 20 mg daily and for ribolavin, 1.7 mg. These amounts are thousands of times less than the amount of glucose your body needs each day to fuel its energy needs. Why is the daily requirement for these vitamins so small?
NAD+ and FAD are not used up but are recycled. NAD+ and FAD are recycled between the electron transport chain and glycolysis or the citric acid cycle. We need a small additional supply to replace those that are damaged
16-ATP synthase enzymes are found in the prokaryotic plasma membrane and in mitochondria and chloroplasts. What does this suggest about the evolutionalry relationship of these eukaryotic organelles to prokaryotes?
a) No, this shows the blue color getting more intense. The reaction decolorizes the blue dye b) No, this shows the dye being decolorized, but it also shows the three mixtures with different initial color intensities. The intensities should have started out the same, since all mixtures used the same concentration of dye c) Correct. The mixtures all start out the same, and then the ones with more succinate (reactant) decolorize faster. The mixture with the highest concentration of succinate decolorizes the fastest.
As a protein, an enzyme has a unique three dimensional shape, and that shape determines which _____________ the enzyme catalyzes.
_______________ are specific because their active sites fit only specific substrate molecules.
Higher temperatures __________________ the enzyme, altering its specific shape and destroying its function
______________ help regulate cellular pH, helping to maintain the normal chemical functioning of cells
If an inhibitor attaches to the enzyme by covalent bonds the inhibition is usually ________________
_________________- can be overcome by increasing the concentration of substrate, making it more likely that a substrate molecule will be nearby when an active site becomes vacant
In photosynthesis the energy of sunlight is used to rearrange the atoms of ___ and _______ to produce ______ and ______.
CO2; H2O; GLUCOSE;O2
In cellular respiration, ________ is consumed as ______ is broken down to _________ and ______; the cell captures the energy released in _____
O2; GLUCOSE; CO2; H2O; ATP
how do our cells extract energy from organic molecules?
The energy available to a cell is contained in the arrangement of electrons in the chemical bonds that hold an organic molecule like glucose together. During cellular respiration, electrons are transferred to oxygen as the carbon hydrogen bonds of glucose are broken and the hydrogen oxygen bonds of water form. Oxygen very strongly attracts electrons, and an electron loses potential energy when it falls to oxygen. If your burn a cube of sugar, this electron fall happens ver rapidly, releasing energy in the form of heat and light. Cellular respiration is a more controlled descent of electrons---more like stepping down an energy staircase, with energy released in small amounts that can be stored in the chemical bonds of ATP
What happens to glucose and oxygen during cellular respiration?
glucose is oxidized and oxygen is reduced to water
Describe in words what the cellular respiration equation is really saying
Glucose loses hydrogen atoms as it is convertd to carbon dioxide; simultaneously, oxygen gains hydrogen atoms in being converted to water. These hydrogen movements represent electron transfers because each hydrogen atom consists of an electron and a proton
When is a molecule said to be oxidized? reduced?
when it loses one or more electrons; reduced when it gains one or more electrons
why do oxidation and reduction always go together?
because an electron transfer requires both a donor and an acceptor
What are the two key players in the process of oxidizing glucose
an enzyme called dehydroganase and a coenzyme called NAD+
What are the three main stages of cellular respiration
1- glycolysis 2- citric acid cycle 3- oxidative phosphorylation
What couples the electron transport chain to ATP synthesis?
As the electron transport chain passes electrons down the energy staircase, it also pumps hydrogen ions (H+) across the inner mitochondrial membrane into the narrow intermembrane space. The result is a concentration ogradient of H+ across the membrane
What are the multienzyme complex catalysis of pyruvate as it under goes chemical "grooming" for the citric acid cycle
1-a carboxyl group (-COO-) is removed from pyruvate and given off as a molecule of CO2 (this is the first step in which CO3 is released during respiration)
2- The two carbon compound remaining is oxidized while a molecule of NAD+ is reduced to NADH
3- a compound called coenzyme A, derived from a B vitamin joins with the two carbon group to form a molecule called acetyl coenzyme A
How does rotenone obstruct cellular respiration
by blocking the electron transport chain near its start and thus preventing ATP synthesis, an dtherefore literally st arves an organism's cells of energy; fish
How does cyanide and carbon monoxide obstruct cellular respiration?
transport blockers that bind with an electron carrier in the fourth protein complex and block the passage of electrons to oxygen.
how do couplers obstruct cellular respiration?
makes the membrane of the mitochondrion leady to hydrogen ions; dinitrophenol (DNP)
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