Monday, August 15, 2011

Science, Plants and Animal Cells, part 2

Plant and Animal Cells, part 2
Last time we looked at the similarities between plant and animal cells. As a review, the six basic things common to both plant and animal cells are: cell membrane, nucleus, endoplasmic reticulum, ribosomes, Golgi apparatus, and mitochondria. There is one other organelle that is present in both plant and animal cells, however, it is much larger, and takes a much more prominent place in the cells of plants. This is the vacuole. The vacuole is essentially a storage facility. It can store water for the plant cell, it can store food for the plant cell, and additionally it can store waste. Because it can store water, a plant that is in need of water will have used the stored water in the vacuoles and cause the cells to become less full, so they are less rigid and the plant is droopy. A plant whose cells have full vacuoles is a plant that is getting enough water.

There are a number of differences between plant and animal cells, as well. Plant cells have cell walls, in addition to cell membranes. The cell wall’s purpose is to make the cell more rigid and is made of cellulose. Plant cells also have chloroplasts. They are what make plants green. These are not found in animal cells at all. Chloroplasts are what convert the sun’s energy into sugar. This sugar in turn feeds the cells, as well as the whole plant. Eventually those sugars are what feed people and animals as well. So while animal cells do not contain chloroplasts, they are vital to the survival of animals.
This brief review of plant and animal cells is by no means all inclusive. Go out to the internet and find pictures and more detailed descriptions. And find more pictures. It is said that a picture is worth a thousand words. In this case that is completely true. Seeing a line drawing of a plant cell and an animal cell next to each other makes the similarities and the differences easy to point out. Also, remember that in fifth grade science, may be the first time your student learns about cells, but it will certainly not be the last. Expect for your student to have to label more and more complex pictures of cells as they advance through the grades.

Monday, August 1, 2011

Science, Plants and Animal Cells, part 1

Plant and Animal Cells, part 1
One of the curriculum standards for fifth grade science is cells. Both plant and animal cells should be included in the study. Your student needs to be able to identify the various cell structures of the cells. He will also need to know the function of the cell structures. How is the student supposed to accomplish this, you ask? Relax homeschooling parent! The internet is full of places that you can investigate to get the content for your unit on cells and cell structure. I’ll give you the basic rundown on plant and animal cells, the similarities, and the differences.

One of the things we need to know is that all living things are made up of cells. Cells are the building blocks of both plants and animals. Cells are responsible for energy production, energy to run the cell, but also to run the larger organism that the cell is a part of. All cells are not created equal however. There are prokaryotic cells, these are simple cells, they lack a true nucleus, and do not have complex cell structures. There are also eukaryotic cells. Plant and animal cells are eukaryotic cells. Eukaryotic cells contain a true nucleus and are considered complex cells. Now, let’s look at the things that are similar between plant and animal cells. First of all, both plant and animal cells contain a cell membrane. This membrane encircles the entire cell, and keeps the contents of the cell separated from the fluid on the outside of the cell. A cell membrane is semi-permeable, meaning it lets some things into the cell, but not everything. It also lets some things out of the cell. The next thing that both plant and animal cells have in common is a nucleus. The nucleus is contained within a nuclear membrane, this keeps the contents of the nucleus separate from the cytoplasm of the cell. One of the most important things contained within the nucleus is the DNA. DNA is the genetic material that will be passed on to other cells.

Endoplasmic reticulum is another organelle within the cytoplasm of the plant and animal cells. There are two types of endoplasmic reticulum, or ER. There is smooth ER which is responsible for the production of lipids and the metabolism of carbohydrates within the cell. Rough ER has nodules attached to its wall, these nodules are ribosomes. Rough ER is responsible for the synthesis of proteins. The ribosomes are primarily responsible for this synthesis of proteins. Ribosomes can be found attached to the rough ER, or within the cytoplasm. Mitochondria are also part of both plant and animal cells. Mitochondria are responsible for converting food energy, which is potential energy, into a form of energy that can actually be used. Mitochondria also contain DNA though not nearly as much as the nucleus. The final organelle that is common to plant and animal cells are Golgi bodies or Golgi apparatus. The Golgi apparatus is responsible for taking the proteins that are produced by the ribosomes and converting those proteins into other, more complex materials. In a way, Golgi apparatus are also used as a storage system for the cell. Next time we will look at the differences between plant and animal cells.