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Does a pulp cell contain all the elements that a 'normal' plant cell contains?
I've searched for an hour to find more information about this but couldn't find anything useful. Is the pulp cell the exception from the general size range of most eukaryotic plant cells, normally between 10 - 100 µm?
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They are not individual cells. In fact, the "juice sacs" (as they are known) are actually specialized, multicellular hairs:
Juice sacs originate as multicellular hairs in which the interior of the enlarged distal part breaks down and fills with liquid. The juice sacs constitute the fleshy, edible pulp of an orange and are the source of the sweet juice.
(Quote and image from Fruit Terminology, palomar.edu)
This is from a botany course; if for some reason that isn't reputable enough, check out the book Anatomy of Seed Plants by Katherine Esau (1960).
Effects of hydrogen peroxide treatment on pulp breakdown, softening, and cell wall polysaccharide metabolism in fresh longan fruit
H2O2 accelerated pulp breakdown development and pulp softening in harvested longans.
H2O2 up-regulated expression levels of longan pulp cell wall degrading-related genes.
H2O2 increased activities of cell wall-degrading enzymes in pulp of harvested longans.
H2O2 reduced the contents of cell wall polysaccharides in pulp of harvested longans.
H2O2 induced longan pulp breakdown and softening via raising cell wall disassembly.
Plant Cell Organelles
The following are examples of structures and organelles that can be found in typical plant cells:
- : This thin, semi-permeable membrane surrounds the cytoplasm of a cell, enclosing its contents. : This rigid outer covering of the cell protects the plant cell and gives it shape. : Chloroplasts are the sites of photosynthesis in a plant cell. They contain chlorophyll, a green pigment that absorbs energy from sunlight. : The gel-like substance within the cell membrane is known as cytoplasm. It contains water, enzymes, salts, organelles, and various organic molecules. : This network of fibers throughout the cytoplasm helps the cell maintain its shape and gives support to the cell. : The ER is an extensive network of membranes composed of both regions with ribosomes (rough ER) and regions without ribosomes (smooth ER). The ER synthesizes proteins and lipids. : This organelle is responsible for manufacturing, storing and shipping certain cellular products including proteins. : These hollow rods function primarily to help support and shape the cell. They are important for chromosome movement in mitosis and meiosis, as well as cytosol movement within a cell. : Mitochondria generate energy for the cell by converting glucose (produced by photosynthesis) and oxygen to ATP. This process is known as respiration. : The nucleus is a membrane-bound structure that contains the cell's hereditary information (DNA).
- Nucleolus: This structure within the nucleus helps in the synthesis of ribosomes.
- Nucleopore: These tiny holes within the nuclear membrane allow nucleic acids and proteins to move into and out of the nucleus.
- Chorion: The chorion is a membrane formed by extraembryonic mesoderm and trophoblast. The chorion undergoes rapid proliferation and forms the chorionic villi. These villi invade the uterine lining and help form the fetal portion of the placenta.
- Yolk Sac: The yolk sac (or sack) is a membranous sac attached to the embryo and formed by cells of the hypoblast. The yolk sac provides nourishment to the early embryo. After the tubular heart forms and starts pumping blood during the third week after fertilization, the blood circulates through the yolk sac, where it absorbs nutrients before returning to the embryo. By the end of the embryonic stage, the yolk sac will have been incorporated into the primitive gut, and the embryo will obtain its nutrients from the mother&rsquos blood via the placenta.
- Amnion: The amnion is a membrane that forms from extraembryonic mesoderm and ectoderm. It creates a sac, called the amniotic sac, around the embryo. By about the fourth or fifth week of embryonic development, amniotic fluid begins to accumulate within the amniotic sac. This fluid allows free movements of the fetus during the later stages of pregnancy and also helps cushion the fetus from potential injury.
- Always use gloves on your hands and goggles for your eyes when dealing with blood.
- Do all of these experiments under adult supervision.
Comparison of cell wall metabolism in the pulp of three cultivars of 'Nanfeng' tangerine differing in mastication trait
Background: Like sweet orange (Citrus sinensis), tangerine (Citrus reticulata) is another citrus crop grown widely throughout the world. However, whether it shares a common mechanism with sweet orange in forming a given mastication trait is still unclear. In this study, three 'Nanfeng' tangerine cultivars, 'Yangxiao-26' ('YX-26') with inferior mastication trait, elite 'YX-26' with moderate mastication trait and 'Miguang' ('MG') with superior mastication trait, were selected to investigate the formation mechanism of mastication trait.
Results: 'MG' had the lowest contents of total pectin, protopectin and lignin and the highest gene expression levels of citrus polygalacturonase (PG) and pectin methylesterase (PME) at the end of fruit ripening, whereas 'YX-26' had the lowest water-soluble pectin (WSP) content, the highest lignin content and the lowest PG and PME expression levels. The contents of cellulose and hemicellulose were similar among the three tangerines.
Conclusion: The fruit mastication trait of C. reticulata was determined by the proportions of WSP and protopectin as well as lignin content, not by cellulose and hemicellulose contents. Pectin content could be a major contribution to the feeling of mastication trait, while PG and PME exhibited an important role in forming a given mastication trait according to the present results as well as previous results for C. sinensis.
Keywords: Citrus fruit mastication trait lignin pectin pectin methylesterase polygalacturonase.
Like animals, plants contain cells with organelles in which specific metabolic activities take place. Unlike animals, however, plants use energy from sunlight to form sugars during photosynthesis. In addition, plant cells have cell walls, plastids, and a large central vacuole: structures that are not found in animal cells. Each of these cellular structures plays a specific role in plant structure and function.
In plants, just as in animals, similar cells working together form a tissue. When different types of tissues work together to perform a unique function, they form an organ organs working together form organ systems. Vascular plants have two distinct organ systems: a shoot system, and a root system. The shoot system consists of two portions: the vegetative (non-reproductive) parts of the plant, such as the leaves and the stems, and the reproductive parts of the plant, which include flowers and fruits. The shoot system generally grows above ground, where it absorbs the light needed for photosynthesis. The root system, which supports the plants and absorbs water and minerals, is usually underground. Figure 6 shows the organ systems of a typical plant.
Figure 6. The shoot system of a plant consists of leaves, stems, flowers, and fruits. The root system anchors the plant while absorbing water and minerals from the soil.
Trichomes (epidermal hairs) are tiny hairs located on the epidermal tissue. Like stomatal guard cells, trichomes are also more specialized and thus have well-defined shapes that contribute to their functions. The trichome of Arabidopsis has been well studied and described over the years.
With large single cells measuring between 200 and 300um in length, different types of trichome have been shown to play a protective role in plants where they protect plants from predators as well as organisms that cause diseases.
Here, the trichome achieves this by either trapping or poisoning the animal to protect the plant. For some of the plants, however, trichomes simply function as barriers that protect inner tissues of leaves.
Unlike the other cells of the epidermal tissue, studies have shown that cell division is arrested in trichomes. Several rounds of endoreduplication are therefore responsible for the expansion of the cell as pavement cells continue dividing.
Several structures form simultaneously with the embryo. These structures help the embryo grow and develop. These extraembryonic structures include the placenta, chorion, yolk sac, and amnion.
The placenta is a temporary organ that provides a connection between a developing embryo (and later the fetus) and the mother. It serves as a conduit from the maternal organism to the offspring for the transfer of nutrients, oxygen, antibodies, hormones, and other needed substances. It also passes waste products (such as urea and carbon dioxide) from the offspring to the mother&rsquos blood for excretion from the body of the mother.
Figure (PageIndex<5>): The placenta is a lifeline that develops between the embryo and mother. It allows the transfer of substances between them. The amniotic cavity is surrounded by a membrane called the amnion, which forms as a sac around the developing embryo. The yolk sac nourishes the early embryo, and the chorion develops into the fetal portion of the placenta.
The placenta starts to develop after the blastocyst has implanted in the uterine lining. The placenta consists of both maternal and fetal tissues. The maternal portion of the placenta develops from the endometrial tissues lining the uterus. The fetal portion develops from the trophoblast, which forms a fetal membrane called the chorion (described below). Finger-like villi from the chorion penetrate the endometrium. The villi begin to branch and develop blood vessels from the embryo.
As shown in Figure (PageIndex<5>), maternal blood flows into the spaces between the chorionic villi, allowing the exchange of substances between the fetal blood and the maternal blood without the two sources of blood actually intermixing. The embryo is joined to the fetal portion of the placenta by a narrow connecting stalk. This stalk develops into the umbilical cord, which contains two arteries and a vein. Blood from the fetus enters the placenta through the umbilical arteries, exchanges gases, and other substances with the mother&rsquos blood, and travels back to the fetus through the umbilical vein.
Chorion, Yolk Sac, and Amnion
Besides the placenta, the chorion, yolk sac, and amnion also form around or near the developing embryo in the uterus. Their early development in the bilaminar embryonic disc is illustrated in Figure (PageIndex<5>).
Plants are autotrophs they produce energy from sunlight through the process of photosynthesis, for which they use cell organelles called chloroplasts. Animal cells do not have chloroplasts. In animal cells, energy is produced from food (glucose) via the process of cellular respiration. Cellular respiration occurs in mitochondria on animal cells, which are structurally somewhat analogous to chloroplasts, and also perform the function of producing energy. However, plant cells also contain mitochondria.
All animal cells have centrioles whereas only some lower plant forms have centrioles in their cells (e.g. the male gametes of charophytes, bryophytes, seedless vascular plants, cycads, and ginkgo).
Plant Cells vs. Animal Cells
However, they have some apparent differences. Firstly, plant cells have a cell wall that surrounds the cell membrane, whereas animal cells do not. Plant cells also possess two organelles that animal cells lack: chloroplasts and a large central vacuole.
These additional organelles allow plants to form an upright structure without the need for a skeleton (cell wall and central vacuole), and also allow them to produce their own food through photosynthesis (chloroplasts).
- Ask your teacher to get you 3ml of red blood cells (centrifuged blood).
- Make salt solutions with the concentrations similar to the plant cells.
Note: Since you will be adding 1ml of blood to your total of 5ml solutions, you have to calculate how much of salt you need to dissolve in the 4ml solution that you will be adding to the blood to make the total concentration of salt equal to 0%, 0.9%, and 5%. Carefully mix the blood gently in the solution without spilling. Make note of any differences in the brightness of color in each of the solutions compared to the pure red blood solution (control).
How does the percentage of intact red blood cells in each slide vary? Is this difference statistically significant? Explain. What are the some of the limitations of this method?
Using these results, explain the difference between the effects of tonicity in animals cells in general compared to plant cells.