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

الأحماض النووية هي بوليمرات للنيكليوتيدات-جزيئات تتكون من سكر البنتوز،وقاعدة تحتوي على نيتروجين،ومجموعة فوسفات. يوجد نوعان من الأحماض النووية:الحمض النووي الريبوزي منقوص الأكسجين،DNA،والحمض النووي الريبوزي،RNA. يختلف الاثنان من حيث البنية الكيميائية،ويُعزى الاختلاف إلى نوع سكر البنتوز ونوع القاعدة النيتروجينية في كل منهما.سكر البنتوز الموجود في RNA هو سكر الريبوز،والذي يحتوي على مجموعة هيدروكسيل مرتبطة بذرة الكربون-2. أما في DNA فيوجد سكر ريبوز منقوص الأكسجين،يتكون من ذرة هيدروجين وليس فيه ذرة أكسجين عند ذرة الكربون-2. ترتبط القاعدة النيتروجينية بذرة الكربون-1 وبالفوسفات عند ذرة الكربون-5.يحتوي كل من RNA و DNA على القواعد أدنين،سايتوسين،وغوانين،لكن DNA يحتوي على ثايمين،بينما يحتوي RNA على يوراسيل. يشكل الغوانين والسايتوسين في كل من DNA و RNA أزواجًا من القواعد المكمّلة،مترابطة بواسطة ثلاث روابط هيدروجينية. يشكل الأدنين والثايمين أزواج القواعد في DNA،بينما يشكل الأدنين واليوراسيل أزواج القواعد في RNA،ويترابط كلاها برابطتين هيدروجينيتين.إنزيم البوليميراز الموجود في كل من DNA و RNA يحفّز على بلمرة النيوكليوتيدات. تتشكل رابطة فوسفور ثنائية الإستر بين،مجموعة هيدروكسيل مرتبطة بذرة الكربون-3،وبين مجموعة الفوسفات المرتبطة بذرة الكربون-5،من النيوكليوتيدة التالية. يؤدي هذا التفاعل إلى ترك الطرف 5'غير مرتبط،مع مجموعة فوسفات حرة،كما يترك الطرف 3'غير مرتبط،مع مجموعة هيدروكسيل حرة.عندما يقترن الجزيئان بواسطة سلسلة مكمّلة،يصبح توجههما غير متوازٍبمعنى أن يقترن الطرف 5'لأحدهما،بالطرف 3'للآخر. هذه السلاسل مترابطة بعضها ببعض بواسطة قوى بين جزيئية،بما في ذلك التأثيرات الكارهة للماء،وتأثيرات فان دير فالس المتبادلة،والروابط الهيدروجينية المحددة،التي تتشكل بين القواعد النيتروجينية. الDNA لولب مزدوج يتكون من سلسلتين متعددة النيوكليوتيد ملتفتان حول بعضهما العض.وعلى العكس،غالبًا ما يتواجد الـRNA على شكل جزيء من سلسلة واحدة. لكن الRNA يستطيع أن يتحد ليشكل RNA أو DNA مكمّل. كما يمكنه أن يُظهر شريط-داخلي لاقتران قواعد مكمّلة،ينتج عنه أنواع مختلفة من بنيات RNA الثانوية،التي تؤدي وظائف مميزة ضمن الخلية.

الأحماض النووية

تعد الأحماض النووية أهم الجزيئات الكبيرة لاستمرارية الحياة. فهي تحمل المخطط الجيني للخلية وتحمل التعليمات الخاصة بوظائفها. 
 DNA و RNA
 النوعان الرئيسيان من الأحماض النووية هما الحمض النووي الريبي منقوص الأكسجين (DNA) والحمض النووي الريبي (RNA). الحمض النووي هو المادة الجينية في جميع الكائنات الحية، بدءاً من البكتيريا وحيدة الخلية إلى الثدييات متعددة الخلايا. إنه موجود في نواة حقيقيات النوى وفي العضيات والبلاستيدات الخضراء والميتوكوندريا. في بدائيات النوى، لا يتم تغليف الحمض النووي في غلاف غشائي. 
 إن المحتوى الجيني الكامل للخلية' هو جينومها، ودراسة الجينوم هي علم الجينوم. في الخلايا حقيقية النواة ولكن ليس في بدائيات النوى ، يشكل الحمض النووي مركبًا مع بروتينات هيستون لتكوين الكروماتين ، وهو مادة الكروموسومات حقيقية النواة. يمكن أن يحتوي الكروموسوم على عشرات الآلاف من الجينات. تحتوي العديد من الجينات على المعلومات اللازمة لصنع البروتينات. كود الجينات الأخرى لمنتجات الحمض النووي الريبي. يتحكم الحمض النووي في جميع الأنشطة الخلوية عن طريق تشغيل الجينات “تشغيل” أو “إيقاف.”
 يشارك النوع الآخر من الحمض النووي، وهو RNA، في الغالب في تخليق البروتين. لا تغادر جزيئات الحمض النووي النواة أبداً ولكنها تستخدم وسيطاً للتواصل مع بقية الخلية. هذا الوسيط هو الرسول RNA (mRNA). أنواع أخرى من الحمض النووي الريبي RNA— مثلrRNA,، tRNA، و RNA— الميكروي كلها تشارك في تخليق البروتين وتنظيمه. 
 يتكون DNA و RNA من مونومريات تسمى النيوكليوتيدات. تشتمل ثلاثة مكونات على كل نوكليوتيد: قاعدة نيتروجينية، سكر بنتوز (خمسة كربون)، ومجموعة فوسفات. ترتبط كل قاعدة نيتروجينية في نوكليوتيد بجزيء سكر، والذي يرتبط بمجموعة أو أكثر من مجموعات الفوسفات. القواعد النيتروجينية، وهي مكونات مهمة للنيوكليوتيدات، هي جزيئات عضوية وسميت بهذا الاسم لأنها تحتوي على الكربون والنيتروجين. إنها قواعد لأنها تحتوي على مجموعة أمينية لديها القدرة على ربط هيدروجين إضافي، وبالتالي تقليل تركيز أيون الهيدروجين في بيئتها، مما يجعلها أكثر أساسية. يحتوي كل نوكليوتيد في الحمض النووي على واحدة من أربع قواعد نيتروجينية محتملة: الأدينين (A) ، والجوانين (G) ، والسيتوزين (C) ، والثيمين (T). يتم تصنيف الأدينين والجوانين على أنها بورينات. الهيكل الأساسي للبيورين' هو حلقتان من الكربون والنيتروجين. يتم تصنيف السيتوزين والثايمين واليوراسيل على أنها بيريميدين لها حلقة كربون-نيتروجين واحدة كهيكلها الأساسي. كل من حلقات الكربون والنيتروجين الأساسية هذه لها مجموعات وظيفية مختلفة مرتبطة بها. في اختصار البيولوجيا الجزيئية، نعرف القواعد النيتروجينية برموزها A و T و G و C و U. يحتوي DNA على A و T و G و C؛ بينما يحتوي RNA على A و U و G و C. 
 سكر البنتوز في الحمض النووي هو ديوكسيريبوز، وفي الحمض النووي الريبي، السكر هو ريبوز. الفرق بين السكريات هو وجود مجموعة الهيدروكسيل على ثاني كربون في الريبوز' وهيدروجين على ثاني كربون في الديوكسيريبوز'. تلتصق بقايا الفوسفات بمجموعة الهيدروكسيل الخاصة بـ 5′ كربون سكر واحد ومجموعة الهيدروكسيل من3′ كربون سكر من النوكليوتيد التالي، والذي يشكل بالنتيجة رابطة 5′–3′ فوسفوديستر. 
 بنية الحلزون المزدوج للحمض النووي
 يحتوي الحمض النووي على بنية ثنائية الحلزون. يقع السكر والفوسفات على السطح الخارجي للحلزون، مما يشكل العمود الفقري للـ DNA'. القواعد النيتروجينية مكدسة في الداخل، مثل زوج من درجات السلم. تربط الروابط الهيدروجينية الأزواج ببعضها البعض. يتم فصل كل زوج أساسي في اللولب المزدوج عن الزوج الأساسي التالي بمقدار 0.34 نانومتر. تعمل خيوط الهيليكس' الثنائية في اتجاهين متعاكسين، مما يعني أن نهاية الكربون 5′ لواحدة من الخيوط ستواجه نهاية الكربون 3′ للخيط المقابل. يُسمح فقط بأنواع معينة من الاقتران الأساسي - يمكن أن يقترن A مع T، ويمكن أن يقترن G مع C. هذه هي القاعدة الأساسية التكميلية. وبعبارة أخرى، فإن خيوط الحمض النووي مكملة لبعضها البعض. 
 < RNA 
 يشارك الحمض النووي الريبي بشكل أساسي في عملية تخليق البروتين تحت إشراف الحمض النووي. عادة ما يكون الحمض النووي الريبي أحادي الجديلة ويتكون من ريبونوكليوتيدات مرتبطة بروابط الفوسفوديستر. هناك أربعة أنواع رئيسية من الحمض النووي الريبي: الRNA المرسال (mRNA) ، والـ RNA الريبي (RNA)، والـ RNA الناقل (tRNA)، والـ RNA الميكروي (miRNA). أول نوع، mRNA، يحمل الرسالة من الحمض النووي، الذي يتحكم في جميع الأنشطة الخلوية في الخلية. إذا كانت الخلية تتطلب بروتيناً معيناً، فإن الجين الخاص بها يتحول إلى وضعية “التفعيل” ويتم تصنيع RNA الرسول في النواة. تسلسل قاعدة RNA هو مكمل لتسلسل تشفير DNA' الذي تم نسخه منه. في السيتوبلازم، يتفاعل mRNA المرسال مع الريبوسومات والآلات الخلوية الأخرى. 
 تتم قراءة mRNA في مجموعات من ثلاث قواعد تعرف باسم الكودونات. يرمز كل كودون لحمض أميني واحد. بهذه الطريقة، يتم قراءة mRNA ويتم تصنيع منتج البروتين. الـ rRNA الريبوسومي' (الرنا الريباسي) هو مكون رئيسي للريبوسومات التي يرتبط بها الرنا المرسال. يضمن الرنا الريباسي المحاذاة الصحيحة للـ mRNA والريبوسومات. يحتوي الـ rRNA الريبوسومي' أيضًا على نشاط إنزيمي (بيبتيديل ترانفسيراز) ويحفز تكوين رابطة الببتيد بين اثنين من الأحماض الأمينية المتوافقة. يعد الحمض النووي الريبي الناقل ((tRNA) أحد أصغر الأنواع الأربعة من RNA، وعادةً ما يكون بطول 70–90 نيوكليوتيداً. يحمل الحمض الأميني الصحيح إلى موقع تخليق البروتين. إن الاقتران الأساسي بين tRNA و mRNA هو الذي يسمح للحمض الأميني الصحيح بإدخال نفسه في سلسلة البولي ببتيد. RNA الميكروي هو أصغر جزيئات RNA، وينطوي دوره على تنظيم التعبير الجيني عن طريق التدخل في التعبير عن رسائل معينة من mRNA. 
 على الرغم من أن RNA أحادي السلسلة، فإن معظم أنواع RNA تُظهر اقتراناً واسعاً للقاعدة داخل الجزيئية بين التسلسلات التكميلية، مما يخلق بنية ثلاثية الأبعاد يمكن التنبؤ بها ضرورية لوظيفتها. 
 هذا النص مقتبس من <a href="https://openstax.org/books/biology-2e/pages/3-5-nucleic-acids">Openstax, Biology 2e, Chapter 3.5: Nucleic Acids</a>.

الأحماض النووية هي أهم الجزيئات الكبيرة لاستمرارية الحياة. يحملون المخطط الجيني للخلية ويحملون تعليمات ل ...

Education

JoVE Core

Chemistry

الكيمياء

واحد

Biochemistry

الكيمياء الحيوية

KEY TERMS AND CONCEPTS

المصطلحات والمفاهيم الأساسية

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

Functional Groups in Organic Chemistry

Functional groups in organic chemistry are groups of atoms that give molecules specific properties. When these groups attach to a carbon skeleton, they can change how the molecule behaves. Some functional groups make a molecule hydrophilic, or water-attracting. Others make it hydrophobic, or water-repelling. Functional groups are a key part of organic chemistry and are also found in major biological molecules. They appear in carbohydrates, proteins, lipids, and nucleic acids. Each functional...

structure of lipids

Lipids, Fats, and Cell Membranes

Lipids are nonpolar molecules that do not mix well with water. They are hydrophobic, which means “water fearing,” because they contain mostly nonpolar carbon-carbon and carbon-hydrogen bonds. In cells, lipids store long-term energy as fats, help insulate plants and animals, and form protective water-repellent layers on feathers and fur. They are also part of cell membranes and serve as building blocks for many hormones. Common lipids include fats, oils, waxes, phospholipids, and steroids. A...

chemistry of the cell

Cell Chemistry: Water and Macromolecules

Cell chemistry includes water, organic molecules, and inorganic ions. These materials shape how cells store energy, build structures, and carry out life processes. Most cellular chemistry and metabolism happen in the watery cytoplasm. Water is a key part of the cell because it has special properties tied to its polarity. In a water molecule, hydrogen and oxygen form polar covalent bonds, so the molecule has no net charge but does have a slightly positive end and a slightly negative end. Oxygen...

dna base pairing

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...

chemistry of carbohydrates

Carbohydrates as Energy and Storage Molecules

Carbohydrates are important energy sources in human and animal diets. Grains, fruits, and vegetables are natural sources of carbohydrates. They help provide energy to the body, especially through glucose, a simple sugar found in starch and many staple foods. Carbohydrates are identified by the stoichiometric formula (CH2O)n, where n is the number of carbons in the molecule. This means the ratio of carbon to hydrogen to oxygen is usually 1:2:1. The name carbohydrate comes from this pattern,...

protein and protein structure

How Protein Shape Controls Function

Proteins are a major class of organic molecules in living systems, and their shape helps determine what they do. They can act as structural, regulatory, contractile, or protective molecules. They also take part in transport, storage, membranes, toxins, and enzymes. All proteins are polymers of amino acids arranged in a linear sequence. A protein’s function depends on its three-dimensional form. For example, an enzyme works when its active site can bind a specific substrate. If local changes or...

amino acids

Amino Acids and Protein Building

Amino acids are the building blocks of proteins. Each amino acid has the same basic structure. A central carbon atom, called the alpha carbon, is bonded to an amino group, a carboxyl group, and a hydrogen atom. Each amino acid also has an R group, or side chain, attached to the central carbon. The R group is different for every amino acid. It helps determine whether an amino acid is acidic, basic, polar, or nonpolar. Scientists call these molecules amino acids because they contain both amino...

peptide bonds

Peptide Bond Formation and Shape

Peptide bonds join amino acids into peptides and polypeptides. They form when the carboxyl group of one amino acid reacts with the amino group of another. This dehydration reaction releases a water molecule and creates a covalent link. As more amino acids are added, the chain becomes a polypeptide. Each polypeptide has a free amino group at one end. This end is the N-terminal, or amino-terminal. The other end has a free carboxyl group. This end is the C-terminal, or carboxyl-terminal. The...

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...

dna replication

DNA Copying: Leading and Lagging Strands

DNA replication copies genetic material before a cell divides. Each original DNA strand serves as a template for a new complementary strand. The result is semiconservative replication, which means each new DNA molecule contains one old strand and one new strand. The two daughter cells then receive DNA with the same sequence. Replication starts when helicase separates the two strands of the double helix. This creates a Y-shaped replication fork. Primase then adds short RNA primers that give DNA...

from dna to protein

The Genetic Code and Codons

The genetic code and codons explain how cells turn DNA information into proteins. Genes first direct the sequence of mRNA, and mRNA then directs the sequence of amino acids that make up proteins. Specific proteins and RNAs carry out this decoding. Cells copy DNA into mRNA so the original DNA stays protected while the cell uses the message for protein synthesis. Copying DNA to RNA is relatively simple. One nucleotide is added to the mRNA strand for every nucleotide read on the DNA strand.

polymers

Polymer Chains and How They Form

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 Chemistry brings general chemistry concepts to life using concise and easy-to-understand animated video lessons. Plus, in the scientist-in-action videos, we demonstrate classical and original research experiments performed in today's laboratories worldwide.

Characteristics of Life

Biology is a natural science that studies life and living organisms, including their structure, function, development, interactions, evolution, ...

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

Levels of Organization

Biological organization is the classification of biological structures, ranging from atoms at the bottom of the hierarchy to the Earth&#x27;s biosphere. ...

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

Viruses are unique biological entities that blur the boundary between living and non-living systems. Although they lack cellular structure and metabolic ...

Size and Structure of Viral Genomes

Viral genomes exhibit remarkable diversity in size, structure, and composition, influencing their replication strategies and interactions with host cells. ...

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

The endosymbiont theory is the most widely accepted theory of eukaryotic evolution; however, its progression is still somewhat debated. According to the ...

Animal and Plant Cell Structure

Animal and plant cells not only differ in their structure, function, and mode of nutrition but also in how they reproduce, specialize, and organize into ...

Evaluate comparative models of various cell types with a focus on organic molecules that make up cellular structures.
EXPLANATION: Students explicitly discuss the structure and function of major cellular organelles in seventh grade. Building on this understanding, Biology I students should shift their focus to the different types of cells found in organisms and how the role of each cell type relates to its composition and the prevalence of different organelles within that cell. An example might include the absence (or enucleation) of the nucleus in red blood cells in mammals providing for increased levels of oxygen transport in organisms or the lack of centrioles in most neurons. Varying cell types can include both prokaryotic and eukaryotic cell types.

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

Intact DNA strands can be found in fossils, while scientists sometimes struggle to keep RNA intact under laboratory conditions. The structural variations ...

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

PIWI-interacting RNAs, or piRNAs, are the most abundant short non-coding RNAs. More than 20,000 genes have been found in humans that code for piRNAs while ...

CRISPR and crRNAs

Bacteria and archaea are susceptible to viral infections just like eukaryotes; therefore, they have developed a unique adaptive immune system to protect ...

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

Protein families are groups of homologous proteins; that is, they have similarities in amino acid sequences and three-dimensional structures. Protein ...

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

Conservation of Protein Domains Over Different Proteins

Protein domains are small structurally independent units that are part of a single amino acid chain.&#160; Although these domains are often structurally ...

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

Intrinsically disordered proteins are a group of proteins that do not fold into specific three-dimensional structures. Their structural flexibility allows ...

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

Binding sites linkages can regulate a protein&#39;s function.&#160; For example, enzyme activity is often regulated through a feedback mechanism where the ...

Amyloid Fibrils

Amyloid fibrils are aggregates of misfolded proteins.&#160; Under most circumstances, misfolded proteins are either refolded by chaperone proteins or ...

Cooperative Allosteric Transitions

Cooperative allosteric transitions can occur in multimeric proteins, where each subunit of the protein has its own ligand-binding site. When a ligand ...

Antibody Structure

Phosphorylation

Ligand Binding Sites

Proteins are dynamic macromolecules that carry out a wide variety of essential processes; however, the activities of most proteins depend on their ...

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

Many proteins form complexes to carry out their functions, making protein-protein interactions (PPIs) essential for an organism&#39;s survival. Most PPIs ...

GTPases and their Regulation

Guanine nucleotide-binding proteins (G-proteins), also known as GTPases, are a superfamily of proteins that regulate many cellular processes, such as cell ...

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

Proteins can undergo many types of post-translational modifications, often in response to changes in their environment. These modifications play an ...

the-equilibrium-binding-constant-and-binding-strength

The Equilibrium Binding Constant and Binding Strength

The equilibrium binding constant (Kb) quantifies the strength of a protein-ligand interaction. Kb can be calculated as follows when the reaction is at ...

protein-complexes-with-interchangeable-parts

Protein Complexes with Interchangeable Parts

Groups of proteins may form a complex where each protein in this complex has a different role in the overall execution of the complex&#8217;s function. ...

Cofactors and Coenzymes

Mechanical Protein Functions

Proteins perform many mechanical functions in a cell. These proteins can be classified into two general categories- proteins that generate mechanical ...

Allosteric Regulation

Structural Protein Function

Structural proteins are a category of proteins responsible for functions ranging from cell shape and movement to providing support to major structures ...

Ligand Binding and Linkage

Allosteric proteins have more than one ligand binding site; the binding of a ligand to any of these sites influences the binding of ligands to the other ...

Protein Networks

An organism can have thousands of different proteins, and these proteins must cooperate to ensure the health of an organism. Proteins bind to other ...

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.
EXPLANATION: Discussions of DNA in earlier grades have been limited to discussions of genes and the role of genes in the appearance and activities of an organism. Biology 1 represents a student's introduction to a molecular model of a DNA as well as the organization of DNA into genes and genes subsequently into chromosomes. Students should address interactions between genes in proteins which regulate both the shape and reproduction of DNA molecules. It is important to note that not all segments of DNA are transcribed for proteins. Portions of DNA are involved in regulating the expression of genes or affect the structure of the chromosomes (replication origin, centromeres, and telomeres).

What is the Cell Cycle?

The cell cycle refers to the sequence of events occurring throughout a typical cell&#8217;s life. In eukaryotic cells, the somatic cell cycle has two ...

Interphase

The cell cycle occurs over approximately 24 hours (in a typical human cell) and in two distinct stages: interphase, which includes three phases of the ...

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

cells-coordinate-growth-and-proliferation

Cells Coordinate Growth and Proliferation

Mitosis and Cytokinesis

In eukaryotes, the cell division cycle is divided into distinct, coordinated cellular processes that include cell growth, DNA replication/chromosome ...

Chromosome Duplication

Cohesins

Condensins

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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