Students enjoyed this class, consolidating their knowledge of carbohydrates, lipids and nucleic acids using soft lollies and toothpicks today. They were able to show that disaccharides are made up of two monosaccharides and polysaccharides are made up of many sugar units (using fruit pastilles) and that lipids consist of a glycerol unit (jersey caramel) and 3 fatty acid chains (jelly snakes). Phospholipids consist of a phosphate group (marshmallow), a glycerol (jersey caramel) and two fatty acid chains. DNA consists of a sugar (fruit pastille) and phosphate (marshmallow) backbone and pairs of nitrogenous bases (jelly joiners), arranged in a double helix. Some showed the two hydrogen bonds between Adenine and Thymine and the three hydrogen bonds between Cytosine and Guanine.
As our next lesson will not be until after the VCE Study Camp, please continue to read through Chapter 2 (Membranes and Cell Organelles), as the practical experiment we are doing at Federation University is all about cell membranes. You will need to understand the following terms and definitions:
- prokaryotic and eukaryotic
- plasma membrane
- phospholipid bilayer
- partially permeable
- diffusion and osmosis (passive transport)
- hydrophilic and hydrophobic (or lipophilic)
- channel-mediated and carrier-mediated
- active transport
- phagocytosis, pinocytosis, exocytosis and endocytosis
- ribosomes, endoplasmic reticulum and golgi complex
- lysosomes, peroxisomes and endosomes
- chloroplasts – including lamella, grana and thylakoids
I suggest you create a set of Quizlet flashcards using these terms and definitions.
What do you think is the largest single cell on earth? Remember there are limits to the size of cells due to absorption of nutrients and oxygen and release of wastes. How does a cell bigger than a cricket ball manage these limits? Where do you think you would find such an organism? These strange forms of life belong to the Kingdom Protista and have been discovered in deep ocean trenches, over ten kilometres beneath the surface. Read more about these fascinating xenophyophores at “Strange Forms of Life Discovered in Ocean’s Blackest Depths“.
Image Source – a YouTube video about Cell Structure
“To grasp the reality of life as it has been revealed by molecular biology, we must magnify a cell a thousand million times until it is twenty kilometers in diameter and resembles a giant airship large enough to cover a great city like London or New York. What we would then see would be an object of unparalleled complexity and adaptive design. On the surface of the cell we would see millions of openings, like the port holes of a vast space ship, opening and closing to allow a continual stream of materials to flow in and out. If we were to enter one of these openings we would find ourselves in a world of supreme technology and bewildering complexity.” Michael Denton (1986) “Evolution: A Theory in Crisis” p328
We continue our study of cells with a look at the chemical composition of cells. Make sure you understand that cells are made up of:
- carbohydrates (monosaccharides, disaccharides and polysaccharides)
- proteins (made up of amino acids)
- lipids (made up of glycerol and fatty acids) and
- nucleic acids (DNA and RNA)
I will be at Professional Development in Melbourne on Friday, so you are asked to finish reading Chapter 3 and answer the review questions for that chapter. There are two 15 minute videos on my desk “The Living Cell” and “The Plasma Membrane”, both of which are useful for consoidating your knowledge of cells. You could also check out the resources for this chapter on the Hawkesdale Biology wiki.
All living organisms consist of cells and all cells are surrounded by a membrane. One of the major functions of the membrane is to regulate the passage of materials into and out of the cell. These materials include dissolved gases, sugars, salts and water. Cell membranes are partially-permeable which means that some substances can easily pass through them whereas others can not. Most materials move by simple diffusion from high concentration on one side of the membrane to a lower concentration on the other. Substances which will not move by passive diffusion require energy and are actively transported.
Water is the most abundant and one of the most important substances in cells. The diffusion of water across a partially-permeable membrane is called osmosis. An egg is a large cell containing mainly water, proteins and salts for the possible benefit of the growing embryo. It is surrounded by a shell, and inside that, a membrane. It provides an excellent model to assist the understanding of the structure and function of membranes. Our experiment will use hen’s eggs, with the shell removed by dissolving the calcium carbonate in acetis acid (vinegar). We will then record the mass of each egg and place them in different concentrations of saline soution (distilled water, 1%, 5%, 10% and 20%). After several hours we will remove the eggs and weigh each to record the mass gained or lost in the solution.Download the practical investigation here: investigating-osmosis-in-chickens-eggs-ss-28
Graph your results to show which eggs gained and lost mass due to the movement of water through the membrane. Did you get any unexpected results? What may have caused any irregularities?
Create a table listing the different forms of transport through cell membranes (passive diffusion, facilitated diffusion, active transport) and describe how each of these methods worked and what materials may be transported using each of these methods.
Concepts in Biochemistry – Cellular Transport
Teacher’s Domain – Transport of substances through the cell membrane
Cell membrane animation on You Tube
This week we started to look at the structure and function of cells. Make sure you can name and identify the following organelles within cells:
- Nucleus and nucleous
- Cell membrane (phosopholipid bilayer)
- Cytoplasm and cytosol
- rough and smooth endolplasmic reticulum
- golgi body (golgi apparatus)
- vacuoles (small in animal cells, large in plant cells)
- cell wall (made of cellulose in plant cells)
- Choroplasts (containing chlorophyll in plant cells).
These are the five lovely students in our Year 11 Biology Class this year. We are starting with Unit 1: Cells in Action. In addition to completing the Chapter 1 Review questions we will be doing the following activities:
Use the iPod Touch app “iCell” by HudsonAlpha Institute for Biotechnology to review the structure and function of organelles within plant, animal and bacterial cells.
Use the “Cells Alive
” website to learn about the relative sizes of different objects
veiwed under a microscope, as well as the study the models of plant, animal and bacterial cells. Biology Corner has an excellent website, with an internet lesson and worksheet
that can be printed. You will look at computer models of cells, learn the functions and the descriptions of the cells and their components.
I would have liked to have known about this game last semester, when we were doing Unit 1: Cells. CellCraft is a free, on-line, educational game where you can build a cell by adding cell organelles, collecting glucose, making ATP and then fight off viruses. This game was made possible by a grant from the Digital Media & Learning Competition. The goal was to make a truly educational game that was also genuinely fun to play. The game will soon have an open forum and eventually downloadable teacher materials.
When you play the game however, be aware that it does not model evolutionary processes – cell organelles did not just ‘appear’ when they were required by the cell. Modelling evolutionary processes would involve a far more complex and time-consuming program. The game helps you to learn and remember the names and functions of various cell organelles. There is a long and somewhat interesting discussion about creationism vs evolution with reference to this game on the Geek Dad blog. In my opinion, the game has achieved it’s goal of assisting students to understand cellular structures and processes in an engaging and student-friendly way.
This is a model of an animal cell made from cake showing the different organelles of a typical cell. The nucleus is shown by the freckle, mitochondrian was shown by the purple jelly beans, the lysosomes were the yellow jelly beans, the centrioles was the musk sticks which were then placed on the cytosol (icing), the vaccuole was shown by two freckles placed upside-down, the endoplasmic reticulum was made with yellow snakes and the rough endoplasmic reticulum was made with yellow snakes with 100’s and 1000’s laces on top to make the ribosomes and for the golgi compex was made by placing a pink snake on the icing.
This activity was enjoyed by the year 11 biology group. Making a model of a cell meant that we could relate to what a real one looked like. This made it easier to remember the names of parts of the cell and what their function was.
Chapter 1 (Cell Discovery and Exploration): Stephanie and James
Chapter 2 (Cell Structure and Function): Chris and Melissa
Chapter 3 (Composition of Cells): Charlotte and Catherine
Chapter 4 (Cell replication – Mitosis and Meiosis): Monique and Chloe
You may like to create a set of Flashcards to help you to revise the first terms work. I have started one set here: Unit 1: Cells in Action Flashcards
Go to Free Online Flashcards and register as a new user. Use the glossary in the back of your text book to list the new words from each chapter and their definitions. You can use the flashcards as a quiz or for revision. Limit yourself to 10 to 20 cards per set.