Introduction, Chapters 1 and 2
Introductory Topics and Questions for class discussion:
1. What is "biology"? We accepted the definition: study of living things.
2. What is the definition of "living"? Living things A) are/have cells (basic living unit); B) acquire and use energy; and C) have a molecular code (DNA) that is inherited by new individuals.
A quotation from your text (p. 4): "The properties of life emerge at the level of the cell". You will be learning more about cells in this week's lab. Enjoy!
http://www.cellsalive.com Another great way to appreciate cells, their diversity and some incredible microphotography. This will nicely supplement what you see in lab and lecture.
planet is organized. If we "group" cells together, we have tissues; if we 'group' tissues, we have
organs; group organs into systems, and group systems into an organism.
Organisms can be grouped into populations, communities, ecosytems and into our
THIS idea of biological organization is a unifying theory. VISUALIZING this idea or concept is important. Figure I.4-5 pg 5, and I-2 pg 3 are important to understanding how living things can be grouped (by level of organization in I.4, by energy acquistion in I.5 and by relationships to other organisms in I.2). Expect a test question asking you to explain in your own words the concept of biological organization.
When you think about the multiple kingdoms of living things on the planet--remember how many areas of biology we are NOT covering this semester. We could spend semesters covering the diversity of life on this planet!
3. Why should you believe the information in the textbook? How do you know it is accurate, reliable and trustworthy?
We talked next about the scientific method and how the textbook is a collection of research experiments carried out by many people, published and then tested by others. If scientists agree on interpretations of lots of those experiments--sooner or later they show up in a textbook!
The scientific method (see fig. I.8 pg 9) can be a really intense process (in my opinion!) Or it can be dryly presented in a textbook. Think about the case study (pg 10) and be ready to discuss it in class. Also consider that COMMUNICATING results is a VERY important part of science. We will talk about what my own experiences (and student researchers working with me) in publishing as an additional example of the scientific method. We will discuss this idea: "if it isn't published, and hasn't been reviewed by scientific peers, it isn't science". Think about this when you ascess a website. Has the information on that site been reviewed and tested by someone? How can you tell?
What was the initial observation made by researchers in the case study (p. 10)? What hypothesis did they next propose and test? What was their experimental design? Where did they go from there?
Issue: Can scientists "prove" things? Some scientists approach science as method of disproving things only. Are there "laws" in biology like there are in physics?
You have just read a case study about cancer research. One point you should think about from that reading: chemistry and biology are intertwined! You really can't understand biology without some knowledge about the chemistry.
Questions and Topics discussed during Lecture:
1. What is an atom? Discover the glossary in the back of the book yet? "Smallest unit of matter that is unique to a particular element" For practical discussion purposes: atoms have subunits "in orbit" around their centers. Atoms form molecules when they "share" subunits. In biological systems, atoms can lose, gain and share electrons.
2. How do atoms interact? Why is understanding how atoms interact relevant to Human Biology 1118?
"When one or more atoms join. . .--the result is a molecule." Atoms can interact by forming different kinds of bonds--they share subunits. Biologically, we are most interested in the subunit "electron" being shared between atoms. Many biological reactions involve an electron being removed, or added and/or shared between atoms of a molecule.
3. What are the 4 most common atoms in living things? Oxygen, carbon, hydrogen and nitrogen. Which one is found only in living things (or things that were once living in nature)? Carbon. Study fig 1.13, p. 24 to understand (and explain on a test) how carbon compounds have a "Tinkertoy" quality (you build them from smaller subunits!)
4. What are the 4 kinds of significant "biological molecules"? Carbohydrates, lipids, proteins and nucleic acids. Study Table 1.2 p. 35 for a summary of these molecules and a listing of answers for #5 below. ALSO review the concept of "functional group". Again, the Tinkertoy analogy is useful. These are atoms or clusters of atoms that can be added or removed from a carbon backbone. When biological molecules are being made or broken down, these groups are being added or removed. How does this happen? Biologically, ENZYMES speed up these types of reactions. See p. 25 for the 5 types of reactions involving functional groups that enzymes perform. (Check out the definition of "enzyme" too.)
5. Why are these molecules significant and worth your time? Nucleic acids are the building blocks of DNA and RNA. We will learn much more about them in later chapters.
Carbohydrates are the most abundant biological molecule. They come in 5- or 6- carbon "units". See p. 26-27. There are a number of words that describe how many units are present in a molecule (mono, di, oligo and poly). These molecules' biological function: as structural materials or as energy packets or stored energy packets.
Lipids (p. 28-29) Structurally, see figure 1.21 for a lipid that would be an important component of a cell's plasma membrane. Think of the properties of "oil and water" and how they don't mix. Some lipid molecules have subunits that are "hydrophobic" and another that is "hydrophilic". That means they organize themselves in a membrane so that the hydrophilic parts are pointing "out" and the hydrophobic parts are pointing "in". This is a NIFTY way to make a membrane "wall". Besides being important to a cell's structure, lipids can also be energy packets. Sterols (lipids without tails) are also an important membrane component (some cholesterol is biologically necessary!). Or they can be important subunits to "signals" that cells use to communicate with each other or with rest of body.
Proteins (p. 30-33): You should understand that the "subunits" that make up a protein are called amino acids. There are 20 kinds of these subunits. Fig. 1.22 shows a few examples, as well as showing you how they are "linked" to become proteins. A few amino acids joined together are a peptide. Three or more equals a polypeptide. Proteins have "multiple" levels of organization or complexity (remember the concept of biological organization?). The primary level is the linear sequence of amino acids. Interactions between the functional groups of amino acids determine bends, kinks and extensions or coils to form (secondary structure). See Fig 1.23 for an example of this. Third (tertiary structure) level involves the folding of the polypeptide. And finally, the fourth level of complexity (or quarternary) is when you combine polypeptides together such as in the example protein hemoglobin (p. 32). You will be hearing a lot about this protein in the future so spend some time reading and thinking about Fig. 1.24.
Why is this issue of "structural complexity" important? Each of these properties affect the shape and function of a protein. If something is "wrong" with the linear sequence or with the folding--a human disease CAN be one outcome. We will talk about examples of this throughout the semester. SO spend some time thinking about a protein's shape and function.
What is the most common protein in human body? See page 32 for the answer. (OR, were you listening in lecture?)
What does it mean to "denature" a protein? It means the three-dimensional shape is disrupted. Why is this biologically relevant? Think about what happens when you cook an egg. The egg white contains the protein albumin--when it is cooked it is denatured. Extreme fever in the human body can do the same thing--your enzymes and other proteins lose their 3-D structure and no longer work.
Who was Robert Hooke? He discovered structures (little rooms) in cork and gets credit for first coining the word "cell" (cellulae). (p. 38)
What is the cell theory? (p. 38) All organisms are composed of one or more cells; the cell is the smallest unit having the properties of life (all review concepts yes?); and continuity of life comes from the fact that cells grow and divide to produce new cells.
Remember to read and understand the key concepts on page 39.
1. What are the basic components of a cell? Plasma membrane, nucleus and cytoplasm.
2. How big are cells? From "yolks" of eggs (ostrich) to tiny red blood cells. A red blood cell is 4-6 um big. How small IS a micrometer? An inch is 2.54 cm, a cm contains 100 mm, 1 mm contains 1000 um.
3. What is the FLUID MOSAIC MODEL? See fig. 2.3, p. 41. This is one of the most important figures in this chapter. Spend some time studying this. The "border" of a cell, its membrane is both "fluid" (dynamic not static" and made of many components (mosaic). Lipids spin, move sideways and flex. They don't just sit there! Understand that lipids are organized into two "sheets" --a lipid bilayer.
4. How do you get things into and out of a cell? Proteins can be embedded in the membrane and have many important functions. They transport necessary things into or out of the cell. Proteins can be grouped according to types of functions: understand what a transport protein is, also a receptor and a recognition protein, and an adhesion protein. There are other ways too. See fig 2.7 p. 44
We have talked about cells being biochemical factories. There are reactions happening in the cell that must be isolated from other reactions. The way a cell isolates and therefore can regulate different kinds of reactions (building or tearing down for example) is by having compartments. Organelles serve this purpose. Learn the different types of organelles as on p. 46. (This should be review from last week's labs too!) Figures 2.9 and 2.10 are really important. Keep in mind, though that there are many kinds of cells--very few cells are exactly like the cell in fig 2.9. It is a generalized diagram!
The remaining sections of the chapter give more detail about each of the organelles. If you need to review any particular organelle--do so. An important section to be sure to study is on p. 50--the cytomembrane system. This may be a new concept to many of you. Study fig. 2.14.
5. Why is the cytomembrane system important? Proteins just don't float around in the cytoplasm willy-nilly. There is a system to make them, modify them and then transport some of them to a defined place. Making proteins or lipids is a complex, fascinating, multi-step process. Did you realize that there is so much "trafficking" of things inside your cells?
Did you know your cells have to deal with everything you put into your body? For example, how do cells deal with alcohol? See p. 51--there are special organelles in your cells in the organs most responsible for "detoxifying" alcohol in your body. Peroxisomes in your liver and kidneys must perform this function. Have you been abusing your peroxisomes?
6. What does the statement "cells have scaffolding" mean? See p. 52-53 and fig 2.18. The cells has internal organization thanks to fibers, threads and lattices in the cytosplasm called a cytoskeleton.
7. What is a metabolic pathway? Why is the subject important? See pg. 54 for overview. Figs 2.20 and 2.21 depict very important summary concepts. Another important summary figure is 2.25. Spend some time thinking about the concept of a metabolic pathway in these terms. The important take-home point: energy molecules (ATP), and the "tinkertoy" parts for the biological molecules must come from food or body storage sites. They are broken down, built up, rearranged, and waste by-products eliminated. The biochemistry is very complex. But fig. 2.25 sums this all up nicely--notice the color coding for proteins, carbohydrates and lipids!
Updated 9/7/98 (rrm) Back to syllabus