Cell in Action

Monday May 2, 2011

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 likely see many more plants, as well as animals like birds and insects. Now imagine if all those living things were gone. That’s how it would be if there were no cells, because cells are what all those living things are made of.


Animals, plants and other living things look different, and contain many different kinds of cells, but when you get down to it, all of us are just a bunch of cells – and that makes cells pretty much the most important thing when it comes to life!


Here’s a video on the difference between animal and plant cells:



Are you wondering what all the different organelles are inside the cell? Here’s a video that goes into all the cool detail (note – this video is more for advanced students):



Now pull out your science journal! As you watch this video below, write down the organelles you see and describe what you think is happening.



What’s going on?


The endoplasmic reticulum, shown in red, transports proteins to the Golgi Apparatus, shown in blue. The Golgi Apparatus packages proteins and sends them where they are needed, either in the cell, or to the cell membrane for transport out of the cell.


Protozoa in the Grass

Monday May 2, 2011

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 you how to grow a protozoa habitat that you can keep in a window for months (or longer!) using a couple of simple ingredients.


Once you have a protist farm is up and running, you’ll be able to view a sample with your compound microscope. If you don’t know how to prepare a wet mount or a heat fix, you’ll want to review the microscope lessons here.


Protozoa are protists with animal-like behaviors. Protists live in almost any liquid water environment. Some protists are vital to the ecosystem while others are deadly.


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Celery Stalk Water Race

Monday May 2, 2011

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 eat is the stalk of the plant.  Plant stalks are designed to carry water to the leaves, where they are needed for the plant to survive.  The water travels up the celery as it would travel up any plant.


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Bacteria in Humans and Dogs

Monday May 2, 2011

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.
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Colored Flowers

Monday May 2, 2011

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.


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Cell Walls of Cotton

Monday May 2, 2011

cotton-plantThe 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 spilling any water.


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Osmosis in Potatoes & Beans

Monday May 2, 2011

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?


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Carbon Dioxide and Photosynthesis

Monday May 2, 2011

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 Earth.  It makes sense that photosynthesis is really important to plants, since it gives them energy, but why is it so important to animals?  Let’s learn a little more about photosynthesis and see if we can answer that question.


There are many steps to photosynthesis, but if we wanted to sum it up in one equation, it would be carbon dioxide (CO2) + water (H2O) makes glucose (C6H12O6) and oxygen (O2).  These words can be written like this:


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Onion Mitosis

Monday May 2, 2011

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 chromosomes line up along the center of the parent cell


Phase 3 – Anaphase: In this phase, the chromosomes break apart, with a complete set of DNA going to each side of the cell


Phase 4 – Telophase: In this phase, a new nuclear membrane forms around each of the sets of DNA


The four stages of mitosis (the cell at the top has not started mitosis) lead to two daughter cells.


A little after telophase, the cytoplasm splits and a new cell membrane forms.  Once again, two daughter cells have formed.  Take a look at this animation for a good overview of mitosis and see if you can identify all the phases.


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Cool Carrot Osmosis

Monday May 2, 2011

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 out how to move water into the cells of a carrot. Second, we’ll look at how to move water within the carrot and trace it. Last, we’ll learn how to get water to move out of the carrot. And all this has to do with cells!


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Cells Exercises

Monday May 2, 2011

Let’s see how much you’ve picked up with these experiments and the reading – answer as best as you can. (No peeking at the answers until you’re done!) Just relax and see what jumps to mind when you read the question. You can also print these out and jot down your answers in your science notebook.


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Answers to Cells Exercises

Monday May 2, 2011

Let’s see how you did! If you didn’t get a few of these, don’t let it stress you out – it just means you need to play with more experiments in this area. We’re all works in progress, and we have our entire lifetime to puzzle together the mysteries of the universe!


Simply click here for printable questions and answers.


Answers:
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Membranes

Monday May 2, 2011

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?


What if we add a teaspoon of salt to the water? Now do you think anything will happen?
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