10.2: Size and Shapes of Viruses
- Page ID
- 3233
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)- Compare the size of most viruses to that of bacteria.
- List 4 shapes of viruses.
Size
Viruses are usually much smaller than bacteria with the vast majority being submicroscopic. While most viruses range in size from 5 to 300 nanometers (nm) , in recent years a number of giant viruses, including Mimiviruses and Pandoraviruses with a diameter of 0.4 micrometers (µm) , have been identified. For a comparison of the size of a virus, a bacterium, and a human cell, scroll down to how big is... on the Cell Size and Scale Resource at the University of Utah webpage (see Figure \(\PageIndex{1}\)A, Figure \(\PageIndex{1}\)B, and Figure \(\PageIndex{1}\)C),
Shapes
Figure \(\PageIndex{1}\)C: Sizes and Shapes of Viruses (Bacteriophages)
a. Helical viruses consist of nucleic acid surrounded by a hollow protein cylinder or capsid and possessing a helical structure (Figure \(\PageIndex{2}\)A).
b. Polyhedral viruses consist of nucleic acid surrounded by a polyhedral (many-sided) shell or capsid, usually in the form of an icosahedron (Figure \(\PageIndex{2}\)B).
- Transmission electron micrograph of Adenoviruses; courtesy of CDC.
- Transmission electron micrograph of poliomyelitis viruses; courtesy of CDC.
- Transmission electron micrograph of poliomyelitis viruses; courtesy of Dennis Kunkel's Microscopy.
c. Enveloped viruses consist of nucleic acid surrounded by either a helical or polyhedral core and covered by an envelope (see Figure \(\PageIndex{2}\)C and Figure \(\PageIndex{2}\)D).
- Transmission electron micrograph of Hepatitis B viruses; courtesy of CDC.
- Transmission electron micrograph of an Influenza A virus; courtesy of CDC.
- Transmission electron micrograph of HIV; courtesy of CDC.
- Transmission electron micrograph showing envelope and glycoprotein spikes Coronaviruses; courtesy of CDC.
- Transmission electron micrograph of herpes simplex viruses; courtesy of Dennis Kunkel's Microscopy.
d. Binal (complex) viruses have neither helical nor polyhedral forms, are pleomorphic or irregular shaped (Figure \(\PageIndex{3}\)), or have complex structures (Figure \(\PageIndex{2}\)F).
- Transmission electron micrograph of the bacteriophage coliphage T4; courtesy of Dennis Kunkel's Microscopy.
We just learned that most viruses are much smaller than bacteria.
- Compare the sizes of viruses and bacteria.
- Why are viruses able to be so much smaller than bacteria
Summary
- Viruses are usually much smaller than bacteria with the vast majority being submicroscopic, generally ranging in size from 5 to 300 nanometers (nm).
- Helical viruses consist of nucleic acid surrounded by a hollow protein cylinder or capsid and possessing a helical structure.
- Polyhedral viruses consist of nucleic acid surrounded by a polyhedral (many-sided) shell or capsid, usually in the form of an icosahedron.
- Enveloped viruses consist of nucleic acid surrounded by either a helical or polyhedral core and covered by an envelope.
- Binal (complex) viruses have neither helical nor polyhedral forms, have irregular shapes, or have complex structures.