Name: dna and rna: genetic instructions
Uploaded: 2020-09-24T15:06:53.000Z
Duration: 2 min 43 s
Channel: JoVE

K12 Standards

Tennessee Academic Standards

High School

Biology

from-molecules-to-organisms-structures-and-processes

From Molecules to Organisms: Structures and Processes

BIO1.LS1.3

Nucleic Acids

Les acides nucléiques sont des polymères de nucléotides molécules composées d'un sucre pentose, une base contenant de l'azote et un groupe phosphate. Il existe deux types d'acides nucléiques:acide désoxyribonucléique, ADN et acide ribonucléique, ARN. Leurs structures chimiques diffèrent selon sur quels sucres pentoses et bases azotées ils contiennent.Le sucre pentose dans l'ARN est le ribose, qui a un groupe hydroxyle attaché au carbone-2. Le sucre dans l'ADN est le désoxyribose, qui n'a qu'un atome hydrogène mais pas d'oxygène au carbone-2. La base azotée est liée au carbone-1 et au phosphate au carbone-5.L'ARN et l'ADN contiennent les bases adénine, cytosine, et guanine;mais l'ADN contient de la thymine, tandis que l'ARN contient de l'uracile. Dans l'ADN et l'ARN, la guanine et la cytosine forment des paires de bases complémentaires, liées par trois liaisons hydrogène. L'adénine et la thymine forment des paires de bases dans l'ADN tandis que l'adénine et l'uracile apparient dans l'ARN, tous deux liés entre eux par deux liaisons hydrogène.Diverses enzymes ADN ou ARN polymérase catalysent la polymérisation des nucléotides. Une liaison phosphodiester est formée entre un groupe hydroxyle attaché au carbone-3 et au groupe phosphate attaché au carbone-5 du nucléotide suivant. Cette réaction laisse une extrémité 5 non attachée avec un groupe phosphate libre et une extrémité 3 non attachée avec un groupe hydroxyle libre.Lorsqu'il est associé à un brin complémentaire, les deux molécules sont antiparallèles, signifiant que l'extrémité 5 d'un brin se couple avec l'extrémité 3'de l'autre. Les brins sont maintenus ensemble par des forces intermoléculaires, y compris les effets hydrophobes, les interactions de van der Waals, et les liaisons hydrogène spécifiques qui forment entre les bases azotées. L'ADN est une double hélice composée de deux chaînes polynucléotidiques enroulés les uns autour des autres.En revanche, l'ARN se trouve souvent sous forme de molécule simple brin. Cependant, l'ARN peut se lier à un ADN ou un ARN complémentaire. Il peut également présenter un appariement de bases complémentaire intra-brin résultant en structures secondaires de différents types d'ARN qui ont des fonctions distinctes dans la cellule.

acides nucléiques

Les acides nucléiques sont les macromolécules les plus importantes pour la continuité de la vie. Ils portent le plan génétique de la cellule et portent des instructions pour son fonctionnement. 
 ADN et ARN 
 Les deux principaux types d'acides nucléiques sont l'acide désoxyribonucléique (ADN) et l'acide ribonucléique (ARN). L'ADN est le matériel génétique de tous les organismes vivants, allant des bactéries unicellulaires aux mammifères multicellulaires. Il se trouve dans le noyau des eucaryotes et dans les organelles, les chloroplastes et les mitochondries. Chez les procaryotes, l'ADN n'est pas enfermé dans une enveloppe membraneuse. 
 L'ensemble du contenu génétique de la cellule est son génome, et l'étude des génomes est la génomique. Dans les cellules d'eucaryotes mais pas dans les procaryotes, l'ADN forme un complexe avec des protéines histones pour former la chromatine, substance des chromosomes d'eucaryotes. Un chromosome peut contenir des dizaines de milliers de gènes. De nombreux gènes contiennent l'information pour fabriquer des protéines. D'autres gènes codent pour les produits ARN. L’ADN contrôle toutes les activités cellulaires en activant ou désactivant les gènes. 
 L'autre type d'acide nucléique, l'ARN, est surtout impliqué dans la synthèse des protéines. Les molécules d'ADN ne quittent jamais le noyau mais utilisent plutôt un intermédiaire pour communiquer avec le reste de la cellule. Cet intermédiaire est l'ARN messager (ARNm). D'autres types d'ARN, comme l'ARNr, l'ARNt et le microARN, sont impliqués dans la synthèse et la régulation des protéines. 
 L'ADN et l'ARN se composent de monomères appelés nucléotides. Trois composantes comprennent chaque nucléotide : une base azotée, un sucre pentose (cinq-carbones) et un groupe phosphate. Chaque base azotée d'un nucléotide est fixée à une molécule de sucre, qui est fixée à un ou plusieurs groupes phosphates. Les bases azotées, constituants importants des nucléotides, sont des molécules organiques et sont ainsi nommées parce qu'elles contiennent du carbone et de l'azote. Elles sont des bases parce qu'elles contiennent un groupe aminé qui a le potentiel de fixer un hydrogène supplémentaire, et donc de diminuer la concentration d'ions hydrogène dans son environnement, ce qui le rend plus basique. Chaque nucléotide de l'ADN contient l'une des quatre bases azotées possibles : l'adénine (A), la guanine (G), la cytosine (C) et la thymine (T). L'adénine et la guanine sont classées comme des purines. La structure primaire de la purine est constituée de deux cycles carbone-azote. La cytosine, la thymine et l'uracile sont classées comme des pyrimidines dont la structure primaire est composée d'un seul cycle carbone-azote. Chacun de ces cycles carbone-azote basiques a des groupes fonctionnels différents qui sont fixés à lui. En biologie moléculaire, nous connaissons les bases azotées par leurs symboles A, T, G, C et U. L'ADN contient A, T, G et C ; alors que, L'ARN contient A, U, G et C. 
 Le sucre pentose dans l'ADN est le désoxyribose, et dans l'ARN, le sucre est le ribose. La différence entre les sucres est la présence du groupe hydroxyle sur le deuxième carbone du ribose et de l'hydrogène sur le deuxième carbone du désoxyribose. Le résidu phosphate se fixe au groupe hydroxyle du carbone 5′ d'un sucre et au groupe hydroxyle du carbone 3′ du sucre du nucléotide suivant, ce qui forme une liaison phosphodiester 5′–3′. 
 Structure à double hélice de l'ADN 
 L'ADN a une structure en double hélice. Le sucre et le phosphate se trouvent à l'extérieur de l'hélice, formant le squelette de l'ADN. Les bases azotées sont empilées à l'intérieur, comme une paire de marches d'escalier. Les liaisons hydrogène relient les paires entre elles. Chaque paire de bases de la double hélice est séparée de la paire de bases suivante par 0,34 nm. Les deux brins de l'hélice s'exécutent dans des directions opposées, ce qui signifie que l'extrémité carbone 5′ d'un brin sera orientée vers l'extrémité carbone 3′ de son brin correspondant. Seuls certains types d'appariement de bases sont autorisés : A peut se coupler avec T et G peut se coupler avec C. Il s'agit de la règle des bases complémentaires. En d'autres termes, les brins d'ADN sont complémentaires. 
 ARN 
 L'acide ribonucléique, ou ARN, est principalement impliqué dans le processus de synthèse des protéines sous la direction de l'ADN. L'ARN est généralement monocaténaire et se compose de ribonucléotides qui sont liés par des liaisons phosphodiester. 
 Il existe quatre types principaux d'ARN : l'ARN messager (ARNm), l'ARN ribosomique (ARNr), l'ARN de transfert (ARNt) et le microARN (miARN). Le premier, l'ARNm, porte le message de l'ADN, qui contrôle toutes les activités cellulaires dans une cellule. Si une cellule a besoin d'une certaine protéine, le gène pour celle-ci se déclenche et l'ARN messager est synthétisé dans le noyau. La séquence des bases de l'ARN est complémentaire à la séquence de codage de l'ADN à partir de laquelle elle a été copiée. Dans le cytoplasme, l'ARNm interagit avec les ribosomes et d'autres machineries cellulaires. 
 L'ARNm est lu suivant des ensembles de trois bases connues sous le nom de codons. Chaque codon code un seul acide aminé. De cette façon, l'ARNm est lu et le produit protéique est fabriqué. L'ARN ribosomique (ARNr) est un constituant majeur des ribosomes sur lesquels l'ARNm se lie. L'ARNr assure le bon alignement de l'ARNm et des ribosomes. L'ARNr du ribosome a également une activité enzymatique (peptidyl transférase) et catalyse la formation de liaisons peptidiques entre deux acides aminés alignés. L'ARN de transfert (ARNt) est l'un des plus petits des quatre types d'ARN, généralement de 70 à 90 nucléotides de long. Il transporte le bon acide aminé vers le site de synthèse des protéines. C'est l'appariement des bases entre l'ARNt et l'ARNm qui permet au bon acide aminé de s'insérer dans la chaîne polypeptidique. Les microARN sont les plus petites molécules d'ARN et leur rôle consiste à réguler l'expression des gènes en interférant avec l'expression de certains messages d'ARNm. 
 Même si l'ARN est mono-brin, la plupart des types d'ARN présentent un appariement de bases intramoléculaire étendu entre des séquences complémentaires, créant une structure tridimensionnelle prévisible essentielle à leur fonction. 
 Ce texte est adapté de <a href="https://openstax.org/books/biology-2e/pages/3-5-nucleic-acids"> Openstax, Biologie 2e, Chapitre 3.5 : Acides nucléiques</a>.

Acides nucléiques

Les acides nucléiques sont les macromolécules les plus importantes pour la continuité de la vie. Ils portent le plan génétique de la cellule et portent des instructions pour son ...

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dna and rna: genetic instructions

DNA and RNA are the nucleic acids that store genetic information and help direct cell activity. These macromolecules carry the cell’s genetic blueprint and the instructions it uses to function. DNA is the genetic material in all living organisms, from single-celled bacteria to multicellular mammals.

In eukaryotic cells, DNA is found in the nucleus and also in organelles such as chloroplasts and mitochondria. In prokaryotes, DNA is not enclosed in a membrane. The full genetic content of a cell is called the genome, and the study of genomes is genomics. In eukaryotes, DNA binds histone proteins to form chromatin, which makes up eukaryotic chromosomes. A chromosome can contain tens of thousands of genes. Many genes code for proteins, while others code for RNA products. DNA also helps control cell activity by turning genes on or off.

RNA is mainly involved in protein synthesis under the direction of DNA. DNA stays in the nucleus and uses messenger RNA, or mRNA, to communicate with the rest of the cell. Other RNA types, including rRNA, tRNA, and microRNA, help with protein synthesis and its regulation. DNA and RNA are built from monomers called nucleotides.

Each nucleotide has three parts: a nitrogenous base, a pentose sugar, and a phosphate group. The nitrogenous bases contain carbon and nitrogen, and they are called bases because an amino group can bind an extra hydrogen and make the local environment more basic. DNA nucleotides use adenine, guanine, cytosine, and thymine. Adenine and guanine are purines, which have two carbon-nitrogen rings. Cytosine, thymine, and uracil are pyrimidines, which have one carbon-nitrogen ring. In shorthand, the bases are written as A, T, G, C, and U. DNA contains A, T, G, and C, while RNA contains A, U, G, and C.

The sugar in DNA is deoxyribose, and the sugar in RNA is ribose. Ribose has a hydroxyl group on its second carbon, while deoxyribose has hydrogen there instead. Nucleotides join when a phosphate group connects the 5′ carbon of one sugar to the 3′ carbon of the next sugar. This forms a 5′–3′ phosphodiester linkage.

DNA has a double-helix structure. The sugar-phosphate backbone is on the outside, and the bases are stacked inside like staircase steps. Hydrogen bonds hold the base pairs together. The two strands run in opposite directions, so the 5′ end of one strand faces the 3′ end of the other. Base pairing follows a complementary rule: A pairs with T, and G pairs with C. That is why the two DNA strands are complementary.

RNA is usually single-stranded and is made of ribonucleotides linked by phosphodiester bonds. Messenger RNA carries the message copied from DNA. In the nucleus, a gene can be turned on and mRNA is made. The mRNA sequence is complementary to the DNA coding sequence. In the cytoplasm, mRNA binds ribosomes and other cell machinery. The message is read in codons, which are sets of three bases. Each codon codes for one amino acid, and the protein is built from that code.

Ribosomal RNA, or rRNA, is a major part of ribosomes and helps align the mRNA correctly. rRNA also has enzymatic activity called peptidyl transferase, which helps form peptide bonds between aligned amino acids. Transfer RNA, or tRNA, is one of the smallest RNA types, usually 70 to 90 nucleotides long. It brings the correct amino acid to the protein synthesis site, and base pairing between tRNA and mRNA helps place the right amino acid in the growing polypeptide chain. MicroRNAs are the smallest RNA molecules, and they regulate gene expression by interfering with certain mRNA messages. Even though RNA is single-stranded, many RNA types form internal base pairs that give them a predictable three-dimensional shape needed for function.

DNA and RNA: Genetic Instructions

functional groups

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Chargaff’s Rules and DNA Pairing

Chargaff’s rules and DNA base pairing explain how DNA strands match up. In double-stranded DNA, adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C). Chargaff also found that A equals T, G equals C, and the total amount of purines (A and G) equals the total amount of pyrimidines (C and T). Watson and Crick later showed why these matches matter. A forms two hydrogen bonds with T, while G forms three hydrogen bonds with C. These pairings keep the DNA double helix a...

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nucleic acids

DNA and RNA are the nucleic acids that store genetic information and help direct cell activity. These macromolecules carry the cell’s genetic blueprint and the instructions it uses to function. DNA is the genetic material in all living organisms, from single-celled bacteria to multicellular mammals. In eukaryotic cells, DNA is found in the nucleus and also in organelles such as chloroplasts and mitochondria. In prokaryotes, DNA is not enclosed in a membrane. The full genetic content of a cell...

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Polymers are long chains of molecules made from repeating units called monomers. The word polymer comes from the Greek words "poly," meaning many, and "mer," meaning parts. Polymers can be found in nature, such as DNA and proteins, or made synthetically, such as plastics. A polymer’s shape helps define its properties. Some polymers form linear chains, while others are branched or arranged in complex networks. Functional groups on a polymer also affect how it behaves. The repeating units in a...

key terms and concepts

Explore how DNA and RNA store genetic information, pair bases, and guide protein synthesis through mRNA, rRNA, tRNA, and microRNA.

DNA and RNA: Genetic Instructions | JoVE K12

chemistry

JoVE Core Chimie anime les concepts de chimie générale en utilisant des leçons vidéo concises et faciles à comprendre. De plus, nos vidéos de scientifiques à l'action présentent des expériences de recherche, classiques ou insolites, effectuées dans des laboratoires modernes du monde entier.

Characteristics of Life

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https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/10647.jpg

Levels of Organization

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the-tree-of-life-bacteria-archaea-and-eukaryotes

The Tree of Life - Bacteria, Archaea, and Eukaryotes

Prokaryotic Cells

Prokaryotes are small unicellular organisms that include the domains &#8212; Archaea and Bacteria. Bacteria include many common microorganisms, such as ...

Introduction to Virus

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Compare and contrast existing models, identify patterns, and use structural and functional evidence to analyze the characteristics of life. Engage in argument about the designation of viruses as non-living based on these characteristics.
EXPLANATION: Students begin to develop patterns of living and non-living organisms in kindergarten and build on detailed characteristics of different classifications of living organisms throughout elementary and middle school. Biology 1 discussions introduce viral particles and viral cycles, building on student understanding of living organisms to engage in an argument regarding the classification of a viral particle as either living or non-living.

BIO1.LS1.1

What are Cells?

Cells are the smallest and basic units of life, whether it is a single cell that forms the entire organism, e.g., in a bacterium, or trillions of them, ...

Eukaryotic Compartmentalization

One of the distinguishing features of eukaryotic cells is that they contain membrane-bound organelles, such as the nucleus and mitochondria, that carry ...

Eukaryotic Evolution

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Animal and Plant Cell Structure

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Evaluate comparative models of various cell types with a focus on organic molecules that make up cellular structures.
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BIO1.LS1.2

Nucleic acids are the most important macromolecules for the continuity of life. They carry the cell&#39;s genetic blueprint and carry instructions for its ...

The DNA Helix

Deoxyribonucleic acid, or DNA, is the genetic material responsible for passing traits from generation to generation in all organisms and most viruses. DNA ...

DNA Base Pairing

Erwin Chargaff&#x2019;s rules on DNA equivalence paved the way for the discovery of base pairing in DNA. Chargaff&#x2019;s rules state that in a ...

The Central Dogma

The central dogma explains the flow of genetic information from DNA nucleotides to the amino acid sequence of proteins.
RNA is the Missing Link Between ...

DNA Packaging

Overview

Eukaryotes have large genomes compared to prokaryotes. In order to fit their genomes into a cell, eukaryotes must pack their DNA tightly inside ...

Organization of Genes

Overview

The genomes of eukaryotes can be structured in several functional categories. A strand of DNA is comprised of genes and intergenic regions. ...

Karyotyping

Describing the number and physical features of chromosomes can reveal abnormalities that underlie genetic diseases. This description is facilitated by ...

Replication in Prokaryotes

Overview

DNA replication has three main steps: initiation, elongation, and termination. Replication in prokaryotes begins when initiator proteins bind to ...

Replication in Eukaryotes

Overview

In eukaryotic cells, DNA replication is highly conserved and tightly regulated. Multiple linear chromosomes must be duplicated with high ...

Mutations

Overview

Mutations are changes in the sequence of DNA. These changes can occur spontaneously or they can be induced by exposure to environmental factors. ...

Transcription

Overview
Transcription is the process of synthesizing RNA from a DNA sequence by RNA polymerase. It is the first step in producing a protein from a gene ...

Translation

Lesson: Translation
Translation is the process of synthesizing proteins from the genetic information carried by messenger RNA (mRNA). Following ...

RNA Structure

Overview
The basic structure of RNA consists of a five-carbon sugar and one of four nitrogenous bases. Although most RNA is single-stranded, it can form ...

RNA Stability

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pre-mRNA Processing

In eukaryotic cells, transcripts made by RNA polymerase are modified and processed before exiting the nucleus. Unprocessed RNA is called precursor mRNA or ...

Types of RNA

Overview
Three main types of RNA are involved in protein synthesis: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). These RNAs ...

MicroRNAs

siRNA - Small Interfering RNAs

Small interfering RNAs, or siRNAs, are short regulatory RNA molecules that can silence genes post-transcriptionally, as well as the transcriptional ...

piRNA - Piwi-interacting RNAs

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CRISPR and crRNAs

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lncRNA - Long Non-coding RNAs

In humans, more than 80% of the genome gets transcribed. However, only around 2% of the genome codes for proteins. The remaining part produces non-coding ...

What are Proteins?

Protein Organization

Protein Folding

Protein Families

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conservation-of-protein-domains-over-different-proteins

Conservation of Protein Domains Over Different Proteins

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Globular and Fibrous Proteins

Many proteins can be classified into two distinct subtypes - globular or fibrous. These two types differ in their shapes and solubilities.
Globular ...

Intrinsically Disordered Proteins

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Protein Complex Assembly

Proteins can form homomeric complexes with another unit of the same protein or heteromeric complexes with different types.&#160; Most protein complexes ...

Conjugated Proteins

Simple proteins and protein complexes contain only amino acids. In contrast, many other proteins, called conjugated proteins, covalently bond with ...

Allosteric Proteins-ATCase

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Amyloid Fibrils

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Cooperative Allosteric Transitions

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Antibody Structure

Phosphorylation

Ligand Binding Sites

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Protein Kinases and Phosphatases

Proteins undergo chemical modifications that trigger changes in the charge, structure, and conformation of the proteins. Phosphorylation, acetylation, ...

Protein-protein Interfaces

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GTPases and their Regulation

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Conserved Binding Sites

Many proteins&#8217; biological role depends on their interactions with their ligands, small molecules that bind to specific locations on the protein ...

Covalently Linked Protein Regulators

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The Equilibrium Binding Constant and Binding Strength

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Protein Complexes with Interchangeable Parts

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Cofactors and Coenzymes

Mechanical Protein Functions

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Allosteric Regulation

Structural Protein Function

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Ligand Binding and Linkage

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Protein Networks

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Integrate evidence to develop a structural model of a DNA molecule. Using the model, develop and communicate an explanation for how DNA serves as a template for self-replication and encodes biological information.
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What is the Cell Cycle?

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Interphase

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The Cell Cycle Control System

Positive Regulator Molecules

Inhibition of CDK Activity

S-Cdk Initiates DNA Replication

M-Cdk Drives Transition Into Mitosis

Mitogens and the Cell Cycle

Replicative Cell Senescence

Abnormal Proliferation

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Cells Coordinate Growth and Proliferation

Mitosis and Cytokinesis

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Chromosome Duplication

Cohesins

Create a model for the major events of the eukaryotic cell cycle, including mitosis. Compare and contrast the rates of cell division in various eukaryotic cell types in multicellular organisms.
EXPLANATION: Students first discuss mitosis in seventh grade, specifically focusing on the role of mitosis in creating genetically identical daughter cells. Biology 1 discussions should connect a student's understanding of gene expression and protein function with the process of mitosis to explore the differentiation of cell types from otherwise identical daughter cells. Discussions should also include varying rates of mitotic division and the relationship between these rates of division and the function of specific cell types within eukaryotic organisms. Examples may include the extremely limited use of mitosis by neurons due to their interconnectedness within neural networks or the rapid rates of mitosis with growing root tips.

BIO1.LS1.6

DNA and RNA: Genetic Instructions

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