Let's get cellular.
To life, to life, biology! In Semester A of this Biology course, we lift our soda bottles to the study of life.
Chances are, you've heard of cells, genetics, and evolution. After all, you can't watch the news or any show on Hulu without hearing about stem cells, DNA evidence, or the controversy over evolution. But can you tell us:
- how plants manage to get energy from the sun?
- how a blond-haired kid can be born to a brown-haired family?
- why exactly carbs are not the evil enemy the media has made them out to be, but the one molecule essential to human survival?
Our lessons, glossaries, readings, and activities could help you out there, dontcha think? Tagged with the Next Generation Science Standards, our Biology course has everything you need to make science your biomass.
P.S. Biology is a two-semester course. You're looking at Semester A, but you can check out Semester B here.
Unit 1. Introduction to Biology
In this introductory unit, we'll answer the big questions of life. No, really. We'll ask the question, "Do you even lift, bro?" Actually, this unit is about the other one, "What is life?" You'll also get comfortable with other big issues of biology, including ye olde scientific method and how biological systems are organized.
Unit 2. The Chemistry of Life
What better way to get acquainted with biology than through...chemistry? That's right; when it comes to life, it's chemical all the way down. (We haven't confirmed how far the turtles go down, but it's pretty far.) In this unit, we'll go straight to the bottom of the biological pyramid by learning some foundational concepts, including atomic bonding, the properties of water, and macromolecules.
Unit 3. Cells
Movin' on up the biological pyramid, we come to the smallest unit of life: the cell. This unit covers the properties and components of eukaryotes and prokaryotes, enzymes, osmosis and diffusion, and everyone's favorite cellular process: mitosis.
Unit 4. Biochemical Pathways
The phrase "biochemical pathway" sounds like the driest, most boring thing ever, but it's actually a topic near and dear your stomach. It's the process by which our nom-noms are broken down by our cells into energy. This unit covers the basics of cellular respiration (aerobic and anaerobic style) and plants' superpower, photosynthesis.
Unit 5. Genetics
Peas changed the world. True story. In this unit, we'll find out how Gregor Mendel discovered genes, and indirectly founded the field of genetics, by observing peas. You'll get cozy with alleles, meiosis, Punnett squares, genetic disorders (well, not too cozy), and other genetics issues.
Unit 6. Molecular Genetics
Our quest to gain total genetic mastery continues in this unit on DNA, the molecule of inheritance. Replication, transcription, and translation will make their appearances here, culminating with some discussion of biotechnology. Mwa ha ha...! Er, pay no mind to that mad science cackle. We totally don't have any plans for creating a race of super apes.
Sample Lesson - Introduction
Lesson 3: Cell Transport
Cell membranes in a nutshell: Cells have stuff inside of them that make them function, like organelles and cytoplasm and a nucleus. Cell membranes consist of a thin layer of plasma, which holds all of these goodies within cells and keeps them separated from the harsh, outside environment.
Think of the cell membrane as the dreaded airport security you have to pass through in order to catch your flight. Those guys don't just let anyone through, and neither does the cell membrane (although the credentials are slightly different, we hear). In other words, the cell membrane keeps the cell safe. It's the bodyguard, the bouncer, the troll under the bridge, the three-headed dog which needs to be appeased by a Scooby snack.
The question is, then, how does the cell membrane select what goes in and out of the cell?
The cell membrane is like Goldilocks. You know, the porridge is too hot, too cold, or just right. The cell doesn't want too much or too little but just the right amount of water and solutes in order to keep the cell comfortable. So the cell membrane regulates how much stuff goes in and out through two processes: osmosis and diffusion. Remember those?
If you've ever been stuck on a hot, crowded, stuffy elevator on Friday afternoon, you know what happens when the doors open: everyone makes a break for it, spreading out as far as possible. This isn't terribly unlike what happens during diffusion. Molecules move from areas of high concentration to low concentration, just like the people on the elevator. Only, of course, molecules aren't in a hurry to get to their weekend started, they do it because of forces and other physics-type stuff. And since scientists seem to take delight in coming up with a new word for everything, they have a special one for the diffusion of water: osmosis. One basic process, two names. Fin.
These two processes are the main ways by which water and other goodies (solutes, if you want to be all science-like) move through the cell membrane, going into and out of the cell.
Sample Lesson - Reading
Reading 3.3: Breaking Into a Cell
Before we can break it down on the dance floor, we have to get past the bouncer, right? Well, before we can check out the innards of a cell, we have to sneak past the cell's bouncer: the cell membrane.
Getting past this gatekeeper is a tough task. It's pretty picky, and only lets certain things inside. Check out the following reading to get up to speed on what molecules have to do to gain entrance into the cellular club.
Whoa, that was a lot of information about a rather complex little guy. Well, actually a trillion little guys. Each of the cells in our bodies has its own cell membrane made up of each of the components listed in the reading: proteins, phospholipids, and cholesterol.
Now that you know the structure of cell membranes, the obvious next question is how molecules get past the gatekeeper. Do they have to wear disguises? It seems like the gatekeeper is no idiot.
Take a gander at this information on the way that substances get into and out of the cell: cellular transport. There are many kinds, just like the types of waste disposal: recycling, composting, trash pickup, etc. Some require energy to complete and some just kind of happen all by themselves. Both types of processes are essential for our well-being, though.
Pay particular attention to the direction of movement of the molecules. This is what keeps our bodies in balance and running in tip-top shape. When cells need stuff, said stuff is allowed to enter the cell; and when it has too much stuff, well, it just pushes that right out.
Now that you have a general idea of what's going on, let's see it in action. Let's look at three simulations of diffusion and osmosis across the cell membrane. Each of these simulations lets us play with the concentration of gases or ions on either side of the membrane or change the membrane pore size. Manipulate the levels of each and watch the simulation play out in different scenarios.
You'll know you've had your fill when you're able to answer these questions:
- What happens when there's more of a substance outside the cell membrane than inside?
- Would many particles per unit space have a high or low concentration? Would few particles per unit space have a high or low concentration?
- What is diffusion?
- What is osmosis?
- What do we call a solution with a greater concentration of something? What about a lower concentration? Same concentration?
Sample Lesson - Activity
Activity 3.3: What if He Took the Day Off?
Anyone ever wondered if school is different on the days they aren't there? How big an impact does a single person have on the flow of the school day? Perhaps it depends on who you are and what you do, right? When one student out of a 1,000 kids doesn't show, the school day probably moves ahead undisturbed. If the cafeteria lady doesn't show, it's the McDonald's across the street for everyone. Imagine the lines.
What would happen if one of the cell membrane components decided to take the day off? For each of the following cell membrane components, briefly describe how the absence of each one would impact the cell's overall function. Remember, only one cell component can be absent at a time—no cell membrane skip days for everyone.
- Course Length: 18 weeks
- Grade Levels: 9, 10, 11, 12
- Course Type: Basic
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Pre-Algebra II—Semester A
Pre-Algebra II—Semester B
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