Kim Woods BIO assignment 2
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bio_130_module__2_overview.rtfModule 2 Overview
The Cell and Energy
Every tissue in every body of every organism is made of cells. The complexity of life ranges from the single-celled amoeba to large mammals containing innumerable cells, with many distinct types performing specific functions. This module will introduce you to the structure and function of cells and will describe the two major types—prokaryotic and eukaryotic cells. You will then be introduced to the various types and functions of specific protein molecules called enzymes, which facilitate cellular processes.
All organisms require energy to perform the functions that sustain their lives. The chemical reactions at the heart of these functions are referred to as an organism's metabolism. The biochemical or metabolic pathways that these reactions take are a series of linked reactions that transform energy into a usable form.
Learning Objectives
Upon completion of this module, you should be able to:
2A
Identify the typical organelles associated with eukaryotic cells.
2B
Examine the differences in organelles found in prokaryotic and eukaryotic cells.
2C
Describe the function of each of the organelles associated with eukaryotic cells.
2D
Name examples of organisms composed of prokaryotic and eukaryotic cells.
3A
State the controlled methods by which materials can be transported through a cell membrane.
3B
Contrast diffusion, osmosis, and dialysis.
3C
Classify the components and molecular parts of a typical cell membrane.
3D
Explain why cells are small.
3E
State what environmental factors are able to alter enzyme activity.
3F
Describe to which group of organic molecules enzymes belong.
3G
Explain why enzymes are so important to all organisms.
3H
Describe what happens when an enzyme and a substrate combine.
3I
Contrast active site and binding site.
3J
Define the term, denature, and provide negative and positive feedback.
3K
Describe enzymatic competition.
3L
Relate the shape of an enzyme to its ability to help in chemical reaction.
3M
Describe why enzymes work in some situations and not in others.
3N
Contrast cofactors, vitamins, and coenzymes.
3O
Explain the importance of ATP.
3P
Describe how the proton pump mechanism generates ATP.
Module 2 Reading Assignment
Enger, E. D., Ross, F. C., & Bailey, D. B. (2012). Concepts in biology (14th ed.). New York: McGraw-Hill. Chapters 4 and 5.
Lecture Notes
The Cell and Energy
Prokaryotic cells are smaller than eukaryotic cells. While eukaryotic cells can be much larger, they are still small. Cell size is important for a couple different reasons. Logistically, small cells are easier to replace. This is why they replicate and split. When cells become too large, it is more beneficial to split off and remain small and effective than to become too large, become less effective, and become harder to replace. The effectiveness of absorption and expulsion through the plasma membrane is another reason why cells are small. Absorption and expulsion become more difficult as cell size increases.
In more recent history, scientists have discovered that there are different types of cells and different functions, but that the basic cell theory still holds true. Cell theory is one of biology’s basic principles. Living organisms must be made up of cells whether they are unicellular or multi-cellular. All cells come from already existing cells and have the same basic configuration. Cells are a basic unit of life that allow energy to flow and hereditary information to be replicated and passed on.
Diffusion occurs within liquids and gases when there are no barriers. Basically, molecules will diffuse into spaces that are less concentrated than their current environments in an attempt to equalize; therefore, molecules are always in motion. Osmosis is passive in its transport of molecules. Molecules follow the direction of the flow of liquid or gas, rather than trying to equal out the concentration. Osmosis occurs each time there is a selectively permeable membrane with varying concentrations on each side of that membrane. Please watch the Cell Membrane Passive Transport video to learn more about the cell membrane, passive transport, and cell biology:
There are a few basic differences in organelles that are found in prokaryotic and eukaryotic cells. Prokaryotic cells are generally smaller cells that are anatomically simple. There is an absence of a nucleus and most other organelles. Prokaryotic cells are bacteria. Eukaryotic cells are usually much larger than prokaryotic cells and are also more intricate. They have a nucleus as well as an assortment of organelles. Eukaryotic cells make up plants, animals, fungi, protozoa, and algae.
Enzymes are vital to all living things because they are the foundations of energy, and energy is needed to survive—even at the cellular level. Enzymes are responsible for controlling and speeding up most biochemical reactions. They are discerning to what reactions are sped up so as not to set off unwanted reactions. Enzymes and the production of energy are important in everything from digestion to reproduction.
A binding site is indiscriminative, which allows an enzyme to attach anywhere there is a binding site. Binding sites do not allow production, however. An active site is discriminative to enzymes because the active site is where the biochemical reaction occurs. In order for any reaction to occur, there needs to be activation energy. Activation energy makes things a bit unstable allowing for the enzyme to start a reaction. Therefore, an enzyme must first attach to an active site and then receive some activation energy in order for a reaction to occur.
Cofactors, vitamins, and coenzymes are intertwined in helping enzymes with their reactions. The major difference in cofactors and coenzymes is that cofactors are inorganic molecules and coenzymes are organic molecules. Cofactors help with biochemical reactions by increasing the rate of the catalysis while coenzymes are essential for some enzymes to carry out reactions. For some enzymes, they are unable to make a reaction until they pair up with another protein, making them a coenzyme. Vitamins, like coenzymes, are organic. Vitamins help to produce coenzymes and are vital for cellular functions. However, by themselves, they do not have any energy, which is why they need to pair with an enzyme.
There are a few environmental factors that can alter enzyme activity. The first is temperature. Temperature is able to change the rate of motion and in some cases, the shape of the enzyme. The rate of motion slows with both high and low temperatures. Change in the shape of an enzyme occurs when there is continually high temperature. Once the enzyme changes shape, it is damaged and will not go back to its original shape. pH is another environmental factor that can change the enzyme activity. With pH, the enzyme shape can be changed when hydrogen ions attach. Lastly, enzyme-substrate concentration can change enzyme activity. If there is too much substrate, the rate is unable to increase unless more enzymes are provided.
ATP, or adenosine triphosphate, is important because it allows energy to be released in a way that does not damage the cell. It releases only the amount of energy that the cells need. ATP is made up of three phosphate groups. These groups hold the energy until the cell needs it. When the cell needs the energy, it breaks off one of the phosphate groups and becomes ADP, or adenosine diphosphate. Breaking down to ADP ensures that the cell will not receive too much energy.
Required Presentations:
Click on the links below to view the Module 2 presentations.
