Molecular Genetics Flashcards
What is the function of the 5’ cap in mRNA?
Protects mRNA from degradation and assists in ribosome binding
The 5’ cap is a modified guanine nucleotide added to the 5’ end of mRNA.
Define ‘exon’.
Coding regions of a gene that are expressed in mRNA
Exons are the parts of the gene that remain in the mature mRNA after splicing.
What is ‘splicing’?
The process of removing introns and joining exons in pre-mRNA
Splicing is crucial for the formation of mature mRNA.
What are ‘introns’?
Non-coding regions of a gene that are removed during splicing
Introns do not contribute to the final mRNA sequence.
Fill in the blank: The sequence __________ is added to the 3’ end of mRNA.
Poly A tail
The poly A tail enhances the stability of mRNA and regulates its translation.
What is pre-mRNA?
The initial transcript that undergoes splicing to form mature mRNA
Pre-mRNA contains both introns and exons.
What does mRNA stand for?
Messenger RNA
mRNA carries genetic information from DNA to the ribosome for protein synthesis.
What is the role of tRNA?
Transfers amino acids to the ribosome during translation
tRNA has an anticodon that pairs with the corresponding codon on mRNA.
What is an anticodon?
A sequence of three nucleotides on tRNA that is complementary to a codon on mRNA
The anticodon ensures the correct amino acid is added during protein synthesis.
What are the two subunits of a ribosome?
Large subunit and small subunit
The ribosome facilitates the translation of mRNA into a polypeptide chain.
True or False: Codons are sequences of three nucleotides in mRNA that specify an amino acid.
True
Codons are essential for translating the genetic code into proteins.
Fill in the blank: The structure of tRNA is often described as a __________ shape.
Cloverleaf
The cloverleaf structure allows tRNA to effectively interact with mRNA and ribosomes.
What are ribosomes made up of?
Ribosomes are made up of protein and ribosomal RNA (rRNA)
Ribosomes are essential cellular structures responsible for protein synthesis.
What is the role of the start codon in translation?
The start codon sets the reading frame for the gene
The start codon is typically AUG, which codes for methionine.
What attaches to the small subunit during the initiation phase of translation?
The initiator tRNA pairs with the start codon
This pairing is crucial for the correct start of protein synthesis.
What happens after the initiator tRNA pairs with the start codon?
The large subunit attaches to the small subunit, forming an active ribosome
This assembly is essential for the continuation of translation.
Fill in the blank: Ribosomes are located in the _______.
cytoplasm
Ribosomes can be free-floating or attached to the endoplasmic reticulum.
What are the two sites on a ribosome involved in translation?
A site and P site
The A site is where aminoacyl-tRNA enters, while the P site holds the tRNA carrying the growing polypeptide chain.
True or False: The large subunit of the ribosome is involved in the formation of peptide bonds.
True
The large subunit contains the catalytic site for peptide bond formation.
What is the significance of the reading frame set by the start codon?
It determines how the sequence of nucleotides is grouped into codons
An incorrect reading frame can lead to different, often nonfunctional proteins.
What is the first step in DNA replication?
Initiation
This involves the unwinding of the DNA double helix.
Which enzyme breaks hydrogen bonds between bases during DNA replication?
Helicase
Helicase is crucial for separating the two strands of DNA.
What role do single-stranded binding proteins (SSBPs) play in DNA replication?
Stabilize the single-stranded DNA
SSBPs prevent the DNA strands from re-annealing.
What is the function of topoisomerase in DNA replication?
Relieves tension in the DNA strands
Topoisomerase prevents supercoiling ahead of the replication fork.
