WHAT SHOULD I KNOW ABOUT RESPIRATION
NAME
ANSWERS__________
Label parts in a mitochondrion and show where glycolysis, fermentation, Krebs cycle, and ETC happen.
Glycolysis happens in the cytoplasm outside of the mitochondrion.
Krebs cycle takes place in the matrix.
Electron Transport Chain (ETC) proteins are part of the cristae.
What is a calorie? Amount of heat it takes to raise 1 gram of water 1˚ Celsius
What is a Calorie? Amount of heat it takes to raise 1000g of water 1˚ Celsius
1000 calories = 1 Calorie
Which of these is used to measure energy in food? Calorie
What is the chemical formula for cellular respiration?
C6H12O6 + 6O2
Energy + 6CO2 + 6H2O
How does this equation compare to the equation for photosynthesis?
They are exact opposites.
What are the reactants of cellular respiration? What are the products?
Reactants = C6H12O6 and O2
Products = CO2 and H2O and energy
What does aerobic mean?
“with oxygen”
What does anaerobic mean?
“without oxygen”
What molecule is the main carbohydrate fuel molecule burned by all living things?
glucose
How do animals store their sugar for later?
As glycogen
How do plants store their sugar for later?
As starch
Which backup molecules are burned for energy during long term exercise when glucose is used up?
When glucose runs out humans burn glycogen. When glycogen is used up cells switch to burning fat.
Which TWO high energy electron carriers are used in respiration?
NAD+ (NADH) and FAD (FADH2)
How are these different from the carrier you learned about for photosynthesis?
Plants use NADP+ (NADPH) for photosynthesis.
What needs to be added to make glycolysis happen?
2 ATP’s are required to get glycolysis started. You also need NAD+ and glucose
What is the NET GAIN of ATP’s during glycolysis?
2 ATP’s are used; 4 ATP’s are produced = net gain of 2 ATP’s 2 NADH are also produced.
What happens to pyruvate/pyruvic acid if there is NO oxygen?
It follows the fermentation pathway.
What are the two kinds of fermentation? Give examples of organisms that would use these.
Lactic acid OR alcoholic
Yeast use alcoholic fermentation to make bread, beer, and wine.
Bacteria use lactic acid fermentation to make foods like yogurt, cheese, buttermilk, pickles, kimchi,
sauerkraut, sour cream
Which kind of fermentation can human cells do?
Humans also use lactic acid fermentation when oxygen is low in muscles.
Give the equations for the two kinds of fermentation:
lactic acid fermentation - no oxygen present
Pyruvic acid + NADH
lactic acid + NAD+
alcoholic fermentation - no oxygen present
pyruvic acid + NADH
alcohol + CO2 + NAD+
Why do cells use fermentation? (Hint: It’s NOT to make alcohol or lactic acid)
To regenerate NAD+ carriers so glycolysis can continue
Which pathways require oxygen and which DON’T?
Glycolysis and fermentation- NO OXYGEN REQUIRED
Cellular respiration- Krebs cycle and ETC- OXYGEN REQUIRED
Describe what happens (give reactants and products) in each of the following pathways:
glycolysis- happens with or without oxygen in cytoplasm outside mitochondria
six carbon glucose breaks down into two - 3 carbon pyruvic acids (pyruvate).
Uses 2 ATPs to get started and produces 4 ATPs (net gain of 2 ATPs) and produces 2 NADH.
alcoholic fermentation – Takes place in cytoplasm without oxygen
Uses energy from NADH to change pyruvic acid into alcohol and releases CO2 ; NAD+ is regenerated;
lactic acid fermentation – Takes place in cytoplasm without oxygen
Uses energy from NADH to change pyruvic acid into lactic acid; NAD + is regenerated;
Krebs cycle- Takes place in matrix of mitochondria when oxygen is present
Coenzyme A picks up 2 carbons from pyruvic acid to form acetyl-CoA and feeds these carbons into the
Krebs cycle to produce 6-carbon CITRIC ACID. During cycle carbons are removed and released as CO2
Each pyruvic acid generates 3 carbon dioxide, 1 ATP, 1 FADH2 and 4 NADH.
Electron transport chain
ETC proteins receive electrons from NADH and FADH 2. As electrons pass down ETC, hydrogen ions (H+)
are pumped into the intermembrane space. Oxygen “catches” the electrons at the end of ETC and water
is formed. H+ ions move through ATP synthase producing 32 ATPs. ETC proteins are part of cristae
inside mitochondrion,
Which molecule forms when glucose is broken in half?
Pyruvic acid (pyruvate)
What happens to pyruvate/pyruvic acid if there IS oxygen available?
Moves into mitochondria and enters Krebs cycle
What molecule acts as a helper to allow the carbons from pyruvate to enter the Krebs cycle?
Co-enzyme A picks up carbons from pyruvic acid and becomes acetyl-CoA
Which molecule forms first when acetyl-CoA passes carbons into the Krebs cycle?
Citric acid (citrate)
What is the other name for Krebs cycle?
Citric acid cycle
What happens to Coenzyme A after it has dropped off its carbons into the Krebs cycle?
Picks up carbons from another pyruvic acid
What are the products of the Krebs cycle?
1 glucose produces 2 ATP, 8 NADH, 6 CO2, 2 FADH2
What happens to CO2, produced during the Krebs cycle?
Released into atmosphere
What happens to the NADH’s and FADH 2’s produced during glycolysis and the Krebs cycle?
Drop their electrons in ETC. NAD+ and FAD carriers are regenerated and used again in glycolysis and
Krebs cycle.
Where do the electrons moving down the Electron Transport Chain (ETC) come from in cellular respiration?
NADH and FADH2
Compare the number of ATP’s made by NADH and FADH2.
NADH makes 3 ATP; FADH2 makes 2 ATP
Why does NADH produce more ATP than FADH2?
FADH2 skips the first ETC protein so less H+ is pumped into intermembrane space
What is the final electron acceptor at the end of Electron Transport?
Oxygen
The ETC uses the energy of the electrons passing down the line to do what?
Pump hydrogen ions (H+) into the intermembrane space
What molecule forms when oxygen collects the electrons at the end of ETC?
Water (H2O) -Oxygen picks up electrons and H+ ions to form water.
Where do H+ ions build up as ETC passes electrons down the line?
intermembrane space
Which ion passes through ATP synthase to provide the energy to make ATP?
Hydrogen (H+) cause ATP synthase to spin and provide energy to make ATP
ADP + P + energy
ATP
Where do the carbons that start in glucose end up following cellular respiration?
Released as CO2 to atmosphere
How many CO2 molecules are produced from one molecule of glucose?
1 glucose (C6H12O6) produces 6 CO2 molecules
Compare the amount of ATP made during fermentation (without O 2) and cellular respiration (with O2)
Fermentation = 2 ATP (produced during glycolysis)
Compare the production of ATP’s during glycolysis, Krebs cycle, and ETC.
Glycolysis = 2 ATP; Krebs cycle = 2 ATP; ETC = 32 ATP
What is creatine and what does it do?
Molecule found naturally in cells (like muscles) that can add phosphate (P) groups onto ADP directly
to make ATP; Sometimes used as a “food supplement”
*If given a diagram of a pathway, you should be able to fill in reactants and products and tell
it go next?
where does