DNA to Proteins

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• 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.