31. Which of the following is least likely to cross a lipid bilayer with no prot

Question

31. Which of the following is least likely to cross a lipid bilayer with no proteins? CO2 02 H20 ATP a steroid hormone such as testosterone 2. Which one of the following describes the hydrophilic component of cholesterol? a phosphate group and a chemical group called choline a single hydrocarbon tail a phosphate group only a group of four planar rings and a hydroxyl group a hydroxyl group only 3. For translation to occur in eukaryotes, mRNA molecules must be transported through which membrane(s)? mitochondrial membrane (inner and outer) nuclear envelope (inner and outer nuclear membranes) endoplasmic reticulum membrane ribosome membrane plasma membrane 04. In intestinal epithelial cells, a transport protein moves glucose into the cytoplasm against its concentration gradient at the same time that it transports Na+ into the cell down its electrochemical gradient. Which of the following CORRECTLY describes this cotransport of glucose and sodium? The Na+ concentration gradient provides the energy for glucose transport No energy source is required for glucose to move against its concentration gradient Energy from ATP directly drives the movement of glucose Na+ can move by simple diffusion, but glucose transport requires a carrier protein

Explanation / Answer

1. ATP

O2 and CO2 are gases so they can easily crops the lipid bilayer.

Steroid hormone has hydrobic non polar groups which make it easier to cross lipid bilayer.

H2O is small polar molecule while ATP is large ionic polar molecule. So comparing both, ATP will be the least likely to cross.

2. A hydroxyl group only.

Carbon rings and carbon chain are both hydrophobic parts of cholesterol.

3. Nuclear envelope (inner and outer nuclear membrane).

mRNA is formed during transcription in nucleus. For protein synthesis by translation mRNA must come out of nucleus and bind with ribosome.

4. The Na+ concentration gradient provides the the energy for glucose transport.

It is an example of secondary active transport where Na+ is transported downhill generating ATP by ATPsynthase which is further utilise for uphill glucose transport.

Related Questions

Navigate

• Browse (All)
• Browse 3
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.