56 terms

Bio 156 Chapter 6

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Distinguish the difference between breathing and cellular respiration
Breathing is the physical act of taking air into the lungs and releasing air out of the lungs.

Respiration is a series of chemical reactions, each controlled by specific enzyme, which results in the formation of ATP. Refers to an exchange of gases. The aerobic harvesting of energy from food molecules by cells.

cells use o2 to break down fuel, releasing co2 as waste.

generating ATP for cellular work is the fundamental function of Cellular Respiration.

Cellular respiration is aerobic.
Identify the kinds of molecules that can be used by the cell to supply energy
...
describe the basic events of glycosis
...
Explain what happens in respiration reactions if no oxygen is present
There would be no ATP produced. Without oxygen to "pull" the electrons down the electron transport chain, the energy stored in NADH cannot be harnessed for ATP energy.
Describe the 3 basic events of respiration:
1. Glycolysis
2. Krebs (citric acid) cycle
3. Oxidative phosphorylation and chemiosmosis
(the way the cell gets energy out of glucose and, temporarily, stores that energy in ATP)


1. gylcolysis - term means "splitting of sugar". Occurs in cytoplasm. begins respiration by breaking glucose into two molecules of a compound called pyruvate.

2. Krebs cycyle -Within the matrix of the Mitochondria - the area outside of the cristae. Completes the breakdown of glucose - pyruvate to carbon dioxide. Electrons are carried to the electron transport chain by NAD+ and FAD.

Main Function of steps 1-2 is to supply the 3rd stage with electrons. Small amount of ATP produced in these two stages is made by substrate-level phosphorylation.

3. Oxidative phosphorylation - involves the electron transport chain and a process know as chemiosmosis.

The energy released from the electron transport chain goes to make approximately 32 ATP molecules by events, collectively called chemiosmosis.

takes place in the wall of the cristae of the mitochondria.

Most ATP produced by cellular respiration is generated here.
how many ATP molecules are made from one molecule of glucose in each stage of cellular respiration?
38 ATP molecules for each glucose molecules, representing about 40% of the energy in glucose. The rest is released as heat.

a working muscle cell spends and must regenerate
Identify and explain the function of NAD+ and FAD
key player in the process of oxidizing glucose.

1. NAD+ = coenzyme nicotinamide adenine dinucleotide. An organic molecule that cells make from the vitamin niacin and use to shuttle electrons in redox reactions. Niacin is the vitamin needed to make NAD+.

2. FAD = Vitamin needed to make FAD is riboflavin.
mitochondria structure.
The mitochondrion is a double membrane organelle. The inner mitochondrial membrane is folded into a series of pouches called the cristae.
State the beginning molecule and the ending molecule in glycolysis.
Beginning - single molecule of glucose

Concludes - with two molecules of another organic compound pyruvate.
How many ATP molecules are generated by glycolysis? What it the net gain?
Glycolysis starts with one molecule of glucose and ends with two pyruvate (pyruvic acid) molecules, a total of four ATP molecules, and two molecules of NADH .

The net gain to the cell is 2 ATP molecules for each glucose molecule that enters glycolysis.
define the term substate-level phosphorylation.
an enzyme transfers a phosphate group from a substrate molecule directly to ADP, forming ATP.
Explain where the events of gylcolysis take place in the cell.
The first step of the process occurs in the cytoplasm of the cell and yields a small amount of energy (measured in units of ATP) and two molecules of pyruvate.

The other steps occur in the mitochondria.

It is an ongoing process as your cells have a constant need for energy.
glycolysis facts
1. universal energy-harvesting process of life
2. does not require oxygen
3. does not occur in a membrane -bound organelle
4. thought o be an ancient metabolic system.
glycolysis
Glycolysis is a series of steps in which a glucose molecule is broken down into two molecules of pyruvic acid. As the chemical bonds in glucose are broken, electrons (and hydrogen ions) are picked up by NAD+, forming NADH. Glucose is oxidized and NAD+ is reduced. A net output of two ATP molecules are also produced in glycolysis for every glucose molecule processed. But most of the energy released by the breakdown of glucose is carried by the electrons attached to NADH.
krebs cycle
The pyruvic acid molecules are modified as they enter the mitochondrion, releasing carbon dioxide. The altered molecules enter a series of reactions called the Krebs cycle. More carbon dioxide is released as the Krebs cycle completes the oxidation of glucose. Two ATPs are formed per glucose, but most of the energy released by the oxidation of glucose is carried by NADH and FADH2.
electron transport chain and chemiosmosis
Almost all of the ATP produced by cellular respiration is banked in the final phase-- the electron transport chain and chemiosmosis. The NADH and FADH2 molecules produced in glycolysis and the Krebs cycle donate their electrons to the electron transport chain. At the end of the chain, oxygen exerts a strong pull on the electrons, and combines with them and hydrogen ions to form water. The electron transport chain uses the downhill flow of electrons to power the process of chemiosmosis, which produces about 34 ATP molecules for each glucose molecule consumed.
what are some of the processes in Plants that require ATP
1. building of starch into glucose
2. active transport of ions across the membranes of cells
3. production of sugars in the Calvin Cycle of photosynthesis
Cellular respiration equation
glucose + O2 + ADP = CO2 +H2O + ATP
how can the rate of cellular respiration be measured
1. Measure the amount of glucose consumed.
2. Measure the amount of oxygen consumed.
3. Measure the amount of carbon dioxide produced
glycolysis overal yield
2 ATP
2 NADH
citric acid cycle overall yield
per molecule of glucose
2 ATP
6 NADH
4FADH2
How many energy-rich molecules has the cell gained by processing 1 molecule of glucose through glycolysis and the citric acid cycle?
the cell has gained a total of
4 ATP
10 NADH
2 FADH2

now must shuttle these electrons to the electron transport chain.
citric acid cycle steps
1. acetyl CoA stokes the furnace
2 and 3.
NADH, ATP, CO2 are generated during redox reactions.
4 and 5.
Redox reactions generate FADH2 and NADH
electron transport chain is built into the...
inner membrane of the mitochondria. the folds of the Cristae of this membrane enlarge its surface area, providing space for thousands of copies of the electron transport chain and many ATP synthase complexes.
what is the final electron acceptor in the electron transfer chain?
oxygen
what are the shuttle molecules in the electron flow?
1. NADH
2. FADH2
what are the final products of cellular respiration?
1. H2O
How is ATP generated by oxidative phosphorylation?
Most of the ATP generated by cellular respiration results from O.P.

The energy derived from the oxidative-reduction reactions of the electron transport chain that transfer electrons from organic molecules to oxygen is used to phosphorylate ADP. By Chemiosmosis, the exergonic reactions of electron transport produce an H+ gradient that drives the endergonic synthesis of ATP

THE YIELD of ATP by O.P. may be 32 or 34 ATP
Where do the Oxygen and Hydrogens , which finally form molecules of water, come from?
(Oxidative Phosphorylation and the electron transport chain)

shuttle molecules NADH and FADH2 in the electron flow reach O2 the final electron acceptor. Each O2 atom (1/2 o2) accepts 2 electrons from the chain and picks up 2 hydrogen ions from the surrounding solution to form H2O. "final product of cellular respiration"
how much ATP is made by chemiosmosis?
34 ATP molecules for each glucose molecule consumed.
what is the function of cellular respiration?
to generate ATP for cellular work. Without energy a cell cannot live.
what is ATP synthesis?
a complicated activity involving the distinct, but related, processes of electron transport and generation of a membrane H+ gradient.
distinguish between anaerobic and aerobic respiration?
involve chemical reactions which take place in the cell to produce energy, which is needed for active processes.

1. aerobic - Takes place in the mitochondria and requires oxygen and glucose, and produces carbon dioxide, water, and energy

2. anaerobic - lacking or not requiring molecular O2

(Unlike aerobic respiration, anaerobic respiration does not need oxygen. It is the release of a relatively small amount of energy in cells by the breakdown of food substances in the absence of oxygen.)
how are NADH and FADH2 produced?
by glycolysis
the grooming of pyruvate and the citric acid cycle.

this energy they carry is used to make 34 molecules of ATP using the Electron Chain Transport and Chemiosmosis.
chemiosmosis ceases without....and cells die from starvation?
O2 the final electron acceptor in the electron transport chain.
what does gylcolysis do instead of using oxygen?
simply generates a net gain of 2 ATP while oxidizing glucose to 2 molecules of pyruvate and reducing NAD+ to NADH.
define the term lactic acid
a colorless syrupy organic acid formed in sour milk and produced in the muscle tissues during strenuous exercise.
What condition creates lactic acid in the cells?
when they have too little oxygen for aerobic respiration to continue—for instance, when you've been exercising very hard.

Lactic acid produced in muscle cells is transported through the bloodstream to the liver, where it's converted back to pyruvate and processed normally in the remaining reactions of cellular respiration.
Other organic molecules that can be used as fuel and the amount of relative energy that can be obtained from each.
Fats - excellent cellular fuel because they contain many hydrogen atoms and thus many energy rich electrons. The cell hydrolyzes fats to glycerol and fatty acids.

proteins -a cell will use most of the amino acids to make is own protein. enzymes will convert will excess amino acids to intermediates of glycolysis or the citric acid cycle. energy harvested by cellular respiration.

sucrose

disaccharide sugars

starch (polysaccharide)
how is starch converted to glucose?
enzymes in digestive tract hydrolyze and then broken down by glycolysis and the citric acid cycle.
Glycogen
a polysaccharide stored in our liver and muscle cells.
Can be hydrolyzed to glucose to serve as fuel between meals.
how much ATP does fat yield?
a gram of fat yields more than twice as much ATP as a gram of starch.
what is the end result of cellular respiration?
CO2 and H2O
respiration
gas exchange or breathing. the exchange of o2 and co2 between an organism and its environment.
Krebs cycle
"citric acid cycle" . the metabolic cycle fueled by Acetyl CoA formed after glycolysis in cellular respiration. Complete the metabolic breakdown of glucose molecules to Carbon dioxide. Occurs in matrix of mitochondria and supplies most of the NADH molecules that carry energy to the electron transport chain.
oxidative phosphorylation
the production of ATP using energy derived from the redox reactions of an electron transport chain.
chemiosmosis
The production of ATP using the energy of hydrogen ion gradients across membranes to phosphorylate ADP; powers most ATP synthesis in cells
Mitochondria
organelle in eukaryotic cells where cellular respiration occurs. Enclosed by two concentric membranes, it is where most of the cells ATP is made.
phosphorylation
the transfer of a phosphate group, usually from ATP, to a molecule. Nearly all cellular work depends on ATP energizing other molecules by phosphorylation.
Flavin Adenine Dinucleotide
a transport molecule within Mitochondria that can accept hydrogen ions and electrons liberated by the citric acid cycle, forming high-energy FADH2.
NADH
a molecule that carries electrons from glucose and other fuel molecules and deposits them at the top of an electron transport chain. generated during glycolysis and the citric acid cycle.
oxidative phosphorylation
There are two connected events here: the electron transport chain, and chemiosmosis.

The electron transport chain is imbedded in the membrane of the cristae of the mitochondria.

The electron transport chain consists of a series of proteins that first pick up electrons (the protein is reduced), then lets them go (oxidized). At each step, a little energy is released.

The electrons to pass down the chain come from all of the NADH and FADH2 molecules, which pick up electrons in glycolysis and the Krebs cycle.

The energy released by the passage of electrons down the electron transport chain goes to pump protons (H+ ions) across the membrane of the cristae to the inside.

Oxygen is the final electron acceptor and, along with some spare protons, combines to form water.

As protons build up inside the innermembrane space of the cristae, a pressure develops. This pressure establishes a gradient, and protons will tend to move from an area of higher concentration to an area of lower concentration. (Remember diffusion and osmosis?)

The only place for those protons to go is back out through special enzymes imbedded in the membrane called ATP synthase enzymes.

The specific event of forced diffusion of protons out through the ATP synthase is called chemiosmosis.

Here is the grand finale.

As protons rush through the ATP synthase enzymes, energy is released. This energy goes to attach phosphates back onto ATP. ATP is phosphorylated! (This is the action of chemiosmosis.)
why is the krebs cycle as cycle?
oxaloacetate is both the first reactant and the final product of the metabolic pathway (creating a loop).

Because the Krebs cycle is responsible for the ultimate oxidation of metabolic intermediates produced during the metabolism of fats, proteins, and carbohydrates, it is the central mechanism for metabolism in the cell.
Name the 2C, the 6C, the 5C, and the 4C compounds in the Krebs cycle.
2C - acetate
6C - Citrate
5C - Ketoglutarate
4C - Oxaloacetate

first compound produced in Krebs cycle is 6C- citrate
How is Carbon Dioxide produced?
Carbon dioxide is produced during the processes of decay of organic materials and the fermentation of sugars.
cellular Respiration
Cellular respiration is going on in every cell in both animals and plants.

1 molecule of glucose plus 6 molecules of oxygen are changed into about 36 molecules of ATP (energy) plus 6 molecules of water and 6 molecules of carbon dioxide during cellular respiration.
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