Hey there Ms. Thompson! I know we x today but I was hoping to learn more about the process of gene expression!
Of course Colin. Let me explain!
First let's begin with the main purpose of gene expression which is the process when our genetic information in our DNA is converted into a functional product such as a protein.
But Ms. Thompson what is DNA?
Colin, let me explain the purpose of DNA in a cell. DNA is a double stranded, double helix molecule that splits into a single strand during cell replication. It always stays in the nucleus except during mitosis. The inside of the strands in this diagram are the nitrogen bases and the outside is made up of the phosphates/sugars. DNA plays an integral process because it is the stores all of the information needed for new organisms to function.
Can you elaborate on the process of gene expression?
Sure!! There are two steps that make up gene expression: transcription and translation. In transcription, which takes place in the nucleus, after replication has occurred, a single strand of DNA is copied to create a new mRNA molecule.
It is able to do this because the code in the DNA tells the cell to connect individual nucleotides as a way to create mRNA using base pairs. The enzyme RNA polymerase allows this part of the process to happen by dividing the DNA into a single stranded molecule temporarily and synthesizes the DNA template to make mRNA. Also, in order for this to happen, the introns are removed and the methyl cap and poly A tail are added.
Interesting. How is it able to do this?
Is that all?
No, then the mRNA leaves the nucleus and the process of translation begins in the cytoplasm. Translation is made up of four main steps; activation, initiation, elongation, and termination. In activation, the correct amino acids are covalently bonded to the correct transfer RNA. Then in initiation, ribosomes come together around mRNA and the start codon is found telling the ribosome to begin the matching process. The mRNA begins shifting through the ribosome. Next, in elongation, The tRNA brings the amino acids to be added to the polypeptide and each new mRNA codon continues matching with tRNA anticodons. Finally, in termination the matching process is finished when the ribosome encounters a stop codon. The results are new peptides that will be stitched together to become proteins for cellular functions.
Fascinating! Such an intricate and precise process.
Indeed it is Colin and a very important one too. Without the thousands of genes that make proteins, the cell cannot function.
Wow! Thank you for everything. I should be one my way now because period 4 starts soon. Have great day and I'll see you in class tomorrow!