Section 1
Viruses Hijack Cells to Reproduce
Viruses cannot reproduce alone, so they attach to host cells, inject their DNA, force the cell to make viral parts, assemble new viruses, and burst out, destroying the cell.
In this Grade 7 Life Science lesson from Chapter 9, students learn why viruses are classified as non-living things despite sharing some characteristics with living organisms, such as having genetic material enclosed in a protein coat called a capsid. Students explore how viruses differ from bacteria in size and structure, and how viruses rely on host cells to reproduce rather than doing so independently. The lesson builds on students' prior knowledge of single-celled organisms and living thing characteristics to explain how viruses cause disease and affect living cells.
Section 1
Viruses Hijack Cells to Reproduce
Viruses cannot reproduce alone, so they attach to host cells, inject their DNA, force the cell to make viral parts, assemble new viruses, and burst out, destroying the cell.
Section 2
Scientists Distinguish Viruses from Living Things
Viruses have genetic material and protein coats but lack characteristics of living organisms. They cannot grow or respond to their environment and need host cells to reproduce.
Section 3
Diseases Spread When Viruses Attack Hosts
Viruses cause illnesses like influenza, polio, and AIDS by damaging host cells. They can spread quickly between humans, animals, and plants, leading to widespread health problems.
Section 4
Filters Separate Organisms by Size
Scientists discovered viruses when filtering liquids to remove bacteria. Even after bacteria were filtered out, some liquids still caused disease because viruses are much smaller than bacteria.
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Section 1
Viruses Hijack Cells to Reproduce
Viruses cannot reproduce alone, so they attach to host cells, inject their DNA, force the cell to make viral parts, assemble new viruses, and burst out, destroying the cell.
Section 2
Scientists Distinguish Viruses from Living Things
Viruses have genetic material and protein coats but lack characteristics of living organisms. They cannot grow or respond to their environment and need host cells to reproduce.
Section 3
Diseases Spread When Viruses Attack Hosts
Viruses cause illnesses like influenza, polio, and AIDS by damaging host cells. They can spread quickly between humans, animals, and plants, leading to widespread health problems.
Section 4
Filters Separate Organisms by Size
Scientists discovered viruses when filtering liquids to remove bacteria. Even after bacteria were filtered out, some liquids still caused disease because viruses are much smaller than bacteria.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter