A collection of blog posts connected to my teaching on biomedical sciences and biochemistry degrees. All views and opinions expressed are my own, and not connected to my past, present or future employers.
This is the second of two videos on how cells make proteins using DNA. In the first video, I looked at the first step, which is making the messenger RNA (mRNA) a process called transcription - Transcription - making proteins from DNA - the mRNA.
In this video, I will guide you through the process of producing the protein from the mRNA, also known as translation. I will look at the coding problem (how many mRNA bases do you need to code from an amino acid), the number of reading frames in a DNA molecule, and how the cell produces protein from the mRNA.
In this video, I will guide you through the first steps in the process of producing RNA from DNA, also known as transcription. In the next video, we will take the next step and examine how we produce the protein from mRNA.
The video looks at the five steps of mRNA production:
initiation — activators bind upstream, often thousands of bases upstream, of the gene. The activators assemble the required proteins (the mediator, chromatin remodelling complex, the RNA polymerase and transcription factors) at the TATA box, which is a DNA sequence close to the gene
production — DNA is transcribed into the pre-messenger RNA
five prime capping — the five prime end of the pre-messenger RNA is capped with some modified nucleotides
splicing — introns are spliced out of the pre-messenger RNA to leave just the exons (exons provide the sequence for the protein)
three prime polyadenylation — addition of a polyadenylated tail to the three prime end of the pre-messenger RNA to give the final mature messenger RNA molecule
The video not only looks at mRNA production but also introduces the idea of non-coding RNA (ncRNA), which are RNA molecules that do not encode proteins. ncRNAs are essential in regulating gene expression and various cellular processes. For example:
transfer RNA (tRNA) — involved in protein synthesis
ribosomal RNA (rRNA) — involved in protein synthesis
microRNA (miRNA) — control gene expression
small interfering RNA (siRNA) — control gene expression
long non-coding RNA (lncRNA) — diverse functions
circular RNA (circRNA) — gene regulation
Piwi-interacting RNA (piRNA) — genome protection
enhancer RNAs (eRNAs) — modulate gene activity
Finally, I cover how to write out DNA sequences, the means of the terms sense and antisense strands, and what we mean by upstream and downstream when talking about DNA and RNA molecules.
In this video, I explore DNA recombination, a process where DNA strands swap segments, usually between similar sequences on sister chromatids. This swapping creates brand-new genetic combinations. DNA recombination isn't just a biological curiosity; it's crucial for increasing genetic diversity and ensuring the stability of our genome.
DNA can be damaged in a number of ways (see How can DNA become damaged in the cell? for more information— and the damage must be corrected for the cell to function correctly.
There are seven ways cells can repair damage to their DNA:
Have you ever been curious about the precision with which DNA is replicated in our cells, or why human pregnancies don't extend to an unimaginable sixteen years?
In my latest video, I examine the process of DNA replication. First, I explore how the DNA double helix is unwound by DNA helicase and how the unwound DNA is stabilised by Single Stranded Binding Proteins. I look at the replication fork and how DNA polymerases copy the DNA strands.
I also cover the formation of Okazaki fragments—short sequences of DNA synthesised on the lagging strand—and how DNA ligase is responsible for stitching these fragments together. Additionally, the video highlights the importance of topoisomerase in preventing the DNA from becoming overly twisted and tangled during replication.
In the video, I examine how the long DNA molecule is packaged into the relatively small nucleus of a cell. I examine how DNA is broken up into chromosomes, how the DNA wraps around the histones to form nucleosomes and chromatosomes, and finally, chromatin.
Please use the form below to download a fact sheet for the video. The fact sheet contains twenty-four key facts from the video, a summary of the packing of DNA into the nucleus and the definitions of twenty-five key terms used in the video.
