Chapter 13 - RNA Flashcards
Contrast the functions of the three main types of RNA.
mRNA: carries info from DNA to other parts of the cell
rRNA: makes up the subunit of a ribosome
tRNA: transfers amino acids to the ribosome
How does transcription differ from DNA replication? Describe at least four differences.
Transcription - segments of DNA serve as templates to produce complementary RNA molecules. The base sequences of the transcribed RNA complement the base sequences of the template DNA. It requires an enzyme known as RNA polymerase.
DNA Replication - Instead, utilizes DNA polymerase, takes place in the nucleus, doesn’t contain uracil, and is double-stranded.
Describe the process in which a molecule of pre-mRNA is converted into a final mRNA molecule.
After being transcribed from DNA, pre-mRNA is reduced in size by discarding introns. The remaining pieces, referred to as the exon, are merged. Finally, a cap and a tail are added to the opposite ends of the mRNA molecule, forming the final mRNA.
Explain the process of translation. (Be able to identify a picture of translation)
It’s the process of decoding an mRNA message into a protein. Translation begins when a ribosome attaches to an mRNA molecule in the cytoplasm. As the ribosome reads each codon of mRNA, it directs tRNA to bring the specified amino acid into the ribosome. One at a time, the ribosome then attaches each amino acid to the growing chain.
What is the central dogma of molecular biology?
The central dogma of molecular biology is that info is transferred from DNA to RNA to protein.
What is a codon? (Be able to read a codon chart)
A codon is a three base sequence that codes for a specific amino acid.
What is the relationship between the codons and anticodons? How is this relationship important to the structure of proteins?
The codon is a set of three nucleotides found in the mRNA sequence. The anticodon is a complementary triplet that is brought to the ribosome by tRNA. The codon is part of the mRNA and the identical anticodon is a part of tRNA. The complementary bases on the codon and anticodon are held together by hydrogen bonds. The ribosome only binds the tRNA to mRNA if it’s carrying an amino acid.
What will happen after the ribosome joins the methionine (hypothetically, tRNA’s amino acid) and phenylalanine?
The bond between methionine and its tRNA will be broken. The tRNA then moves away from the ribosome, which enables it to bind with another methionine. The ribosome will then move on to the next codon.
When does DNA replication happen?
It happens before mitosis begins.
In a point mutation, what would have the worst effect on the function of the protein?
An insertion or deletion at the beginning of the gene would have the worst effect on the function of the protein.
What are mutations?
Mutations are heritable changes in genetic info.
What is the difference between gene and chromosomal mutations?
Gene mutations produce changes in a single gene. Chromosomal mutations produce changes in whole chromosomes.
What are 3 examples of gene mutations?
A substitution is when one base is change to a different one. Insertions add one base and deletions remove one base. They are also called frameshift mutations.
What are 4 examples of chromosomal mutations?
Deletion involves the loss of all or part of a chromosome. Duplication produces an extra copy of all or part of a chromosome. Inversion reverses the direction of a part of a chromosome. Translocation is when part of a chromosome breaks off and attaches to another.
What are some possible causes for mutations?
Some mutations arise from mutagens or chemical or physical agents.
