Bio Chapt. 4

Calvin cycle

A process by which a photosynthetic organism uses energy to synthesize simple sugars from CO2 (carbon dioxide).

Chemosynthesis

A process by which some organisms use chemical energy instead of light energy to make energy-storing, carbon-based molecules. However, these organisms still need ATP for energy. Like plants, chemosynthetic organisms make their own food. It is the raw materials that differ.

Cellular respiration

A process of producing ATP by breaking down carbon-based molecules when oxygen is present. Cellular respiration is an AEROBIC process, which means it needs oxygen to take place. Cellular respiration takes place in mitochondria, which are often called the cell's "powerhouse" because they make the most of a cell's ATP. Cellular respiration and photosynthesis are not true opposites, but you can think of them in that way. The chemical equation of cellular respiration is basically the reverse of photosynthesis. C6H12O6 + 6O2 ====> 6 Co2 + 6H2O a sugar oxygen carbon dioxide water Up to 38 ATP molecules are made from the breakdown of one glucose molecule-2 from glycolysis and 34 or 36 from cellular respiration.

Anaerobic

Does not need oxygen to take place.

Photosystems

During the light-dependent reactions, energy is captured and transferred in the thylakoid membranes by two groups of molecules called photosystems. The two photosystems are called photosystem I and photosystem II. Photosystems II and I absorb energy from sunlight and transfer energy to the Calvin cycle.

Fermentation

Is an anaerobic process (no oxygen needed) that allows glycolysis to continue. Fermentation removes electrons from NADH molecules and recycles NAD molecules for glycolysis. Glycolysis, just like cellular respiration, needs a molecule that picks up electrons. It needs molecules of NAD. Without NAD, glycolysis would stop.

Alcohol fermentation

Is an anaerobic process (no oxygen needed) that begins at the same point as lactic acid fermentation. That is, glycolysis splits a molecule of glucose and produces two net ATP molecules, two pyruvate molecules, and two NADH molecules. Pyruvate and NADH enter alcohol fermentation. Two NADH molecules provide energy to break down pyruvate into an alcohol and carbon dioxide. As the NADH molecules are used, they are converted back into molecules of NAD. The molecules of NAD are recycled back to glycolysis. The recycling of NAD+ allows glycolysis to continue. The products of this process are two molecules of alcohol, often ethyl alcohol, two molecules of carbon dioxide, and two molecules of NAD+. Just like lactic acid fermentation, alcohol fermentation recycles NAD+ and so allows glycolysis to keep making ATP. When making bread, the carbon dioxide product is what causes the bread to rise. Bacteria that relies upon fermentation play a very important role in the digestive systems of animals. p. 124

Aerobic

Needs oxygen to take place.

Producers

Organisms that produce the source of chemical energy for themselves and for other organisms. Plants are producers that are the main sources of chemical energy for most organisms on Earth. If you eat only plants, you get the chemical energy directly from the plants. If you eat meat, you get the chemical energy from plants indirectly through the tissues of the animals you consumed.

Photosynthesis vs. Cellular Repiration

See chart on page 121.

Chemical energy

The cells of all organisms need chemical energy for all of their processes. The chemical energy used for most cell processes is carried by ATP.

Thylakoids

Stacks of coin-shaped, membrane-enclosed compartments; also called grana. The membranes of the thylakoids contain chlorophyll, other light-absorbing molecules, and proteins.

Chemiosmotic gradient

The difference in H+ ion concentration.

Lactic acid fermentation

Suppose that a molecule of glucose has just been split by glycolysis in one of your muscle cells, but oxygen is unavailable. A process called lactic acid fermentation takes place. Lactic acid, C3H6 O3, is what causes your muscle to "burn" during hard exercise. p.123

Chlorophyll

A molecule in chloroplasts that absorbs some of the energy in visible light. Plants have 2 main types of chlorophyll, called chlorophyll a and chlorophyll b. Together, these two types of chlorophyll absorb mostly red and blue wavelengths of visible light. Neither type absorbs much green light. The green color of plants comes from the reflection of light's green wavelengths by chlorophyll.

Product of Cellular Respiration (including glycolysis)

1) Carbon dioxide from the Krebs cycle and from the breakdown of pyruvate before the Krebs cycle. 2) Water from the electron transport chain 3) A net gain of up to 38 ATP molecules for every glucose molecule -- 2 from glycolysis, 2 from the Krebs cycle, and up to 34 from the electron transport chain.

Photosystem II and electron transport

1) Energy is absorbed from sunlight. 2) Water molecules are broken down. 3) Hydrogen ions are transported across the thylakoid membrane.

Photosystem I and energy-carrying molecules

4) Energy is absorbed from sunlight 5) NADPH is produced when electrons are added to NADP 6) Hydrogen ions diffuse through a protein channel. 7) ADP is changed into ATP when hydrogen ions flow through ATP synthase.

Photosynthesis

A process that captures energy from the sunlight to make sugars that store chemical energy. Therefore, directly or indirectly, the energy for almost all organisms begins as sunlight. 1) Energy from sunlight is absorbed. Water molecules are broken down and oxygen is released. 2) Energy-carrying molecules, including ATP, transfer energy. 3) Carbon dioxide molecules are used to build sugars. 4) Six-carbon simple sugars are produced. The sugars are often used to build starches and cellulose. 6 CO2 + 6 H2O =======> C6H12O6 + 6O2 carbon dioxide + water =light, enzymes> a sugar + oxygen

ADP

Adenosine diphosphate is a lower-energy molecule that can be converted to ATP by the addition of a phosphate group. If ATP is a wallet filled with money, ADP is a nearly empty wallet. Adding a phosphate group to ADP makes ATP, but it's not easy to do it because it requires a large, complex group of proteins. If just one of these proteins is faulty, ATP is not produced.

ATP

Adenosine triphosphate is a molecule that transfers energy from the breakdown of food molecules to cell processes. You can think of ATP as a wallet filled with money. Just as a wallet carries money that you can spend, ATP carries chemical energy that cells can use. Carbohydrates are the molecules most commonly broken down to make ATP. However, lipids store the most energy. When fats are broken down, they yield the most ATP. ATP has 3 phosphate groups, but the bond holding the third group is very unstable and easily broken. When the phosphate is removed, energy is released and ATP becomes ADP.

Glycolysis

Anaerobic process in which glucose is broken down into two molecules of pyruvate and two net ATP are produced. Glycolysis takes place in a cell's cytoplasm and does not need oxygen. p. 117

Grana

Grana (singular, granum) are stacks of coin-shaped, membrane-enclosed compartments called thylakoids.

Electron transport chain

Higher-energy electrons leave the chlorophyll and enter an electron transport chain, which is a series of proteins in the membrane of the thylakoid.

Chloroplasts

Membrane-bound organelles where photosynthesis takes place in plants. Chloroplasts absorb energy from sunlight and produce sugars through the process of photosynthesis. Most of the chloroplasts are in the leaf cells that are specialized for photosynthesis. The two main parts of the chloroplasts needed for photosynthesis are the grana and the stroma.

Krebs cycle

The first main part of cellular respiration. A process during cellular respiration that breaks down a carbon molecule to produce molecules that are used in the electron transport chain. This process occurs in the mitochondrion. p. 119

Stroma

The fluid that surrounds the grana inside a chloroplast.

Electron transport chain

The second main part of cellular respiration. Energy from the Krebs cycle is used to produce ATP. p. 120

Light-dependent reactions

These reactions capture energy from sunlight. The reactions take place within and across the membrane of the thylakoids. Water and sunlight are needed for the first two steps of photosynthesis.

Light-independent reactions

These reactions use energy from the light-dependent reactions of photosynthesis to make sugars. These reactions occur in the stroma of chloroplasts. Carbon dioxide molecules are needed during steps 3 and 4 of photosynthesis.

Calvin cycle (second stage of photosynthesis)

Uses energy from the first stage (light-dependent) to make sugars. 1) Carbon dioxide molecules are added to 5-carbon molecules already in the Calvin cycle. 6-carbon molecules are formed. 2) ATP and NADPH from the light-dependent reactions is used by enzymes to split the 6-carbon molecules. 3-carbon molecules are formed and rearranged. 3) Most of the 3-carbon molecules stay in the Calvin Cycle, but after two 3-carbon molecules have left the cycle, they are bonded together to build a 6-carbon sugar, such as glucose. 4) Energy from ATP molecules is used to change the 3-carbon molecules back into 5-carbon molecules. The 5-carbon molecules stay in the Calvin cycle and are added to new CO2 molecules that enter the cycle.