What are Polyribosomes quizlet?
Polyribosome (Polysome) aggregation of several ribosomes attached to one mRNA molecule. RNA Processing. modefication of RNA before it leaves the nucleus, a process unique to eukaryotes.
How big is a codon?
This demonstrated that the coding unit is 3 nucleotides. The nucleotide triplet that encodes an amino acid is called a codon. Each group of three nucleotides encodes one amino acid.
Which event occurs during the elongation stage?
During the elongation stage, the ribosome continues to translate each codon in turn. Each corresponding amino acid is added to the growing chain and linked via a bond called a peptide bond. Elongation continues until all of the codons are read.
How many nucleotides make up a codon?
A codon is a DNA or RNA sequence of three nucleotides (a trinucleotide) that forms a unit of genomic information encoding a particular amino acid or signaling the termination of protein synthesis (stop signals). There are 64 different codons: 61 specify amino acids and 3 are used as stop signals.
What are polyribosomes and what is their function?
Polyribosomes attached to the endoplasmic reticulum synthesize proteins for export from the cell (e.g., digestive enzymes) and for placement within the plasma membrane (e.g., ion channel proteins).
What are polyribosomes and what happens at these structures?
A polyribosome (or polysome or ergosome) is a group of ribosomes bound to an mRNA molecule like “beads” on a “thread”. It consists of a complex of an mRNA molecule and two or more ribosomes that act to translate mRNA instructions into polypeptides.
Is DNA a code?
The DNA Code and Codons The DNA code is really the ‘language of life. ‘ It contains the instructions for making a living thing. The DNA code is made up of a simple alphabet consisting of only four ‘letters’ and 64 three-letter ‘words’ called codons.
Who wrote the DNA code?
DNA consists of a code language comprising four letters which make up what are known as codons, or words, each three letters long. Interpreting the language of the genetic code was the work of Marshall Nirenberg and his colleagues at the National Institutes of Health.
What is the job of tRNA?
transfer RNA / tRNA Transfer ribonucleic acid (tRNA) is a type of RNA molecule that helps decode a messenger RNA (mRNA) sequence into a protein. tRNAs function at specific sites in the ribosome during translation, which is a process that synthesizes a protein from an mRNA molecule.
Which event occurs during elongation in DNA replication quizlet?
Which event occurs during the elongation stage? Peptide bonds form, and anticodons match up to complementary codons. A stop codon enters the ribosome, release factors bind the ribosome, mRNA detaches from the ribosome and the polypeptide chain, ribosomal subunits separate; all of these occur.
What are the 64 codons?
The genetic code includes 64 possible permutations, or combinations, of three-letter nucleotide sequences that can be made from the four nucleotides. Of the 64 codons, 61 represent amino acids, and three are stop signals. For example, the codon CAG represents the amino acid glutamine, and TAA is a stop codon.