DNA Replicationand RNA Production

Selent

Replication

The process of copying DNA The two chains of nucleotides separate by

unwinding and act as templates for new nucleotide chains.

Step by Step Replication

The DNA chains unwind and divide at the replication fork. The protein DNA Helicase moves along the DNA

breaking the weak hydrogen bonds between the nitrogen bases.

DNA Polymerase binds to the separated strands of DNA and assembles new nucleotides in a complimentary chain Covalent bonds hold the phosphates and sugars

together. Hydrogen bonds hold the nitrogen bases together.

DNA Replication Annimation

Speed of Replication

DNA replication begins at several locations along the molecule of DNA

This allows for faster replication Human DNA replication would take about

33 days with one replication fork but with about 100 replication forks human DNA replication can be completed in 8 hours.

Results and Errors

Each new molecule of DNA will have 1 chain of nucleotides from the original molecule and 1 new chain of nucleotides.

Mutations are changes in the nucleotide sequence.

When the wrong nucleotide is inserted DNA polymerase can back up and remove it, then replace it with the correct one.

Types of Mutations

Substitution (point mutation) – when one nucleotide is switched for a different nucleotide.

Deletion – the loss of a piece of chromosome Inversion – a piece of chromosome breaks off

and is reattached backwards Translocation – A piece of chromosome

breaks off and is reattached in a different location

RNA Production

RNA Transcription – the rewriting of the genetic code from DNA into RNA.

RNA is responsible for the movement of genetic information from the DNA in the Nucleus to the site of protein synthesis in the Cytoplasm.

Characteristics of RNA

RNA is single stranded – made of linked nucleotides.

Sugar in RNA is Ribose. RNA does not contain the nitrogen base

Thymine, instead it contains the nitrogen base Uracil. Uracil bonds with Adenine.

Types of RNA

Messenger RNA (mRNA) – consists of nucleotides in a single uncoiled chain. Carries genetic information from the DNA in the nucleus to the ribosome of eukaryotic cells.

Types of RNA

Transfer RNA (tRNA) – consists of a single chain of about 80 RNA nucleotides folded into specific shapes. Carries amino acids to the ribosome and

matches with mRNA

Types of RNA

Ribosomal RNA (rRNA) – consists of nucleotides in a globular form, along with proteins they make up the ribosome where proteins are made.

Transcription

Transcription is the process by which DNA is copied into RNA

Step by Step Transcription

RNA Polymerase binds to a specific region on the DNA, called the promoter. In eukaryotes promoters mark the

beginning of a single gene. In prokaryotes they mark the beginning of

several functionally related genes.

Step by Step Transcription

RNA polymerase separates the strands of DNA and begins adding RNA nucleotides to form a complimentary strand of RNA for the gene on DNA. Base pairing rules apply the same as I DNA

except Uracil takes the place of Thymine.

Step by Step Transcription

Transcription continues until RNA polymerase reaches a termination signal. Termination signal is a specific sequence of

nucleotides that marks the end of the gene. RNA polymerase releases the strand of DNA

and the strand of RNA.