Protein Synthesis (Updated)

Summary

Highlights

• DNA's genetic code is the blueprint for proteins, vital for various functions ⚙️.
• Transcription takes place in the nucleus where DNA is transcribed into mRNA 📜.
• The mRNA leaves the nucleus to enter the cytoplasm where translation occurs, creating proteins 🎨.
• tRNA reads mRNA in triplets called codons, matching them with anticodons to add amino acids 🎯.
• Methionine usually starts the amino acid chain, guided by the mRNA codon chart ⛳.

Key Takeaways

• Protein synthesis is how DNA's information leads to protein creation, crucial for life 🌟.
• DNA codes for proteins that do various jobs in the body, including transport and structure 🔬.
• RNA plays a massive role in this process, with mRNA, tRNA, and rRNA all contributing to protein synthesis 🧬.
• Transcription and translation are the major steps, with transcription happening in the nucleus and translation in the cytoplasm 📜➡️🔧.
• A codon chart is essential to understand how sequences code for specific amino acids, dictating the resulting protein. 🗺️

Overview

Chapters

• 00:00 - 00:30: Introduction The introduction chapter explains the connection between DNA and traits, using eye color as an example. It describes how DNA contains genetic information coding for eye color. This trait, eye color, depends on a pigment in the eyes, which is produced thanks to proteins that genes (portions of DNA) code for. The chapter sets the stage for understanding how DNA translates into physical traits through proteins.
• 00:30 - 01:00: What is Protein Synthesis? This chapter delves into the process through which DNA leads to protein formation, known as protein synthesis. The term 'synthesis' essentially means 'to make something', and in this context, protein synthesis refers to the making of proteins. The chapter emphasizes the significance of proteins, explaining that they are crucial because they perform a variety of functions such as transport, providing structure, and acting as enzymes.
• 01:00 - 01:30: Importance of Proteins This chapter emphasizes the essential role of proteins in the body. It explains that proteins are crucial for various functions, including protecting the body. The chapter highlights the continuous process of protein synthesis happening in cells, driven by DNA located in the nucleus. It also touches on the presence of noncoding DNA and genes that may remain inactive.
• 01:30 - 02:00: DNA and RNA This chapter introduces the role of RNA in gene expression, particularly how information from DNA is utilized within the cell. It highlights the goal of transporting genetic information from the nucleus to facilitate protein synthesis, positioning RNA as a crucial component in this process. Additionally, it briefly mentions that RNA is a nucleic acid similar to DNA, hinting at an accompanying video for a detailed comparison of RNA and DNA.
• 02:00 - 02:30: Process Overview This chapter provides an overview of the process of protein synthesis, highlighting its significance. The narrator mentions that the discussion is simplified for the sake of brevity and encourages further exploration of the topic. Protein synthesis is broken down into two primary steps: transcription and translation.
• 02:30 - 03:30: Transcription This chapter explains the concept of transcription in biology, emphasizing how DNA is transcribed into RNA. The mnemonic of 'C' in 'transcription' preceding 'L' in 'translation' by alphabetical order is highlighted as an aid to remember that transcription precedes translation. The process occurs in the nucleus and involves an enzyme called RNA polymerase, which connects complementary bases to transcribe DNA into a message.
• 03:30 - 04:00: mRNA to Ribosome The chapter 'mRNA to Ribosome' discusses the formation of mRNA from RNA bases as a crucial component in protein synthesis. Messenger RNA (mRNA) is a single-stranded chain of RNA that serves as a messenger carrying genetic code from DNA, essential for the translation process in the ribosome. It emphasizes that the mRNA is based on DNA and often requires significant editing before it can function effectively in translation, highlighting the critical nature of mRNA editing in biological processes. The chapter encourages further reading on mRNA editing due to its fascinating and crucial role in molecular biology.
• 04:00 - 04:30: Translation Basics The chapter titled 'Translation Basics' explains the process of mRNA moving from the nucleus to the cytoplasm in eukaryotes. Here, it attaches to a ribosome, which is made of ribosomal RNA (rRNA), easily remembered by the 'r' in rRNA. This process of the ribosome building protein is called translation. The chapter also hints at the availability of excellent clips and animations that illustrate the translation process.
• 04:30 - 05:00: Codons and Anticodons The chapter discusses the basics of protein synthesis in the cytoplasm, focusing on tRNA molecules. These transfer RNA molecules carry amino acids, the building blocks of proteins. To synthesize proteins, these amino acids are assembled to form proteins.
• 05:00 - 05:30: Using Codon Charts This chapter explains the role of tRNA and mRNA in protein synthesis. The tRNA is responsible for bringing the correct amino acids together, but it needs instruction for which amino acids to bring. This instruction comes from the mRNA, which directs the tRNA by presenting complementary bases. When tRNA finds its matching bases on the mRNA, it transfers its amino acid, aiding in the construction of a protein.
• 05:30 - 07:00: Building the Protein The chapter explains how tRNA reads mRNA in sets of three bases, known as codons, to bring in amino acids necessary for protein synthesis. For example, the tRNA reads the codon AUG on the mRNA, which matches the complementary anticodon UAC on the tRNA, carrying the amino acid methionine.
• 07:00 - 08:30: Conclusion A tRNA with a UAC anticodon pairs with an AUG codon on mRNA, transferring its amino acid, methionine, to the growing peptide chain. The tRNA will leave, leaving behind methionine as the first amino acid in the sequence. This process sets the stage for the translation to continue with the next codon.

Protein Synthesis (Updated) Transcription

• 00:00 - 00:30 Captions are on! Click CC at bottom right to turn off. Stay up to date with us by following us on Twitter (@AmoebaSisters) and Facebook! After learning about DNA, have you ever wondered, how can the DNA actually result in a trait? Let's take an example - like eye color. Yes, your DNA has the genetic information that codes for the color of your eyes. Your eye color is based on a pigment that is inside the eyes. But, in order to have that pigment, you have genes, which are portions of DNA, that can code for proteins which help make that pigment.
• 00:30 - 01:00 So what we’re going to talk about is how your DNA can lead to the making of a protein. This process is called protein synthesis. Synthesis essentially means to “make something” so protein synthesis means to make protein. And you may wonder, “What’s the big deal about proteins?” Well you may not realize this but proteins are kind of a big deal. They do all kinds of things. Proteins are involved in transport, in structure, in acting as enzymes that make all kinds of
• 01:00 - 01:30 materials, in protecting the body…and so much more. You've got to make proteins - it’s essential for you to live. And what is so COOL is that you are making proteins right now as you sit and watch this video. It’s happening in your cells. They’re making proteins. So back to your DNA and its role in all of this. All of your cells have DNA---well a few exceptions---and that DNA is in the nucleus. Some DNA is noncoding DNA. Some DNA makes up genes that are not activated.
• 01:30 - 02:00 More about that in our gene regulation video. But we’re going to talk about genes that are coding for active proteins. So how are we going to get the information from these genes out of the nucleus so that the cell can start producing the proteins that it needs to make? Well let us introduce you to the amazing work of RNA. We have a video comparing and contrasting RNA---we’ll be brief here in saying that RNA is a nucleic acid like DNA.
• 02:00 - 02:30 But it has a few differences. Its role in protein synthesis also is HUGE. Before we get into the process, please note our typical disclaimer: we tend to simplify topics while staying as accurate as we can---but as always, we hope you will have the desire to explore this complex, amazing process later on to learn all about the extra information that we don’t have the ability to include in this short video. In protein synthesis, we can look at two major steps. One is transcription and the other is translation.
• 02:30 - 03:00 Transcription has a C in it, and translation has an L in it. I remember that C comes before L in the alphabet, which helps me remember that transcription comes first. I like a lot of alphabet mnemonics. Now, transcription is when we’re going to transcribe the DNA into a message. In your cells, the DNA is in the nucleus, so therefore, we’re doing transcription in the nucleus. In the step of transcription, an enzyme called RNA polymerase will connect complementary
• 03:00 - 03:30 RNA bases to the DNA. These RNA bases are bonded together to form a single stranded mRNA. The m in mRNA stands for messenger. Messenger RNA consists of a message made of RNA that has been based on the DNA. We do want to mention that this mRNA is not usually ready to go right away. There's usually a significant amount of mRNA editing that occurs--- we highly encourage you to do some reading about that because it’s not only fascinating---it’s critical for
• 03:30 - 04:00 the process to work correctly. So what's something great about being mRNA? Well in eukaryotes, you get out of the nucleus. The mRNA can go out of the nucleus into the cytoplasm where it’s going to attach to a ribosome. Ribosomes make protein. The ribosome is made of rRNA, and that’s an easy one to remember because the “r” stands for ribosomal RNA. The ribosome is going to build our protein in the next step called translation! You know, you can find a lot of great clips and animations on translation that are just
• 04:00 - 04:30 fantastic. We’re just going to break down some basics of what's happening. In the cytoplasm, if you look at this, you have all these tRNA molecules available. tRNA stands for transfer RNA. They carry an amino acid on them. An amino acid is the monomer for a protein; it's a building block for protein. Since we’re making proteins, we’re going to need those amino acids to build it. If you have a bunch of amino acids together, you can build a protein.
• 04:30 - 05:00 So it’s the tRNA that is going to bring those amino acids together to make that. But wait, how does the tRNA know which amino acids to bring? That’s why the mRNA, the message, is so important because it’s going to direct which tRNAs come in and therefore which amino acids are transferred. All of these tRNAs are looking for complementary bases. When they find the complementary bases on the mRNA, they transfer their amino acid
• 05:00 - 05:30 When tRNA is bringing in the amino acids, it reads the bases---represented by these letters here on the mRNA--- in threes. So it doesn’t read one letter at a time; it reads it in triplets. That’s called a codon. So, for example, in this mRNA, the tRNA would read the codon AUG. One of these tRNAs contains a complementary anticodon---which in this case is UAC. All tRNAs that have the anticodon UAC will be carrying an amino acid called methionine.
• 05:30 - 06:00 A tRNA with the UAC anticodon comes in to pair with the complementary AUG codon on the mRNA. It transfers the amino acid it carries, methionine. The tRNA will eventually leave, but it will leave behind its amino acid. That’s the first amino acid before looking at the next codon. Before we do the next codon to carry this on--- if you’re wondering---how did you
• 06:00 - 06:30 know that the tRNA that went with the AUG codon would be carrying an amino acid called methionine? Well, for that, you will find a codon chart helpful! You can learn to use a codon chart to determine which amino acid each mRNA codon will code for. Isn’t is so fascinating that scientists have been able to determine which amino acid corresponds with these codons? I used to have a codon chart poster and just marvel at that. You can see on a codon chart that the AUG codon on the mRNA codes for methionine.
• 06:30 - 07:00 AUG is also considered a start codon as methionine is typically going to be your first amino acid in proteins. There are many types of amino acids in the codon chart, but there are even more possible codon combinations. That means there can be more than one codon that code for the same amino acid. For example, according to the mRNA codon chart, all of these mRNA codons here code for the same
• 07:00 - 07:30 amino acid: leucine. That means their complementary tRNAs all carry the same amino acid: leucine. Ok, so going back to the mRNA---let’s try the next codon on this mRNA. CCA. On the codon chart, you can see that codes for the amino acid proline. The complementary tRNA has the anticodon GGU and look, there’s the proline that we knew it would be carrying. The tRNA will transfer that amino acid and eventually leave where it can go pick up another
• 07:30 - 08:00 amino acid. These amino acids are held together by a peptide bond. And it will keep on growing. Typically at the very end of the mRNA, there is a stop codon. Stop codons do not code for an amino acid, but when the ribosome reaches it, it indicates that the protein building is finished. So the result of translation is that you built a chain of amino acids that were brought in certain sequences based on the coding of the mRNA.
• 08:00 - 08:30 But remember that mRNA was complementary to the DNA. So the DNA ultimately was the director of the entire protein building, of course, it couldn’t have done it without some serious help from mRNA, rRNA, and tRNA. Protein folding and modification may occur and the protein may need to be transported---this can all vary based on the protein's structure and function. Another fascinating topic for another Amoeba Sisters video. Well that’s it for the Amoeba Sisters and we remind you to stay curious!