Non-Protein-Making Organelles

Cell Membrane

The cell membrane is a very complex organelle. In factA statement based on direct observation that is repeatedly confirmed., it’s so complex that I have another mini lecture to tell you about it. Before moving forward in this mini lecture, you only need to know one thing. A cell membrane separates the inside of a cell. It keeps the inside apart from its external environment. As we’ve already seen in class, cell membranes love to take up that pinkish purplish stain. This allows us to see it very clearly. It’s evident in this picture of adipose tissue.

Cytoplasm vs Cytosol

The cytosol is the liquid that is on the inside of the cell. Some of you might be saying wait I thought that was the ICF or the intracellular fluidThe fluid inside a cell, primarily composed of cytosol.. Kind of. If we’re talking about 1 cell, we would call the fluid inside the cell the cytosol. If we were talking about all of the cellsThe basic structural and functional units of life. in your body, I would use the term intracellular fluid. Notice the distinction of 1 cell and all cells. Some of you also might be asking are there cells with no cytosol? It’s not a period not as we know it right now. Life as we know it consists of cells that have an internal liquid structure. In the cytosol, there are tons of negatively charged proteinsLarge molecules made of amino acids with various functions in the body.. It also contains lots of amino acids and a whole lot of potassium(K⁺): Major ICF cation; essential for muscle and nerve function. cations. Students often confuse the term cytosol outside of plasm. The term cytoplasmThe gel-like substance within a cell that contains organelles and cytosol. does refer to the cytosol or the fluid inside the cell but it also includes the organellestructures within a cell that perform specialized functions. that are inside of the cell period in this class we’re usually referring to the cytoplasm and it’s usually a safe bet to use that term oversight or sol period

Villi and Microvilli

Villi and microvilliTiny projections on the surface of epithelial cells that increase surface area for absorption. are projections of the cell membrane. These are not tails. These are not hairs. They do not extend off of the cell membrane. They are actual projections of the cell membrane, as shown in this figure here. We will see villiFinger-like projections in the small intestine that increase surface area for absorption. and microvilli on organs that need to increase their surface area in a small space. Your small intestine and your lungs both need to increase their surface area. This is to serve your needs for oxygen and glucoseA simple sugar that is the main source of energy for cells.. If either of these organs were hollow balloons or tubes, you would not take in glucose fast enough. You also wouldn’t take in oxygen fast enough to keep you alive. I have taught from textbooks before that tell you that the surface area of the lungs could cover a tennis court and i would like to know who actually did that experiment to confirm that period

Cilia (singular: Cilium)

Cilia are tiny hairs on cells located in mucous membranes. It’s the plural form of the word cilium. Recall that mucus membranes line openings to the outside. And they must maintain moisture because the external environment is constantly drying them out. Cilia can sometimes be confused with flagellaLong, whip-like structures used by some cells (e.g., sperm) for movement.. However, flagella are much longer structures, kind of like a tail, whereas ciliaHair-like projections on the surface of some cells that move fluids or particles. are more like hairs. Cilia don’t act alone. There are usually thousands of them, if not more, on the apical surface of epithelial cells on mucous membranes. That’s the fancy way of saying on the cells that line the opening. Cilia will usually beat rhythmically moving the mucus in one direction. In your trachea all of the cilia are waving from bottom to top or inferiorBelow or toward the lower part of the body. to superiorAbove or toward the upper part of the body.. As all of the cilia wave the mucus moves superiorly. You swallow mucus from your trachea into your esophagusThe muscular tube that transports food from the pharynx to the stomach via peristalsis. every moment. You’re unaware of it. Your stomach enzymesProteins that speed up chemical reactions in the body. can break it apart and digest it.

Cytoskeleton

Cytoskeleton functions very much like the bone skeleton of an entire human in providing support for other organelles. The cytoskeleton A network of protein filaments that provide structure, shape, and movement to cells. is an internal network of different types of proteins that are fibrous. There are three types of these proteins which I’m sure you can guess their difference by their names. Microtubules are larger than microfilaments and intermediate filaments are in between. Many years ago it was thought that the cytoskeleton’s purpose was solely a support mechanism to maintain cell shape. However, more research in the 21st century revealed new findings about proteins. It showed that groups of proteins move substances around the cell. They use the cytoskeleton as a network of pathways.

Centrosomes and Centrioles

A centrosome is a pair of centriolesCylindrical structures involved in organizing microtubules and cell division. which are barrel shaped structures. During mitosis or cell division, microtubules extend from the centrosomesThe region near the nucleus that contains centrioles and helps organize the cytoskeleton.. They connect to the kinetochores of the central mirrors of chromosomes. This connection then pulls the sister chromatids to opposite sides of the cell in mitosis.

Flagella

The flagellum is basically a tail. However, instead of moving back and forth repeatedly, this tail has a rotary motion. This rotary motion is much more efficient.  The only cell in the human body that has a flagellum your spermatozoa which is the official name for sperm. The flagellum is a structure found completely outside of the cell membrane. However, it is connected to something called a basal body. This basal body is a large routine that is in the cell membrane. Human sperm exposed to additions higher than 94°F during developmentThe process of growth and differentiation. will not develop a flagellum correctly. This is why testicles both are not within a body cavity but are held external to all body cavities. That external distance reduces the heat of the testicles to approximately 94°F or the temperature at which flagella correctly form. This is also the source of infertility for a lot of men who wear underwear that is tightly binding.

Mitochondria

The other energyThe capacity to do work or cause change. converting organelle is mitochondria.  It’s a common mistake to think that chloroplasts are present only in plants. Mitochondria are often thought to be present only in animals, but they are present in both plants and animals.  Once the plants make glucose from photosynthesis, it is then used by mitochondria to make ATPThe energy currency of cells used for muscle contraction..  For animals, we eat plants to provide the glucose to make ATP.  Either way, it’s a mitochondrion that makes ATP.  Much like chloroplasts, there is a set up of membranes that allows the creation of gradients.  The energy in these gradients are harnessed to make ATP.  Kind of like the Hoover damn, that converts running waterThe universal solvent essential for life. into electricity.  While creating ATP, mitochondria consume oxygen and glucose, producing carbon dioxide and water as waste.  If you’re a plant, that’s awesome. You can use these things to harness the energy of the sun. This enables you to create glucose.  It’s a cycle!

Lysosomes

Lysosomes are basically little stomachs that float around the inside of a cell and digest things like broken down organelles.  The term “lyso” mean ‘To split.”  Rumors have it that it is the origin of the brand name Lysol.  Lysosomes originate from the Golgi apparatus and contain digestive enzymes.  An interesting, but upsetting disease called Tay-sacs comes from a malfunction of lysosomes.  In Tay-sacs disease, the lysosomes do not contain an enzyme for lipid breakdown.  This is a genetic disease in which the DNA code for the enzyme is not present.  The lysosomes become engorged with lipidsOrganic molecules including fats, oils, and steroids. from the inability to break them down.  As the lysosomes fill and fill, they crowd out other organelles of cells and essentially becomes fatal.

Peroxisomes

Our little vesicles of death. Different than lysosomes, peroxisomes are present to break down unfamiliar substances. A peroxisome will not break down and recycle organelles. It focuses on breaking down things that have entered the cell by endocytosisThe process of a cell engulfing material by wrapping its membrane around it.. Macrophages, which are cells capable of consuming bacteria and viruses, use peroxisomes to kill foreign substances. If you work in a laboratory setting, you will most likely use ethanol or rubbing alcohol to sterilize instruments. You may also use very concentrated hydrogen peroxide to sterilize things. Peroxisomes use that concept as well. Peroxisomes are little vesicles that are full of very concentrated hydrogen peroxide. When the peroxisome fuses with the vessel created from endocytosis, the hydrogen peroxide acts quickly. It kills the invading substance immediately. In this picture the hydrogen peroxide is the green little pac-mans. They poke holes in the cell membrane of that brown little bacterium. Just poking holes in a cell membrane is quite effective. It causes water to move by way of osmosis out of the bacterium. This action shrivels the bacterium.