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Animal Cell Specialisation Alevel Biology OCR AQA Edexcel
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Animal Cell Specialisation in a Snap! Unlock the full A-level Biology course at http://bit.ly/2uN82lA created by Adam Tildesley, Biology expert at SnapRevise and graduate of Cambridge University. • SnapRevise is the UK’s leading A-level and GCSE revision exam preparation resource offering comprehensive video courses created by A* Oxbridge tutors. Our courses are designed around the OCR, AQA, SNAB, Edexcel B, WJEC, CIE and IAL exam boards, concisely covering all the important concepts required by each specification. In addition to all the content videos, our courses include hundreds of exam question videos, where we show you how to tackle questions and walk you through step by step how to score full marks. • Sign up today and together, let’s make A-level Biology a walk in the park! • The key points covered of this video include: • • 1. The Need for Specialisation • 2. Specialisations of Erythrocytes • 3. Specialisations of Neutrophils • 4. Spermatozoa • 5. Epithelial Cells • • The Need for Specialisation • • A multicellular organism needs to carry out many different tasks at the same time. For example humans need to reproduce, protect against disease, and digest food. These tasks require different proteins, organelles, and cell shapes. For example, sperm cells need to have a haploid number of chromosomes - whilst other cells need a diploid number. Cells in multicellular organisms have evolved to become more specialised to their functions. • • Specialisations of Erythrocytes • • Cells in the blood are an example of how cells are specialised to their function. Erythrocytes (red blood cells) transport oxygen to the cells of the body. They are small cells - which means they have a large surface area to volume ratio. As a result, oxygen can diffuse in and out of the cell efficiently. Erythrocytes also have a well-developed cytoskeleton that allows them to bend. This allows them to squeeze through narrow capillaries. • • Specialisations of Neutrophils • • Neutrophils are another type of blood cell - a white blood cell. They travel to sites of infection and engulf any bacteria or fungi they find there. Neutrophils are much larger than erythrocytes because they don’t need to enter the smallest capillaries. They travel to sites of infection by moving along a gradient inflammatory chemicals. This is called chemotaxis and is possible because neutrophils have receptors for inflammatory chemicals. Neutrophils also possess a multi-lobed nucleus instead of a round one. A multilobed nucleus allows them to move around more quickly and engulf material. • • Spermatozoa • • Spermatozoa (or sperm cells) are specialised for swimming and fertilisation. They have a tail (undulipodium) which allows them to swim. The moment of the tail requires ATP so sperm have lots of mitochondria. They are also long and thin which makes them streamlined. Once a sperm cell has swum to an egg cell (ovum) it digests the coating on the outside of the egg cell. It does this with an organelle called an acrosome. This is a special type of lysosome which contains the digestive enzyme lysozyme. Once the sperm has digested the outside of the ovum its haploid nucleus can enter to form the zygote. • • Epithelial Cells • • Epithelial cells make up the lining between the body and the outside. For instance, the cells that line the alveoli in the lungs are epithelial cells. One type of cell in epithelial tissue is the squamous epithelial cell. This type of cell is thin and flat which reduces the diffusion distance. In the trachea there are ciliated epithelial cells. The cilia allow mucus to be moved along the trachea. • • Summary • • Multicellular organisms work more efficiently when their cells are specialised to different roles. • Epithelial Cells are specialised for diffusion and moving substances
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