Bio201A and no clue what I am doing.

google it

For you first question, think about what the fluid mosaic model discusses and determine how water molecules and phospholipids would react to each other. Could a fully developed cell function without DNA and why? What is the function of DNA? I think by looking at these questions you can find your answers.

Thank you for the advice!!

Your welcome. Hope it helped.

The fluid-mosaic model describes the plasma membrane of animal cells. The plasma membrane that surrounds these cells has two layers (a bilayer) of phospholipids (fats with phosphorous attached), which at body temperature are like vegetable oil (fluid). And the structure of the plasma membrane supports the old saying, “Oil and water don’t mix.”

Each phospholipid molecule has a head that is attracted to water (hydrophilic: hydro = water; philic = loving) and a tail that repels water (hydrophobic: hydro = water; phobic = fearing). Both layers of the plasma membrane have the hydrophilic heads pointing toward the outside; the hydrophobic tails form the inside of the bilayer.

Because cells reside in a watery solution (extracellular fluid), and they contain a watery solution inside of them (cytoplasm), the plasma membrane forms a circle around each cell so that the water-loving heads are in contact with the fluid, and the water-fearing tails are protected on the inside.



The fluid-mosaic model of plasma membranes.

Proteins and substances such as cholesterol become embedded in the bilayer, giving the membrane the look of a mosaic. Because the plasma membrane has the consistency of vegetable oil at body temperature, the proteins and other substances are able to move across it. That’s why the plasma membrane is described using the fluid-mosaic model.

The molecules that are embedded in the plasma membrane also serve a purpose. For example, the cholesterol that is stuck in there makes the membrane more stable and prevents it from solidifying when your body temperature is low. (It keeps you from literally freezing when you’re "freezing.") Carbohydrate chains attach to the outer surface of the plasma membrane on each cell. These carbohydrates are specific to every person, and they supply characteristics such as your blood type.

The Process:

Cellular respiration occurs in all living things. It takes place within the mitochondria, and its main goal is to produce adenosine triphosphate (ATP). Mitochondria (below) are found in the majority of eukaryotic cells, and their numerous folds serve as locations for the production of ATP molecules. Cellular respiration can be described by a simple ‘formula’ that encompasses all of the factors that play a role in the process.
The formula above starts out with oxygen and a sugar, glucose, on the left hand side, and through a series of reactions and processes that make up cellular respiration, we are left with the end results (right side).

The process of cellular respiration is known as an aerobic process; this means that oxygen is required in order for the process to take place. As you can see, water is one of the results of cellular respiration, and water is formed from the transfer of the hydrogen atoms in glucose to oxygen. The hydrogen transfer plays a very crucial role in cellular respiration, and for that reason, oxygen is fundamental to the production of energy during cellular respiration. The other starting ‘factor’ for cellular respiration is a sugar, and a commonly used fuel is glucose; one glucose molecule can produce up to 38 ATP molecules.

The Stages:

In order to produce the ATP, glucose must be broken down over several steps. These steps can be categorized into the 3 main stages of cellular respiration with the first stage being Glycolysis. During the stage of Glycolysis, one glucose molecule is broken down by two ATP molecules thus creating two new molecules of pyruvic acid. In addition to the two new pyruvic acid molecules that are created, four new ATP molecules will also be produced as a result of the production of the pyruvic acid molecules. Next, the pyruvic acid molecules will convert into acetyl CoA and they will be passed onto the 2^nd stage known as the Citric Acid Cycle (A.K.A. the Krebs Cycle).

Now moving on to the Citric Acid Cycle (also commonly referred to as the Krebs cycle). It was previously mentioned that we now have two acetyl CoA molecules that we got from the pyruvic acid molecules. During the Krebs Cycle, the acetyl CoA are broken down into carbon dioxide molecules. Along with the formation of the two carbon dioxide molecules per each acetyl CoA, one ATP molecule is also made. The Krebs Cycle takes place within the matrix of the inner membrane of the mitochondria. There is an image below depicting the Krebs Cycle in its entirety.

In the picture depicting the Krebs Cycle (middle image), you see that there are two electron carriers in the input column, these are NAD+ and FAD. We will elaborate on these in the final stage of cellular respiration known as the Electron Transport Chain (ETC). The ETC is the 3^rd stage of cellular respiration. It occurs in the inner membrane of the mitochondria. You see that the NAD+ carrier turns into NADH after receiving electrons (this is known as a redox reaction), then the NADH transfers its electrons to the ETC. Each time that an NADH molecule transfers its electrons to the ETC, energy is released. Going back to the main goal of cellular respiration: to create ATP for cellular work, during this final stage of cellular respiration there is an enzyme called ATP synthase that accounts for 34 of the 38 ATP molecules made per glucose molecule.

Thank you!!!

Passive does not requires energy, whereas active transport does. Diffusion is the movement of a molecule across a semi-permeable barrier down its concentration gradient (from a region of high concentration to one of lower concentration).

Dialysis is the movement of solutes (things dissolved in water) across a semipermeable membrane from a more concentrated to a less concentrated state (so if you have a lot of salt inside a dialysis bag, that's sitting in a beaker of water, the salt will move out into the water; if you have a bag full of water sitting in a beaker of salt water, the salt will move into the bag).

Osmosis is the movement of water--specifically water--across a semi-permeable membrane from a region of low solute concentration to a region of high solute concentration (so, in the above example, exactly opposite to the direction of salt movement).

Okay now its starting to make a little since!