Label the Parts of This Enveloped Influenza Virus

One influenza A virus particle cut open, with a close-up of its envelope.

Label the Parts of This Enveloped Influenza Virus

Name Date

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1 2 3 4 5 6 7 8
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Write the name of each numbered part.Answer key

  1. Hemagglutinin (HA)
  2. Neuraminidase (NA)
  3. Envelope
  4. RNA segments
  5. M2 ion channel
  6. Matrix protein (M1)
  7. Nucleoprotein (NP)
  8. Polymerase complex

Drawn for this site on 2026-10-01 from plain geometry. Licence: own work.

Each numbered ring is a button. Use the arrow keys to move between them and Enter to choose. Names are read out in Study, and once a part is answered.

Next step Next: the parts every virus shares

All 8 parts on the diagram

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Whole virus 4

  1. Hemagglutinin (HA) The more common of the two spikes. It is the protein that binds the virus to a cell.
  2. Neuraminidase (NA) The less common of the two spikes. It lets newly made virus particles get free of the cell they formed in.
  3. Envelope A lipid bilayer that wraps the whole particle. It is taken from the membrane of the cell the virus formed in.
  4. RNA segments The genome is eight separate pieces of RNA. Each is coated with nucleoprotein and coiled into a rod, called a ribonucleoprotein.

Close up 4

  1. M2 ion channel A protein that forms a channel for ions through the envelope. It helps to free the RNA segments once the virus is inside a cell.
  2. Matrix protein (M1) A layer of protein just under the envelope. It lies between the envelope and the RNA segments.
  3. Nucleoprotein (NP) The protein that coats the RNA. RNA and nucleoprotein together make the coiled rod.
  4. Polymerase complex Three proteins bound to each RNA segment. Together they copy the RNA.

How this list was compiled: Every name was checked on 2026-10-01 in two independent sources. (1) Wikipedia, text only: Influenza A virus (the section on structure and the table of the genome), https://en.wikipedia.org/wiki/Influenza_A_virus . (2) Nayak, Balogun, Yamada, Zhou and Barman, Influenza virus morphogenesis and budding, Virus Research 143 (2009), an open-access review read in full through Europe PMC, https://europepmc.org/article/PMC/PMC2730999 . Licence: own work

The drawing: Drawn for this site on 2026-10-01 from plain geometry; nothing traced. Licence: own work

How it works

Label the parts of this enveloped influenza virus in two views: the whole particle cut through the middle, and a close-up of its envelope. Tap a name to read about the part, then press Quiz me.

Read the full guide

The whole virus

Hemagglutinin is the club-shaped spike and the more common one. Neuraminidase has a thin stalk and a box-shaped head. Both stand in the envelope, the band round the particle. The coiled rods in the middle are the eight RNA segments.

The close-up

The M2 ion channel is the short tube through the membrane, and the matrix protein is the row of ovals packed underneath. One RNA segment is drawn large: beads of nucleoprotein, with the polymerase complex at one end.

  • An enveloped virus is one wrapped in a lipid membrane. On this drawing the envelope is the band the spikes stand in.

Questions and answers

What are the parts of an influenza virus?

An envelope set with two kinds of spike, hemagglutinin and neuraminidase, and with M2 ion channels; a layer of matrix protein under the envelope; and eight RNA segments, each coated with nucleoprotein and carrying a polymerase complex.

What are the spikes on an influenza virus?

Two proteins that stand in the envelope. Hemagglutinin, the more common one, binds the virus to a cell. Neuraminidase lets newly made virus particles get free of the cell they formed in.

Why is influenza called an enveloped virus?

Because each particle is wrapped in an envelope, a lipid bilayer taken from the membrane of the cell it formed in. The spikes and the M2 ion channels are set in that envelope.

How many RNA segments does influenza A have?

Eight. Each is a separate piece of RNA coated with nucleoprotein, with a polymerase complex of three proteins bound to it.

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