Chapter 9: Cellular Respiration and Fermentation

Pyruvic acid

________ enters the Krebs cycle, where a little more energy is given off.

Chemical pathways

________ that need oxygen are called aerobic.

Krebs cycle

The ________ and electron transport chain are both aerobic.

Photosynthesis

________ gives off oxygen, and cellular respiration uses that oxygen to release energy from food.

Heterotrophs

Must eat other living things for food

Autotrophs

Make their own food through photosynthesis

Fermentation

The process by which cells release energy in the absence of oxygen

Cells

________ break down food molecules over time, getting a little bit of chemical energy at key steps.

NAD+

Nicotinamide adenine dinucleotide: an electron carrier involved in glycolysis

Cellular respiration

The process that releases energy by breaking down glucose and other food molecules in the presence of oxygen

Oxygen

________ is used at the end of the electron transport chain; any time a cell needs more energy, it needs more ________, too.

chemical process

A(n) ________ that does not need oxygen is called anaerobic.

NADH

The ________ made during glycolysis can enter the mitochondrion to join the ________ and FADH2 made by the Krebs cycle.

Mitochondria

The organelles most important in cellular respiration

Electrons

________ are then passed from all of those carriers to the electron transport chain, which uses them to change ADP into ATP.

ATP

For quick bursts of energy, the body uses ________ already in muscles and ________ from lactic acid fermentation.

Krebs cycle

The ________ and electric transport chain take place inside the mitochondria.

Photosynthesis

________ and cellular respiration can be thought of as opposite processes, as the equations for ________ and cellular respiration are the reverse of each other.

Glycolysis

________ is an anaerobic process.

pyruvic acid

Step 2: Enzymes split CO2 off from ________, leaving a 2- carbon molecule, and NADH is produced from NAD.

cellular respiration

For exercise longer than 90 seconds, the body uses ________.

Krebs cycle

The ________ takes place within the matrix- the innermost space of the mitochondrion.

Glycolysis

The first stage of cellular respiration

Photosynthesis

________ produces food molecules and removes carbon dioxide from the air, and cellular respiration puts it back.

Cellular respiration

________ gives off carbon dioxide, water, and energy and the process can be summarized like this:

Krebs cycle

Together, glycolysis, the ________, and the electron transport chain make about 36 molecules of ATP per molecule of glucose.

Glycolysis

________ does not need oxygen, meaning that ________ can quickly get chemical energy to cells when there is not any oxygen present.

Krebs cycle

During the ________, pyruvic acid is broken down into carbon dioxide in a series of steps that release chemical energy.

Energy in food can be measured in units called calories

the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius

The Krebs cycle takes place within the matrix

the innermost space of the mitochondrion

Step 1

Pyruvic acid from glycolysis enters the mitochondrions matrix

Step 2

Enzymes split CO2 off from pyruvic acid, leaving a 2-carbon molecule, and NADH is produced from NAD

Step 3

The 2-carbon-atom molecule joins a 4-carbon-atom molecule to become citric acid

Step 4

More CO2 and NADH are made as citric acid becomes a 4-carbon-atom molecule

Step 5

More reactions make high-energy molecules of ATP, FADH2, and NADH

Step 6

The 4-carbon atom molecule can go through the cycle again

You have three main sources of ATP

ATP already in muscles, ATP made by lactic acid fermentation, and ATP made by cellular respiration

Calorie

The amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius

Krebs cycle

The second stage of cellular respiration

Electron transport chain

The third stage of cellular respiration

Aerobic

Chemical pathways that need oxygen are called aerobic

Anaerobic

A chemical process that does not need oxygen

Matrix

The innermost space of the mitochondrion