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Kristen Erzsebet Koopmans
HL Biology

Looking for trends and discrepancies – although most organisms
conform to cell theory, there are exceptions
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All organisms are composed of one or more
cells and these are the smallest units of life
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As a result, all cells contain DNA and when they reproduce, this
DNA is passed onto the daughter cells
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In order for cells to carry out processes and activities
that contribute to the activity of the organism; cells produce energy and metabolic waste as
part of their energy flow
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Organisms can either be unicellular or multicellular
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coli found in lakes which exist as single-celled organisms
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s

A single cell of E
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Because cells carry out different functions, they
have different parts adapted to the processes
carried out
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Even
though there are some core parts that most cells have, there are some exceptions
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We decide whether something is living or non-living according to the
mnemonic name MRS GREN; movement, respiration, sensitivity, growth, reproduction,
excretion and nutrition
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They have sizes that follow the surface area to volume ratio, as well as having a single
nucleus, cell membrane and cytoplasm
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These specific cells reproduce by mitosis
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Even though
they reproduce differently and have varied functions, they all have similar structures
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Acetabularia
is a type of algae which can grow up to 7cm long
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Muscle cells are also quite large measuring up to 300mm
as well as having multiple nuclei in one cell
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Acetabularia - a single-celled algae
which can grow a million times
Red blood cells are also an exception as they do not
bigger than a normal cell would
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Aseptate hyphae is a combination of both exceptions, as they are large and are multinucleated
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A protoctist such as an amoeba is also an exception due to the fact that even though it is a
single celled organism, it can carry out all the necessary functions that of a multicellular
organism
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A sperm cell however, can only carry out
one function which is to pass on genetic information to the embryo from the father
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Even though they aren’t exactly living, they
can’t be classified as non-living either to a certain extent
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Thus this
conforms to the theory that cells pass their DNA down to their daughter cells
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However, to say that the virus is a cell is simply
incorrect as they don’t carry out all characteristics of living organisms except for
reproduction
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There is no specific boundary between
one cell and the next, and this is due to the fact that
the cells secrete calcium phosphate outside of the cell
membrane which solidifies and spreads throughout
the structure in the form of concentric layers
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View from a microscope
of a bone fragment
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Kristen Erzsebet Koopmans
HL Biology

Therefore this is a large exception to the cell theory, and so in the beginning of time when
the first organism came to be, there had to be a concept of cell theory which was broken in
order to do this
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Although this essay lists many exceptions, most cells
conform to the rules of cell theory

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