Tutor profile: Christina D.
Describe how bacteria share genes through conjugation, transformation, and transduction.
Bacteria can transfer genes in a variety of way including conjugation, transformation, and transduction. Bacterial transfer of genes allows them to pass on genes that help them to survive and adapt to their environment. First, conjugation is the process of transferring genetic material through direct contact between two bacteria. This can happen via a pilus, which is like a a bridge that one bacterium extends to another. Once attached, the donor bacterium can then transfer one strand of its plasmid DNA (which is circular) to the other bacterium through the pilus. The donor bacterium and the recipient bacterium will then synthesize complementary strands to make complete plasmids. The recipient bacterium now has the genes from the donor's plasmid and can produce proteins coded for on that plasmid, which can be advantageous to bacterial survival. Transformation can occur through the process of a bacterial cell taking up DNA fragments from a bacterial cell that has lysed. The bacterium can then incorporate this DNA into its own genetic material. Lastly, transduction is the process through which a bacteriophage, which is essentially a virus that infects bacteria, transfers genetic material between bacteria. A bacteriophage infects one bacterium and incorporates genes from that bacterium into the phage's own genetic material. When the phage infects another bacterium, it transfers the first bacterium's genetic material into the next bacterium. That bacterium can then incorporate the transferred genetic material into its own genome.
Describe the structure, purpose, and function of the nephron of the kidney. Include an example of a hormone that acts on the nephron and the effect(s) it produces.
The nephron is the functional unit of the kidney. It filters the blood, produces urine, and allows the body to excrete metabolites, ions, wastes, and water. There are over a million nephrons in each kidney which emphasizes their importance in maintaining fluid balance, reabsorbing important solutes, and getting rid of toxins. The nephron consists of an afferent and efferent arteriole (it's helpful to connect these terms to nerves!) which supplies to and takes filtered blood from the kidney, respectively. Next, the renal corpuscle is the place where filtration of the blood takes place. It consists of the glomerulus, which is a capillary network, and the Bowman's capsule which is the space where filtrate begins to form. The nephron then continues into the proximal tubule and then into the loop of Henle. The loop of Henle is made of the thin descending limb and the thick ascending limb which are each permeable to different things. Next, filtrate flows into the distal tubule which loops back around to pass by the glomerulus where paracrine signaling can take place (this has an effect on blood pressure regulation). Finally, the filtrate flows into the collecting duct which joins with other nephrons and directs urine out of the kidney through various structures. The nephron works through three main processes: filtration, reabsorption, and secretion. Filtration is the process of filtering substances out of the blood and into the tubule of the nephron. All filtration occurs in the renal corpuscle. Reabsorption is the process of pulling solutes, water, and other compounds back into the blood depending on body osmolarity and hydration, for example. Secretion is the process of secreting extra substances into the filtrate to remove them from the blood. This can help enhance excretion of a substance. One example of a hormone that acts on the nephron loop is vasopressin, also known as ADH, which acts on the collecting duct to increase water reabsorption when plasma osmolarity gets too high, blood pressure gets too low, and blood volume gets too low. Increasing water reabsorption decreases plasma osmolarity as well as increases blood volume and thus increases blood pressure.
Given the equation 5(x+3)=4(2x-4), solve for x and describe what mathematical property would you use.
For this equation, you would use the distributive property for the first step which involves distributing the number in front of the parentheses to all values inside the parentheses. Starting with the left-hand side of the equation, 5 would be distributed to x and 3, resulting in 5 times x plus 5 times 3. For the right side of the equation, 4 would be distributed to 2x and 4. Remember the minus sign! This would result in 4 times 2x minus 4 times 4. So, we have 5x + 15=8x - 16. In order to solve for x, we need to get x by itself on one side, so we add 16 to both the left and right sides of the equation which results in 5x +31=8x. Next, we would subtract 5x from both sides of the equation which leaves us with 31=3x. The final step is to divide both sides by 3 in order to have x by itself which gives us a final answer of 10.3 (rounded to the nearest tenth).
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