what materials may have trouble diffusing across the plasma membrane?
what is fluid mosaic? what is included in this named model?
what happens in your body if you drink seawater?
do membrane proteins make phospholipids? if not, where are they made?
in our bodies, glucose is used in cellular respiration. what type of energy conversion occurs for glucose to contract our muscle cells to pick up a book?
what is a metabolic pathway, give an example of a metabolic pathway within a cell?
what are all the parts of an atp molecule?
what does it mean when the plasma membrane is described as semi permeable?
what is activation energy? how do enzymes help change the activation energy in a metabolic pathway?

Question

Accepted Answer

Since there are multiple sub - questions related to biological concepts (like plasma membrane, cellular respiration, ATP, enzymes, metabolic pathways etc.), we'll use the Answer - Explanation Format for each sub - question:

### Sub - question 1: What materials may have trouble diffusing across the plasma membrane?
# Brief Explanations:
Large, polar, or charged molecules (e.g., ions, large proteins, polysaccharides) have trouble diffusing across the plasma membrane. The plasma membrane is mainly composed of a phospholipid bilayer with a hydrophobic interior. Non - polar molecules can diffuse easily, but polar and charged molecules are repelled by the hydrophobic core, and large molecules can't pass through the small spaces between phospholipids.
# Answer:
Large, polar, or charged molecules (e.g., ions, large proteins, polysaccharides)

### Sub - question 2: What is fluid mosaic? What is included in this named model?
# Brief Explanations:
The fluid mosaic model describes the structure of the plasma membrane. It is "fluid" because the phospholipids and proteins can move within the membrane. The "mosaic" part comes from the diverse arrangement of proteins (integral and peripheral), phospholipids, cholesterol (in animal cells), and carbohydrates (attached to lipids or proteins) in the membrane.
# Answer:
- Fluid Mosaic: A model for plasma membrane structure.
- Included: Phospholipids (forming bilayer), integral/peripheral proteins, cholesterol (animal cells), carbohydrate - lipid/protein complexes.

### Sub - question 3: What happens in your body if you drink seawater?
# Brief Explanations:
Seawater has a higher solute (salt, mainly NaCl) concentration than body fluids. When you drink it, the osmotic gradient causes water to leave your cells (osmosis: water moves from low solute to high solute concentration). This can lead to dehydration of cells, especially in the digestive tract and other tissues, and may cause symptoms like thirst, nausea, and in severe cases, organ dysfunction.
# Answer:
Water leaves cells (osmosis) due to high solute in seawater, causing cell dehydration, thirst, nausea, potential organ dysfunction.

### Sub - question 4: Do membrane proteins make phospholipids? If not, where are they made?
# Brief Explanations:
Membrane proteins do not make phospholipids. Phospholipids are synthesized in the endoplasmic reticulum (ER). Specifically, the smooth endoplasmic reticulum (SER) in eukaryotic cells is responsible for the synthesis of phospholipids, which are then incorporated into membranes.
# Answer:
No. Phospholipids are made in the endoplasmic reticulum (especially smooth ER).

### Sub - question 5: In our bodies, glucose is used in cellular respiration. What type of energy conversion occurs for glucose to contract our muscle cells to pick up a book?
# Brief Explanations:
In cellular respiration, glucose (chemical energy) is converted to ATP (also chemical energy, but in a more usable form for cells). Then, when muscle cells contract, the chemical energy in ATP is converted to mechanical energy (for muscle contraction to pick up the book). So the overall conversion is chemical energy (glucose) → chemical energy (ATP) → mechanical energy (muscle contraction).
# Answer:
Chemical energy (glucose) → chemical energy (ATP) → mechanical energy (muscle contraction)

### Sub - question 6: What is a metabolic pathway, give an example of a metabolic pathway within a cell?
# Brief Explanations:
A metabolic pathway is a series of enzyme - catalyzed chemical reactions in a cell that convert a starting molecule into a final product, often with intermediate steps. For example, glycolysis is a metabolic pathway. In glycolysis, glucose (a 6 - carbon sugar) is broken down into two molecules of pyruvate (3 - carbon compound) in the cytoplasm, and energy in the form of ATP and NADH is produced.
# Answer:
- Metabolic Pathway: Series of enzyme - catalyzed reactions converting a molecule to a product (with intermediates).
- Example: Glycolysis (glucose → pyruvate, produces ATP/NADH).

### Sub - question 7: What are all the parts of an ATP molecule?
# Brief Explanations:
ATP (adenosine triphosphate) is composed of three parts: an adenosine (which is adenine, a nitrogen - containing base, bonded to ribose, a 5 - carbon sugar) and three phosphate groups ($PO_4^{3 - }$) bonded in a chain to the ribose.
# Answer:
Adenine (base), ribose (sugar), three phosphate groups.

### Sub - question 8: What does it mean when the plasma membrane is described as semi - permeable?
# Brief Explanations:
Semi - permeable (or selectively permeable) means the plasma membrane allows some substances to pass through (e.g., small non - polar molecules, water via aquaporins) while preventing others (e.g., large polar/charged molecules) from passing freely. It regulates the entry and exit of substances to maintain cell homeostasis.
# Answer:
Allows some substances to pass, blocks others; regulates substance entry/exit for homeostasis.

### Sub - question 9: What is activation energy? How do enzymes help change the activation energy in a metabolic pathway?
# Brief Explanations:
Activation energy is the minimum energy required for a chemical reaction to start. Enzymes act as biological catalysts. They lower the activation energy of a reaction by providing an alternative reaction pathway with a lower energy barrier. This allows the reaction to occur more quickly at physiological temperatures.
# Answer:
- Activation Energy: Minimum energy for a reaction to start.
- Enzymes: Lower activation energy by providing an alternative pathway.

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QUESTION IMAGE

Question

Explanation:

Sub - question 1: What materials may have trouble diffusing across the plasma membrane?

Answer:

Sub - question 2: What is fluid mosaic? What is included in this named model?