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Cell structure
- Nucleus
- Contains DNA
- DNA arranged
into long thin
threads known as
chromosomes
- In most cells
the
chromosomes
are arranged in
homologous
pairs
- Surrounded
by nuclear
envelope
- This has pores to
allow communication
between the nucleus
and cytoplasm
- Contains DNA
- Plasma membrane
- Sea of
phospholipids -
arranged as a
bilayer
- Intrinsic and
extrinsic
proteins float
within the
phospholipids
- Selectively permeable
barrier - controls
movement of
substances between the
internal and external
environments
- Sea of
phospholipids -
arranged as a
bilayer
- Lysomes
- Formed by
the golgi
apparatus
- Contain
digestive
enzymes -
proteases and
lipases
- Important to protect the
cell from the effect of
these enzymes before they
are released at the cell
surface membrane or into
a phagocytic vesicle
- Formed by
the golgi
apparatus
- Mitochondria
- Mostly protein,
but also contains
some lipid, DNA
and RNA
- Power house of
the cell
- Energy is stored in high
energy phosphate bonds
of ATP
- Mitochondria convert energy from the
breakdown of glucose into adenosine
triphosphate (ATP)
- Responsible for
aerobic respiration
- Metabolic activity of a cell is
related to the number of cristae
(larger surface area) and
mitochondria
- Mostly protein,
but also contains
some lipid, DNA
and RNA
- Ribosomes
- Small organelles
often attached to the
ER but also found in
the cytoplasm
- Large (protein) and small
(rRNA) subunits form the
functional ribosome
- Subunits bind with
mRNA in the cytoplasm
- This starts translation
of mRNA for protein
synthesis (assembly of
amino acids into
proteins
- This starts translation
of mRNA for protein
synthesis (assembly of
amino acids into
proteins
- Subunits bind with
mRNA in the cytoplasm
- Free ribosomes make proteins used in the cytoplasm.
Responsible for proteins thatgo into solution in
cytoplasm or form important cytoplasmic, structural
elements
- Ribosomal ribonucleic
acid (rRNA) are made in
nucleus of cell
- Small organelles
often attached to the
ER but also found in
the cytoplasm
- Endoplasmic reticulum
- Rough ER
- Have ribosomes attached
to the cytosolic side of
their membrane
- Found in cells that
are making proteins
for export (enzymes,
hormones, structural
proteins, antibodies)
Thus, involved in
protein synthesis
- Modifies proteins by the addition of
carbohydrates, removal of signal
sequences
- Phospholipid synthesis
and assembly of
polypeptides
- Have ribosomes attached
to the cytosolic side of
their membrane
- Smooth ER
- Have no ribosomes attached
and often appear more
tubular than the rough ER
- Necessary for steroid
synthesis, metabolism
and detoxification, lipid
synthesis
- Numerous in the liver
- Have no ribosomes attached
and often appear more
tubular than the rough ER
- Rough ER
- Golgi apparatus
- Stack of
flattened sacs
surrounded by
membrane
- Receives protein-filled vesicles from the rough ER (fuse
with Golgi membrane)
- Uses enzymes to modify these
proteins (e.g. add a sugar
chain, making glycoprotein)
- Adds directions for destination of protein package - vesicles
that leave Golgi apparatus move to different locations in cell
or proceed to plasma membrane for secretion
- Involved in processing, packaging, and secretion
- Other vesicles that leave
Golgi apparatus are
lysosomes
- Stack of
flattened sacs
surrounded by
membrane
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