Unit 3 Reflection

In Unit 3, we learned about the function, structure, and importance of the cell. There are two main types of cells, prokaryotes, a simple cell with no nucleus only one chromosome, usually bacteria, and eukaryotes, multi-organelled, nucleus-containing, complex cells. The cell has many different structures that have specialized functions and work together to help sustain life. For example, the nucleus gives the instructions to the cell, the ribosomes assemble the proteins, the endoplasmic reticulum synthesizes the proteins, and the golgi apparatus ships proteins via vesicles throughout the cell. In addition, we learned about osmosis and diffusion, where molecules diffuse from a high concentration to low concentration until equilibrium. During osmosis, water, a solvent, diffuses through the cell towards the higher solute concentration, in order to create an equilibrium. Isotonic solutions have equal solute concentration inside and outside of the cell, hypertonic solutions have a higher concentration of solutes outside of the cell, and hypotonic solutions have a higher solute concentration inside the cell. In the beginning there was a prokaryote, but then there came autotrophs, which could make their own food. Soon, heterotrophs came into play, which could consume its food, and some bacteria survived when eaten by a cell, turning into the first eukaryote, the cell provided protection for the bacteria, while the bacteria provided food for the cell. This became known as the endosymbiotic theory.



Autotrophs use light to create food using photosynthesis, a process that occurs in the leaf of a plant. Inside the leaf chlorophyll contains stacks of thylakoids called granum. There are two main processes in photosynthesis, light dependent reactions, where light is absorbed in the thylakoids an produces NADPH and ATP, by ATP Synthase, and water is split, releasing oxygen and pumping hydrogen ions into the thylakoid membrane, and light independent reactions(Calvin Cycle) in the stroma, where sugar, or glucose, is produced using carbon dioxide, ATP, and NADPH from light reactions. Both heterotrophs and autotrophs do cellular respiration, which is divided into three steps, glycolysis, which occurs in the cytoplasm and creates two ATP and pyruvic acid, the Krebs Cycle, which converts molecules from glycolysis into 2 ATP, carbon dioxide, and NADH and FADH2, and the electron transport chain, which uses oxygen, NADH, and FADH2 to convert ADP into ATP. In total 36 ATP is produced from one glucose molecule.

During the unit, I felt that I understood the material well, but the concepts, at times, could be very tricky to grasp. The number of organelles and their specialized jobs could be confusing and the osmosis and diffusion concept was sometimes vague in my mind. When we got to the photosynthesis and cellular respiration section, the concepts were confusing, but as we did more things to help reinforce the ideas, such as drawing diagrams and reviewing photosynthesis and cellular respiration, I could begin to see the puzzle pieces being put together. Unfortunately, we missed out on some labs because of safety issues, which was a setback and a disappointment, but it was a good lesson about the consequences of not being safe and organized. Despite the setbacks, I felt that I was successful in learning about the cell and how life was created because of this extraordinary thing.