Central Dogma Flashcards
When does DNA replication occur in the cell cycle?
S phase
What enzyme is responsible for the unwinding of the double-helix?
DNA Helicase; it breaks the hydrogen bonds between complementary base pairs
What enzyme is responsible for joining fragments together during the replication of the lagging strand?
DNA ligase
Describe the replication of the lagging strand
Because the strand runs anti-parallel to the leading strand (runs in the 3’ to 5’ direction), replication occurs discontinuously. Replication must occur in sections known as Okazaki fragments
What is meant by a “semi-conservative” model?
The original strand of DNA acts as a template for the synthesis of a new strand. Each DNA molecule contains one parent strand and one daughter strand
Function of DNA polymerase
Adds new nucleotide bases to growing chain in 5’ to 3’ direction
What are the stages of transcription?
Initiation, elongation, termination
Describe elongation
RNA polymerase unwinds double helix and adds nucleotides to growing mRNA molecule in 5’ to 3’ direction
Describe termination
RNA polymerase reaches end of the gene, transcription is stopped because of a termination signal
Where does initiation of transcription occur?
The promoter region
What is RNA splicing and where does it occur?
Nucleus; Introns (non-coding regions of pre-mRNA molecule) are removed; exons (coding regions) are joined together to create a mature mRNA molecule
Where does translation occur?
Ribosomes
Describe initiation in translation
mRNA binds to ribosome; tRNA recognizes start codon on mRNA and binds w/ anticodon
What is the start codon?
AUG
Elongation in translation
Newly arrived amino acid is joined to growing peptide chain; catalyzed by rRNA
