ribosomes?do not have a cell wall,are not surrounded by a membrane,do not contain cytoplasma,or all oftheabove

Answer 1

A ribosome is an organelle in cells that assembles proteins. Ribosomes are composed of ribosomal RNA and ribosomal proteins (known as a Ribonucleoprotein or RNP). It translates messenger RNA (mRNA) into a polypeptide chain (e.g., a protein). It can be thought of as a factory that builds a protein from a set of genetic instructions. Ribosomes can float freely in the cytoplasm (the internal fluid of the cell) or bound to the endoplasmic reticulum, or to the nuclear envelope. Since ribosomes are ribozymes, it is thought that they might be remnants of the RNA world.

Ribosomes were first observed in the mid-1950s by Romanian cell biologist George Palade in the electron microscope as dense particles or granules[1] for which he would win the Nobel Prize. The term ribosome was proposed by scientist Richard B. Roberts in 1958:

During the course of the symposium a semantic difficulty became apparent. To some of the participants, microsomes mean the ribonucleoprotein particles of the microsome fraction contaminated by other protein and lipid material; to others, the microsomes consist of protein and lipid contaminated by particles. The phrase “microsomal particles” does not seem adequate, and “ribonucleoprotein particles of the microsome fraction” is much too awkward. During the meeting the word “ribosome” was suggested; this seems a very satisfactory name, and it has a pleasant sound. The present confusion would be eliminated if “ribosome” were adopted to designate ribonucleoprotein particles in the size range 20 to 100S.

– Roberts, R. B., Microsomal Particles and Protein Synthesis[2]

The structure and function of the ribosomes and associated molecules, known as the translational apparatus, has been of research interest since the mid 20th century and is a very active field of study today.

Answer 2

A ribosome is an organelle in cells that assembles proteins. Ribosomes are composed of ribosomal RNA and ribosomal proteins (known as a Ribonucleoprotein or RNP). It translates messenger RNA (mRNA) into a polypeptide chain (e.g., a protein). It can be thought of as a factory that builds a protein from a set of genetic instructions. Ribosomes can float freely in the cytoplasm (the internal fluid of the cell) or bound to the endoplasmic reticulum, or to the nuclear envelope. Since ribosomes are ribozymes, it is thought that they might be remnants of the RNA world.

Ribosomes are the workhorses of protein biosynthesis, the process of translating messenger RNA (mRNA) into protein. The mRNA comprises a series of codons that dictate to the ribosome the sequence of the amino acids needed to make the protein. Using the mRNA as a template, the ribosome traverses each codon of the mRNA, pairing it with the appropriate amino acid. This is done using molecules of transfer RNA (tRNA) containing a complementary anticodon on one end and the appropriate amino acid on the other.

Protein synthesis begins at a start codon near the 5' end of the mRNA. The small ribosomal subunit, typically bound to a tRNA containing the amino acid methionine, binds to an AUG codon on the mRNA and recruits the large ribosomal subunit. The large ribosomal subunit contains three tRNA binding sites, designated A, P, and E. The A site binds an aminoacyl-tRNA (a tRNA bound to an amino acid); the P site binds a peptidyl-tRNA (a tRNA bound to the peptide being synthesized); and the E site binds a free tRNA before it exits the ribosome.

Answer 3

Isn't that cute? They just pasted the exact same wikipedia entry for answers. If Wikipedia ever starts copyrighting a whole lotta people in here are going to get in trouble. I just love how people will paste a whole long piece when the answer is as simple as "All of the above". I'm gonna make it my resolution to go through and NOT vote for pasted wikipedia answers. Thumbs down to you both.

By the way, the answer is all of the above.

Answer 4

Ribosomes are comprised of rRNA and some other proteins. They do not have a cell wall or cytoplasm.

Answer 5

ribosomes dont have a cell wall and it dont contain cytoplasm n thats all that i know of

Answer 6

I do remember from my anatomy class that they do not have a membrane, but sorry don't know about the rest.

Answer 7

All of the above.