hhmi Biolnteractive Virus Explorer Click & Learn Student Worksheet INTRODUCTION What do the flu, HIV, and coronaviruses have in common, and how are they different? You’ll learn more about these and other viruses in the Virus Explorer Click & Learn. In the Click & Learn, you can explore the structures and biology of 10 different viruses, as well as how these viruses impact humans and other organisms. PROCEDURE Follow the instructions as you proceed through the Click & Learn, and answer the questions in the spaces provided. Open the Virus Explorer Click & Learn and click on the “About” tab at the bottom. Use the information in this tab to answer the following questions. a. List four ways in which viruses can differ from each other. b. In the table below, describe what each abbreviation in this Click & Learn means. able[[Abbreviation,Description],[nm,Nanometer],[bp,Base Pair],[ss,Single-Stranded],[ds,Double-Stranded]] Close the “About” tab and return to the main page. Find the “1” icon next to each viral characteristic across the top. Click on each icon to learn more about that characteristic, then answer the associated question below. a. Envelope: The envelope is an outer layer that some, but not all, viruses have. How does an envelope form? b. Host(s): From the virus’s perspective, why is the host important? c. Genome Type: What are four characteristics of viral genomes that may vary among viruses?
The Correct Answer and Explanation is:
Answers to the HHMI Biointeractive Virus Explorer Click & Learn Student Worksheet
a. Four ways in which viruses can differ from each other:
- Size: Viruses can vary in size, with some being as small as 20 nm and others reaching up to 300 nm or more.
- Genome Type: Viruses may have either RNA or DNA as their genetic material. Furthermore, these genomes can be single-stranded or double-stranded.
- Envelope Presence: Some viruses have an envelope, which is an outer lipid layer, while others do not. The envelope is typically derived from the host cell membrane.
- Host Range: Viruses can infect a wide variety of hosts, including animals, plants, fungi, bacteria, and even archaea. This is dependent on the virus’s specific adaptations for host recognition and entry.
b. Abbreviations in the Click & Learn:
| Abbreviation | Description |
|---|---|
| nm | Nanometer (unit of length, 1 nm = 1 billionth of a meter) |
| bp | Base Pair (a pair of nucleotides in a DNA or RNA molecule) |
| ss | Single-Stranded (refers to a viral genome that is made up of a single strand of nucleotides) |
| ds | Double-Stranded (refers to a viral genome made of two complementary strands of nucleotides) |
1. Envelope: How does an envelope form?
The envelope of a virus forms from the host cell membrane during the process of viral replication and budding. When new viral particles are synthesized inside the host, they are assembled and then “bud” out of the host cell. As the virus exits the host cell, it takes a piece of the host’s lipid bilayer with it, creating the envelope. This envelope may also contain viral proteins that are crucial for the virus to infect other cells.
2. Host(s): Why is the host important from the virus’s perspective?
From the virus’s perspective, the host is crucial because it provides the necessary machinery and resources for replication. Viruses cannot reproduce on their own; they rely on the host cell to replicate their genome, produce viral proteins, and assemble new viral particles. The host provides the environment for the virus to reproduce and spread to other cells, enabling the virus to survive and propagate.
3. Genome Type: Four characteristics of viral genomes that may vary among viruses:
- Type of Nucleic Acid: Viruses may have RNA or DNA as their genetic material.
- Strand Number: The genome may be single-stranded (ss) or double-stranded (ds).
- Genome Structure: Some viral genomes are linear, while others are circular.
- Size and Complexity: The size of the genome can vary greatly, from a few thousand base pairs (bp) to over a hundred thousand base pairs, and some genomes may contain complex sequences or additional functional genes.
In summary, viruses can differ in several key characteristics, including their envelope structure, host range, and genome type. These differences determine the virus’s ability to infect specific organisms and how it interacts with its host.
