DNA replication and the genetic code Flashcards Preview

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Flashcards in DNA replication and the genetic code Deck (24)
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DNA Replication: The Cell's Extreme Team Sport


When DNA replicates two new DNA molecules are formed. Each one consists of one old strand of DNA and one new strand of DNA. What is this known as?

Semi-conservative replication


What is the name of the enzyme that unzips the DNA?

DNA helicase


After the DNA molecule is 'unzipped' free nucleotides pair with the bases on the template strand. What is the name of the enzyme which catalyses the formation of phosphodiester bonds between these bases?

DNA polymerase


What is the first step in DNA replication?

An enzyme called DNA helicase travels along the DNA molecule and brakes the hydrogen bonds holding the base pairs together. It 'unzips the DNA'


After the DNA is unzipped what happens next?

Free nucleotides then pair with their complementary bases.


After the free nucleotides are lined up what happens next?

The bases are joined together by an enzyme called DNA polymerase


DNA polymerase is only able to move along the template strand in one direction. Which direction is this?

3 to 5


Once the DNA molecule is unzipped the two strands have separate names. What are these names?

The leading strand and the lagging strand


Why is the leading strand named the leading strand?

DNA polymerase is able to continuously move along this strand is it moves in the 3 to 5 direction. It is therefor a lot faster to replicate.


Why is the lagging strand called the lagging strand?

DNA is not able to continuously move along this strand (discontinuous replication) because it moves in the 5 to 3 direction. It is therefor a lot slower to replicate.


Along the lagging strand the DNA is produced in sections. What are the names of these sections?

Okazaki fragments


Some sequences of bases are not matched correctly. What is this known as?

A mutation


Scientists believe that DNA must code for a sequence of amino acids. What is this called?

The genetic code


What is a codon?

It is a sequence of three bases


What does each codon code for?

An amino acid


A section of DNA that contains all the codons for an entire protein is known as what?

A gene


Why is the genetic code known as being universal?

Because all organisms use the same code


What is another word used to describe a codon?

A triplet code


How different codons are there?

64 (4 bases, so 4^3)


What does the start codon do?

It signals the start of the genetic sequence


What does the stop codon do?

They signal the end of the genetic sequence


Why is it important to have only one codon being the start codon?

It ensures that there is no overlapping of the genetic code


Why is the genetic code said to be degenerate?

The genetic code is degenerate because there are many instances in which different codons specify the same amino acid.