Name: how viruses infect cells and multiply
Uploaded: 2019-03-11T09:21:23.000Z
Duration: 50 s
Channel: JoVE

K12 Standards

Louisiana Student Standards for Science

High School

Life Sciences

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

From Molecules To Organisms: Structures And Processes

HS-LS1-8

What are Viruses?

الفيروس هو بنية تحمل موادها الجينومية على شكل حمض نووي ريبي أو حمض نووي لتغزو وتتكرر داخل خلية مضيفة بعد أن ترتبط الفيروس بالمستقبلات السطحية على الخلية المضيفة تدخل وتتفكك بسرعة لتفك بذلك شيفرة المواد الجينية في حالة فيروسات الحمض النووي يوجه الحمض النووي الفيروسي بروتينات استنساخ الخلايا المضيفة لتركيب نسخ جديدة من الجينوم الفيروسي والتي يجري نسخها وترجمتها بعد ذلك في البروتينات الفيروسية أخيرًا يعيد المضيف تجميع هذه المكونات الفيروسية في ذرية سامحة لجُسيم فيروس واحد بإنتاج ألف أخرى الأمر الذي يؤدي غالباًإلى موت الخلية المضيفة

ياماوتشي ، يوهي ، وآري هيلينيوس. "دخول الفيروس في لمحة." J Cell Sci 126 ، العدد 6 (15 مارس 2013): 1289-95. [<a href = "https://doi.org/10.1242/jcs.119685" target = "__blank" >المصدر</a>]

لين ، ديريك إم ، بريت كوسكيلا ، وهنري سي لين. "العلاج بالعاثيات: بديل للمضادات الحيوية في عصر مقاومة الأدوية المتعددة". المجلة العالمية لعلم الأدوية والعلاجات المعدية المعوية 8 ، العدد 3 (6 أغسطس 2017): 162-73. [<a href = "https://doi.org/10.4292/wjgpt.v8.i3.162" target = "__blank" >المصدر</a>]

نيكايز ، فاليري. "مناعة المحاصيل ضد الفيروسات: النتائج والتحديات المستقبلية". الحدود في علوم النبات 5 (21 نوفمبر 2014). [<a href = "https://doi.org/10.3389/fpls.2014.00660" target = "__blank" >المصدر</a>]

ما هي الفيروسات؟

<h4>نظره عامه</h4>

الفيروس عبارة عن جسيم معدي مجهري يتكون من جينوم الحمض النووي الريبي أو الحمض النووي المحاط بقشرة بروتينية. إنه غير قادر على التكاثر من تلقاء نفسه: يمكنه فقط إنتاج المزيد من الفيروسات عن طريق دخول خلية واستخدام أجهزتها الخلوية. عندما يصيب الفيروس خلية مضيفة ، فإنه يزيل غلافها البروتيني ويوجه آلية المضيف لنسخ وترجمة مادته الجينية. تجمع الخلية المختطفة المكونات المتضاعفة الي الآلاف من السلالة الفيروسية ، والتي يمكن أن تمزق وتقتل الخلية المضيفة. ثم تستمر الفيروسات الجديدة في إصابة المزيد من الخلايا المضيفة.

<h4>لماذا دراسة الفيروسات؟</h4>

يمكن للفيروسات أن تصيب أنواعاً مختلفة من الخلايا: البكتيريا والنباتات والحيوانات. الفيروسات التي تستهدف البكتيريا ، والتي تسمى عاثيات بكتيرية (أو العاثيات) ، وفيرة للغاية. تركز الأبحاث الحالية على العلاج بالعاثيات لعلاج الالتهابات البكتيرية المقاومة للأدوية المتعددة لدى البشر. كما تتم دراسة الفيروسات التي تصيب النباتات المزروعة بشكل كبير لأن الأوبئة تؤدي إلى خسائر فادحة في المحاصيل وخسائر اقتصادية.

اكتشفت الفيروسات لأول مرة في القرن التاسع عشر عندما ابتلي محصول مهم اقتصادياً ، نبات التبغ ، بمرض غامض _ تم تحديده لاحقاً باسم فيروس موزاييك التبغ. للفيروسات الحيوانية أهمية كبيرة في كل من البحوث البيطرية والبحوث الطبية. علاوة على ذلك ، تكمن الفيروسات وراء العديد من الأمراض التي تصيب الإنسان ، بدءاً من نزلات البرد ، وجدري الماء ، والهربس ، وانتهاءً بالعدوى الأكثر خطورة مثل الحمى الصفراء والتهاب الكبد والجدري.

<h4>بنية فيروس</h4>

تأتي الفيروسات في مجموعة متنوعة من الأشكال المتخصصة في مهاجمة الخلية المستهدفة. المكونان الرئيسيان لجميع الفيروسات هما الجينوم الفيروسي وغلافه البروتيني الواقي ، المعروف باسم كابسيد. يتكون الجينوم الفيروسي من الحمض النووي الريبي أو الحمض النووي الفردي أو مزدوج الشريط ، وهو يشفر البروتينات التي تشكل الكابسيد. يُعرف الجينوم الفيروسي والكابسيد معاً باسم النوكليوكابسيد.

 من السمات الفريدة للعديد من فيروسات حقيقيات النوى وجود غشاء فسفوليبيد ، يُعرف باسم الغلاف الذي يحيط بالكابسيد. ينشأ هذا الغلاف عادةً من أغشية الخلايا المضيفة المصابة سابقاً ، ولكن يمكن أن يشتمل أيضاً على بروتينات فيروسية (تسمى بروتينات الغلاف) مرتبطة به. أخيراً ، تحتوي بعض فيروسات الحيوانات على مجموعة من البروتينات المشفرة بالفيروس ، السلالة الفيروسية ، في الفراغ بين الغلاف والكابسيد.

<h4>العدوى الفيروسية</h4>

يمكن تقسيم دورة الحياة الفيروسية إلى الخطوات الخمس التالية: التعلق ، والدخول ، والنسخ المتماثل ، والتجميع ، والتحرير. تساعد البروتينات الموجودة على سطح الفيروس في التعرف على خلايا مضيفة معينة. تستخدم بعض الفيروسات هذه البروتينات السطحية للارتباط بمستقبلات الخلايا المضيفة وبدء الاستيعاب عن طريق الالتقام الخلوي ، بينما يمكن للفيروسات المحاطة بالمغلف أن تندمج مباشرة مع غشاء الخلية المضيفة.

لا تدخل بعض العاثيات إلى الخلية ؛ يقومون بحقن الجينوم (والإنزيمات الفيروسية) في الخلية المضيفة. بمجرد دخول الفيروس إلى الخلية ، يصبح غير مغطى ويوجه آلية الخلية المضيفة لنسخ وترجمة جينومها الفيروسي. تحزم الخلية المضيفة النسخ الجديدة من الجينوم الفيروسي في جزيئات فيروسية لتكوين ذرية. يمكن تخزين فيروسات النسل في الخلية المضيفة قبل إطلاقها أو تنبثق باستمرار من الخلية عن طريق التبرعم من غشاء الخلية. تصنف دورة العدوى الفيروسية على أنها تحللية أو مسببة للتحلل. في الدورة التحللية ، تنفجر الفيروسات الجديدة من الخلية المضيفة وبالتالي تقتلها. في الدورة المسببة للتحلل ، يتم دمج الحمض النووي الفيروسي في جينوم المضيف حيث يظل نائماً ويتم نسخه في كل مرة تتكاثر فيها الخلية المضيفة.

نظره عامه

الفيروس هو جسيم معدي مجهري يتكون من جينوم الحمض النووي الريبي أو الحمض النووي المحاط بغلاف بروتيني إنه غير قادر على التكاثر على ...

Education

JoVE Core

Biology

علم الأحياء

Genetics

علم الوراثة

Viruses

الفيروسات

KEY TERMS AND CONCEPTS

المصطلحات والمفاهيم الأساسية

how viruses infect cells and multiply

Viruses infect cells and make new copies by using a host cell’s own machinery. A virus is a tiny infectious particle with an RNA or DNA genome inside a protective protein coat. It cannot reproduce on its own, so it must enter a cell to make more viruses.

After infection, the virus sheds its protein coat and uses the host cell to transcribe and translate its genetic material. The cell then assembles many new viral particles. In many cases, these new viruses rupture the host cell and kill it. The released viruses can then infect other cells.

Viruses can attack bacteria, plants, and animals. Viruses that infect bacteria are called bacteriophages, or phages, and they are very abundant. Scientists also study phages as a possible therapy for multidrug-resistant bacterial infections in humans. Plant viruses matter because outbreaks can cause major crop and economic losses.

Animal viruses are important in both veterinary research and medical research. Viruses were first discovered in the 19th century during studies of tobacco plants with a mysterious disease. That disease was later identified as Tobacco mosaic virus. Viruses are also linked to many human illnesses, including the common cold, chickenpox, herpes, yellow fever, hepatitis, and smallpox.

Viruses vary in shape, but they share two main parts: the viral genome and the capsid. The genome can be single-stranded or double-stranded RNA or DNA, and it carries the instructions for making capsid proteins. The genome and capsid together form the nucleocapsid. Many eukaryotic viruses also have an envelope, which is a phospholipid membrane often taken from a host cell. Some animal viruses also contain a tegument, a layer of viral proteins between the envelope and the capsid.

A viral infection usually follows five stages: attachment, entry, replication, assembly, and release. Viral surface proteins help the virus recognize the right host cell. Some viruses bind to host receptors and enter by endocytosis, while enveloped viruses can fuse with the host cell membrane. Some bacteriophages do not enter the cell at all. They inject their genome and viral enzymes into the host cell instead.

Once inside, the virus is uncoated and directs the host cell to copy and read its genetic material. The host cell packages the new genomes into viral particles to form progeny viruses. These progeny may stay in the cell for a time or leave by budding from the cell membrane. Viral infection can be lytic or lysogenic. In the lytic cycle, new viruses burst out and kill the host cell. In the lysogenic cycle, viral DNA becomes part of the host genome, stays dormant, and is copied when the host cell divides.

How Viruses Infect Cells and Multiply

what are viruses?

Viruses infect cells and make new copies by using a host cell’s own machinery. A virus is a tiny infectious particle with an RNA or DNA genome inside a protective protein coat. It cannot reproduce on its own, so it must enter a cell to make more viruses. After infection, the virus sheds its protein coat and uses the host cell to transcribe and translate its genetic material. The cell then assembles many new viral particles. In many cases, these new viruses rupture the host cell and kill it.

viral structure

How Virus Shapes Help Infection

Viruses have specific structures that help them infect host cells and trigger immune responses. Each virus has a core that contains either a DNA-based or RNA-based genome. That core is surrounded by a protective protein coat called the capsid. The capsid is made of smaller subunits called capsomeres. The capsid and the genome-containing core together are called the nucleocapsid. Viruses are often grouped by capsid design. Most viruses have either icosahedral or helical capsids, but some have...

lytic cycle of bacteriophages

How Phages Infect and Burst Bacteria

Bacteriophages, or phages, are viruses that infect bacteria. They have a distinctive head-tail shape. In the lytic cycle, a phage first attaches to the outside of a bacterial cell. Tail proteins bind to specific receptor proteins on the bacterium’s surface. After attachment, the phage tail injects its DNA genome into the bacterial cytoplasm. The phage then uses the bacterium’s cellular machinery to make proteins needed for replication and dispersal. When phage replication is complete, some of...

lysogenic cycle of bacteriophages

Prophage Integration in Bacteria

The lysogenic cycle shows how bacteriophages can infect bacteria without killing the host right away. In this cycle, the phage genome joins the bacterial genome. The integrated phage DNA is called a prophage, and the bacterium copies it each time it replicates. Some prophages can switch back into the lytic cycle. This change can happen after DNA damage or even without an obvious outside trigger. When the prophage is induced, the phage begins making new virus particles again. Prophages can...

retrovirus life cycles

How Retroviruses Replicate in Host Cells

Retroviruses replicate by copying their RNA genome into DNA inside a host cell. After entry, the viral enzyme reverse transcriptase makes a double-stranded DNA copy from the single-stranded RNA genome. The viral DNA is then carried into the nucleus and inserted into the host genome by integrase. Once integrated, the retroviral DNA is transcribed whenever the host genome is transcribed. This produces new viral RNA that can be copied and used again. The new RNA moves into the cytoplasm, where it...

viral recombination

How Viruses Swap Genes and Spread

Viral gene swapping can happen when more than one virus infects the same cell. After the viruses break open and expose their genomes for replication, matching regions can pair up and exchange sequences. This process is called recombination. Viruses with segmented genomes can also swap whole segments, which is called reassortment. These changes can help create new diseases. Some diseases can infect more than one species. Pigs can be infected by some human and bird viruses, along with the...

viral mutations

How Virus Mutations Drive Outbreaks

Virus mutations can change how quickly a virus evolves and spreads. A mutation is a change in the sequence of bases in DNA or RNA. Some mutations happen when the genome is copied. They are caused by errors made by polymerase enzymes, which replicate DNA or RNA. RNA viruses often change faster than DNA viruses because RNA polymerase does not proofread its work. That means RNA-based genomes, such as HIV, can gather mutations more quickly. Mutation and recombination give viruses the raw material...

key terms and concepts

Learn how viruses enter host cells, use cellular machinery to replicate, and spread through lytic and lysogenic cycles in plants, animals, and bacteria.

How Viruses Infect Cells and Multiply | JoVE K12

JoVE Core series brings biology to life through over 300 concise and easy-to-understand animated video lessons that explain key concepts in biology, plus more than 150 scientist-in-action videos that show actual research experiments conducted in today’s laboratories.

biology

Texas Essential Knowledge and Skills

BIO.5

BIO.5.D

Georgia Standards of Excellence

9-12

SB4.c

myJoVE Corporation

Nucleic Acids and Nucleotides

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

Nucleic Acid Structure

The pentose sugar in DNA is deoxyribose, while in RNA the pentose sugar is ribose. The difference between the sugars is the presence of the hydroxyl group ...

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 ...

From DNA to Protein

The flow of genetic information in cells from DNA to mRNA to protein is described by the central dogma, which states that genes specify the sequence of ...

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 ...

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 ...

Genomic DNA in Prokaryotes

The genome of most prokaryotic organisms consists of double-stranded DNA organized into one circular chromosome in a region of cytoplasm called the ...

Genomic DNA in Eukaryotes

Eukaryotes have large genomes compared to prokaryotes. To fit their genomes into a cell, eukaryotic DNA is packaged extraordinarily tightly inside the ...

Overview

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

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 ...

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 ...

DNA as a Genetic Template

What is Gene Expression?

A gene is a stretch of DNA that serves as the blueprint for functional RNAs and proteins. Since DNA is comprised&#160; of nucleotides and proteins are ...

Transcription

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

Translation

Translation is the process of synthesizing proteins from the genetic information carried by messenger RNA (mRNA). Following transcription, it constitutes ...

Ribosomes

Ribosomes translate genetic information encoded by messenger RNA (mRNA) into proteins. Both prokaryotic and eukaryotic cells have ribosomes. Cells that ...

tRNA Activation

Initiation of Translation

Termination of Translation

What are Cells?

Cell Diversity

The concept of a cell started with microscopic observations of dead cork tissue by Robert Hooke in 1665. Hooke coined the term &#34;cell&#34; based on the ...

Cells of the Epidermis

The epidermis is made of four or five layers of epithelial cells, depending on its location in the body. From deep to superficial, these layers are the ...

Bone Cells and Tissue

Bones contain a relatively small number of cells entrenched in a matrix of organic and inorganic components. Although bone cells compose only a small ...

Gross Anatomy of Skeletal Muscles

The connective tissues play a significant role in arranging the muscle fibers into a hierarchical structure that forms a complete muscle. Consider a ...

Structure of Cardiac Muscles

Cardiac muscle, or myocardium, is a specialized type of muscle found exclusively in the heart. Its unique structural and functional characteristics enable ...

structure-and-organization-of-smooth-muscles

Structure and Organization of Smooth Muscles

In the human body, smooth muscle tissue is found lining the visceral and tubular organs such as the liver, lungs, blood vessels, and respiratory tract.
...

Chromosome Replication

Before a cell can divide, it must accurately replicate all of its chromosomes, including the DNA and its associated histone and non-histone ...

Neurons: The Cell Body and the Dendrites

A typical nerve cell comprises three main components: the cell body, dendrites, and the axon. The cell body, also known as the soma or perikaryon, serves ...

Lampbrush Chromosomes

In 1882, Flemming observed lampbrush chromosomes (LBC) in salamander eggs. Later in 1892, R&#252;ckert observed LBCs in shark egg cells and coined the ...

Neurons: The Axon

The axon is a long, thin extended portion of the neuron that carries impulses from its cell body toward the effector cell.
Axoplasm, the axon&#39;s ...

Polytene Chromosomes

Polytene chromosomes are giant interphase chromosomes with several DNA strands placed side by side. They were discovered in the year 1881 by Balbiani in ...

Nervous Tissue: Neuron Types

Neurons, the fundamental units of the nervous system, can be classified based on both their structural and functional characteristics.
Structurally, ...

Euchromatin

The extent of chromatin compaction can be studied by staining chromatin using specific DNA binding dyes. Under the microscope, the dense-compacted regions ...

Nervous Tissue: Glial Cells

Glial cells or neuroglia are non-neuronal cells in the nervous system that outnumber neurons. These include astrocytes, oligodendrocytes, microglia, and ...

Heterochromatin

Lymphoid Cells and Tissues

Lymphoid cells and lymphoid tissues are the two major components of lymphoid organs.
Lymphoid cells consist of immune system cells such as B and T ...

chromatin-position-affects-gene-expression

Chromatin Position Affects Gene Expression

Chromatin is the massive complex of DNA and proteins packaged inside the nucleus. The complexity of chromatin folding and how it is packaged inside the ...

Two structural features of the DNA molecule provide a basis for the mechanisms of heredity: the four nucleotide bases and its double-stranded nature. The ...

Organization of Genes

Chromosome Structure

A functional eukaryotic chromosome must contain three elements: a centromere, telomeres, and numerous origins of replication.
The centromere is a DNA ...

Construct an explanation based on evidence for how the structure of DNA determines the structure of proteins which carry out the essential functions of life through systems of specialized cells. Emphasis is on the conceptual understanding that DNA sequences determine the amino acid sequence and thus protein structure. Students can produce scientific writing, or presentations, and/or physical models that communicate constructed explanations.

HS-LS1-1

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 Scientific Method

The scientific method is a detailed, empirical problem-solving process used by biologists and other scientists. This iterative approach involves ...

Taxonomy

Taxonomy is the science of defining and naming groups of biological organisms based on shared characteristics. It uses a hierarchy of increasingly ...

Phylogeny

Phylogeny is concerned with the evolutionary diversification of organisms or groups of organisms. A group of organisms with a name is called a taxon ...

Develop and use a model to illustrate the hierarchical organization of interacting systems that provide specific functions within multicellular organisms. Emphasis is on functions at the organism system level such as nutrient uptake, water delivery, or organism movement in response to neural stimuli. An example of an interacting system could be an artery depending on the proper function of elastic tissue and smooth muscle to regulate and deliver the proper amount of blood within the circulatory system.

HS-LS1-2

Overview of Metabolism

Living cells constantly carry out various chemical reactions which are necessary for their proper functioning. These reactions are interlinked to one ...

Regulation of Metabolism

Cellular needs and conditions vary from cell to cell and change within individual cells over time. For example, the required enzymes and energetic demands ...

Positive and Negative Feedback Loops

Animal organs and organ systems constantly adjust to internal and external changes through a process called homeostasis (&#34;steady state&#34;). Examples ...

Functions of Life

Human life is characterized by a variety of functions that are essential for survival and well-being. These functions include metabolism, movement, ...

Requirements for Human Life

The Earth and its atmosphere have provided humans with air, water, and food, but these are not the only requirements for survival. Humans also require a ...

What is Homeostasis?

Maintaining homeostasis requires that the body continuously maintain its internal conditions. Each physiological condition has a particular set point, ...

Negative and Positive Feedback

Homeostatic Imbalance

Homeostasis is the maintenance of a stable internal environment within the body, which is crucial for the proper functioning of cells, tissues, organs, ...

pH Homeostasis

Acid-base homeostasis is essential for maintaining normal physiological activities in humans. The pH of various body fluids is strictly regulated because ...

homeostatic-imbalances-in-body-temperature

Homeostatic Imbalances in Body Temperature

Hyperthermia is an umbrella term for elevated body temperature that occurs when heat production exceeds the body&#39;s ability to dissipate it.
...

Regulation of Food Intake

The hypothalamus releases peptides influencing feeding behavior.
Two hypothalamic neuronal groups participate in this process.
Neuropeptide Y (NPY) and ...

Plan and conduct an investigation to provide evidence that feedback mechanisms maintain homeostasis in living organisms. Examples of investigations could include heart rate responses to exercise, stomate responses to moisture and temperature, root development in response to water levels, or cell response to hypertonic and hypotonic environments.

HS-LS1-3

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

The Mitotic Spindle

Centrosome Duplication

Spindle Assembly

Attachment of Sister Chromatids

Forces Acting on Chromosomes

Separation of Sister Chromatids

Use a model to illustrate the role of the cell cycle and differentiation in producing and maintaining complex organisms. Emphasis is on conceptual understanding that mitosis passes on genetically identical materials via replication, not on the details of each phase in mitosis.

HS-LS1-4

How Viruses Infect Cells and Multiply

Description

Transcript

More videos by Standards