DNA to Proteins 3-4

The sequence of nitrogen bases found in the DNA are responsible for determining what type of protein will be created by the cell. Proteins are small molecules that basically control our bodies.

What is RNA RNA is similar to DNA with a couple of changes: RNA is single stranded Instead of using the nitrogen base thymine RNA uses uracil.

Types of RNA mRNA – messenger RNA carries the coded message found in the DNA out into the cytoplasm of the cell where the proteins will be made tRNA – transfer RNA carries amino acids, which are the building blocks of proteins, to the be used to build the protein

Types of RNA rRNA – a small strand of RNA that makes up part of a ribosome.

Gene to Protein

Steps to Protein Creation Transcription – making a strand of mRNA from a segment of DNA and then the mRNA leaves the nucleus of travels to the cytoplasm of the cell Translation – uses the strand of mRNA as a template to piece together amino acids to form the protein

Transcription Transcription – the DNA strand is unzipped to allow a strand of mRNA to be created from its exposed nitrogen bases The new strand of mRNA are made by matching new nitrogen bases with the exposed nitrogen bases from the unzipped strand of DNA.

Once the mRNA is made and processed in the nucleus, it will leave the nucleus through small openings in the nuclear membrane called pores. Once in the cytoplasm, the process of translation will begin.

What are proteins made of? Proteins are made of smaller building blocks called amino acids. The amino acids are pieced together to form a very long chain that then folds over to create a very specific shaped structure we call a protein. Each type or protein has a specific job based on its shape.

The mRNA consists of the nitrogen bases A,U,C,G arranged in a specific order. Proteins consist of chains of the 20 amino acids arranged in a specific order. So what is the link between the two?

Codons A codon is a sequence of three nucleotides in a row which code for a certain amino acid. Each codon codes for one or more amino acids.

Start Codon – tells where the translation will begin , it will always be AUG Stop Codon – one of three specific codons indicating where translation will stop; UAA, UAG, UGA

Translation Once the mRNA has left the nucleus, the process of translation is ready to begin. In translation, amino acids are arranged in order according to the sequence of codons located on the mRNA. This sequence of amino acids will determine the shape of the final protein.

tRNA This is the molecule that will carry a specific amino acid to the ribosome to be attached to the chain of amino acids called a polypeptide chain (pre-protein). The tRNA is similar in structure to mRNA in that it has nitrogen bases. Anticodon – a series of three nitrogen bases at one end of the tRNA used to match with the mRNA codons

Ribosomes Ribosome play an important role in translation. They are the location where the mRNA and tRNA come together to join the amino acids to from the protein.