Describe how homeostatic control systems in species of microbes, plants and
animals support common ancestry.
All “Homeostatic Control Systems” have THREE things in common:
A. Receptor
B. Control Center
C. Effector
Microbe: Food is obtained, Waste is excreted (semi-permeable Membrane… Nucleus, Food
Vacuoles)
From the web: Homeostasis is just a big word for balance.
The mammal uses the heat it generates to keep itself in balance and able to run. The reptile has to get that heat from
the environment so the mammal has to eat at least twice a day and the reptile can go with a meal only once a day. It
needs to burn less energy just to stay alive. If a snake eats a big meal then it can afford to bask in the sun and wait a
long time before it has to do anything except breathe and digest.
Plants control themselves with water; buy cooling with respiration and by going dormant when it gets too cold.
Evergreens are the few plants that don't do that. They keep going year round; usually because they live in cold
climates.
Osmosis is how plants pump water and nutrients around. It can release energy, and can be made to do work, as when
a growing tree-root splits a stone. So a plant uses water and osmosis to help keep it in homeostasis.
Mammals use insulin to regulate the amount of glucose they have in their blood and they burn glucose for energy (to
create ATP). Plants use glucose as well and make it through photosynthesis and they continue to grow as long as they
get sunshine and the CO2, nitrogen and other things they need for life. Most plants lose their leaves in winter so that
they can remain in homeostasis with the reduced temperatures and sunshine. They sacrifice part of themselves to
survive.
Cactus leaves have changed into thorns so they don't lose much water through them and they rely on the chlorophyll
in the main body to conduct photosynthesis to make the sugar and burn it to make the ATP they need to live. There
sacrifice to homeostasis is to give up the leaf, and they can't use it to rotate to catch sunlight. The sacrifice gives them
extra protection though and conserves water by reducing body expose so it is worth it.
An annual plant doesn't worry about homeostasis too much it just dies each year. Perennials are plants that live more
than two years and they need to worry about homeostasis.
Plants do whatever they need to do to remain in homeostasis, they are willing to sacrifice part of themselves, they go
dormant or even just die off to remain in homeostasis, if they die then they can't keep it up and so just quit, often they
fall back to just the root system to re-sprout when conditions are right next year. There is no one system they use, but
several that they use them to remain in balance with life. Animals do the same, and how much energy you spend
maintaining homeostasis determines how you live. The tiny shrew lives a very fast life and has to eat its own weight in
food each day because to stay in balance it needs to. Plants don't move much they generate energy from sunlight,
water, and CO2; which becomes ATP the energy currency of life. They don't have to have as complex a system to
remain in balance and where we use a heart and a bloodstream the plant can use osmosis to pump its water and
nutrients around. It takes less energy for a plant to remain in balance.
An advantage of homeostatic regulation is that it allows an organism to function effectively in a broad range of
environmental conditions. For example, ectotherms tend to become sluggish at low temperatures, whereas a colocated endotherm may be fully active. That thermal stability comes at a price since an automatic regulation system
requires additional energy. One reason snakes may eat only once a week is that they use much less energy to maintain
homeostasis."
ATP is the "molecular currency" of intracellular energy transfer. In this role, ATP transports chemical energy within
cells for metabolism. It is produced as an energy source during the processes of photosynthesis and cellular respiration
and consumed by many enzymes and a multitude of cellular processes including biosynthetic reactions, motility and
cell division. In signal transduction pathways, ATP is used as a substrate by kinases that phosphorylate proteins and
lipids, as well as by adenylate cyclase, which uses ATP to produce the second messenger molecule cyclic AMP."
Plants make ATP in the Krebs cycle, via photosynthesis. They can move their leaves to catch the sun, but otherwise
they don't move very much. A Venus Fly trap adds animals to its diet because it specializes in living in poor soil so it
needs the extra nutrients.
Plants use xylem as just one more method to remain in homeostasis, buy helping the process of osmosis
All of this is done to make the energy of life and to maintain the balance for life.
Explain how conditions where signal transduction is blocked or defective can
be deleterious, preventative or prophylactic. (Hypertension, Diabetes, Heart
Disease)
Signal Transduction has two processes:
A. A signaling molecule activates a specific receptor protein on the cell membrane.
B. A second messenger transmits the signal into the cell, eliciting a physiological response.
With multicellular organisms, numerous processes are required for coordinating individual cells to
support the organism as a whole; the complexities of these processes tend to increase with the
complexity of the organism. Sensing of environments at the cellular level relies on signal
transduction. Signal transduction refers to any process by which a cell converts one kind of signal or
stimulus into another. These processes most often involve ordered sequences of biochemical
reactions inside the cell, which are carried out by enzymes, activated by second messengers
resulting in what is known as a "signal transduction pathway". Signal transduction is usually rapid,
lasting milliseconds in the case of ion flux, minutes for the activation of protein and lipid mediated
kinase cascades, or hours and days in terms of gene expression. In single-cell organisms, signal
transduction pathways determine how the cell senses and responds to its environment. In multicellular organisms, a multitude of different signal transduction pathways are required for
coordinating the behavior of individual cells to support the function of the organism as a whole. As
may be expected, the more complex the organism, the more complex the repertoire and
interconnectivity of signal transduction pathways. Thus, sensing of both the external and internal
environment at the cellular level relies on signal transduction.
Many diseases such as diabetes, heart disease, inflammation and cancer arise from defects in signal
transduction pathways, underscoring the critical importance of signal transduction in medicine as
well as biology.
Diabetes: When insulin binds on the cellular insulin receptor, it leads to a cascade of cellular
processes that promote the usage or, in some cases, the storage of glucose in the cell. The
effects of insulin vary depending on the tissue involved, e.g., insulin is most important in the
uptake of glucose by muscle and adipose tissue. The insulin signal transduction pathway is
composed of trigger mechanisms that serve as signals throughout the cell. There is also a
counter mechanism in the body to stop the secretion of insulin beyond a certain limit. Namely,
those counter-regulatory mechanisms are glucagon and epinephrine.
Heart Disease: If the signals received to initiate the complex process of heart muscle
contraction are weak or not timed properly the resulting release of glucose to power the heart
muscle may not be sufficient to sustain normal heart function. Muscle contractions may be
either weak or not timed properly to co-ordinate with other heart muscles. In some cases there
may be a lack of sufficient amount of a particular enzyme which may result in the signal
transduction pathway within the cell to function improperly. Normal heart function is a very
complex process involving a great number of steps which all must take place in proper
sequence.
Hypertension: Signal transduction is important for contraction and relaxation of smooth
muscle. Defective signal transduction could lead to chronic hypertension.
With regards to transport systems, explain how within multicellular
organisms, specialization of organs contributes to the overall functioning of
the organism:
Organ
Structure
Relates to function how?
Heart
Muscular, with multiple chambers
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Arteries
Muscular, durable
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Deliver oxygen-rich blood to all of the tissues
Deliver oxygen-poor blood to the respiratory
structures
Keep oxygen-rich blood and oxygen-poor blood
separate
Allow for endothermy
Handles the high pressures well
Stretches and recoils when heart contracts and
relaxes
Substances stay in the blood
Veins
One-way valves
Capillaries One-cell thick
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Prevents backflow of blood
Continues the closed circuit
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Allows for diffusion of nutrients and gases
Allows for diffusion of waste products
Short diffusion distance
High surface area (total)