BIO 101

Quiz #1

1. Compare and contrast condensation and hydrolysis

            In short the difference between condensation and hydrolysis is that in condensation, one molecules is separated into two molecules, releasing a byproduct of H₂O.  In hydrolysis, the same two molecules are joined with free H₂O creating one molecule.  To get specific, during the process of condensation of two sugar molecules; using enzymes, a hydroxyl group separates from one of the glucose molecules, while a single hydrogen atom separates from the other glucose molecule.  The resulting open bonds on the two glucose molecules covalently bond together.  The free floating hydroxyl group and the hydrogen atom join to form water.

            In hydrolysis, the same reaction causes the covalent bond between the two glucose molecules to separate and use free floating water to fill the gaps left open from the broken covalent bond.

2. Compare and contrast anaerobic and aerobic metabolism in muscle cells.  What are the effects of each on the individual?

            Aerobic metabolism differs from anaerobic metabolism in the fact that the previous occurs only in the cytoplasm.  The later occurs inside mitochondria, and yield considerably more ATP.  To be precise it yields 32-34 more ATP than aerobic metabolism.  During anaerobic metabolism in muscle cells, glycolysis-taking place in the cytoplasm of cells create and release 2 ATP.  To create 2 ATP, glycolysis metabolizes glucose or any other carbohydrate molecule into two 3-carbon pyruvate molecules.  Using the process of phosphorylation phosphate atoms are added to the carbohydrate, which is eventually broken into 2 pyruvate molecules containing 3 carbons each (pyruvate).  The net return is 2 NADH, 2 pyruvate, 2 ATP, and the byproduct H₂O.

            After glycolysis, cell metabolism uses the Krebs Cycle and the electron transport system to release 34 more ATP.  The Krebs Cycle releases 2 ATP, while the electron transport system in cell membranes release 28 ATP during the process.  Four additional ATP are released from 2 FADH which are transported into the mitochondria through transport proteins.  In addition to the ATP release using the Krebs Cycle and electron transport, the byproduct CO₂ is created.  This byproduct if not released or used by the muscle cells creates lactate, or as I have known it as a swimmer, lactic acid.  To highlight the differences, glycolysis gives off water and the aerobic respiration of glucose gives off CO₂.

3. Outline the cytomembrane system.  Describe the cell membrane properties contributing to endocytosis and exocytosis.

The cytomembrane system consists of a system that makes lipids and proteins into useable products.  It consists of the following organelles: Endoplasmic Reticulum (ER), including the rough and smooth ER, Golgi bodies, and vesicles.

            The ER has two parts, the rough ER and the smooth ER.  The rough ER, which gets its appearance from many ribosomes attached to its exterior, is responsible for the formation of proteins.  The smooth ER, which is connected to the rough ER, is responsible for making lipids.  After releasing vesicles into the cytoplasm the Golgi body packages the proteins into useable

The Golgi bodies receive proteins created by the rough ER and packages them for shipment in vesicles, to various locations into or out of the cell.

The properties of the cell membrane, which make it possible to form vesicles, during endocytosis, and accept vesicles into the cell membrane are due in part to it’s formation of lipids.  The cell membrane, formed in lipid bilayers is fluid and accepts vesicles from within the cell.  The hydrophobic lipid tails always facing inward, toward another hydrophobic lipid tail, while the two heads of the lipids will face out, and are hydrophilic.  It is this hydrophobic and hydrophilic characteristic which makes it possible for the cell membrane to separate when a vesicle contacts the interior wall of the cell, resulting in exocytosis.

The opposite but similar process also occurs during endocytosis.  During endocytosis, the outer wall collapses in creating a new vesicle with needed nutrients for cell life.  As the new vesicle is forming, the cell wall gently curves in and collapses at the top of the budding vesicle.  As the two sides collapse together to form the top of the vesicle, the hydrophobic tails and hydrophilic heads’ properties allow them to separate and rejoin with the heads pointing outward.