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Cells
1.1.1.f
• compare the ultrastructure of a leucocyte and a palisade
mesophyll cell, as seen with an electron microscope, to
illustrate the differences between animal and plant cells
as examples of eukaryotic cells (to include the cell
surface membrane, Golgi apparatus, rough and smooth
endoplasmic reticulum (ER), ribosomes, lysosomes,
vesicles, mitochondria, chloroplasts, cytoskeleton, cell
wall, nucleus and nucleolus);
Task
Draw and label an animal cell and a plant cell.
What is a cell?
Cells are the basic unit of life. They are small membrane-bound
structures containing several smaller structures called organelles.
There are two main categories of cell, each of which have
important different structural properties:
eukaryotic cell, including the cells
of animals and plants
prokaryotic cell, including
bacterial cells.
The cell membrane and cytoplasm
All cells, and all true organelles,
are contained within a
membrane, based on a
phospholipid bilayer.
The cell membrane holds a
cell together and controls
what enters and leaves the
cytoplasm, as it is a selectively permeable barrier.
The cytoplasm comprises a liquid called cytosol, and all the
organelles suspended in it (except the nucleus in eukaryotes).
The cell membrane and cytoplasm are universal features of
the living cell.
Cells need energy to carry out vital processes.
o Where does this energy come from?
o What is the name of the process that releases
energy?
The universal energy carrier
Cells need a constant supply of energy to carry out vital
processes such as protein synthesis, DNA replication and cell
division.
This energy originally comes from fuel
molecules, such as glucose, consumed by
the organism. These are broken down
during aerobic or anaerobic respiration,
and the energy released is used to make
adenosine triphosphate (ATP).
ATP
ADP
ATP diffuses throughout the cell, and breaks down into
adenosine diphosphate (ADP), releasing chemical energy
wherever it is needed.
Eukaryotic Cells
What is a eukaryote?
A eukaryote is any organism consisting of
one or more cells that contain DNA in a
membrane-bound nucleus, separate from
the cytoplasm.
Eukaryotes include:
• animals
• plants
• fungi
• a diverse group known as the
protists (or protoctists).
All eukaryotic cells contain a large number of specialized,
membrane-bound organelles.
The organelles of protein synthesis