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Living Things!!!!: Where Do They Come From?

This document discusses living things and cells. It explains that: 1. All living things are made up of one or more cells. 2. All new cells come from pre-existing cells. 3. The cell is the basic unit of life according to the cell theory. It also describes viruses, noting that they are made of genetic material surrounded by protein and can only reproduce by infecting host cells, unlike true living things. There is debate around whether viruses should be considered living.

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141 views6 pages

Living Things!!!!: Where Do They Come From?

This document discusses living things and cells. It explains that: 1. All living things are made up of one or more cells. 2. All new cells come from pre-existing cells. 3. The cell is the basic unit of life according to the cell theory. It also describes viruses, noting that they are made of genetic material surrounded by protein and can only reproduce by infecting host cells, unlike true living things. There is debate around whether viruses should be considered living.

Uploaded by

api-310503032
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Living Things!!!!

Where do they come from?


Living things?

u Living things come only from other living


things.
u The term “cell” originated from Robert Hooke, a
17th century scientist.
u That term is still used today to describe the structures
that living things are made of.
The Cell Theory

u Cell theory: the theory in biology that explains


the structure and source of all living things
u 3 important statements:
1. All living things are made up of one or more cells
2. All new cells come from pre-existing cells
3. The cell is the basic unit of life
Protein coat

Viruses…living? Non-
living?
Genetic material

u Virus: a strand of genetic material


surrounded by a protein layer that can
Tail infect and reproduce in a host cell
Fibres
u They DO NOT contain cell parts that
plant, and animal cells do.
u Unlike cells, they CANNOT…:
u Take in nutrients
u Use energy
u Produce wastes
Viruses

u Viruses must be inside the cell of another organism (host) to


reproduce
u Otherwise they’re dormant (inactive)
u Dormant viruses:
u Cannot carry out any life functions…
u Can stay dormant for hours, days, or even months before they reach a
host!!
u Only function of a virus is to reproduce once inside a host.
u Examples: flu, cold
Argument…

u Most scientists do not consider viruses to be alive


because they do not have the characteristics of
living things
u However, some discoveries from the last few
decades could support that they’re living…
u What do you think?

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