Topic 2Homeostasis in

Organisms

It's all a

bout balance.

As a collection of organized biological systems, a living thing

must keep all of its biological systems stable.

To maintain this internal stability, called _________________, an organism

must continually monitor and respond to changes in the

environment.

HOMEOSTASIS

Basic Biochemical ProcessesBiochemical processes are the

CHEMICAL processes that occur within an organism.

Since all organisms need both

ENERGY and MATERIALS

for their biochemical processes to occur, two of the most important processes

involve storing energy in matter and retrieving that energy as needed.

These processes are calledPHOTOSYNTHESIS and RESPIRATION.

H

O

H

The process of storing solar energy as chemical bond energy in organic molecules,

such as GLUCOSE, is called PHOTOSYNTHESIS.

Photosynthetic organisms include:PLANTS

ALGAEmany SINGLE-CELLED organisms

Photosynthesis

The energy for life comes primarily from the SUN.

However, solar energy can’t be directly used by living things.

Photosynthesis converts solar energy into chemical bond energy, which living things can use.

+

Photosynthesis requires specialized pigment molecules to capture and

convert the solar energy. In plants, these green pigment

molecules are called CHLOROPHYLL and stored in oval-shaped organelles

called CHLOROPLASTS.DRAW andLABEL ME!

Thylokoid stack

stroma

PHOTOSYNTHESIS(A Brief Overview)

http://www.teachertube.com/video/photosynthesis-62625

One of the most common energy-rich organic molecules

produced by photosynthesis is the sugar GLUCOSE.

It’s made by combining two inorganic compounds, CARBON DIOXIDE (CO2)

and WATER (H2O).

Fortunately for us, photosynthesis also produces a

valuable waste product, OXYGEN.

In sentence form, the reaction of photosynthesis would read:

Six molecules of CARBON DIOXIDE react with 6 molecules of WATER,

in the presence of LIGHT, to produce GLUCOSE and 6 molecules

of OXYGEN.

Written as a chemical equation,

photosynthesis is:

The simple sugars produced by photosynthesis can be used in two ways:

·as a source of _____________ for the organism, or

·as a building block of other ________________________like ___________Complex COMPOUNDS

STARCH

ENERGY

Do pg 3 an 4 Photosynthesis reviewFor homework check.

The process of breaking down the simple organic molecules made by

photosynthesis to release the stored energy is called RESPIRATION

ALL organismscarry out this important

process.

The energy contained in organic molecules is too much for any

organelle to safely use.

Instead, this energy is used to create smaller molecules called ATP

(Adenosine triphosphate).By using ATP like a rechargeable battery, an organelle can get just the right amount of energy it needs to carry out its function.

Respiration is basically photosynthesis in reverse.

In sentence form,6 molecules of Oxygen react with one molecule of glucose to produce energy (in the form of ATP ),6 molecules of carbon dioxide and 6 molecules of water .Notice that the solar energy used in photosynthesis to make glucose is released as chemical bond energy in ATP

Written as a chemical equation, respiration is:

Once complex carbohydrates (like Starch) have been broken down into simpler molecules (like Glucose ) by digestion,the process still isn’t complete.

The energy-rich molecules are now small enough to travel to all cells of the body.However, the energy captured in the molecules by photosynthesis is still trappedas chemical bond energy.

To get the energy back out,the molecules must pass through a series ofchemical reactions controlled by special proteins (____Enzymes _).

The series of chemical reactions is called __Cellular Respiration __.

There are two types of cellular respiration:

 1) Aerobic RespirationUses ___ Oxygen __. Releases the most energy (as_

ATP__). Produces __carbon dioxide_ and

__water__ as  waste.

2) Anaerobic Respiration (aka Fermentation) Doesn’t need ____oxygen_____. Releases very little energy. (Only 2 ATP!) Two types:

 Lactic Acid Fermentation (Animals) Produces ____Lactic Acid___ as  waste (builds up in cells and causes muscles to cramp up).

Alcoholic Fermentation (Yeast, Bacteria) Produces Alcohol.

The energy released through respiration is used to attach a single phosphate group (P) to a molecule of Adenosine Diphosphate (ADP). In this way, the energy released from simple molecules is stored in amounts much smaller and safer for the cell organelles to use. This new molecule that the cells use for their energy is called Adenosine Triphosphate (_ATP__).

In organisms with membrane-bound organelles (like a nucleus, golgi, ER, etc),the _Mitochondria__ is the site where respiration occurs.As you can probably imagine, cells that are very active would require a lot of energy. Any cell that requires a lot of energy would need to have many mitochondria in it.What type of tissue would be made of cells with lots of mitochondria inside? (Hint: It moves a lot.)_____Muscle ___

Do respiration activity pg 7

SynthesisAnother important biochemical process involves making complex organic molecules from simple ones. This is called SYNTHESIS.

GLUCOSE is commonly used as a building block for making larger molecules to store excess energy. The molecules can be simply connected to form long chains of simple sugars, or re-arranged for long-term storage.

STARCH- Long chains of simple sugars

LIPIDS (FATS)- Food reserve (long-term)

Do organic compound chart pg . 9

Small diagram Large diagram

A Catalyst is any substance that can affect

the rate of a chemical reactionwithout ever getting used up.

Enzymes are protein catalysts.

EnzymesA Catalyst is any substance that

can affect the rate of a chemical reaction without ever getting used up. Enzymes are protein catalysts.

Examples of Biochemical Reactions Requiring Enzymes Digestion Synthesis Cellular Respiration Photosynthesis

Enzyme activity is critically dependent on shape. Just like a lock must have a certain-shaped key to work properly, an enzyme’s shape must match the compound they’re meant to work on. Any enzyme whose shape is altered will no longer work.

Factors That can Alter an Enzyme’s Ability to Work)

1) Shape--Enzymes can lose their shape when exposed to high temperatures or acids and bases.

2) TemperatureHigh temperatures cause more collisions

between molecules3) pH (Acidic or Basic)

Enzymes which work in different places will be adapted to work best at the pH normally found in that place. An enzyme which works well in the acidic environment of the stomach wouldn’t work as well in the basic environment of the small intestine.

4) Concentration The rate of reaction is dependent on the

concentration of both the substrate, and the enzyme

Hydrolysis

HomeostasisUsing __________________ as an example,

you can see why maintaining a ___________ internal environment is so important for living things. If things are too far out of whack (so to speak), bad things start happening. Warm weather can help you to do things, but a high fever can cause an __________________ to lose its shape (denature) and stop working.

enzymesstable

enzyme

Since your internal and ___________ environment are continually changing, your body has to monitor these changes continually and make adjustments as needed. Maintaining a stable ____________ environment is called __________________ and the way living things monitor the changes and respond is called _____________________.

external

internal

homeostasis

feedback.

Try as we may, it’s nearly impossible to maintain a perfectly stable internal condition. Things are always changing. For this reason, the best we can hope to achieve is a “___________________________________”. When something changes, our bodies take corrective action to reverse the change. When the change becomes too great, we reverse the action. In the form of a graph, this process would look something like these examples:

“dynamic equilibrium”

Body Temperature and Dynamic Equilibrium

Blood Glucose Level and Dynamic Equilibrium

Feedback MechanismsThe way an organism’s systems

detect, and respond to, changes to restore homeostasis is called a feedback mechanism. These mechanisms can either increase the change (________________ feedback) or squash the change (_______________________ feedback).

positive

negative

Positive FeedbackWhen a pregnant woman feels a “need” to push during childbirth, this is a result of a positive feedback system. As the baby pushes against the base of the uterus, the mother’s body feels a greater need to contract the muscles around the uterus. The baby gets squeezed harder against the base, the contractions get stronger, etc, until the baby is born.

Negative FeedbackThis is the most common type of

feedback mechanism, designed to ____________things from getting out of

control. Below are a couple of examples in humans and one from your house!

HOME HUMAN

Stop

Disruptions of Homeostasis (Disease)

Make sure you know these!!!!!!!!!!!!!!!

PathogensDisease-causing organisms (See

below)Common Pathogens:

Make sure you know these

CancerSome cells may lose the ability to

control how quickly they grow or how they develop. The result is often a mass of defective cells called a ________________.Fortunately, most cancerous cells are recognized as “foreign” because of abnormal proteins in their cell membranes. The body’s immune system then attempts to destroy them. Most of the time it works. Sometimes it doesn’t.

tumor

The Immune SystemWhen our other defenses don’t work and we

become invaded by pathogens or our cells stop working correctly, our immune system swings into action.

Pathogens, foreign substances, or cancer cells can be identified by proteins embedded in their surfaces or cell membranes called __________________.

When foreign (“not self”) antigens are detected, the immune system creates ______________ to engulf and destroy the attacker and/or antibodies to attack or flag them for attack by more white blood cells. Kind of like “popping smoke” over an enemy’s position, showing attack planes where to attack.

antigens

White blood cells

Make sure you know all parts of this diagram

Nice thing, your immune system “learns”. Once an effective antibody’s been made, some of the white blood cells that made it stick around. Just waiting for the day when the pathogen may return. That way, they can start making the right kind of antibody again, right away this time.

VaccinationsRemember that your immune system can

“learn”? Well, it can also be “taught”.Antigens on the surface of live pathogens can

also be found on __________ or ____________________ ones, as well.

Doctors have found that they can teach the immune system how to prepare for future attack by injecting dead or weak versions of pathogens into the body. The immune system swings into action. White blood cells start making _____________________ until they make them with the right shape. Sometimes, these white blood cells remain for good. Other times, the body requires a “booster” as a reminder.

dead weakened

antibodies

Damage to the Immune SystemFactors which can weaken the

immune system:• _______________• _______________• _______________• _______________

ageStressFatigueHIV/AIDS

Unwanted Immune Responses___________________

Rapid, excessive immune responseProduction of histamines to produce:

-mucus-sneezing-itching-rash-swelling

Inability to recognize “_________” cellsAttacks on __________________ organstransplanted

self

Allergies

Make sure you understand this chart!!!!!!!!!!!

Now complete the questions on page 22-25. Your answers will be graded tomorrow. There should be NO TALKING while you complete these.