1. UNIT 1: THE
NATURE OF LIFE
CHAPTER 1: THE
SCIENCE OF
BIOLOGY
Ms. Petrucci
Biology
2. Chapter 1: The Science of Biology
Vocabulary
Section 1-4: Tools and Procedures
• Metric system
• Microscopes
• Compound Light Microscopes
• Electron Microscopes
• SEM
• TEM
• Cell Culture
• Cell Fractionation
3. 1-4 Tools and Procedures
• What is the most
dangerous thing in a
Science Lab?
18. Laboratory Techniques
• Cell Cultures – single cell grown on nutrients will divide
and form millions of cells
19. Laboratory Techniques
• Cell Fractionation – technique in which cells are broken
into pieces and parts are separated.
20. Working Safely in Biology
• Lab Safety Handout
• Lab One – Using a Compound Microscope
• Chapter Test Next Week!
Editor's Notes
Human Error
Consider the autoclave, which scientists use to sterilize tools and which issues scalding steam to do so. Or consider the heat gun, which is used to dry glassware and to warm distillation devices. It can also ignite anything flammable that gets too close. Glass containers in a vacuum can implode, spraying shards everywhere. Centrifuge rotors can fail, causing explosions that throw shock waves throughout a lab filled with chemicals. Steel vessels built to contain liquids and gases at hundreds of pounds of pressure per square inch can rupture, hurling metal at lab workers. Yet none of these instruments is nearly as dangerous as the only thing found in every single laboratory on earth: us.
When lab accidents result in death or serious injury, human error is usually to blame.
Metric system – decimal system of measurements, units are scaled on multiples of 10.
SI is a revised version of the metric system
Units used include meters (m), kilograms (kg), liters (L), and Celsius degrees (oC)
Length is measured in Meters, Centimeters, and millimeters.
Snail 1 = 23mm
Snail 2 = 35mm
Snail 3 = 26mm
Volume measured in Liters and mililiters
What is the volume of the liquid in the graduated cylinder pictured?
43mL
Grams or Kilograms
Mass is the amount of matter an object has. It does not change from location to location.
Weight is the measure of the gravitational force between objects.
If a dog weighs 75lbs on earth, it may weigh only 48 lbs on the moon because of the difference in gravity.
Temperature – The measure of hotness (Celsius)
Many devices have been invented to accurately measure temperature. It all started with the establishment of a temperature scale. This scale transformed the measurement of temperature into meaningful numbers. In the early years of the eighteenth century, Gabriel Fahrenheit (1686-1736) created the Fahrenheit scale. He set the freezing point of water at 32 degrees and the boiling point at 212 degrees. These two points formed the anchors for his scale.
Later in that century, around 1743, Anders Celsius (1701-1744) invented the Celsius scale. Using the same anchor points, he determined the freezing temperature for water to be 0 degree and the boiling temperature 100 degrees. The Celsius scale is known as a Universal System Unit. It is used throughout science and in most countries.
There is a limit to how cold something can be. The Kelvin scale is designed to go to zero at this minimum temperature. The relationships between the different temperature scales are:
oK = 273.15 + oC oC = (5/9)*(oF-32) oF = (9/5)*oC+32
At a temperature of Absolute Zero there is no motion and no heat. Absolute zero is where all atomic and molecular motion stops and is the lowest temperature possible. Absolute Zero occurs at 0 degrees Kelvin or -273.15 degrees Celsius or at -460 degrees Fahrenheit. All objects emit thermal energy or heat unless they have a temperature of absolute zero.
If we want to understand what temperature means on the molecular level, we should remember that temperature is the average energy of the molecules that composes a substance. The atoms and molecules in a substance do not always travel at the same speed. This means that there is a range of energy (the energy of motion) among the molecules. In a gas, for example, the molecules are traveling in random directions at a variety of speeds - some are fast and some are slow. Sometimes these molecules collide with each other. When this happens the higher speed molecule transfers some of its energy to the slower molecule causing the slower molecule to speed up and the faster molecule to slow down. If more energy is put into the system, the average speed of the molecules will increase and more thermal energy or heat will be produced. So, higher temperatures mean a substance has higher average molecular motion. We do not feel or detect a bunch of different temperatures for each molecule which has a different speed. What we measure as the temperature is always related to the average speed of the molecules in a system
Data analysis is the process of interpreting the meaning of the data we have collected, organized, and displayed in the form of a table, bar chart, line graph, or other representation. The process involves looking for patterns—similarities, disparities, trends, and other relationships—and thinking about what these patterns might mean.
When analyzing data, ask students questions such as:
What pattern do you see?
What does this graph tell you?
Who could use this data? How could they use it?
Why is this data shown in a line graph?
The process of collecting, organizing, and analyzing data is not always a simple, sequential process; sometimes a preliminary analysis of a data set may prompt us to look at the data in another way, or even to go back and collect additional data to test an emerging hypothesis. For example, students could survey their classmates on how they are transported to school (such as by car, by bus, by foot, or another way), and then display the data in a circle graph.
After analyzing the data in this graph, students might look at the data in a different way. Students might be interested in finding out more about people who are transported to school by car. Why do they ride in a car to school? Are they on a bus route? Do they carpool with other students? Are they close enough to school to walk, but choose to ride? Is the neighborhood between home and school too dangerous to walk through? Do the people who walk sometimes ride in a car, also? They might discover that most students in the "other" category ride their bikes to school, and decide to create an additional category.
In all grades, students look at graphical displays and describe them by identifying aspects such as the greatest value, the least value, and the relationship of one data point to another. Students in the intermediate grades learn how to summarize or characterize a data set in greater depth by determining the range and two measures of center, the mode and median. Students in the upper grades learn to find the third measure of center, the mean, and also to determine quartiles, identify outliers, and, for scatterplots, calculate a line or curve of best fit and describe any resulting correlation. High-school students should be able to design their own investigations that include effective sampling, representative data, and an unbiased interpretation of the results.
At every grade level, you should encourage students to think about the meaning of the data they have collected and displayed. The crucial question is "Why?"
Why Is It Important?
The ability to make inferences and predictions based on data is a critical skill students need to develop.
In studying data and statistics, students can also learn that solutions to some problems depend on assumptions and have some degree of uncertainty. The kind of reasoning used in probability and statistics is not always intuitive, and so students will not necessarily develop it if it is not included in the curriculum. (NCTM, 2000). Data analysis is crucial to the development of theories and new ideas. By paying close attention to patterns, the stories behind outliers, relationships between and among data sets, and the external factors that may have affected the data, students may come to have a deeper understanding of the crucial distinction between theory and evidence.
zing data -- Tables, Graphs, Charts, Drawings, Models, etc.
A graph helps make patterns easier to recognize and understand.
Starting with Robert Hooke in the 1600s, the microscope opened up an amazing new world—the world of life at the level of the cell. As microscopes continued to improve, more discoveries were made about the cells of living things. However, by the late 1800s, light microscopes had reached their limit. Objects much smaller than cells, including the structures inside cells, were too small to be seen with even the strongest light microscope. Then, in the 1950s, a new type of microscope was invented. Called the electron microscope, it used a beam of electrons instead of light to observe extremely small objects. With an electron microscope, scientists could finally see the tiny structures inside cells. In fact, they could even see individual molecules and atoms. The electron microscope had a huge impact on biology. It allowed scientists to study organisms at the level of their molecules and led to the emergence of the field of molecular biology. With the electron microscope, many more cell discoveries were made. Figure below shows how the cell structures called organelles appear when scanned by an electron microscope.
A stereoscopic or dissecting microscope is a relatively low magnification (often 2x-30x) microscope that is good for viewing large objects. As its name implies, it is better than a compound microscope for dissecting many materials (e.g. small animals, plants, organs) because it produces a 3-dimensional image.
Although its magnification is generally less than that of a compound microscope, it has a couple of advantages over compound scopes. First, it has a large depth of field, so you can observe thick objects with most parts in focus at the same time. Second, you can illuminate your sample using incident light as well as transmitted light, so that thick objects which will not transmit much light can be illuminated adequately to view.
Dissecting microscopes have an objective lens which often allows a continuous range of magnification (from 2-30x), controlled by a magnification knob. There is a focus knob, and a source of transmitted light (adjustable); many scopes also contain a source of incident light. Another difference from a compound microscope is that the stage is much farther from the objective lens, allowing large objects to be placed on the stage.
Microscopes produce a magnified image of structures
Light microscopes may be simple or Compound.
(one lens) or (two or more lenses)
**Specimen can remain alive**
http://www.udel.edu/biology/ketcham/microscope/scope.html
www.biologycorner.com/microscope/
SEM - 3-D image TEM - through an image
**Specimens cannot be observed while alive**
1.Both SEM and TEM are two types of electron microscopes and are tools to view and examine small samples. Both instruments use electrons or electron beams. The images produced in both tools are highly magnified and offer high resolution. 2.How each microscope works is very different from another. SEM scans the surface of the sample by releasing electrons and making the electrons bounce or scatter upon impact. The machine collects the scattered electrons and produces an image. The image is visualized on a television-like screen. On the other hand, TEM processes the sample by directing an electron beam through the sample. The result is seen using a fluorescent screen. 3.Images are also a point of difference between two tools. SEM images are three-dimensional and are accurate representations while TEM pictures are two-dimensional and might require a little bit of interpretation. In terms of resolution and magnification, TEM gains more advantages compared to SEM. Read more: Difference Between TEM and SEM | Difference Between | TEM vs SEM http://www.differencebetween.net/science/difference-between-tem-and-sem/#ixzz38JV4JRdk
