- Session Day Time Pre Practical 6 Eukaryotic Cells And Mitosis Cells Are Small Making Them Difficult To See Clearly U 1 (56.59 KiB) Viewed 10 times
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Session(day/time): PRE-PRACTICAL 6 - EUKARYOTIC CELLS AND MITOSIS Cells are small making them difficult to see clearly under a light microscope. Stains are therefore used to give cells a detailed and often precise colour contrast. This is achieved through a physical or chemical interaction between the dye and a cellular component which is often very specific. It is important to realise that no one staining method will demonstrate all details of all structures. In today's practical you will perform an epithelial cheek cell stain to allow the visualisation of the epithelial cells under the light microscope. You will then observe prepared stained slides of mitotic plant and animal cells. The root apex of a plant is ideal for studying stages in mitosis because located within the first few millimetres of each tipis actively dividing tissue, where mitotic cell division proceeds very rapidly. In today's exercise you will also identify the stages of mitosis in plant cells and in animal cells. Please read through the below practical instructions in conjunction with your week 8 lecture notes on 'Cell division - Mitosis' (and revisit your wed 4 lecture notes on Eukaryote cell structure) to help you complete the practical and answer the questions below (in pen). 1. CONCISELY list 3 key structural differences between plant and animal cells. [3 marks) a 2. List each phase of the cell cycle including any subdivisions, for a dividing mammalian cell. Outline the main events that occur and provide an approximate duration where possible [6 marks]
Practical 6 Eukaryotic cols 1 OLOGY A Exercise B. Mitosis in plant cells: Prepared slides Collect a prepared slide of Allium cepa (onion) which is a longitudinal section through the root-tip of the plant (the zone of maximum cell division occurs just behind the root tip in the centre of the root). 2. Using the light microscope (40X obſ)) Identify as many stages of mitosis as possible. 3. Prepare annotated drawings for three stages of mitosis in which you can clearly see the spindle. Refer to the mitosis figure below. 4. Pick a representative field of view.Count a minimum of 100 cells. Yes, you do actually have to count 100 cells in the field of view. This is a common tosk done by scientists (we usually count for more than 100), so it's quite reasonable to expect it of you in today's practical class. While counting the 100 cells in 1 (or more) field(s) of view, identify which phase of the cell cycle they are in. Note: telophase may be confused with prophase - however, the presence of two nuclei in a small cell with a thin wall between them is the best identifier. Tabulate the results. 5. Assuming that a complete cell cycle takes 24 hours and that the numbers of cells in a phase is an indication of the time spent in that phase, calculate the percent time that each cell spends in each of the phases using the equation below: Hours of stage = 24 x Number of cells in stage Total number of cells counted nes M0 Szer yst cur ulde nees Exercise C Mitosis in animal cells: Fish tissue 1. Collect a prepared slide of mitosis in animal cells. 2. Examine the preparation under high power (40X obj)) of the microscope. Identify as many stages of mitosis as possible. Use the figure below as a guide. 3. Make notes in your practical handout on the differences in size and visible structures (such as the spindle fibres) that can been seen between mitotic animal and plant cells. 4. Draw three stages of mitosis in animal cells, Tabulate the approximate proportion of cells in each of the phases of the cell cycle and calculate percent time spent in each phase as done in steps 4 and 5 of exercise B. Figure: Stages of mitosis in animal cells NEW 11:1 3
CUYA Exercises B & C: Mitosis in plant and animal cells. Prepare annotated drawings for three Practical 6. Eukaryotic cells and ]