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Art connection

Illustration a shows bacteriophage T4, which houses its DNA genome in a hexagonal head. A long, straight tail extends from the bottom of the head. Tail fibers attached to the base of the tail are bent, like spider legs. In b, adenovirus houses its DNA genome in a round capsid made from many small capsomere subunits. Glycoproteins extend from the capsomere, like pins from a pincushion. In c, the HIV retrovirus houses its RNA genome and an enzyme called reverse transcriptase in a bullet-shaped capsid. A spherical viral envelope, lined with matrix proteins, surrounds the capsid. Glycoproteins extend from the viral envelope.
Viruses can be either complex in shape or relatively simple. This figure shows three relatively complex virions: the bacteriophage T4, with its DNA-containing head group and tail fibers that attach to host cells; adenovirus, which uses spikes from its capsid to bind to host cells; and HIV, which uses glycoproteins embedded in its envelope to bind to host cells. Notice that HIV has proteins called matrix proteins, internal to the envelope, which help stabilize virion shape. (credit “bacteriophage, adenovirus”: modification of work by NCBI, NIH; credit “HIV retrovirus”: modification of work by NIAID, NIH)

Which of the following statements about virus structure is true?

  1. All viruses are encased in a viral membrane.
  2. The capsomere is made up of small protein subunits called capsids.
  3. DNA is the genetic material in all viruses.
  4. Glycoproteins help the virus attach to the host cell.

Types of nucleic acid

Unlike nearly all living organisms that use DNA as their genetic material, viruses may use either DNA or RNA as theirs. The virus core    contains the genome or total genetic content of the virus. Viral genomes tend to be small, containing only those genes that encode proteins that the virus cannot get from the host cell. This genetic material may be single- or double-stranded. It may also be linear or circular. While most viruses contain a single nucleic acid, others have genomes that have several, which are called segments.

In DNA viruses, the viral DNA directs the host cell’s replication proteins to synthesize new copies of the viral genome and to transcribe and translate that genome into viral proteins. DNA viruses cause human diseases, such as chickenpox, hepatitis B, and some venereal diseases, like herpes and genital warts.

RNA viruses contain only RNA as their genetic material. To replicate their genomes in the host cell, the RNA viruses encode enzymes that can replicate RNA into DNA, which cannot be done by the host cell. These RNA polymerase enzymes are more likely to make copying errors than DNA polymerases, and therefore often make mistakes during transcription. For this reason, mutations in RNA viruses occur more frequently than in DNA viruses. This causes them to change and adapt more rapidly to their host. Human diseases caused by RNA viruses include hepatitis C, measles, and rabies.

Virus classification

To understand the features shared among different groups of viruses, a classification scheme is necessary. As most viruses are not thought to have evolved from a common ancestor, however, the methods that scientists use to classify living things are not very useful. Biologists have used several classification systems in the past, based on the morphology and genetics of the different viruses. However, these earlier classification methods grouped viruses differently, based on which features of the virus they were using to classify them. The most commonly used classification method today is called the Baltimore classification scheme and is based on how messenger RNA (mRNA) is generated in each particular type of virus.

Questions & Answers

who is the father of evolution
Ferkah Reply
complete the table below based on the levels of biological organization
Lovely Reply
Give me Examples of living thing which have 2 or more flagella?
Mahesh Reply
insect and plants
qax
bacteria and chlamydompnas
Berhanu
reproduction it's full meaning
Gift Reply
full meaning of ATP
Gifty
A life process in which living things increase their population through sexual or non sexual intercouse
Danisha
please explaination
Daniel
Gifty ATP means Adenosine tri phosphate
Mahesh
the process by which organisms produce their own kind.
Berhanu
reproduction is the process where living organisms producess their offspring
jerry Reply
what is reproduction
Nmesoma Reply
why some kinds of students are failed
Ahmadi Reply
lack of concentration
Faith
lack of guidance and counseling
ali
what's the divination of openstax
John
don't mind about reading
aine
lack of focus
Afolayan
What is the meaning of optic
Kisaky Reply
Giving a specific section of the alimentary canal,describe 3 ways in which physical digestion occurs.
Kisaky
mouth when chewing
ephraim
what is population
Ivy Reply
total number of people living in an area
FILDA
a number of people lives in one catigorize area or named area
Oburak
what is a cell
Chiko Reply
basic and functional unit of life
Edwin
cell is tissues that makes up functional life in human or un animal.
Oburak
is the smallest basic unit of life.
Kisaky
Is the smallest baic unit. o
Kisaky
why cell is very important to human body
Ahmadi
what is diffusion
Henry
diffusion is a process of mix of particles from higher concentration to the lower one,to make the body functional normal
Adam
what is effusion
Mahesh
what is soil
FILDA Reply
Is the finely divided material covering the earth crust.
Kisaky
is the upper moist of layer of the earth surface
Ahmadi
what is reducing sugar
Erica Reply
in genetics which disease is also termed as the queen disease
Phinihas Reply
what are the types of cell
Teye Reply
prokaryote ,eukaryote, akaryotes
bonney
what is akaryotes ?
Chriscia
multicellular and unicellular
Edwin
akaryotes are organisms that function as eukaryotes and prokaryotes
Edwin
akaryotes are cell with no nucleus
Edwin
biology is the study of living organisms
bonney Reply
what's the divination of open stax?
John
biology is designed for multi- semester biology course for science Major
John

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Source:  OpenStax, Biology. OpenStax CNX. Feb 29, 2016 Download for free at http://cnx.org/content/col11448/1.10
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