Biology Unit 2

Explain the role of catabolic and anabolic pathways in cellular metabolism and how they relate to exergonic and endergonic reactions.

Catabolic pathways = Metabolic pathways which release energy by breaking down complex molecules to simpler compounds. (e.g. Cellular respiration which degrades glucose to carbon dioxide and water; provides energy for cellular work.) exergonic Anabolic pathways = Metabolic pathways which consume energy to build complicated molecules from simpler ones. (e.g. Photosynthesis which synthesizes glucose from CO2 and H2O; any synthesis of a macromolecule from its monomers.) endergonic

Describe how the carbon skeleton of glucose changes as it proceeds through glycolysis and the Krebs Cycle.

In glycolysis, the skeleton will change in two ways. The ring must be opened, and then the glucose will be cleaved into 2 3-carbon molecules known as glyceraldehyde. These are straight chained. Following glycolysis and the Krebs cycle, but before the electron transport chain and oxidative phosphorylation, the carbon skeleton of glucose has been broken down to CO2 with some net gain of ATP. Most of the energy from the original glucose molecule at that point in the process, however, is in the form of NADH

Describe the structure and roles of the extracellular matrix in animal cells.

Most animal cells release materials into the extracellular space. The primary components of these materials are proteins. Collagen is the most abundant of the proteins. Its fibers are interwoven with carbohydrate-containing protein molecules called proteoglycans. Collectively, these materials are called the extracellular matrix . Not only does the extracellular matrix hold the cells together to form a tissue, but it also allows the cells within the tissue to communicate with each other.

Distinguish between substrate level phosphorylation and oxidative phosphorylation.

Oxidative phosphorylation refers to the formation of ATP via chemiosmosis during cellular respiration. Substrate level phosphorylation takes place during glycolysis (cytoplasm) and citric acid cycle (mitochondrial matrix) and is due to direct phosphorylation of ADP to form ADP but does not involve the ATP synthase.

Describe the functions of the cytoskeleton.

The cytoskeleton is a series of intercellular proteins that help a cell with shape, support, and movement. Cytoskeleton has three main structural components: microfilaments, intermediate filaments, and microtubules.

Describe the two main stages (Light Reaction and Dark reaction) of photosynthesis in terms of what they accomplish, where they take place in the chloroplast, and what the products are from each stage.

a. In the light-dependent reactions of photosynthesis, the energy from light propels the electronsfrom a photosystem into a high-energy state. In plants, there are two photosystems, aptly named Photosystem I and Photosystem II, located in thethylakoid membrane of the chloroplast. The thylakoid membrane absorbs photon energy of different wavelengths of light. b. The part of photosynthesis that occur without photons. Neither reaction can occur without the other

Explain how temperature, pH, cofactors, and enzyme inhibitors can affect enzyme activity.

a. Temperature at the low end can reduce the chance of chemical reactions and at higher temperature proteins could denature. b. extremely high and low levels of pH can cause a complete cease in enzyme actvity. c. Cofactors greatly increase the effectivacy of enzymes. Things like vitamins d. Enzyme inhibitors, well, inhibit enzymes

Explain the role of the electron transport chain in cellular respiration.

a. The electron transport chain shuttles electrons down a series of redox reactions that release energy used to make ATP. b. Redox: Lose charge, gain in energy (electrons are negative, once electrons are gained, they gain energy but lose charge).

Explain how feedback inhibition prevents a cell from wasting chemical resources.

feedback inhibiton is a negative feedback loop: Reaction A also produces B, once B hits a high enough level it shuts down reaction A, ensuring that reactants are not over used.