Translation

What are the two types of mutations? Define each.

1) gene mutations: change within single gene caused by substitutions, insertions, or deletions of nitrogen bases when gene is being copied 2) chromosome mutations: change in number or structure of chromosomes; may involve loss of all or part of chromosome or provide extra copies of all or part of chromosome. In some instances a piece of a chromosome breaks off and attaches to non-homologous chromosome

When does a ribosome become functional?

Large and small subunits join to form functional ribosomes when they attach to an mRNA

Describe the structure of a ribosome

a) A ribosome has two subunits. They are called the large subunit and the small subunit. These subunits are made in the nucleolus. b) A ribosome is composed of proteins and ribosomal RNA c) A ribosome has one binding site for mRNA and three binding sites for tRNA. d) Ribosomes may be found attached to the endoplasmic reticulum or floating freely in the cytoplasm.

If the sequence of nucleotides along the mRNA molecule is AUG CCG GGA AGA CCC, how many amino acids would be in the newly formed protein?

5

If a section along the DNA molecule had a nucleotide sequence of TAC GCA ATC, the complimentary section on the RNA molecule would be?

AUG CGU UAG

What is the importance of mutations to life on Earth?

Some may cause change in organism that makes it better suited for environment. These are more likely to survive, reproduce and pass traits on to offspring. This is mechanism of Natural Selection.

Distinguish between a termination signal (terminator) and a stop codon.

Terminator: base sequence on DNA molecule that tells RNA polymerase where end of gene is located Stop codon: base sequence on mRNA that tells ribosome it has reached end of protein building instructions

Three codons do not call for any amino acid. What role is played by these codons?

These are stop codons: base sequence on mRNA that tells ribosome it has reached end of protein building instructions

Explain how a substitution of one nitrogen base for a new nitrogen base might affect the protein being formed

a) may or may not have any effect on protein being made b) depends on whether substitution is in first, second or third position of codon c)if substitution is in first or second position, will definitely call for different amino acid being added to growing polypeptide chain d) whether or not this affects functioning of protein will depend on how crucial particular amino acid is to functioning of protein e) substitution in third position of the codon less likely to cause change in protein f) substitution in third base would have no effect whatsoever: called silent mutation g) not all in third base silent mutations h) only one codon for amino acid tryptophan (UGG), so substitution in third base would cause change in protein being manufactured

Explain how a deletion or an addition of a nitrogen base might affect the protein being formed.

a) will have a disastrous effect on protein being made b) all nucleotides downstream will be improperly grouped into codons c) would alter reading of entire rest of sequence d) near BEGINNING of sequence would have greater effect than near END of sequence: called frameshift mutations e) not likely functional protein will be produced