PLEASE HELP I'M TAKING THE SEMESTER QUIZ!!!!!

How do temperature and concentration of monounsaturated phospholipids change the rate at which molecules permeate the plasma mem

Nikitich [7]

Answer: At low temperatures the fluidity of the membrane decreases and it favors fluidity. The higher the concentration of unsaturated fatty acids, the less tightly the phospholipids can bind and the more fluid (more permeable).

Explanation:

The plasma membrane is a lipid layer that delimits the entire cell, dividing the extracellular medium from the intracellular (the cytoplasm of a cell). They are composed of phospholipids, which are molecules composed of glycerol, a phosphate group and two lipid chains (such as fatty acids). Glycerol is a three-carbon molecule that functions as the backbone of this membrane. A geometry is formed that allows the phospholipids to line up side by side to form broad sheets. They are insoluble in water, but their unique geometry causes them to aggregate in layers without any energy input, as they possess a hydrophilic phosphate head and a hydrophobic tail consisting of the two fatty acid chains. The hydrophilic heads of the phospholipids in a bilayer membrane face outward and are in contact with the aqueous fluid inside and outside the cell. Because water is a polar molecule, it readily forms electrostatic (charge-based) interactions with the phospholipid heads.

Selective permeability is a property of the plasma membrane and other semipermeable membranes that allow only certain particles to pass through them. In this way, those particles that are needed by the cell can enter the cell and those that are not useful to the cell are prevented from entering. In the same way, the cell can eliminate the particles it has produced as waste. In this way, the entry and exit of substances through the membrane is regulated and the correct functioning of the cell is achieved.

For a particle to be able to cross the plasma membrane it must have a size equal to or smaller than the pores of the membrane, it must have the opposite charge to the charge of the membrane or simply have a neutral charge, and if it is larger than the pores it must be dissolved in a solution, decreasing its size and thus be able to enter the cell through the membrane.

Plasma membranes are fluid and this fluidity depends on their lipid composition and temperature. Depending on the temperature, membrane lipids can be found in two different states or phases: gel (solid-like, with more rigid hydrocarbon chains) and liquid crystal (more fluid, with more mobile hydrocarbon chains). At low temperatures the fluidity of the membrane decreases and in these conditions the increase of its concentration favors fluidity. The temperature at which the transition from one state to the other occurs is the phase transition temperature (Tc). At values below Tc, the bilayer is in the gel state and at higher values it passes to the liquid crystal. It should be noted that there is an equilibrium between the gel state and the liquid crystal state and that the characteristics of the lipids of the bilayer condition the transition temperature. In the case of bilayers consisting of only one type of lipid, the Tc is well defined. But biological membranes are complex lipid mixtures and the transition from one state to another occurs over a range of temperatures. The presence of short-chain or unsaturated fatty acids reduces the transition temperature, while saturated fatty acids and the increase in the length of the hydrocarbon chains cause this temperature to rise. Then, phospholipids with unsaturated fatty acid tails cannot bind as tightly due to the bent structure of their tails. For this reason, a membrane of unsaturated phospholipids remains fluid at lower temperatures than a membrane of saturated phospholipids.

The fluidity of a membrane is the ability of a molecule to move through it. In short, the higher the concentration of unsaturated fatty acids, the less tightly the phospholipids can bind and the more fluid (more permeable) the membrane will be even at low temperatures. However, at low temperatures the fluidity of the membrane decreases (lower permeability) but the effect will depend on the composition of the fatty acids. To determine the exact permeability, it is necessary to relate the concentration of unsaturated bonds and the length of the fatty acids in the phospholipids and the temperature.

8 0

2 years ago

Which of these statements best compares gravitational and electromagnetic forces in the solar system? (2 points) Electromagnetic

Soloha48 [4]

Gravitational is only attracted and electromagnetic is both atrractive and repulsive since it depends what you are talking about

6 0

2 years ago

Which factor does not greatly influence the rate of

jonny [76]

Answer:

a. transcription

Explanation:

Sugar transport in phloem is referred to as pressure flow and it involves the movement of sugar through the phloem vascular tissue from the regions where sugar is synthesized (by photosynthesis) to other parts of the plant's body that require sugar.

The parts of plants where sugar is synthesized (usually the leaf) is known as sugar source while the parts where they are transported is referred to as the source. Sources are usually areas of of high osmotic concentration and high water pressure while sinks are usually areas of low osmotic concentration and low water pressure.

Hence, sugar transport in the phloem can be said to be influenced by the rate of sugar production at the source (rate of photosynthesis), turgor pressure as well as sugar concentration in sinks and sources.

The only option that has no known effect on sugar transport in the phloem is transcription.

The correct option is a.

7 0

3 years ago

As hominids evolved, they created increasingly sophisticated tools. Based on this information, which of

Igoryamba

Answer:

In order to communicate how to make the tools, they must have been capable of language.

Explanation:

3 0

3 years ago

Read 2 more answers

How does carbon not get lost when it moves through the carbon cycle

Greeley [361]

Answer:

Carbon is the chemical backbone of life on Earth. Carbon compounds regulate the Earth’s temperature, make up the food that sustains us, and provide energy that fuels our global economy. Carbon moves from one storage reservoir to another through a variety of mechanisms. For example, in the food chain, plants move carbon from the atmosphere into the biosphere through photosynthesis. They use energy from the sun to chemically combine carbon dioxide with hydrogen and oxygen from water to create sugar molecules. Animals that eat plants digest the sugar molecules to get energy for their bodies. Respiration, excretion, and decomposition release the carbon back into the atmosphere or soil, continuing the cycle. The ocean plays a critical role in carbon storage, as it holds about 50 times more carbon than the atmosphere. Two-way carbon exchange can occur quickly between the ocean’s surface waters and the atmosphere, but carbon may be stored for centuries at the deepest ocean depths. Rocks like limestone and fossil fuels like coal and oil are storage reservoirs that contain carbon from plants and animals that lived millions of years ago. When these organisms died, slow geologic processes trapped their carbon and transformed it into these natural resources. Processes such as erosion release this carbon back into the atmosphere very slowly, while volcanic activity can release it very quickly. Burning fossil fuels in cars or power plants is another way this carbon can be released into the atmospheric reservoir quickly.Human activities have a tremendous impact on the carbon cycle. Burning fossil fuels, changing land use, and using limestone to make concrete all transfer significant quantities of carbon into the atmosphere. As a result, the amount of carbon dioxide in the atmosphere is rapidly rising; it is already considerably greater than at any time in the last 800,000 years. The ocean absorbs much of the carbon dioxide that is released from burning fossil fuels. This extra carbon dioxide is lowering the ocean’s pH, through a process called ocean acidification. Ocean acidification interferes with the ability of marine organisms (including corals, Dungeness crabs, and snails) to build their shells and skeletons.

6 0

2 years ago