This past week in lab we got up close and personal with some familiar foods to learn about why they look and feel the way they do. The first plant we examined was the red cabbage. We were given cabbage leaves pretreated with digestive enzymes, which we then washed, filtered, and centrifuged. All of this was done in order to remove the cell wall leaving the protoplast behind. By removing the cell walls of the cabbage cells we were able to see them in a whole new light. While normally the cell wall would cause cells to be rigid and rectangular, these cells were circular. The outward pressure that is exerted by vacuoles is easy to see once the counterbalance of the cell wall is removed! Speaking of vacuoles, the vacuoles of the red cabbage are what gives it its distinctive color. As can be seen in the picture many of the smaller vacuoles are filled with blue and purple anthocyanin pigments. These pigments have been shown to have benefits for human health and may even help to prevent cancer. (On a personal note, over the summer I worked on a farm and was able to take home a lot of produce. One evening I made a stir fry with possibly the most potent and powerful purple cabbage in the world and immediately after had the first migraine I've had in years. I don't know that it was the anthocyanins but after that I definitely believe in the power of cabbages.) After we got a good look at the insides of a cell, and watched the cytoplasm move around for a while, we exposed our protoplasts to several different types of solution to see how they would react. Normally a plant cell, unlike an animal cell, has the cell wall to shield them so they can be a bit more resistant to things like changes in the concentration of solutes around them. However, because protoplasts don't have a cell wall, we thought that they would react more along the lines of animal cells. Our predictions were right, and the protoplasts reacted visibly to the different solutions that we tried. Pictured about is how they shriveled up after being treated with salt, but we also exposed them to pure water (some of them exploded) and detergent (membranes were basically melted away, but not very quickly or anything). As well as looking at the insides of cabbages, last week we also covered the insides of other edible plants. Specifically we looked at the ground tissue of pears and avocados. We observed their sclerenchyma cells, which are what gives these fruits their texture. We stained both the pear and the avocado with TBO, which stained the lignified cell walls of the sclerenchyma blue so they were easy to see. When we looked at the pear, it was easy to see that there were a lot of sclerenchyma cells as basically the whole sample was tinted blue. These are the brachysclereids or "stone cells" that you can feel when you eat pears. It was neat to be able to see the pit canals that went through the cell walls, especially when we looked at 400x magnification. It definitely explained why pears have the texture that they do! We also stained avocado with TBO in order to look at its sclerenchyma cells. Like the pear, it had brachysclereids, but it had fewer of them and they were more sprinkled throughout the tissue. In the images above, the brachysclereids are the dark blue dots. Overall the avocado cells seemed a lot softer and blobbier looking, while the pear cells had more clearly defined borders. Avocados are much creamier and softer than pears in general so this makes sense. In fact I would rarely describe an avocado as gritty at all and previously wouldn't have compared it to a pear in any way.
All in all, it was very cool to get to look at some common fruits and veggies under the scope! I really like looking at things that I actually eat because it's knowledge that is directly connected to my life outside of class. Out of everything that we looked at last week, I think I was most interested in the avocado slide because it wasn't what I expected an avocado to look like. I definitely didn't think an avocado would be a great candidate for staining, or that avocado fruits had any particular structure besides just mush. I was happily surprised to be proved wrong! -Ally Kershner
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Submitted by Brandon Quann
Hello and welcome to my very first blog post ever. I’ve decided to add my own twist to my post so I've included some of my favorite Kanye West instrumentals to add to the "ambiance" of my post, to start the playlist press play down below.
This week in lab we learned about the inner workings of seeds, seedlings, and plant cells. We carried out experiments by conducting dissections, staining plant tissues with various biological stains, preparing and viewing microscope slides, and illustrating our findings. In our lab we observed numerous plants and tissues types, however I will be focusing on our experiments with Elodea cells as well as plastids within bell peppers.
Who knew pondweed could be so interesting?
It has been quite some time since my high school biology class so when I saw that we would be studying Elodea cells in lab this week I had a trip down memory lane to my first encounter with the plant. Our observations began with making a simple wet mount of the leaf and viewing it under 100x and 400x magnification. Once we had our slides made we began searching for and sketching trichomes, chloroplasts, nuclei, vacuoles, cell walls, and any other organelles we could find.
Elodea leaves were then stained with a different biological stain called Toluidine Blue O (TBO). TBO creates a variety of colors when in contact with different tissue types, the structures/ organelles and their corresponding stain color are in the following list: pectin found in cell walls, cell wall tissue, and nuclei. Based on these corresponding colors it is apparent that most abundant tissue found in Elodea leaves is from the cell wall (see photo above). A few nuclei are also visible from the stain however this is the first time I have used TBO so I am not sure if I allowed the stain enough time to work to its full potential.
How much do Plastids cost?
dependent on environmental conditions or maturity of the fruit. These 3 different types of plastids have their own individual phenotypic differences as well as different functional roles in the cell. The photo above on the left shows the tissue of a green bell pepper with high levels of chloroplasts, these chloroplasts are the main site of photosynthesis and appear green because of the chlorophyl inside. However if the fruit is left on the plant to mature for a longer period of time the chloroplasts will be converted into chromoplasts. These chromoplasts are non-photosynthetic and work to synthesize and store pigments called carotenes, which are yellow, orange, or red in color (depending on how long they are left to mature). The conversion of chloroplasts into chromoplasts can be seen in the photo above on the right which shows a tissue sample of a red bell pepper full of red chromoplasts.
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AuthorContent is created by students participating in the Plant Structure course at Oregon State University for Winter 2017. Archives
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