Enzymes
Errors
Replication Fork
Basic DNA facts
100

What is the name of the enzyme that unwinds the DNA Strands?

Helicase

100

What would happen if endonuclease didn't do its' job correctly?

Mutations

100

What is the “Y-shaped” structure formed when DNA is opened for copying?

The replication fork

100

The strand that is made in fragments is the __________ strand.

Lagging strand

200

Which enzyme synthesizes nucelotide primers?

DNA polyermase

200

Is there an error if A-G and C-T, if so state correct it

A-T and C-G

200

Why are hydrogen bonds broken in the start of replication?

They are broken so the strands can separate (break bonds of nucleotides)

200

Why is DNA semi-conservative

One strand is used as a template for the DNA polyermase

300

Which enzyme seals nicks in the sugar-phosphate backbone?

DNA ligase

300

If helicase doesn’t unwind the DNA, what will happen?

The replication fork will never open, so replication cannot start.

300

What does the replication fork expose so new DNA can be built? (the name of the strand)

The template strands

300

DNA replication is described as __________ because each new molecule contains one old strand.

Semi-conservative

400

What enzyme unwinds the DNA before helicase?

Topoisomerase

400

If ligase doesn’t seal the Okazaki fragments, what will happen?

The lagging strand will have gaps and won’t form a complete, continuous DNA strand.

400

The strand that is made continuously is called the __________ strand.

Leading strand

400

What direction does DNA polymerase build DNA in?

5' → 3' direction

500

What enzyme prevents strands from winding back together

SSBP - single stranded binding proteins

500

If primase doesn’t lay down RNA primers, what will happen?

DNA polymerase won’t be able to start building new DNA.

500

Why is the lagging strand made in short fragments at the replication fork?

Because DNA polymerase can only build in the 5'→3' direction, so it must work in pieces (Okazaki fragments)

500

The short fragments created on the lagging strand are called __________.

Okazaki fragments