Protein Synthesis | Cells | Biology | FuseSchool

Summary

This video script delves into the fascinating process of protein synthesis, starting from DNA in the nucleus to the formation of proteins in the cytoplasm. It explains how DNA is transcribed into mRNA, which then travels to the ribosome for translation into a polypeptide chain. The script highlights the roles of codons, tRNA, and the essential and non-essential amino acids in creating the body's proteins, emphasizing the importance of understanding RNA and the steps of transcription and translation.

Takeaways

• 🧬 DNA is the blueprint for protein synthesis, with a specific sequence of amino acids determined by the order of DNA bases.
• 🌀 A set of three DNA bases, known as a codon, codes for a specific amino acid, such as GGT for Glycine.
• 🥗 There are 20 standard amino acids that make up body proteins, with 9 essential ones that must be obtained through diet.
• 🍽 Non-essential amino acids can be synthesized by the body, unlike the essential ones.
• 🧬 Over 20 amino acids are involved in protein synthesis, but there are more than 250 types of amino acids that may have other functions.
• 🔬 Understanding RNA is crucial for grasping protein synthesis, as it plays a key role in the process.
• 📜 The process of protein synthesis involves two main stages: transcription (in the nucleus) and translation (in the cytoplasm).
• 🧬 Transcription is when RNA polymerase unwinds the DNA and creates a complementary mRNA strand from the DNA template.
• 🚀 mRNA carries the genetic code from the nucleus to the cytoplasm where it attaches to a ribosome for translation.
• 🔠 Translation is the process where ribosomes and tRNA work together to assemble amino acids into a polypeptide chain based on the mRNA sequence.
• 🔬 tRNA molecules match the codons on the mRNA and deliver the corresponding amino acids to build the protein.
• 🧬 The polypeptide chain folds into its functional form, completing the protein synthesis process.

Q & A

What are proteins made of?

Proteins are made of a long chain of amino acids.

How does the order of DNA relate to protein synthesis?

The order of the bases in DNA determines which protein is made by coding for a specific order of amino acids.

What is the term for a set of three bases in the DNA molecule that codes for a particular amino acid?

The 3 base codes are known as codons.

Can you provide an example of a codon and its corresponding amino acid?

GGT is a codon for the amino acid called Glycine.

How many amino acids are there that make up our body's proteins?

There are twenty amino acids that make up our body's proteins.

What are essential amino acids and why are they called 'essential'?

Essential amino acids are nine in number and must be taken in through our diet because our body cannot manufacture them.

What is the role of RNA in protein synthesis?

RNA is crucial in protein synthesis as it carries the genetic code from DNA to the ribosomes where proteins are made.

What is the name of the process where the DNA code is copied and carried to the ribosome?

This process is called transcription.

What is the enzyme responsible for unwinding and unzipping the DNA strands during transcription?

The enzyme is called RNA polymerase.

How does the ribosome contribute to protein synthesis?

The ribosome sticks amino acids together to make a polypeptide chain, following the order coded for by the mRNA.

What is the process called where the ribosome assembles the protein from amino acids?

This process is called translation.

What is the function of Transfer RNA (tRNA) in the ribosome during translation?

Transfer RNA (tRNA) molecules carry specific amino acids and base pair with the mRNA inside the ribosome to ensure the correct protein is made.

How does the polypeptide chain eventually form into a protein?

The polypeptide chain folds into the required protein structure after being assembled by the ribosome.

Outlines

00:00

🧬 DNA and Protein Synthesis Overview

This paragraph introduces the concept of protein synthesis, explaining that proteins are composed of amino acids coded by DNA. It emphasizes the importance of understanding DNA and RNA, as well as the role of codons in determining amino acid sequences. Essential and non-essential amino acids are differentiated, and the process of protein synthesis is set to be explored in detail throughout the video.

🧬 Transcription: From DNA to mRNA

The paragraph delves into the first stage of protein synthesis, transcription, which occurs in the nucleus. It describes how RNA polymerase unwinds DNA, and only one strand is selected for replication. Complementary RNA nucleotides pair with the DNA template, forming a new mRNA strand. This mRNA carries the genetic code from the nucleus to the cytoplasm for the next step in protein synthesis.

🌐 Translation: mRNA to Polypeptide Chain

This section explains the translation process where the mRNA sequence is read by ribosomes in the cytoplasm to construct a polypeptide chain. The ribosome assembles amino acids in the order specified by the mRNA codons. Transfer RNA (tRNA) molecules, each carrying a specific amino acid, base pair with the mRNA inside the ribosome, ensuring the correct sequence for protein formation. As tRNAs continue to match with mRNA codons, the amino acid chain elongates, eventually folding into the functional protein.

Keywords

💡Protein Synthesis

Protein synthesis is the process by which cells create proteins, which are essential for the structure, function, and regulation of the body's tissues. In the video, it is the central theme, explaining how proteins are made from amino acids following the genetic code in DNA. The script describes the two main stages of protein synthesis: transcription and translation, which are key to understanding how genetic information is used to build proteins.

💡Amino Acids

Amino acids are the building blocks of proteins, with each protein being a unique sequence of these acids. The script mentions that there are twenty amino acids that constitute our body's proteins, with nine of them being essential, meaning they must be obtained through diet as the body cannot produce them. Amino acids are central to the concept of protein synthesis as they are the components that are assembled into proteins.

💡DNA

DNA, or deoxyribonucleic acid, is the molecule that carries the genetic instructions for the development, functioning, and reproduction of all known living organisms. In the script, DNA is highlighted as the starting point for protein synthesis, as it contains the code for the order of amino acids in a protein. The video suggests watching a 'what is DNA' video for a refresher, indicating its foundational role in the topic.

💡Codons

Codons are sequences of three nucleotides on RNA that correspond to a specific amino acid. The script uses the example of 'GGT' as a codon for the amino acid Glycine, illustrating how the genetic code is read in sets of three to determine which amino acid is added to the growing protein chain during translation.

💡Essential Amino Acids

Essential amino acids are those that cannot be synthesized by the human body and must be obtained through diet. The script specifies that there are nine essential amino acids, emphasizing the importance of diet in acquiring the necessary building blocks for protein synthesis.

💡Non-Essential Amino Acids

Non-essential amino acids are those that the body can produce on its own. The script contrasts these with essential amino acids, explaining that while there are only twenty amino acids used to build proteins, the body's ability to manufacture some of them means that not all must be ingested through food.

💡mRNA (Messenger RNA)

mRNA is a single-stranded RNA molecule that is transcribed from DNA and carries genetic information from the nucleus to the ribosomes in the cytoplasm. The script describes mRNA as the molecule that 'copies' the DNA code and carries it to the ribosome, where protein synthesis occurs. It is a crucial intermediate in the process of translating genetic information into a functional protein.

💡Transcription

Transcription is the first stage of gene expression where the information from a segment of DNA is copied into RNA. The script details the process of transcription, explaining how the enzyme RNA polymerase unwinds DNA and creates a complementary mRNA strand that will carry the genetic code for protein synthesis.

💡Translation

Translation is the process by which the mRNA sequence is decoded by the ribosome to produce a specific polypeptide chain, or protein. The script describes translation as the stage where the ribosome reads the mRNA codons and assembles the corresponding amino acids into a protein, following the genetic instructions.

💡Ribosomes

Ribosomes are the cellular structures where protein synthesis occurs. The script explains that ribosomes are located in the cytoplasm and are the site where amino acids are assembled into proteins according to the sequence specified by the mRNA.

💡tRNA (Transfer RNA)

tRNA is a type of RNA that plays a critical role in protein synthesis by carrying specific amino acids to the ribosome during translation. The script describes how tRNA molecules match the codons on the mRNA with the corresponding amino acids, ensuring the correct protein is synthesized.

Highlights

Proteins are composed of amino acids which are coded by DNA.

DNA sequence determines the specific order of amino acids in protein synthesis.

A set of three DNA bases, known as a codon, codes for a specific amino acid, such as GGT for Glycine.

There are 20 amino acids that constitute our body's proteins, with 9 being essential and must be obtained through diet.

The body can produce non-essential amino acids, and there are over 250 other amino acids that do not form proteins.

RNA plays a crucial role in protein synthesis, and understanding it is prerequisite to comprehending the process.

DNA, located in the nucleus, is transcribed into mRNA by the enzyme RNA polymerase.

Transcription is the process where the DNA code is copied into mRNA within the nucleus.

mRNA travels from the nucleus to the cytoplasm where it attaches to a ribosome for protein synthesis.

The ribosome is the site of protein synthesis, where amino acids are linked together to form a polypeptide chain.

Transfer RNA (tRNA) molecules carry specific amino acids and base pair with mRNA inside the ribosome.

tRNA ensures the correct order of amino acids is maintained for accurate protein formation.

The polypeptide chain grows as tRNA molecules match with mRNA codons, eventually folding into the final protein structure.

Protein synthesis involves the unzipping of DNA by DNA polymerase around the gene.

The mRNA formed during transcription carries the genetic code from the nucleus to the cytoplasm.

Translation is the process where the mRNA sequence is read by tRNA to assemble the polypeptide chain.

The final step in protein synthesis is the folding of the polypeptide chain into the functional protein structure.

Transcripts

Proteins are made of a long chain of amino acids which is being coded for by DNA.

The order of the basis of DNA determines which protein is made by coding for a specific order of amino acids.

This is protein synthesis

and in this video, we're going to look at how it works.

You may want to watch our ‘what is DNA’ video first to remind yourself all about DNA.

A set of three bases in the DNA molecule codes for a particular amino acid.

GGT for example codes for the amino acid called Glycine.

The 3 base codes are known as codons. So GGT is a “codon” for Glycine.

So there are twenty amino acids that make up our body’s proteins. Nine of these we need to take in through our diet as our body cannot manufacture them.

These are known as essential amino acids. Our body can however manufacture non-essential amino acids.

Whilst 20 amino acids build up proteins, there are actually many others that do not form proteins, possibly over 250.

They may form sugar for example.

Before we start, you need to know what RNA is - so you may want to watch our ‘what is RNA’ video first.

So let's now look at how proteins are actually synthesized.

The DNA is in the nucleus and cannot move, but the ribosomes in the cytoplasm are where the proteins are made.

This means the code from the DNA needs to be copied and carried across to the ribosome

by a molecule called messenger RNA or mRNA before the protein can be made.

Let’s have a look at how this all works.

In the nucleus, the enzyme RNA polymerase unwinds and unzips the two strands of DNA that contain the protein-making gene.

Only one of these strands is going to be replicated.

Complementary RNA nucleotides base pair with the chosen strand.

RNA polymerase also then binds the RNA nucleotides together making a new RNA strand.

This is called messenger RNA or mRNA.

And this whole process inside the nucleus is called transcription.

The mRNA then travels from the cell nucleus and out into the cytoplasm, until it reaches and attaches to a ribosome.

The ribosome then sticks amino acids together to make a polypeptide chain,

following the order of amino acids as coded for, by the mRNA.

Three base codons on the mRNA code for one amino acid.

And this whole process in the ribosome is called translation.

So let’s look at translation in a little more detail.

What is actually happening inside the ribosome.

Transfer RNA or tRNA molecules, carrying specific amino acids,

base pair with the mRNA inside the ribosome.

So the tRNA brings in the amino acids and the mRNA provides the information

of the exact order that the amino acids need to be bonded together

to ensure that the correct protein is made.

As more and more tRNA's match up with the mRNA, the amino acid chain becomes longer and longer.

And eventually the polypeptide chain will form into the protein.

So there we have protein synthesis.

Inside the nucleus, the DNA molecule is unzipped from around the gene by DNA polymerase.

The DNA is then replicated and mRNA is formed in the process of transcription.

The mRNA has traveled out of the nucleus and into the cytoplasm, where it binds with a ribosome.

In the ribosome, the nucleotide sequence of the mRNA is translated by the tRNA

which carry the related amino acids.

The polypeptide chain is formed, and will eventually fold into the required protein.

So there is protein synthesis.