Maintaining a Balance9.2.1
Mrs Lowery
9.2.1 Temperature Regulation
• Most organisms are active in a limited temperature range– What is metabolism?– What are enzymes?– What is the role of enzymes in metabolism?– What is enzyme specificity?– How does pH, temperature and substrate
concentration alter enzyme activity??
AIM: Tuesday 9th October
• To be able to define– Homeostasis– Enzyme– Metabolism– Metabolic pathway
• REF – Kiss Pg. 1 – 3, Handouts, Text Pg.
Definition: Enzyme
• Enzymes are biological catalysts that speed up metabolic (chemical) reactions eg. digestion & respiration
• Enzymes are not changed or used up by the reaction they catalyse
• Enzymes are globular proteins that have a specific 3D (tertiary) shape and active site that is substrate specific
Enzymes have a SPECIFIC 3D Structure
• Chain of amino acids
• Order of amino acids determines shape of enzyme
• Shape of active site is IMPORTANT
Metabolism
• Metabolism is the sum of all the chemical reactions within a cell:
Metabolism = catabolism + anabolism
– Catabolism = degradation/breaking down, some release energy and raw materials
• eg. ATP → ADP + P and digestive processes– Anabolism = synthesis/building up
• eg. DNA replication, glucose → glycogen
Catabolic Reactions - Breaking
Anabolic Reactions - Building
AA
AA
AACONDENSATION
REACTION
PROTEIN
Peptide Bond
Peptide Bond
Metabolic Pathway
• Series of enzyme controlled reactions where the product of one reaction becomes the substrate for the next reaction
• Helps to organise metabolism:
A B CEnzyme 1 Enzyme 2
METABOLIC DISORDERS• Diseases of inborn errors in the metabolism of
phenylalanine and tyrosine• Biochemical Pathway:
E1 E2 E4
melaninE3
Phenylalanine → tyrosine → homogentisic acid → further metabolic products
An error here means the pathway stops at this point - & accumulation of this chemical prior eg. tyrosine
Phenylketonuria - PKU• Serious disease – untreated leads to severe mental
retardation• Results from defect in enzyme E1 that converts
phenylalanine to tyrosine:
• Leads to accumulation of phenylalanine in the body• Symptoms: mousy body odour, light skin colour,
excessive muscular tension, eczema
E1 E2 E4
melaninE3
Phenylalanine → tyrosine → homogentisic acid → further metabolic products
PKU
Albinism• Due to lack of enzyme E3 that makes melanin
from tyrosine:
• Therefore albino people cannot make melanin which pigments (colours) skin, hair & eyes
• Albino – white hair, very pale skin, pink eyes & eyes and skin are very sensitive to sunlight
E1 E2 E4
melaninE3
Phenylalanine → tyrosine → homogentisic acid → further metabolic
products
ALBINISM
You are seeing the blood vessels = pinkish
ALBINISM: Common in nature
Do you think these animals will be successful reproductively?Explain in terms of natural selection & Mate selection
Pink Dolphin - Albino
All-black Penguin
An example of this is albinism, where a break downin the metabolic pathway involved in the productionof melanin, results in the individual not being able tomake melanin and therefore becoming a different colour.
Alkaptonuria• Due to lack of enzyme E4:
• Affected children appear normal – but detected when nappies start turning black
• Blue-black discolouration of ears, tips of nose etc.
• Often have severe arthritis as the metabolite (homogentisic acid) accumulates in the cartilage of joints
E1 E2 E4
melaninE3
Phenylalanine → tyrosine → homogentisic acid → further metabolic products
How do genes control what happens in these reactions?
Gene 1 Gene 2 Gene 3
Enzyme 1 Enzyme 2 Enzyme 3
Different genescode for differentenzymes.
Enxymes & Metabolic Pathways
Enzyme 1 Enzyme 2 Enzyme 3
They change molecules from one form into another
Action of enzyme 1Changes this substrate
to this product: this now becomes the substrate for Enzyme 2 to act upon
Enzymes & Metaboic Pathways?
Enzyme 1 Enzyme 2 Enzyme 3
They change molecules from one form into another
Action of enzyme 2
Changes this substrate
to this product: which now becomes the substrate for Enzyme 3
Enzymes and Metabolic Pathways
Enzyme 1 Enzyme 2 Enzyme 3
They change molecules from one form into another
Action of enzyme 3Changes this
to this
The action of the enzymes combines to turn
into
via a number of steps – a METABOLIC PATHWAY
How do genes control what happens in these reactions?
Gene 1 Gene 2 Gene 3
Enzyme 1 Enzyme 2 Enzyme 3
A B C D
Gene 1 Gene 2 Gene 3
Enzyme 1 Enzyme 2 Enzyme 3
A B C D
Gene 1 Gene 2 Gene 3
Enzyme 1 Enzyme 2 Enzyme 3
A B C D
If there is a mutation, what happens then?
We have a mutation at this pointbecause of a base substitution onthe DNA.
Mutations and their effects on Biochemical pathways
mRNA
• Every 3 bases on an mRNA strand (codon) codes for an amino acid in a protein
• A protein is a long chain of amino acids, that folds into a specific shape
• It is the order of amino acids that determines the SHAPE of the protein, and hence the SHAPE of the active site in an enzyme
Mutations and their effects on Biochemical pathways
mRNA
is replaced with
because of this.
Mutations and their effects on Biochemical pathways
mRNA
Mutations and their effects on Biochemical pathways
mRNA
This has implications for the amino acids sourced at Translation
This amino acid is affected by the mutation and another oneis inserted in its place, according to the new code.
The new protein takes on a new shape because of this.
Mutations and their effects on Biochemical pathways
mRNA
Assume this is the enzyme that is important for the reaction that turns
Gene 1 Gene 2 Gene 3
Enzyme 1 Enzyme 2 Enzyme 3
A B C
The mutation of Gene 3 results in a different enzyme 3
This ‘new enzymecannot turn C into Dbecause it is a different shape.
C D
This no longer takes place with the mutation, resulting in a build up
of in the body, which is more often than not a problem.
It results in the body becoming poisoned by the build up of this product. Diseases like this are called INBORN ERRORS OF METABOLISM
Aim: Wednesday 10 October
• To be able to identify the role of enzymes in metabolism, describe their chemical composition and use a simple model to describe their specificity on substrates
• REF – Text Pg. 2-8, KISS Pg. 3-5,
Main Points
• Role – catalyse biological reactions eg. converting glucose to glycogen for storage
• Metabolism = sum of all chemical reactions in the organism (catabolism & anabolism) relies on enzymes
• They are proteins with a specific 3D shape that has an active site that is SPECIFIC to it’s substrate.
Enzymes & Energy Use
• Endergonic reactions – anabolic reactions are usually endergonic, requiring the INPUT of energy
• Exergonic reactions – catabolic reactions are usually exergonic, RELEASING energy
• Think Ender = in (sounds like enter) and Ex = exit (out)
Final energy state of products
Initial energy stateof substrates
Activation energyof uncatalysed reactionsActivation energy
of enzyme catalysedreaction
Progress of reaction (time)
Ene
rgy
leve
ls o
f m
olec
ules
Enzymes lower the activation energy required
Enzymes lower the activation energy
Enzymes have a specific 3D shape
Protein Structure
(Therefore Enzyme
structure)
How do Enzymes work
• There are two theories• Lock and Key – simplified version• Induced Fit – widely accepted version
Lock and Key
• My key won’t open your door locks• Enzyme/substrate complexes are like locks & keys
• The substrate “fits” into the enzyme in the same way a key fits into a lock
Lock and Key
Active Site – specific shape to “fit” or recognise substrate
Lock & Key model
E
Active site
Two molecules are bonded together at the active site and leaveas something different.
ANABOLIC REACTION – JoiningEnergy REQUIRED – Endergonic
Lock & Key model
Active site
E E ES S
P1
P2
Draw this now
Lock & Key model
E
Active site
One molecule binds to the active site and leavesas something different.
Catabolic Reaction – breakingEnergy RELEASED = exergonic
Lock & Key model
S S
P1
P2
E E E
Active site
Draw this now
Enzymes & co-factors
Carboxypeptidase with Zinc Glucose oxidase with FAD
Co-factors and how they work
Active site
Without the co-factor the enzyme cannot function.
E
Co-factors and how they work
E
Active site
Without the co-factor the enzyme cannot function.
After the co-factor has bound to the active site, the enzymecan work as before.
Co-factors and how they work
E
Without the co-factor, the active site cannot join the substances together. Add the co-factor and the substancescan be joined. Some POISONS work by competing for the site occupied by the co-factor & therefore inhibit enzyme action.
Draw this NOW!
E
Induced Fit model of enzyme action
• More widely accepted model to explain enzyme action
• Explains why enzymes are so specific and only bond to one substrate (substrate specificity)
• Active site changes shape to accommodate the substrate
Induced Fit
Induced Fit
Induced fit hypothesis - when glucose (red) comes close to the hexokinase active site it induces a conformational shift in the enzyme to better hold the substrate glucose.
Induced fit model – a variation on the lock & key model
The enzyme changes shape, so that it can accommodate the substrate, which can fit into the active site as a result.
Once this is complete, the enzyme returns to its original shape.
Induced fit model – a variation on the lock & key model
The enzyme changes shape, so that it can accommodate the substrate.
The substrate can fit into the active site with the new shapeof the enzyme. The enzyme works on the substrate in thisform and once this is complete, it returns to the original shape.
DRAW THIS
Condensation: glucose to glycogenCondensation uses enzymes like this:
E
Two molecules are bonded together at the active site and leaveas something different.
Why does the condensation of glucose to glycogen occur???
Condensation of carbohydrates
To n
Enzymes in action here
H2O is given off
Condensation of a protein = polymerisation
Enzymes in action here
n
Amino acids are joined together by peptide bondsTo make proteins – REMEMBER?
H2O is given off
Hydrolysis
Hydrolysis uses enzymes like this.
E
One molecule binds to the active site and leavesas something different.
Hydrolysis of carbohydrates
Enzymes in action here
H2O is used upto break these bonds
Carbohydrates are broken down into smaller units.
Hydrolysis of a protein which is broken down into amino acids
Enzymes in action here
What might the function of the H2O be?
H2O is used up tobreak these bonds
Co-factor
Aim : Thursday 11 October
• To be able to explain the effects of temperature, pH and substrate concentration on enzyme action
• REF Kiss Pg. 3-4, Handouts, Text Pg. 4-5
Enzymes DENATURE
• Can you un-cook an egg? Heating to high temperatures permanently destroys/alters the 3D shape of proteins.
• Since all enzymes are proteins, high heat can alter the shape of an enzyme changing the shape & therefore specificity of it’s active site
• The enzyme is said to be DENATURED• Changes to pH also alter the active site &
denature enzymes.
Effect of temperature
• The temperature at which an enzyme works most rapidly is known as the optimum temperature
• As temperature increases, so does enzyme activity....to a point, beyond this point, activity decreases until the enzyme is DENATURED– As enzyme molecules receive heat energy it
increases the kinetic energy & therefore number of collisions – increasing the rate of reaction
Enzymes and Temperature
Enzymes: Human Body
Temperature & denaturing• Most enzymes are denatured at temperatures
above 60°C• Vibrations may cause the secondary, tertiary and
quaternary structure of protein to break, altering the vital shape of active sites, denaturing the enzyme – does not recognise SUBSTRATE
Protein Structure
(Therefore Enzyme
structure)
pH & Enzyme Activity
• Extremes of pH irreversibly denature enzymes (hydrogen bonds are irreparably broken).
• Changes in pH which are less extreme affect enzyme activity temporarily (the change is reversible)
• Every enzyme has a pH at which it is most active. This is the optimum pH for that enzyme
pH & Enzyme Activity
pH & Enzyme activityStomach – optimal
pH 2HCl present
Intestines – optimal pH 7-9Bile added via gallbladder
Substrate Concentration
• The higher the substrate concentration the faster the reaction because there is an increased chance of collision with an enzyme
• This is true until saturation point – at this point all the active sites are occupied, so the addition of more substrate makes no difference
Substrate Concentration
• The rate of enzyme-controlled reaction is affected by the concentration of the substrate…… to a point where all the active sites are occupied and then the concentration of enzymes becomes the LIMITING factor (Point A).
A
Substrate concentration
Enz
yme
activ
ity
• Explain what happens UNTIL Point A
• Explain what happens after Point A
• Explain how we could increase enzyme activity from Point A
SATURATION POINT
Enzyme Concentration
• The more enzyme molecules present, the more likely there will be a collision with substrate to form an enzyme-substrate complex = faster rate of reaction
• But, if amount of substrate is limited, adding more enzymes will have no further effect
PRACTICAL WORK
• Aim – to determine the effect of high temperature on the rate of enzyme activity
Introduction
• Hydrogen peroxide will break down to water and oxygen very slowly at room temperature :
Hydrogen peroxide → oxygen + water• Manganese dioxide is a catalyst which speeds
up the breakdown of hydrogen peroxide• Catalase is a biological catalyst which also
breaks down hydrogen peroxide. It is present in all living cells eg. Liver, potato
Results table
• Record the quantity of bubbles produced by each reaction & record your observations
Tube Temp (°C)
Reactants Observation
A 30 Hydrogen Peroxide
B 30 Hydrogen peroxide + Catalase
C 30 Hydrogen Peroxide + Manganese dioxide
D 90 Hydrogen Peroxide
Method: apparatus
• Water bath at 30o C Water bath at 90o C
Hydrogen Peroxide
Hydrogen Peroxide+ Yeast (catalase)
Hydrogen Peroxide + Manganese dioxide
Hydrogen Peroxide
A B C D
Add ONE drop of detergent to each test-tube
ResultsTube Temp
(°C)Reactants Observation
A 30 Hydrogen Peroxide No Bubbles
B 30 Hydrogen peroxide + Catalase
Many bubbles
C 30 Hydrogen Peroxide + Manganese dioxide
Many bubbles
D 90 Hydrogen Peroxide Few bubbles
Conclusions
1. Which two tubes are compared to show that high temperatures speed up the breakdown of hydrogen peroxide?
2. Which two tubes are compared to show that catalysts speed up the breakdown of hydrogen peroxide?
3. Which two tubes are composed to show that biological catalysts speed up the breakdown of hydrogen peroxide?
A and D
A and C
A and B
PRAC - Handout
• Enzyme Experiment – Fast Froth• Aim – to see the effect of temperature, pH and
surface area on the activity of enzymes• REFER TO HANDOUT
PRAC – Answers to Questions1. Froth is an indication that the hydrogen peroxide is breaking down to
form oxygen – a gas – that produces the bubbles2. Test-tube B (high surface area) made most froth3. Increasing the SA of the potato, and therefore exposing more catalase
enzyme, increases the amount of active sites available to form enzyme-substrate complexes with the hydrogen peroxide – therefore testtube B is faster than A
4. Test-tube A produces more bubbles, because the enzyme is still functioning. Whereas, the enzyme has been denatured by high temperature in test-tube C and no longer recognises the substrate to catalyze the reaction.
5. Test-tube D did not produce much froth because the high pH has altered the active site, causing denaturing. The enzyme no longer recognises the substrate and therefore no reaction occurs
PRAC – Fast Froth
Conclusion:• Our results indicate that the activity of an
enzyme is affected by temperature, pH and surface area.
• High temperatures and altered pH can denature an enzyme
• And increasing SA can increase the activity of the enzyme (to a saturation point).
Enzyme Activity
• Enzyme activity is measured as the amount of substrate converted by a known amount of enzyme in a given time
How does ATP work?
Adenosine
Adenosine Adenosine
AdenosinePP P PP
PP PP
P
ATPaseCauses ATP to lose a P
30.7 kJ
ATP ADP + PEnergy released
ATP ADP + PEnergy gained Respiration
Aim – Tuesday 16th October
• To be able to define and explain the 2 stages of homeostasis and explain negative feedback
• REF : Text Pg. 10-19, KISS Pg. 6 -9 & Today’s handouts
Homeostasis
• The maintenance by an organism of a constant (or almost constant) internal state, regardless of external environmental change– Temperature regulation– Blood sugar levels, pH levels– Water content/salt balance (osmoregulation)
• 2 Stages of homeostasis1. Detect the change (receptor)2. Counteract the change (effector)
Homestasis
• Homeostasis involves co-ordination between various control systems
• In mammals – Nervous system– Endocrine (hormonal) system
STIMULUS Receptorcell
Sensory Neurone
CNS MotorNeurone
Effector:Muscle/gland
Response: counteracts the stimulus
Central Nervous System - CNS
• The nervous system controls your actions. It coordinates different parts of your body so that they work together and are able to bring about correct responses
• The Central Nervous System is the brain and spinal cord. They are both made of delicate nervous tissue. The brain is protected by the skull & the spinal cord is protected by your backbone (vertebral column)
Spinal Cord
Neurons
• Signals are sent through the nervous system in the form of electro-chemical impulses through neurons (nerve cells). There are 2 main types of neurons:
1. Sense organs are our receptors. They send messages to the CNS telling it what happened. These messages are sent along sensory neurons
2. Muscles and glands are our effectors. The CNS sends messages to them telling them what to do. These messages are sent along motor neurons
Structure of a Neuron
Neurons are Specialised Cells• Branched nerve endings• Long axon• Myelin sheath (fatty sheath) = insulation• Branched dendrites
Neurons
Remember – Neurons are SPECIALISED cells
Sensory Neuron
• Transmit nerve impulses to the spinal cord and brain from all over the body.
Relay Neuron (Interneuron)
• Transmits nerve impulses from one neuronal dendrite to the axon of another neuron.
• All are found only in the gray matter of the brain or spinal cord.
Motor Neuron
• Carries impulses away from the spinal cord and brain to muscles or glands
Neurons
Endocrine System
• The hormonal system, or endocrine, system helps maintain homeostasis.
• Hormones can affect things like the rate of metabolism, growth and sexual development.
A hormone is a chemical produced by an endocrine gland that travels in the blood
to activate target cells
Hormones
• Can you place the following endocrine glands?
• Adrenal• Ovaries• Testes• Thyroid• Pituitary• Pancreas
Negative Feedback Loop• Any changes from the set-point (ideal value)
are detected by sensory receptor cells• The response by effector cells is to counter-act
the change (hence ‘negative’), acting to return to the set-point
Homeostasis & Normal Range
• The set-point is the ideal value, and the internal environment fluctuates around this.
• Only when an upper/lower limit is reached does it trigger a negative-feedback response
Upper Limit – triggers response to counteract the increase
(ideal value)
Lower Limit – triggers response to counteract the decrease
Hom
eost
asis
& B
P
Skin & Temperature Regulation
• The enzymes of the human body have an optimum temperature of 37°C, so it is important to maintain this temperature for efficient enzyme controlled reactions eg. DNA replication, protein synthesis & respiration.
• The hypothalamus of the brain acts as a thermostat – it contains receptors that are sensitive to the blood temperature of the brain and also receives impulses from the skin
Skin & Temperature Regulation• The hypothalamus senses changes in skin &
blood temperature and sends nerve impulses to the skin:
When you’re too cold:
1.Hairs stand on end to keep you warm2.No sweat is produced3.The blood supply to the skin closes off4. Result – you warm up
When you’re too hot:
1.Hairs lie flat 2.Sweat is produced3.The blood supply to the skin opens up to release body hear4. Result – cool down
Temperature Regulation
TASK
• Draw a negative feedback loop that shows the body’s response to changes in temperature from the set-point
• Include the following labels:– Set-point– Control Centre– Stimuli– Effectors– Receptors– Feedback/Response
Include what the RESPONSES are to the stimuliFor example:• Vasoconstriction or
Vasodilation• Piloerector response• Sweat production
Questions Pg. 18 – 19 TEXT
1. Where is the temperature-control centre located and how is it organised?
2. What are the 4 main responses to being too cold? 3. What are the 3 main responses to being too hot?4. What is the difference between vasoconstriction and
vasodilation and how is it linked with temperature regulation?
5. Explain how sweating cools the body
AIM - Friday 19th October
• To be able to describe range of temperatures over which life is found
• Compare ectothermic & endothermic organisms
• Discuss adaptations of NAMED Australian Organisms to assist temperature regulation
• Identify responses of plants to temperature change
Temperature Range
• Living things are found across a broad range of temperatures• -70°C at the poles, 56°C in deserts or 350°C in
hydrothermal vents• Variation in temperature worldwide provides niches
for many different species• Individual species cannot survive within a broad
range and they need a NARROW range• Optimal range – narrow band – comfortable• Tolerance range – survivable range, uncomfortable
Tolerance Range
Ectothermic organisms
• Depend on external source (environment) for heat energy
• Includes fish, amphibians, reptiles & most invertebrates
• Influenced by the ambient temperature & so body temperature fluctuates over a wider range of temperatures
Ectothermic Adaptations• Organisms adapt their
behaviour to regulate body temperature
• Shade/sun seeking depending on energy needs – body alignment varies
• Activity pattern varies depending on temp
• Hibernation in extended cold period
Endothermic Organisms
• Rely on internal sources such as metabolic activity for heat energy
• Maintains temperature at a stable level, within a very narrow range – regardless of ambient temperatures
• Includes birds and mammals• Small animals have higher metabolic rate,
because tends to lose heat more quickly due to SA:Vol Ratio
Endothermic Adaptations
• Brown fat – metabolised in cold conditions to produce heat in cool conditions eg. Bentwing Bat
• Sweating, panting, licking saliva onto body, altering blood flow to cool body in hot conditions
Fairy Penguin
• Feathers produce insulating layer, traps layer of air – puff up in colder weather
• Huddling in wind for warmth
• Swimming to cool down• Burrows for reducing
exposure
Plant Responses to High Temp
• Plant enzymes (eg. Those responsible for photosynthesis) are damaged or denatured by high temperatures
• Plants cannot seek shade/move as animals can, therefore behavioural adaptations to high temperatures are limited
• Plants have structural & physiological adaptations to surviving high temperatures
Plant Adaptations to HIGH TEMP
• Transpiration – evaporative cooling• Turgor response – wilting• Leaf orientation – reduce surface area exposed to
sun• Regulate stomatal opening • Leaf fall – reduces SA for heat absorption and
reduces transpiration water loss• Epicormic Shoots – response to fire• Lignotubers -
Plant Adaptations
Plant Adaptations to LOW TEMP
• Organic “Anti-Freeze” – prevents cell sap/cytoplasm freezing
• Thermogenic plants – lotus, flowers produce heat• Dormancy – in winter, periods of low water/light
availability• Abscission – deciduous trees lose leaves in response
to shorter days• Vernalisation – flowering in response to low
temperatures (accurate timing of flowering for pollinators)
Plant Adaptations
TASKS
• Read & Highlight KISS Pg. 10 – 11• Complete Worksheet 4 & MARK using the
answers at back• Make a summary of NAMED Australian
organisms that have specific adaptations to regulate temperature– Ectotherm– Endotherm– Plant