DNA Replication

Helicase - separates double-standed DNA into single-stranded templates

What is the the first step in enzyme functions during DNA replication?

Primase - deposits short RNA primers

What is the the second step in enzyme functions during DNA replication?

DNA - polymerase elongates the growing strand in the 5’ to 3’ direction

What is the the third step in enzyme functions during DNA replication?

DNA ligase - joins gasos between existing deoxyribonucleotides

What is the the forth step in enzyme functions during DNA replication?

Helicase

In a mutant cell, DNA replication fails because double-stranded DNA does not separate properly at the replication fork. A mutation in which enzyme is most likely the cause?

DNA Polymerase

Polymerizes nucleotides to create complementary strands of DNA and functions during active elongation of new strands

Primase

Synthesizes new RNA strands “from scratch” and functions during active elongation of new strands

Helicase

Breaks hydrogen bonds as it helps unwind DNA and functions during active elongation of new strands

Ligase

Seals gaps between new DNA fragments on the lagging strand and functions when replication of new strands is nearly completed

Exonuclease

Removes nucleotides from the end of DNA strands and DNA polymerase has this type of enzymatic activity during proofreading

Endonuclease

Used during excision repair after UV damage creates T-T dimers, removes nucleotides from the middle of DNA strands, and used during mismatch repair after replication has finished

Both Exonuclease and Endonuclease

Uses hydrolysis to break phosphodiester geometry in DNA

Recognize site of damage

What is the first step of how an enzyme repair damage?

Break the backbone, open up the double helix and remove bases

What is the second step of how an enzyme repair damage?

Replace excised bases with the correct ones

What is the third step of how an enzyme repair damage?

Catalyze phosphodiester linkages to reestablish a continuous strand

What is the fourth step of how an enzyme repair damage?