Page 104 - The Miracle in the Cell

Blood capillary Blood capillary
1. The protein hormone diffuses 1. Steroid hormone diffuses from the
from the blood into the fluid blood into the fluid between the cells.
between cells.
Plasma
2. The hormone diffuses membrane
through the cell mem-
Inactive receptor molecule brane of the target cell.
found in the cell membrane Cytoplasm
of the target cell
3. The hormone moves
into the nucleus and Nucleus
binds with a receptor.
2. With the binding of the
hormone to the receptor, cer- 4. The hormone/receptor
tain enzymes are activated. complex triggers the
3. The AMP molecule reading of the desired Receptor
activates new enzymes. protein. molecule
5. The relevant genes for
4. The activated enzymes cause the desired protein are
changes in the cell activity (e.g., the transferred into mRNA,
active transport of special molecules which then moves Reading of
across the cell membrane). towards the cytoplasm.
mRNA message

Hormones that bind
Surface receptors to the surface recep-
tors
Figure 5.6 a) In the first
cell, calcium ions are
present in low concen-
trations. With the
binding of certain Calcium ions in low Calcium ions in
hormones (peptide or concentrations high concentrations
protein hormones, or
hormones such as
epinephrine), the order Transport proteins in the
is given to increase the blood
calcium ion
concentration.
b) Certain hormones
Hormone
(steroids, thyroxin)
delivered via blood cir- Receptors
culation and carried by
Nucleus Structure of the
protein transporter mole- receptor/hormone
cules, enter into the cell.
complex
By binding to special
receptors in the cell nucleus, they facilitate the reading of certain genes, allow-
ing for production of the desired proteins.

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