Chapter 12: Transcription and Translation
What causes mutations?
- errors in replication - can be caused by chemicals or radiation
What does RNA polymerase actually do?
It produces the mRNA copy of DNA during transcription It uses DNA as the template It creates a new strand of nucleotides complementary to the bases in DNA Anything that should become A becomes a U
Do all genes (DNA) encode information to make a protein?
NO
Which protein enzyme is used for transcription?
RNA polymerase
When does translation stop?
When a "stop" codon is encountered that signals the end of the protein
What is a mutation?
a change in a cell's genetic message
What is a missense substitution?
amino acid gets completely replaced
What do mutations do to the shape of a protein?
changes the shape of the protein, which changes the function of the protein or inhibits it from doing what is is supposed to do
Where does translation occur?
cytoplasm
What is a silent substitution?
does not create any bad thing because there is no change at the protein level
What is a nonsense substitution?
does not finish the job that it's supposed to do it stops too early
What happens to nucleotides in a mutation?
mutations involve substitutions, additions, or deletions to nucleotides
What are mutations in somatic cells?
mutations that will NOT be passed to future generations but WILL be passed to all other somatic cells derived from it
What are mutations in germ-line cells?
mutations that will be passed to future generations
Where does transcription occur?
nucleus
What is a substitution?
swap one nucleotide base with another one
Which enzyme brings amino acids to ribosomes to make proteins?
tRNA
What is the Central Dogma?
the flow of information: DNA to RNA to protein
What is translation?
the transfer of information from RNA to protein ribosome moves along the mRNA molecule 3 nucleotides at a time
What is the genetic code?
universal and employed by all living things codon (three nucleotides) --> amino acid
When does translation start?
when the ribosome encounters a "start" codon
