Higher unit 2 Flashcards
Cell metabolism
Thousands of biological reactions that occur within a living organism
Reactions are catalysed by enzymes
Catabolic pathway
Breakdown of complex moles clues to simpler ones usually releasing energy and often proving building blocks
Anabolic pathway
Biosynthesis of complex molecules from simpler building blocks and require energy to do so
Example of catabolism
Aerobic Resperation
Releases energy needed for synthesis of proteins from amino acids
Examples of anabolism
ATP in the transfer of energy between catabolic and anabolic resperation
What allows processes to to under precise controls
Reversible and irreversible steps
Alternective routes
Allow sips in the pathway to be bypassed
Occurs when the cell has a plentiful supply of sugar
Cell membrane
Bouncy that separates the internal living contents of the cell from its external surrounding
What does the fluid mosaic model of the cell membrane show
Fluid by layer of constantly moving phospholipid molecules that form a stable boundary
Freely permeable
Molecules such as carbon dioxide which are small enough to diffuse the the phospholipid by layer in a cell membrane
Protein pores
Lager molecules transported by certain protein molecules.
Transport molecules contain pores
Channel forming
Channel forming
Provide channels for specific substances to diffuse across the membrane
Protein pumps
Certain protein molecules wich act as carrier molecules recognise specific ions and transfer them across the membrane
Conditions required for protein pumps
Temp
Availability of oxygen and food
Theses factors affect reparation rate and active transport
Enzymes in membrane
Protein molecules are embedded in a membrane of phospholipids are enzymes which catalyse the straps in a metabolic process essential to the cell
Rate of chemical change is indicated by
The amount of chemical change per unit time that occurs per unit time
Activation energy
Energy needed to break chemical bonds in the reactant chemical
When do chemical bonds break
The molecules do reactants have absorbed enough energy to make than unstable
This is called transition state when the reaction can occur
Properties and function of a catalyst
Lower activation energy
Speed up rate of chemical reaction
Take part in reaction but remains unchanged at the end
Active site
Located on enzymes surface Flexible and dynamic not rigid structure Shape is determined by: chemical structure Bonding between amino acids in a polypeptide chain
Induced fit
Ensues that the active site comes into very close contact with molecules of substrate
Increases chance of reaction taking place
When shape of active site changes to fit the substrate induced fit is formed
Weekend chemical bonds that must be broken in reaction
Reduces activation energy
Products then have low affinity for active sit and are released
Factors affecting enzyme action
Tepmetature
PH
Adequate supply of substrate
Inhibtors
Slow down the rate of an enzyme controlled reaction or bring it to a halt
Effect of low substrate concentration
Reaction rate is slow
Since there are too few molecules present to make maximum use of all active sites on enzyme molecules
Effect of high substrate concentration
Increase in reaction rate
More active sites can be involved
Why do rate of reaction graphs level off
All active sites are occupied so reaction slows down
What are enzymes in a metabolic pathway coded by
One or more genes
Why do some metabolic pathways only operate under cetain circumstances
Prevent resources being wasted
What controls the owning and offing of certain stages in a pathway
Inducer - on
Repressor - off
Competitive inhibition
Competes with substrate bind to active site
Similar molecular structure of substrate
Reversible
Slows down rate of reaction as active site is blocked by in it or and substrate cannot bind
Without competitive inhibitor increasing substrate contraction effect on rate
Increase in rate of reaction
End point - when all active sites on enzymes are occupied by substrate
Faster rate of reaction than with competitive inhibitor
With competitive inhibitor substrate conctartion effect on rate
Gradual increase in rate
Increasing concentration outnumbers inhibitor substrate so more and more active sites are occupied by substrates than inhibitor
Non - competitive inhibtor
Doesn’t combine directly with enzymes active site
Attaches to non-competing active site
Changes shape of active site of enzyme molecule and causes substrate not being able to bond to active site
Slows enzyme controlled reactions
Non - reversible when substrate concentration increases
Feedback inhibition
Occurs when concentration of end product becomes critical and inhibits an earlier enzyme, blocking the pathway, preventing further synthesis of the end-product
When some of the end product combined to enzyme 1 it prevents conversion from different stages
What property of a competitive inhibitor enables it to compete with the substrate
Molecular shape is similar to that of substrate
How is the concentration the difference of ions inside and outside the cell maintained
E.g Pottasium and sodium
The sodium-potassium pumps by active transport sodium to the outside and pattasium inside
What does the increase in oxygen concentration have on the uptake of ions
Increases
Slows down when energy becomes a limiting factor
Why would 2 lines on a concentartion/rate graph fail to meet if a higher concentration of substrate were used
There would be a few enzyme sites blocked by inhibitors
Affinity of substrate and products for active site
Substrate have high affinity for active site and products have low infinity allowing then to leave
Cellular respiration
Series of metabolic pathways which brings about the release of energy from a foodstuff
And regulation of high energy molecules ATP
Adenosine triphosphate
Composed to adenosine and 3 inorganic phosphate groups
When the bonds between the phosphates break energy is released
Phosphorylation
Enzyme controlled process
Phosphate group is added to a molecule
ADP + Pi ——> ATP
When phosphate and energy is transferred from ATP molecules of a reactant in a metabolic reaction, makes the pathway more reactive
Cytoplasm
Glycolysis (Absence of oxegen)
Splitting of glucose Begins in cytoplasm Glucose is broken down to form pyruvate Series of enzyme controlled reactions Doesn’t require oxegen
Energy investment phases:
2 ATP are used up per molecule from the first half of chain
Energy pay off phases:
4 molecules of ATP are produced from second half of chain
Irreversible
Net gain of 2 ATP
H ions are released from substrate by dehydrogenase enzyme
These are passed to a coenzyme molecule of NAD forming NADH
Process happens twice
Citic acid cycle (Oxegen)
Private is broken down to carbon dioxide and an acetyl group
Acetyl group combines with coenzyme A to form acetyl coenzyme A
Further H ions release forming NADH
Acetyl coenzyme A combines with oxaloacetate to form citrate
Enzyme mediated stages
Occurs in central matrix of mitochondria
Dehydrogenase enzyme removes H ions and electrons from repertory substrate and pass them to the coenzyme NAD to form NADH
Electron transport chain
Consists of a group of carrier proteins
They are found in chains attached to the inner membrane of mitochondria
NADH from the glycolytic and citric acid pathways releases electrons and passes them to the electron transport chain
When coming to end of chain combine with oxegen - at the same time oxegen combined with hydrogen to form water
In absence of oxegen cell cannot get energy from this
ATP synthesis
ATP synthase is an enzyme which synthesises ATP
Enzyme is located in the membrane of the mitochondrion
Energy to drive the synthesis of ATP comes from a flow of hydrogen ions across the membrane
As hydrogen ions pass through ATP synthase channel part of the enzyme rotates, generating ATP
Why do organisms not need to store ATP
ATP is manufactured at the same time it is used up
Transfer of energy vis ATP
Catabolic energy releasing reactions - resperation
Anabolic energy consuming reactions - synthesis of proteins
Transcription
Replication of DNA
Nerve impulses
Fermentation
2 ATP
Pyruvate takes alternative pathway due to no oxegen
Animals(some bacteria):
Glucose —-> pyruvate ——>(causes O2 debt to increases) —-> lactate ——.> (O2 debt repaid)
Plants:
Glucose —-> pyruvate ——> ethanol—-> CO2
Metabolic rate
The quantity of energy consumed by an organism per unit of time called metabolic pathway.
How can metabolic rate be measured
Oxegen costumed per unit time
CO2 production per unit time
Energy production- as heat per unit time
Circulatory system in vertebrates
Blood moved through blood vessels by heat pumping
Capillaries allow oxygen to pass through blood stream
Single circulatory system
Fish
Blood passes through 2 chambers of the heart
Blood flows to the gills at high pressure but is deleted to capillary beds at a low pressure
Double circulatory system
Blood passes through the great twice for each complete circuit of the body
Blood is pumped to both the lungs and the body’s capillary beds at high pressure ensuring a vigorous flow to all parts
Incomplete system
Amphibians and reptiles
One ventricle in the heart
Some mixing of oxygenated blood from the lungs and the deoxygenated blood from the body occurs
Complete system
Birds and mammals
2 ventricles in heart
No mixing of oxygenated and deoxygenated blood
What can metabolic rate be affected by
Abiotic factors
Temperature
PH
Salinity - level of salt
Conformers
Internal environment is dependent on external environment
Use behaviour responses to maintain optimum metabolic rate
Narrow range of ecological niches
Regulators
Maintain their internal environment regardless of the external environment
Higher range of ecological niche - requires energy
Physiological means - control their inner steady rate - energy is needed
Physiological homeostasis
Maintenance of the body’s internal environment whin limits of the bossy external environment
Brought about by negative feedback control - requires energy
Negative feedback control (corrective mechanism)
When factors affect the body’s internal environment - ducted by receptors
Receptors send out nerve impulses or hormonal messages which are received by effectors
The effector brings out certain responses which counter react the original deviation
And return the system to set point
Provides stable environmental conditions
Ectotherm
Animal which is unable to regulate its body temperature by physiological means
E.g fish, reptiles, invertebrates, amphibians
Body temperature varies directly with the external environment
Obtain most body heat by absorbing it from external environment
Endotherms
Animal which is able to maintain its body temperature at a relatively constant level independent of the temperature of the external environment
E.g birds and mammals
High metabolic rate which generates most of their body heat
Importance of regulating body temperature
Most enzymes work best at 35-40 degrees
What does efficient and active metabolism consist of
Enzyme controlled reactions and processes involving molecular diffusion that proceed at octal rates regardless of external envirnments
Hypothalamus
Body’s temperature monitoring centre
sensitive to nerve Impulses
Has central thermoreceptors which receive nerve impulses from skin thermoreceptors and sensitive to changes in temp of blood
Thermoreceptors
Centre hypothalamus
Sensitive to changes in the temperature
Of blood which intern reflect changes in the temperature of the body core
Responds to information by sending nerve impulses to the effector
This triggers corrective feedback mechanism nad returns the body temperature to the normal
Skin
In response to nerve impulses from the hypothalamus, the skin acts as an effector
Insulates body e.g shivering, increase metabolic rate
Vasodilation
Arterielles leading to skin become diluted
Allows large volume of blood to flow through capillaries near the skin surface
So the blood is able to lose heat through radiation
Increase the rate of sweating
Heat energy from the body is used to convert the water in sweat to water vapour lowering body temperature
Vasoconstriction
Arterioles leading to the skin become restricted
Allows only a small volume of blood to flow through surface capillaries
Little heat is lost from radiation
Contraction of erector muscle
More effective in furry niemals than humans
Hairs being raised from skin surface
Wide layer of heat (for conductor of heat)
Id trapped between the animals body and the external environment
Layer of insulation reduces heat loss
Physiological homeostasis
Maintain everything of the body’s internal environment within certain tolerable limits despite changes in the body’s external environment
Advantage of negative feedback control
Provides stable conditions needed by its body to function efficiently despite wide fluctuations in the external environment
2 effector hypothalamus sends nerve impulses to
Skin
Skeletal muscles
Why do animals with smaller body size loose more heat with low temperature
Smaller animals need higher metabolic rate because it has the largest surface area
Relative to its body size from which heat can be lost
Smaller animals respire quicker
Fish
Single circulatory system - primitive
2 chamber in heart - 1 artria- 1 ventricle
Low pressure of blood arriving at skeletal muscles
Amphibians and reptiles
Incomplete double circulatory system - intermediate
3 chamber in heat - 2 atria - 1 ventricle
High pressure of blood arriving at skeletal muscles
Mammals and birds
Complete double circulatory system - advanced
4 chambers in heart - 2 artria - 2 ventricles high pressure of blood arriving at skeletal muscles
Advantage of enzyme modification of glucose
Trapped inside and cannot diffuse out of the cell
Channel protein
Allows relatively large molecules to pass through
Small molecules and ions can pass through phospholipids
Presence/absence of enzymes in metabolic pathways
Presence - Reactions proceeds
Absence - reaction prevented
Where is NAD located in the mitochondria
Inner membrane
Homeostasis
The maintenance of a steady internal environment independent of the external environment
Surviving adverse conditions
Reduction in metabolic rate enables an organism to avoid expending excessive quanitities of energy trying to stay warm in extremely cold climate or sat cool in a extremely warm climate
Adaptation
Enables organisms to survive adverse conditions
Types of adaption
Structural
Physiological
Behavioural
Structural adaption
Involving specialised structures possess by the organism E.g bigger body size in colder climates - less surface area which heat is lost
Physiological
Depending on ways in which the organisms body and metabolism operate e.g hibernation conserves energy
Behavioural
Depending on the ways in which the organism responds to stimuli E.g share a den - heat loss from external environment decreases
Migration to warm climate
Dormancy
Occurs as part of an organisms life cycle when its growth and development and temporarily arrested
Metabolic rate decreases
Preventive dormancy
Organism becomes dormant before the arrival of adverse conditions
Consequential dormancy
Organism becomes dormant after the arrival of adverse conditions
Adverse conditions
When the external environment changes exceeding the limits the organism metabolic rate can survive
Advantage of consquential dormacy
Organism can remain active for longer and continue to exploit available resources
Disadvantage of consequential dormancy
May kill off many organisms before they have had time to become dormat
Hibernation
Endothermic animals - consume extra food which becomes laid down as a store of fat Rate of metabolism drops Decrease in body temperature Slower heart rate Slower breathing rate Inactivity
Aestivation
How animals survive Period of extreme heate and drought
E.g covers its self in mucus forming waterproof layer
Daily torpor
Animals rate of metabolism and activity become greatly reduced for every 24 hour cycle Slow heart rate Slow breathing arte Decrease in bod temperature Decreases rate of energy consumption
Migration
Relocating to more suitable conditions
relatively long distance
Avoid metabolic adversity
What is metabolis adversity caused by
Shortage of food and low temperature
Ringing with metal bands
To see if they have returned
Metal band placed around there legs
Satallite tracking
Transmitters are glued to the animals body or implanted under its skin
Information receives by on-earth orbiting satalites
Tracks animals routes
Innate behaviour
Inherited and inflexible
Response to an external stimulus
Such as a change in day length
Done buy all members of species
Learnerd behaviour
Gained by experience and trial and error
Flexible
Transmission by members in a social group
microganisms
bacteria archaea eukaryotes need energy from organic food produce useful metabolic products e.g bread
industrial uses
easy cultered reproduce and grow quickly food substrate is cheap produce useful products metabolism can be manipulated easily bu changing environmental factors
Energy used to grow microbes
Unicellular algae- light energy - photosynthesis
Bacteria + fungi - chemical substrate
Types of growth media
Liquid medium -broth
Solid medium - agar jelly
Essential nutrients are added
Lab - growth medium - Petri dish, flask or bottles
Industrial - huge stainless steel fermenters
Culture conditions
Chemical composition of growth medium
Environmental conditions
Chemical composition of growth medium
Raw materials - produce cellular building blocks - e.g amino acids, nucleic acid - biosynthesis + producing new cella
Environmental conditions
PH
Temperature
Sterility
O2 concentration
Fermentation
Aerobic and anaerobic processes
Compete sence when there is a change to the optimum conditions, also control when the total amount of product is produced
Made from stainless stell, plastic or glass so non permeable
Conditions for culturing in a fermenter
30 degrees
10% oxegen
PH7
0.2 molar glucose solution
Growth
Occurs when the rate of synthesis of organic materials by an organism exceeds the rate of their breakdown
Why is dry biomass more reliable
Fresh biomass verwies depending on water availability
How is growth of bacteria and fungi measured
Increase in cell number over a period of time
Doubling time
Time needed for a population of unicellular organisms doubling
Lag phase
Enzymes are infused to a metabolic substrate
Little to no increase
Cells adjust to growth medium
Increased metabolic activity
Log or exponential phases
Cells grow and multiply at the maximum rate
No limiting factors
Stationary phase
Nutrients become depleated Nutrients begin to run out Rate of cell division decreases New cells equal the death rate Can result in second metabolite
Second metabolite
Ecological advantage
Reproductive potential and chance f survival by expanding its range and out completing its rivals
E.g antibiotics
Death phase
Lack of nutrient substrate
High concentration of toxic metabolites
Undergo lysis (bursting)
Viable cell count
The number of cells that are alive and capable of reproduction
Total cell count
All cells dead or alive
Sterilisation
Prevents contamination by other species
How can pH be controlled
Buffering
Addition of acid and alkalis
