Category Archives: Cell biology

iPod apps for Biology learners

ipod_panorama2

I’m enjoying loading up my new iPhone with lots of science and maths apps, including some that are especially relevant to VCE Biology students.  Mitosis is a free app that has images, videos, a glossary, a ‘tutor’ and other resources from wikipedia, Botanical Society of America, NOVA online and Florida State University. It has images and written and audio descriptions of each of the phases as well as a 10 question multiple choice test. Hudson Alpha Institute for Biotechnology has produced another free app called iCell, which has annotated 3D images of animal, plant and bacterial cells. You can select organelles and read about their structure and function. So, if you already have an iPod touch or an iPhone, these are the two I would recommend for VCE Biology. If you have any other suggestions, please leave a comment below.

Another free app, that might not be quite as useful is Phyto, which is a phytoplankton identification App from Shawn E. Gano. It has images, descriptions, flashcards and pronounciation of 28 different species of phytoplankton. I’ll be looking forward to a similar app. for Australian freshwater macroinvertebrates! I also downloaded “Ecosystems” which I thought would be interesting, but it is specific to an exhibition at the California Science Centre and only useful if you were actually doing a tour of the exhibit.

Play and Learn – CellCraft

cellcraft screen shot

Image Source

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.

Revision of Unit 1: Cells in Action

animal cell cake

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

Mitosis – Cell replication

mitosis in an African globe lily endosperm

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This week we have started Chapter 4: Cell Replication, looking at how cells divide for growth, maintenance and repair. Watch the Cells Alive animation that shows the four stages of Mitosis – Prophase, Metaphase, Anaphase and Telophase. The in-between phase is Interphase, when the chromosomes are not visible. What stage is shown in the electron micrograph above? How can you tell?

This site, at NOVA Online, shows how mitosis and meiosis compare. The McGraw-Hill site also has a good animation showing mitosis and cytokinesis (division of cytoplasm and formation of two separate cells).

The most recent edition of New Scientist has an interesting article about how bone cells form –  bone marrow cells can be induced to form bone, fat or blood depending on chemical and physical cues. In an experiment performed at the University of Chicago, scientists induced bone marrow cells to form bone cells in angular moulds (star-shaped or rectangular) and fat cells in curvy moulds (circles and flower shapes).

Investigating Osmosis with Chicken Eggs

egg with shell removed

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This week’s practical experiment involves using chicken’s eggs as a model for the cell – even though the egg is not a single animal cell, it is a good model because it has a semi-permeable membrane that shows the effect of  osmosis on animal tissue. 

“The plasma membrane of the cell is essential for separating the extracellular and intracellular environments. Made of a semipermeable bilayer of phospholipids embedded with proteins, the plasma membrane acts as a molecular gatekeeper to prevent certain substances from crossing, while granting access to others. Simple elements and compounds, like water, oxygen, and carbon dioxide may easily pass through. Larger, more complex molecules like carbohydrates and proteins must seek aid from the carrier proteins within the bilayer in a process known as facilitated diffusion.

Diffusion is the movement of molecules down a concentration gradient from an area of higher concentration to an area of lower concentration. Simple diffusion is an example of passive transport, which occurs without energy input from the cell. Similarly, osmosis, or the movement of water molecules across a membrane from an area of higher concentration to an area of lower concentration, does not require energy input from the cell. Cells existing in an extracellular environment that has a higher solute concentration than inside of the cell are in a hypertonic solution. When the extracellular solute concentration is lower than intracellular solute concentration, the cell exists in a hypotonic solution. In an isotonic solution, the extracellular and intracellular solute concentrations are the same.” from http://www.sd5.k12.mt.us/ghs/sci/young/documents/Lab–EggOsmosis.pdf

In this experiment, which solutions will cause water to move into the egg (cell) and which solutions will cause water to move out of the egg?

More pictures of this experiment here: An Egg-sellent Osmosis Experiment

Welcome Back! Unit 1: Cells – the Units of Life.

cheek cells

Image Source: Stained cheek cells as viewed through a light microscope

We will be aiming to finish one chapter of your text each fortnight to get through the unit 1 course prior to mid-year exams. This first Area of Study is all about the history, structure and function of cells. You will need to understand the names for each of the cell organelles and what they do within the cell. You will need to know what chemicals cells are made up of – mostly carbon, hydrogen and oxygen, but also phosphoros, sulfur, calcium and nitrogen. These elements make up the amino acids (chains of amino acids make up proteins), carbohydrates, lipids and nucleic acids that form the organelles. Check out the Cells Alive site for animations of animal, plant and bacterial cells. We will be completing the worksheet using this site during the first couple of weeks.

Heart pumps out new cells!

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Swedish scientists have used radioactive carbon-14 to show that between 0.5 and 1.0% of heart cells regenerate each year, depending on age. Read more here.

We were talking about bees in class during the last week of term – I happened upon this interesting article from the Scientific American – “Plan Bee: As Honeybees Die Out, Will Other Species Take Their Place?”

I’ve also added a few more resources to the Free Stuff! column on the RHS – Check out “Biology Q and A” for over 1800 questions and answers about Biology.

Quia Quizzes!

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“The first high-resolution close-up photographs of the H5N1 avian flu virus, taken by science photographer Lennart Nilsson, appeared in the Swedish daily Dagens Nyeter (DN) on November 7, 2005, in what the newspaper said was a world exclusive.”

Try these fun activities from Quia to revise Unit 1: Area of Study 1: Cell Structure and Function.

Cell organelles: http://www.quia.com/jg/1624832.html (Word search, Concentration or Flash Cards)

Cell organelles and Photosynthesis review: http://www.quia.com/ba/265821.html (Battleships)

Cells – Who wants to be a millionaire? : http://www.quia.com/rr/450977.html

The cell and plasma membrane: http://www.quia.com/cb/447399.html (Challenge board)

Stages of Mitosis: http://www.quia.com/rd/161026.html (Ordered List)

Revision of Unit 1: Area of study 1: Cells in Action

 
Use My Studiyo to create your own quiz to revise one of the following concepts:

  • Types of cells (prokaryotic, eukaryotic, plant, animal, bacterial)
  • Mitosis
  • Structure and function of cells
  • Biomacromolecules
  • Photosynthesis and respiration
  • Transport across membranes

Make sure you have at least ten questions.