IB Biology Topic A2.3.2 Diversity of Structure in Viruses Revision Notes (HL)

IB Biology Topic A2.3.2 Diversity of Structure in Viruses Revision Notes (HL) | RevisionDojo

Written by official IB examiners

Viral Diversity: Why No Two Virus Families Look Alike

Viruses vary enormously in shape, size, and genome type, far more than living cells do.
They exhibit multiple structural solutions to parasitism, making them highly adaptable.

Shapes and Sizes: How Viruses Vary in Form

Viruses are categorized by their capsid shape:
1. Icosahedral (spherical): Symmetrical, 20-sided structure (e.g., adenoviruses and herpesviruses).
2. Helical (rod-shaped): Spiral capsid arrangement (e.g., tobacco mosaic virus).
3. Complex: Icosahedral head + helical tail (e.g., bacteriophages).
Most viruses are small, typically ranging from 20 to 300 nanometers, though some are much larger:
1. Bacteriophage lambda: ~50 nm.
2. Mimivirus: Up to 750 nm, one of the largest known viruses.

Note

Viruses do not grow like living organisms.
Their size is fixed, but they must remain small enough to enter their host cells and replicate efficiently.

Genetic Material: DNA or RNA, Single or Double-Stranded

Unlike living organisms (DNA only), viruses use DNA or RNA in varying forms:
1. Single-stranded (ss) or double-stranded (ds)

Nice try, unfortunately this paywall isn't as easy to bypass as you think. Want to help devleop the site? Join the team at https://revisiondojo.com/join-us. exercitation voluptate cillum ullamco excepteur sint officia do tempor Lorem irure minim Lorem elit id voluptate reprehenderit voluptate laboris in nostrud qui non Lorem nostrud laborum culpa sit occaecat reprehenderit

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Duis aute irure dolor in reprehenderit

Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit.

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

Unlock the rest of this chapter with a free account

Viral Diversity: Why No Two Virus Families Look Alike

Viruses vary enormously in shape, size, and genome type, far more than living cells do.
They exhibit multiple structural solutions to parasitism, making them highly adaptable.

Shapes and Sizes: How Viruses Vary in Form

Viruses are categorized by their capsid shape:
1. Icosahedral (spherical): Symmetrical, 20-sided structure (e.g., adenoviruses and herpesviruses).
2. Helical (rod-shaped): Spiral capsid arrangement (e.g., tobacco mosaic virus).
3. Complex: Icosahedral head + helical tail (e.g., bacteriophages).
Most viruses are small, typically ranging from 20 to 300 nanometers, though some are much larger:
1. Bacteriophage lambda: ~50 nm.
2. Mimivirus: Up to 750 nm, one of the largest known viruses.

Note

Viruses do not grow like living organisms.
Their size is fixed, but they must remain small enough to enter their host cells and replicate efficiently.

Genetic Material: DNA or RNA, Single or Double-Stranded

Unlike living organisms (DNA only), viruses use DNA or RNA in varying forms:
1. Single-stranded (ss) or double-stranded (ds)

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

IB Biology Topic A2.3.2: Diversity of Structure in Viruses Notes

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

Viral Diversity: Why No Two Virus Families Look Alike

Shapes and Sizes: How Viruses Vary in Form

Genetic Material: DNA or RNA, Single or Double-Stranded

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Viral Diversity: Why No Two Virus Families Look Alike

Shapes and Sizes: How Viruses Vary in Form

Genetic Material: DNA or RNA, Single or Double-Stranded

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account