Unit 16 Module 2: Cells

How do lipids, carbohydrates, proteins, and nucleic acids come together to form a living organism?

By forming a cell. These organic compounds are the raw materials needed for life, and a cell is the smallest unit of an organism that is still considered living. Cells are the basic units that make up every type of organism.

Some organisms, like bacteria, consist of only one cell. Other organisms, like humans, consist of trillions of specialized cells working together. Even if organisms look very different from each other, if you look close enough you’ll see that their cells have much in common.

Most cells are so tiny that you can’t see them without the help of a microscope. The microscopes that students typically use at school are light microscopes. Robert Hooke created a primitive light microscope in 1665 and observed cells for the very first time. Although the light microscope opened our eyes to the existence of cells, they are not useful for looking at the tiniest components of cells. Many structures in the cell are too small to see with a light microscope.

Scientific Concepts:

Understand what cells are, how cells form the basis for all life
Understand the development of the cell theory
Know the function of the major cell organelles
Understand how material enters and exits cells
Understand the methods of cell division, and which types of organisms use each

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	Cell in Action Cells make up every living thing. Take a look at all the living things you can see just in your house. You can start off with you and your family. If you have any pets, be sure to include them. Don’t forget about houseplants as well – they’re alive. Now take a walk outside. You’ll … Continue reading "Cell in Action"
	Protozoa in the Grass This experiment allows you to see protozoa, tiny-single celled organisms, in your compound microscope. While I can go in my backyard and find a lot of interesting pond scum and dead insects, I realize that not everybody has a thriving ecosystem on hand, especially if you live in a city. I am going to show … Continue reading "Protozoa in the Grass"
	Celery Stalk Water Race If you think of celery as being a bundle of thin straws, then it’s easy to see how this experiment works. In this activity, you will get water to creep up through the plant tissue (the celery stalk) and find out how to make it go faster and slower. The part of the celery we … Continue reading "Celery Stalk Water Race"
	Bacteria in Humans and Dogs Some organisms, like bacteria, consist of only one cell. Other organisms, like humans, consist of trillions of specialized cells working together. Even if organisms look very different from each other, if you look close enough you’ll see that their cells have much in common. Most cells are so tiny that you can’t see them without … Continue reading "Bacteria in Humans and Dogs"
	Colored Flowers When plants are watered, the water travels up the roots of the plant, and to all of the plant’s parts. So, with sunlight and time, the colored water eventually made to the plant’s flowers, creating the color change you observed.
	Cell Walls of Cotton The cell wall organelle supports and protects the cell. Cell walls have small holes, called pores, in them. This lets water, nutrients, and other substances into the cell. Here’s what you do: First, take out your science journal. Write down how many cotton balls you think will fit into a full glass of water without … Continue reading "Cell Walls of Cotton"
	Osmosis in Potatoes & Beans One way substances can get into a cell is called passive transport. One special kind of passive transport is osmosis, when water crosses into the cell. This experiment allows you to see the process of osmosis in action. Are you ready?
	Carbon Dioxide and Photosynthesis Photosynthesis is a process where light energy is changed into chemical energy. As we said in the last section, this process happens in the chloroplast of plant cells. Photosynthesis is one of the most important things that happen in cells. In fact, photosynthesis is considered one of the most important processes for all life on … Continue reading "Carbon Dioxide and Photosynthesis"
	Onion Mitosis In eukaryotes there is a nucleus, so a more complex process called mitosis is needed with cell division. Mitosis is divided into four parts, or phases: Phase 1 – Prophase: In this phase the nuclear membrane begins to break down and the DNA forms structures called chromosomes. Phase 2 – Metaphase: In this phase the … Continue reading "Onion Mitosis"
	Cool Carrot Osmosis The carrot itself is a type of root—it is responsible for conducting water from the soil to the plant. The carrot is made of cells. Cells are mostly water, but they are filled with other substances too (organelles, the nucleus, etc). We’re going to do two experiments on a carrot: first we’re going to figure … Continue reading "Cool Carrot Osmosis"
	Membranes Here’s a fun experiment that shows you how much stuff can pass through a membrane. Scientist call it the semi-permeability of membranes. Before we start, take out your science journal and answer this question: What do you think will happen when we stick a piece of celery into a glass of regular water. Anything special? … Continue reading "Membranes"

Scientific Concepts:

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