Students in Year 11 Biology are learning the phases of mitosis, so we baked and decorated these cupcakes. Students now have a good understanding of what happens inside the nucleus during:
Watch the Cells Alive Interactive and describe where in each cycle are the three checkpoints that allow DNA replication and mitosis to continue. Why is it incorrect to suggest that the cell is “resting” during interphase, between mitotic cycles?
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).
This week we are looking at reproduction – by the end of this unit you will understand the concepts of sexual and asexual reproduction and describe how reproduction occurs in unicellular and multicellular organisms. You will learn that prokaryotes reproduce by binary fission and that eukaryotes can also reproduce asexually by mitosis, budding, parthenogenesis or vegetative reproduction (runners, rhizomes, tubers, bulbs and cuttings). More about asexual reproduction here. PowerPoint about Asexual Reproduction at SlideShare. Introduction to Reproduction and asexual reproduction at About Biology.
Sexual reproduction occurs in both plants and animals and involves the production of gametes by meiosis. Fertilization (when male and female gametes meet) can be external, as in many marine and freshwater organisms, or internal, as in most terrestrial vertebrates, such as birds, reptiles and mammals.
“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.
This week we are starting Chapter 4: Cell Division. On Friday we watched a Clickview video showing the process of cytokinesis and mitosis, which included a discussion with a cancer surgeon about the types of treatments (chemotherapy and radiation) used to prevent cells dividing and multiplying, as they do in tumours. All living organisms undergo cell division – in unicellular organisms (such as bacteria and yeast) it is how they reproduce. In multicellular organisms, cells divide and multiply for growth, repair and maintenance.
Certain tissues, such as root tips and bone marrow, actively grow and divide and it is relatively easy to find cells undergoing mitosis. We will look at some prepared slides to see the different stages of mitosis – prophase, metaphase, anaphase and telophase – and cells in which the chromatin is not visible (interphase).