1. the codons that signal the end of a polypeptide chain are called (1 point)
promoters
introns
exons
terminators

2. which of the following occurs after a codon and anticodon form hydrogen bonds? (1 point)rrna and protein combine to form a ribosome.
a three-base sequence binds to a peptide.
a dehydration reaction forms a peptide bond.
trna carrying an amino acid binds to the ribosome.

3. during translation, the type of amino acid that is added to the growing polypeptide depends on the (1 point)
codon on the mrna and the anticodon on the rrna.
anticodon on the mrna and the anticodon on the trna.
anticodon on the rrna and the codon on the mrna.
codon on the mrna and the anticodon on the trna

1. Terminators

2. A dehydration reaction forms a peptide bond

3. Codon on the mRNA and anticodon on the tRNA

Explanation:

1. A codon is a group of three nucleotide sequences on the mRNA that corresponds to a specific amino acid. The full set of codons is called the GENETIC CODE. The genetic code includes 64 possible combinations of three letter nuceotide sequences (coding) that can be made from four nucleotides. Of the 64 codons, 61 codes for an amino acid while 3 codons are Stop signals.

The three stop codons are UAA, UAG and UGA. These codons signal the end of the polypeptide chain during translation i.e. once they are read in the ribosome, translation stops. They are commonly known as NONSENSE/TERMINATION CODONS as they do not code for an amino acid. They cause the release of the growing polypeptide chain from the ribosome because there are no tRNA's with anticodons complementary to the stop codons.

2. Translation cannot occur in the ribosome without transfer RNAs or tRNA. A tRNA is a special RNA molecule that matches an mRNA codon with the amino acid it codes for. Each tRNA contains a set of three nucleotides called ANTICODON. During the process of translation, a tRNA reads the mRNA codon using its anticodons. This is done by matching the base through pairs in the codon through hydrogen bonding following the base pair rule.

After the hydrogen bond binding between the tRNA anticodon and the mRNA codon, the first tRNA on the P site of the ribosome transfers its amino acid to the amino acid on the newly arrived tRNA on the A site, forming a PEPTIDE bond between the two amino acids, losing a water (H2O) molecule in the chemical reaction.

3. The anticodon of a given tRNA binds to a specific mRNA codon in a hydrogen bonding in order to read it using the complementary base pairing rule. After reading, the tRNA then carries the amino acid (on its amino acid attachment site), specifically the one encoded by the mRNA codon it reads. This enables the amino acid to be added to the polypeptide chain (future protein) being formed.

For example, the tRNA's anticodon (AAG) reads the mRNA codon with UUC nucleotide. Since the UUC codon codes for Phenylalanine, the tRNA then carries the amino acid Phenylalanine to the growing polypeptide chain.