DNA concept map

continuous on the leading strand and discontinuous on the lagging strand

Central dogma : DNA -> RNA->Protein

DNA= Deoxyribose nuclic acids

Transcription

Translation

The synthesis of mRNA copied from the DNA base sequences by RNA polymerase

Replication

Translation is the synthesis of polypeptides on ribosomes

Semi conservative proccess that depends on complementary base pairing

continuous on the leading strand and discontinuous on the lagging strand

Enzymes involved

Helicase unwinds the double helix and separates the two strands by breaking hydrogen bonds

DNA polymerase links nucleotides together to form a new strand, using the pre-existing strand as a template

The amino acid sequence of polypeptides is determined by mRNA according to the genetic code

Depends on complementary base pairing between codons on mRNA and anticodons on tRNA

Structure

Discovery

Nucleosomes help to supercoil the DNA

Can only add nucleotides to the 3' primer

These enzyms help fuel DNA replication

Rosalind Franklin's investigated and discovered the double helix structure of DNA through x-ray diffraction. This idea was later exposed by Watson and Crick

The regions of DNA that do not code for porteins are limitws to regulators of gene expressions, introns, telomrers, and genes for tRNA's

DNA is composed and Adenine, Guanine , Thymine, and Cytosine

supercoiling helps pack genetic material into the nucleus

DNA polymerase 3 adds new nucleotides to the C3 hydroxyl group
on the ribose/deoxyribose sugar such that the strand grows from the 3'end

DNA Gyrase moves in advance of helicase and relieves strain and prevents supercouliing on the separated strands

DNA polymerase 1 removes the RNA primers and replaces them with DNA

DNA ligase joins the Okazaki fragments together to create a continuous strans

RNA primase synthesises a short RNA primer on each template strand to provide an attachment and initiation point for DNA polymerase 2

Occurs during the S phase of interphase

Helicase unwinds the double helix seperating the strands of DNA

it breaks the hydrogen bonds between the two strands

Single stranded binding proteins keep the seperated strands apart so that nucleotides can bind

DNA gyrase moves in advance of helicase and relieves strain and prevents the DNA supercoiling again

Each strand of parent DNA is used as template for the synthesis of the new strands

Syntheiss always occurs in 5'-> 3' direction on each new strand

Leads to formation of okasaki fragments

To synthesise a new strand first an RNA primer is synthesized on the parent DNA using RNA primase

Next DNA polymerase III adds the nucleotides (to the 3 ́ end) added according to the complementary base pairing rules; adenine pairs with thymine and cytosine pairs with guanine; (names needed, letters alone not accepted)

Nucleotides added are in the form of as deoxynucleoside triphosphate. Two phosphate groups are released from each nucleotide and the energy is used to join the nucleotides in to a growing DNA chain.

DNA polymerase I then removes the RNA primers and replaces them with DNA

DNA ligase next joins Okazaki fragments on the lagging strand

Because each new DNA molecule contains both a parent and newly synthesised strand DNA replication is said to be semi-conservative.