Cell membrane functions: true or false?

Question

free ribisomes differ from membrane-bound ribosomes in that free ribosomes specialize in synthesizing proteins for export (secretion) from the cell.

one function of integral proteins in the plasma membrane of cells is to form channels to allow passage of nonpolar solutes into the cell.

thanks for your help!

Answer 1

1. False.

Membrane bound ribosome translate as they force the protein into the ER (endoplasmic reticulum), which then sends it to the Golgi apparatus and then out of the cell.

2. True.

Its just true, haha.

Cheers.

Answer 2

true and true.

From Wiki:

Free ribosomes

Free ribosomes are free to move about anywhere in the cytoplasm (within the cell membrane). Proteins that are formed from free ribosomes are used within the cell. Proteins containing disulfide bonds using cysteine amino acids cannot be produced outside of the lumen of the endoplasmic reticulum.

[edit] Membrane-bound ribosomes

When certain proteins are synthesized by a ribosome they can become "membrane-bound". The newly produced polypeptide chains are inserted directly into the endoplasmic reticulum by the ribosome and are then transported to their destinations. Bound ribosomes usually produce proteins that are used within the cell membrane or are expelled from the cell via exocytosis.

Free and membrane-bound ribosomes differ only in their spatial distribution; they are identical in structure and function. Whether the ribosome exists in a free or membrane-bound state depends on the presence of a ER-targeting signal sequence on the protein being synthesized.

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Answer 3

http://wiki.answers.com/Q/Is_the_followi...