Which organelle is the defining difference between prokaryot

Which organelle is the \'defining\' difference between prokaryotic and eukaryotic cells? What is the main function of each of the following? Endoplasmic Reticulum Extracellular matrix Mitochondria Central vacuole Chloroplasts Plasmodesmata Cyanide is a poison which blocks the production of ATP from glucose. Which structure would be the main target of the cyanide in a poisoned cell? An animal cell is placed into a hypotonic solution that makes the cell burst. When a plant cell is placed in the same solution it does not burst. What structure keeps plant cells from bursting? A mouse cell bearing blue protein surface markers is fused with a human cell bearing red surface markers. The resulting cell has blue and red markers randomly mixed on its surface. Explain how this can happen in terms of the \'Fluid\' Mosaic Model. b. Why did all the protein markers stay on the surface, instead of flipping into the inside of the membrane? Describe the differences between simple diffusion, facilitated diffusion, and active transport. Indicate which way the concentration gradient goes, whether a carrier molecule is needed, and ATP is needed. Make a TABLE if that is easier.

Solution

Ans. 12. Nucleus.

A cell having nucleus is said to be eukaryotic. The prokaryotic cells lack nucleus.

Ans. 13. Endoplasmic reticulum- Synthesis of secretory protein in rough endoplasmic reticulum. Synthesis of some lipids in smooth ER lumen. Releases vesicles that coalesce to form Golgi bodies. Etc.

14. Extracellular matrix- May act as reservoir of some ions and moles. May serve as a platform for cellular homeostasis, to which the cytoplasm can exchange matter (ions, water, etc.) as and when needed. Crucial for the multicellularity because ECM helps cell adhere and interact together. Etc.    

15. Mitochondria: Generate large amount of ATP from respiratory substrates (carbohydrates, fats) through oxidative phosphorylation.

16. Central vacuole in plant cells may act as reservoir for water and solutes as well as helps maintaining turgor pressure.

17. Chloroplast: Carries out photosynthesis.

18. Plasmodesmata: It is the cytoplasmic connection between two adjacent plant cells. Thus, mediates exchange of cellular contents between the connected cells.

19. Cyanide binds to cytochrome c oxidase and inhibits its activity. Once blocked, cytochrome c oxidase can’t transfer electrons to O₂, thus also inhibiting oxidative phosphorylation and cellular respiration.

Ans. 20. Cell wall.

When an animal cell is placed in a hypotonic solution while keeping all variables identical, the animal cell is most likely to swell and burst. Unlike plant cell, animal cells do not have cell wall. So, when as water gradually enters into the cell, it swells. At a threshold, when the plasma membrane can no longer withstand the intracellular osmotic pressure, it ruptures. The rigid cell wall of plant cell prevents swelling of the membrane beyond its boundary, thus plant cell can’t burst.

Thus, the animal cell lyses in hypotonic solution whereas the plant cell is able to maintain its cellular integrity.

Ans. 21. A. The lipid and protein molecules, associated with lipid bilayer through non-covalent interaction in the plasma membrane can exhibit transition from one to another region of the surface. When two cells are fuse together, their plasma membrane fuse together to forms a larger cell. The surface protein markers, attached to the lipid bilayer with non-covalent interactions (say, H-bonds, hydrophobic interactions, etc.), can change its position because of the dynamic nature (continuously forming and breaking) of these weak interactions. The process may continue to attain an equilibrium distribution of the two different surface markers. Thus, they may also appear randomly distributed on the surface of new fused membrane.

Ans. 21. B. Proteins are large macromolecules, so they can’t diffuse into the cell. However, they remain on the cell surface through weak, non-covalent interactions between the phospholipids of membrane and amino acids in protein.

Ans 22.   

Simple diffusion

Facilitated diffusion

Active transport

Transporter Protein

required

No

Yes

Yes

Gradient

Along the gradient

Along the gradient

Against the gradient

ATP required

No

No

Yes

	Simple diffusion	Facilitated diffusion	Active transport
Transporter Protein required	No	Yes	Yes
Gradient	Along the gradient	Along the gradient	Against the gradient
ATP required	No	No	Yes