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CELLS: ANIMAL CELLS 13 FEBRUARY 2013 Lesson Description In this lesson we will discuss the following: The Cell Theory Terminology Parts of a Microscope The definition of a Cell Examples of Cells Type of Cells Plant and Animal Cells Parts of Animal Cells: Organelles Key Concepts The Cell Theory All living things are made up of cells and are either unicellular or multicellular. Cells are the smallest working units of all living things that show the characteristics and properties of life. All cells come from preexisting cells through cell division. How do living organisms compare in size: Diagram adapted from Via Afrika Life Sciences Grade 10 Learners Book Important Terms: Cell Cell membrane Centriole Centrosome Chromatin network Cytoplasm Endoplasmic reticulum Golgi body Mitochondrion Nucleus Nucleolus Nuclear membrane Organelle Phagocytic Pseudopodia Ribosomes Vacuole Parts of a Microscope: Diagram adapted from Via Afrika Life Sciences Grade 10 Learners Book Examples of Cells Diagram of a Red blood cell Diagram of a Nerve cell Diagram of a Bacterial cell Diagram of an Amoeba cell Type of Cells Prokaryotic Eukaryotic Prokaryotic Cells Diagram of a Bacterial Cell Characteristics of Prokaryotic cells No true nucleus ,have stands of DNA or RNA Do not have structures surrounded by membranes Few internal structures One-celled organisms, e.g. Bacteria Eukaryotic Cells Diagram of a Plant Cell Characteristics of Eukaryotic cells Have a true membrane bound nucleus Have structures surrounded by membranes Complex internal structures Typical Animal and Plant Cells Diagram showing the cross section of a typical animal cell Diagram showing the cross section of a typical plant cell Parts of Animal Cells A typical animal cell consists of the following parts: A Cell membrane A Nucleus The Cytoplasm The various organelles Cell Membrane Outer membrane of cell that controls movement in and out of the cell Double layer Diagram showing the structure of a cell membrane The fluid mosaic model describes the structure of the plasma membrane. Different kinds of cell membrane models have been proposed, and one of the most useful is the Fluid-mosaic model. In this model the membrane is seen as a bilayer of phospholipids in which protein molecules are embedded. Channels/pores - A channel in the cell's plasma membrane. This channel is made up of certain proteins whose function is to control the movement of food and water into the cell. These channels are made up of certain proteins. Nucleus Diagram showing the structure on a nucleus The nucleus is the control center of the cell. It is the largest organelle in the cell and it contains the DNA of the cell. The DNA of all cells is made up of chromosomes. DNA (Deoxyribonucleic Acid) contains all the information for cells to live, perform their functions and reproduce. Inside the nucleus is another organelle called the nucleolus. The nucleolus is responsible for making ribosomes. The circles on the surface of the nucleus are the nuclear pores. These are where ribosomes and other materials move in and out of the cell. The Cytoplasm Diagram showing the internal contents of Cytoplasm Cytoplasm refers to the jelly-like material with organelles in it. If the organelles were removed, the soluble part that would be left is called the cytosol. It consists mainly of water with dissolved substances such as amino acids, vitamins and nutrients in it. Cellular Organelles Mitochondrion Diagram showing the electron micrograph of a mitochondrion Mitochondria are membrane-enclosed organelles distributed throughout the cytosol of most eukaryotic cells. Their main function is cellular respiration in which y convert the potential energy of food molecules into ATP. Every type of cell has a different amount of mitochondria. There are more mitochondria in cells that have to perform lots of work, for example- your leg muscle cells, heart muscle cells etc. Other cells need less energy to do their work and have less mitochondria. Diagram showing the internal structure on a mitochondrion Structure of Mitochondrion Mitochondria have: an outer membrane that encloses the entire structure an inner membrane that encloses a fluid-filled matrix between the two is the intermembrane space the inner membrane is elaborately folded with shelf like cristae projecting into the matrix. Ribosomes Diagram showing the structure of a ribosome Ribososmes are organelles that help in the synthesis of proteins. Ribosomes are made up of two parts, called subunits. They get their names from their size. One unit is larger than the other so they are called large and small subunits. Both these subunits are necessary for protein synthesis in the cell. When the two units are docked together with a special information unit called messenger RNA, they make proteins. Some ribosomes are found in the cytoplasm, but most are attached to the endoplasmic reticulum. While attached to the ER, ribosomes make proteins that the cell needs and also ones to be exported from the cell for work elsewhere in the body. Endoplasmic Reticulum Diagram showing the structure of the endoplasmic reticulum It is a network of membranes throughout the cytoplasm of the cell. There are two types of ER. When ribosomes are attached it is called rough ER and smooth ER when there are no ribosomes attached. The rough endoplasmic reticulum is where most protein synthesis occurs in the cell. The function of the smooth endoplasmic reticulum is to synthesize lipids in the cell. The smooth ER is also helps in the detoxification of harmful substances in the cell. Lysosomes Diagram showing the structure of Golgi and lysosomes. Lysosomes receive cellular and endocytosed proteins and lipids that need digesting. The metabolites that result are transported either by vesicles or directly across the membrane. Lysosomes basically function as the cell's recycling compartment Golgi Complex Diagram showing the structure of Golgi complex It is organelle in the cell that is responsible for sorting and correctly shipping the proteins produced in the ER. Just like our postal packages which should have a correct shipping address, the proteins produced in the ER, should be correctly sent to their respective address. In the cell, shipping and sorting done by the Golgi complex. It is a very important step in protein synthesis. If the Golgi complex makes a mistake in shipping the proteins to the right address, certain functions in the cell may stop. Vesicles Vesicles- This term literally means "small vessel". This organelle helps store and transport products produced by the cell. Some vesicles deliver materials to parts of the cell and others transport materials outside the cell in a process called exocytosis Cilia Diagram showing the structure of Cilia Cilia are thread-like projections of certain cells that beat in a regular fashion to create currents that sweep materials along Flagella Diagram showing the structure of flagella Flagella may extend to the rear of a cell and push it forward by snakelike wriggling, or stick out in front and draw it along. We humans possess both flagella and cilia. Each sperm cell is propelled by a trailing flagellum that accelerates the little torpedo forward in its quest to fertilize an egg. Centrosome Diagram showing the structure of centrosome and centriole The centrosome, is an area in the cell where microtubules are produced. Plant and animal cell centrosomes play similar roles in cell division, and both include collections of microtubules, but the plant cell centrosome is simpler and does not have centrioles. During animal cell division, the centrioles replicate (make new copies) and the centrosome divides. Centriole (animal cells only) Diagram showing the structure of centriole Each centriole is a ring of nine groups of fused microtubules. There are three microtubules in each group. Microtubules (and centrioles) are part of the cytoskeleton. In the complete animal cell centrosome, the two centrioles are arranged such that one is perpendicular to the other. Questions Question 1: The following flow chart illustrates the relationship between two important processes found in the cells of plants. a.) Identify the metabolic processes that organelles X and Y control respectively. (2) b.) Name the carbohydrate that is formed by X and used by Y. (1) c.) Provide labels for parts A, B and C. (3) d.) Give ONE structural adaptation of each organelle and describe how this enables the organelle to function efficiently. (4) [10] Question 2: The following diagram illustrates a light microscope used in a Life Sciences laboratory to study microscopic structures. Study the diagram and answer the questions. a.) The table below contains a list of labels in column A. Match the letters in the diagram with the correct labels and write the letter in column B. Column A i. Objective lens ii. Fine adjustment knob iii. Body tube Column B (3) b.) The table below contains a list of different functions in column A. Match the letters in the diagram with the correct function and write the letter in column B. Column A i. This part moves the body tube to focus the object clearly.(big movement) ii. The lower lenses, which are moveable, allowing you to view objects under different magnification. iii. This part reflects light onto the slide. Column B (3) Question 3: Consider the following mind map: Write a paragraph using the mind map above. Ensure that you include all the topics and bullet points in the mind map. Your paragraph should not be longer than one page. The following rubric will be used to mark your paragraph. Criteria Ability to express themselves scientifically Biological correctness and use of terminology. 1 2 3 Facts not clear and not linked. Many grammatical errors. Confusion. Many biological errors. Some flaws of information. Some clear facts. Few errors. Vague understanding and interpretation of mind map. Clear facts, but not all linked yet. Some errors. Adequate understanding and interpretation of mind map. 4 Improved linking of facts. Few errors of impact. Almost everything biologically correct. Links Magnification simulation http://www.cellsalive.com/howbig.htm Animal / Plant Cell http://www.cellsalive.com/cells/cell_model.htm 3D animation of a cell: http://www.xvivo.net/the-inner-life-of-the-cell/ 5 Facts clearly expressed and linked. No errors. Mind map perfectly understood and interpreted. Additional info used. Total