Name: dna to protein: central dogma steps
Uploaded: 2020-11-23T11:47:33.000Z
Duration: 1 min 25 s
Channel: JoVE

K12 Standards

Minnesota Academic Standards in Science

9-12

Life Science

1.1.1 9L.1.1.1.1

The Central Dogma

The central dogma of molecular biology states that information encoded in DNA is transferred to RNA, which then directs the synthesis of proteins, based on these instructions.

First, in the process of transcription, DNA is used as a template to synthesize messenger RNA, mRNA, which represents a copy of the coding strand. Except the thymidines are replaced uracils.

Next, in the process of translation in eukaryotes, mRNA travels to a ribosome. Here, codons, groups of three nucleotides, in the mRNA, bind to complementary sequences on transfer RNA, tRNA molecules. Each of which is attached to a particular amino acid, depending on the specific codon.

For example, the codon CCA binds to a tRNA attached to proline, while AGC binds to a tRNA attached to serine. In this way, the genetic code specifies the order in which the amino acids are arranged in the resulting polypeptide. Polypeptides are often then further processed to become functional proteins.

the central dogma

<h4>Overview</h4>

The central dogma of biology states that information encoded in the DNA is transferred to messenger RNA (mRNA), which then directs the synthesis of protein. The set of instructions that enable the mRNA nucleotide sequence to be decoded into amino acids is called the genetic code. The universal nature of this genetic code has spurred advances in scientific research, agriculture, and medicine.

<h4>RNA Is the Missing Link between DNA and Proteins</h4>

In the early 1900s, scientists discovered that DNA stores all the information needed for cellular functions and that proteins perform most of these functions. However, the mechanisms of converting genetic information into functional proteins remained unknown for many years. Initially, it was believed that a single gene is directly converted into its encoded protein. Two crucial discoveries in eukaryotic cells challenged this theory: First, protein production does not take place in the nucleus. Second, DNA is not present outside the nucleus. These findings sparked the search for an intermediary molecule that connects DNA with protein production. This intermediary molecule, found in both the nucleus and the cytoplasm, and associated with protein production, is RNA.

During transcription, RNA is synthesized in the nucleus, using DNA as a template. The newly-synthesized RNA is similar in sequence to the DNA strand, except thymidine in DNA is replaced by uracil in RNA. In eukaryotes, this primary transcript is further processed, removing the protein non-coding regions, capping the 5&rsquo; end and adding a 3&rsquo; poly-A tail, to create mRNA that is then exported to the cytoplasm.

<h4>The Rules for Interpreting the mRNA Sequence Constitute the Genetic Code</h4>

Translation occurs at ribosomes in the cytoplasm, where information encoded in the mRNA is translated into an amino acid chain. A set of three nucleotides codes for an amino acid and these triplets are called codons. The set of rules that outline which codons specify a particular amino acid make up the genetic code.

<h4>The Genetic Code Is Redundant</h4>

Proteins are created from 20 amino acids in eukaryotes. Combining four nucleotides in sets of three provides 64 (43) possible codons. This means that it is possible that individual amino acid can be encoded by more than one codon. The genetic code is said to be redundant or degenerate. Often, but not always, codons that specify the same amino acids differ only in the third nucleotide of the triplet. For example, the codons GUU, GUC, GUA, and GUG all represent the amino acid valine. However, AUG is the only codon that represents the amino acid methionine. The codon AUG is also the codon where protein synthesis starts and is therefore called the start codon. Redundancy in the system minimizes the harmful effects of mutations. A mutation (i.e., change) at the third position of the codon might not necessarily result in a change of the amino acid.

<h4>The Genetic Code Is Universal</h4>

With a few exceptions, most prokaryotic and eukaryotic organisms use the same genetic code for protein synthesis. This universality of the genetic code has enabled advances in scientific research, agriculture, and medicine. For instance, human insulin can now be manufactured on a large scale in bacteria. This is done using recombinant DNA technology. Recombinant DNA consists of genetic material from different species. Genes encoding human insulin are joined with bacterial DNA and inserted into a bacterial cell. The bacterial cell performs transcription and translation to produce the human insulin encoded in the recombinant DNA. The resulting human insulin is used to treat diabetes.

Overview

The central dogma of biology states that information encoded in the DNA is transferred to messenger RNA (mRNA), which then directs the synthesis ...

Education

JoVE Core

Molecular Biology

Unit 1

DNA, Cells, and Evolution

KEY TERMS AND CONCEPTS

dna to protein: central dogma steps

The central dogma explains how genetic information moves from DNA to RNA to protein. This flow is a key idea in molecular biology. It helps show how cells use genes to make the molecules that carry out work.

DNA stores the instructions for making proteins. During transcription, a gene in DNA is copied into RNA. The RNA then carries that message to the next stage.

In translation, the RNA message is used to build a protein. Proteins do much of the cell’s work, so this process connects genes to traits and cell function. Understanding the central dogma helps students see how information in DNA becomes an active product in the cell.

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The central dogma explains how genetic information moves from DNA to RNA to protein. This flow is a key idea in molecular biology. It helps show how cells use genes to make the molecules that carry out work. DNA stores the instructions for making proteins. During transcription, a gene in DNA is copied into RNA. The RNA then carries that message to the next stage. In translation, the RNA message is used to build a protein. Proteins do much of the cell’s work, so this process connects genes to...

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key terms and concepts

Learn how genetic information moves from DNA to RNA to protein through transcription and translation, and how this process helps cells make proteins.

DNA to Protein: Central Dogma Steps | JoVE K12

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DNA to Protein: Central Dogma Steps

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