unit 2 Flashcards
Define cell metabolism
total set of reactions in a cell
What are metabolic pathways (+ other info)
series of enzyme catalysed reactions within a cell
- integrated meaning diff pathways are inter linked
- may have reversible and irreversible steps
Define anabolic reactions
synthesis reactions that build up small molecules into large molecules and require energy
Define catabolic reactions
degradation reactions that break down large molecules into smaller molecules and release energy
How do membranes allow molecules through
Protein pore allow or restrict the passage of molecules through the membrane
What are protein pumps
move molecules across the membrane and require energy to do this
What do enzymes in membranes do
catalys specific biochemical reactions
How can metabloc reactions be controlled
by the presence or absence of enzymes
or the regulation of key enzyme activity
Define induced fit
how the active site of enzyme may change shape to better fit the substrate as the substrate binds
Describe enzymes affect on activation energy
enzymes lower the activation energy
Substrate molecules have a …. affinity for the ……. which means ….
high affinity for the active site meaning they bind readily
Products have a …. affinity for the …. meaning ….
low affinity for the active site meaning they can leave the active site
As substrate concentration increases …. but ….
the rate of reaction increases but will eventually become constant as it reaches its optimum rate
How to change reversible reactions
the presence of substrate or removal of product can drive a sequence of reactions in a particular direction
What do competitive inhibitors do
bind to an active site preventing the substrate from binding
How can competitive inhibition be reversed
increasing the substrate concentration
What do non competitive inhibitors do
bind away from the active site which has an effect of changing the shape of the active site preventing the substrate from binding
When does feedback inhibition occur
this occurs when the end product of a metabolic pathway reaches a critical concentration
Define feedback inhibition
where the end product inhibits an earlier enzyme in a metabolic pathway which prevents further synthesis of the end product
Define respiration
the breakdown of respiratory substrates to release energy in the form of ATP
Define glycolysis
the breakdown of glucose to pyruvate in the cytoplasm
What are the two phases of glycolysis
the energy investment phase and the and the energy pay off phase
What happens in the energy investment phase
ATP is required to phosphorylate glucose and intermediates
What does phosphorylation in the energy investment phase result in
the generation of more ATP in the energy pay off phase
What is the net gain of ATP in glycolysis
2
What is the end product in glycolysis
pyruvate
What happens in aerobic glycolysis
pyruvate is broken down into an acetyl group
What does acetyl combing with and form (respiration)
combines with coenzyme A to form acetyl coenzyme A
Where does the citric acid cycle take place
in the matrix of the mitochondria
What happens to the acetyl group after it combines with coenzyme A
combines with oxaloacetate to form citrate
What happens to citrate
it is gradually converted back into oxaloacetate in a series of enzyme controlled steps
What is produced/released in the citric acid cycle
produces ATP and releases carbon dioxide
What do dehydrogenase enzymes do
they remove hydrogen ions and electrons from intermediates and pass them to the coenzyme NAD to form NADH
What happens to hydrogen ions and electrons from NADH
passed to the electron transport chain
Where is the electron transport chain located
the inner mitochondrial membrane
What happens when electrons are passed along the electron transport chain
they release energy
What is the electron transport chain
a series of carrier proteins on the inner mitochondrial membrane
What does the energy released in the electron transport chain do
allows hydrogen ions to be pumped across the inner mitochondrial membrane into the space between the inner and outer mitochondrial membrane
How is ATP produced in the electron transport chain
the flow of hydrogen ions through the inner membrane portein ATP synthase
Describe the role of oxygen in respiration
oxygen is the final hydrogen/electron acceptor as it combines with the hydrogen ions and electrons to form water
What is fermentation
occurs in the cytoplasm at the lack of oxygen
Fermentation results in much ….. than aerobic respiration
much less ATP production
What happens to pyruvate in animal cells
it is converted into lactate
this is a reversible reaction
What happens to pyruvate in plants and fungi
it is converted into ethanol and carbon dioxide
this is an irreversible reaction
ATP is used to …… which require energy
to transfer energy to processes which require energy
What cellular processes require energy
Protein synthesis, contraction of muscles, active transport, DNA replication and carbon fixation
Metabolic rates can be compared by …..
measuring oxygen consumption, carbon dioxide production or heat production
Oxygen consumption can be measured using ….
an oxygen probe
Carbon dioxide can be measured using ….
a carbon dioxide probe
Heat production can be measured using ….
a calorimeter
Organisms with high metabolic rates ….
require efficient delivery of oxygen to cells
Rate birds+mammals, reptiles+amphibians and fish by their metabolic rates (high to low)
birds and mammals -> reptiles and amphibians -> fish
What circulatory system do birds and mammals have + explain it
complete double circulatory system with two atria and two ventricles
What circulatory systems do amphibians and most reptiles have + explain it
incomplete double circulatory system with two atria and one ventricle
What circulatory system do fish have + explain it
single circulatory system with one atria and one ventricle
Why are complete double circulatory systems the most efficient
they enable higher metabolic rates by preventing the mixing oxygenated and deoxygenated blood
+
they also keep blood at high pressures allowing efficient oxygen delivery to cells
The metabolic rate of an organism is affected by ….. eg ….
abiotic factors eg temperature salinity and pH
The internal environment of conformers is dependent on …..
the external environment
How do conformers tolerate variations in the external environment
behavioural responses eg lizards basking in the sun
Define conformers abilities
low metabolic costs (do not require energy) and can only occupy a narrow range of ecological niches
The internal environment of regulators is ….
maintained regardless of the external environment
Regulators use metabolism to ….
control their internal environment eg water balance, temperature, blood sugar
Define homeostasis
the use of physiological mechanisms to maintain internal body conditions at optimum levels
Define regulators abilities
they expend energy (eg to migrate and avoid adverse conditions) and occupy a wider range of ecological niches
Define thermoregulation
the maintenance of a constant internal temperature
What is the temperature monitoring centre in the body
the hypothalamus
How does the hypothalamus recieve and send messages
recieves messages through nerve impulses from thermo-receptors in the skin and sends messages through nerve impulses to effectors
Define negative feedback control
uses corrective responses to revers changes in internal tempereature to return temperature to normal //or// a change in a factor triggers a mechanism which results in that factor returning to normal level (set point)
What are the 3 human responses to increase in body temperature/overheating
+ sweating - body heat is used to evaporate water in sweat thereby cooling the skin
+ vasodilation - increased blood flow to the skin increases heat loss by radiation
+ reduction in metabolic rate - to reduce heat production
What are the 4 human responses to decrease in body temperature/overcooling
+ shivering - rapid involuntary muscle contraction generates heat
+ vasoconstriction - decreased blood flow to the skin decreases heat loss by radiation
+ contraction of hair erector muscles - traps a layer of insulating air
+ increase in metabolic rate - to produce more heat
Why is maintenance of body temperature required + what does it ensure
for optimal enzyme activity
ensures high diffusion rates required to maintain metabolism
Regulators are unable to maintain their internal environment when ….
when the external environment varies beyond tolerable limits for normal metabolic activity
Define dormancy
part of a lifecycle allowing survival during conditions when the energy costs of metabolic activity would be too high
During dormancy the metabolic rate …..
is reduced to save energy
Define predictive dormancy
occurs before the onset of adverse conditions
Define consequential dormancy
occurs after the onset of adverse conditions
How do some animals survive low winter temperatures
hibernation
How do some organisms survive high temperatures/drought
aestivation
Define daily torpor
when some animals with high metabolic rates can temporarily reduce their metabolic rate eg hummingbirds
Why do animals migrate/what is migration
migration involves relocating to an area with more suitable environmental conditions
uses energy to avoid adverse conditions
What is innate behaviour
behaviour that is inherited (migration can be this)
What is learned behaviour
behaviour that parents teach/is developed as a result of experience (migration can be this)
How can migration be tracked
radio/satellite tracking, marking, radar and sonar
Micro-organisms include ….
archea, bacteria and some eukaryotes
Micro-organisms use …. and produce ….
microorganisms use a wide variety of substrates for metabolism and produce a range of products from their metabolic pathways
Describe micro-organisms growth media
contains raw materials for biosynthesis and an energy source
Some microorganisms produce their own …. and some require ….
produce their own complex molecules for biosynthesis (e.g amino acids vitamins and fatty acids) and some require complex molecules in the growth medium
Where is the energy source for a microorganism derived from
from a chemical substrate or from light in photosynthetic micro organisms
How is a fermenter used in the culture of micro organisms
- provides optimum conditions through control of temp, oxygen level and pH
- provides sterile conditions to reduce competition for nutrients with unwanted microorganisms and reduces the risk of spoilage of the product
Examples of products produced in fermenters
antibiotics, enzymes, vaccines
What are the four phases of frowth and changes in culture conditions graph
lag
log
stationary
death
Explain the lag phase of the graph
enzymes are induced to metabolise substrates + cells adjust to conditions
Explain the log phase of the graph
rapid growth of micro-organisms due to plentiful nutrients / cells grow and multiply at maximum rate
Explain the stationary phase of the graph
due to nutrient depletion and toxic metabolites begin to accumulate / number of cells dying is equal to number of cells produced
Explain the death phase of the graph
due to toxic metabolites accumulation and lack of nutrients / number of cells dying exceeds number being produced
+ only viable cell count shows in this phase
Define secondary metabolites
produced in the stationary phase and may confer an ecological advantage in the wild by allowing the micro-organism to outcompete other species e.g antibiotics
Define viable cell count
only the living cells
Define total cell count
both living and dead cells
What does mutagenesis of recombinant DNA technology do?
improve wild strains of micro organisms
Define mutagenesis
the creation of mutations and can be achieved using mutagenic agents e.g. uv light, x-rays and gamma rays, mustard gas
Exposure of microorganisms to mutagenic agents results in …
mutations which may produce an improved strain of micro organism e.g. give an increased yield of product
What is recombinant dna technology
describes taking a gene from an organism and transferring it into a micro organism to enable the micro organism to produce plant or animal proteins
What is a vector (DNA)
a DNA molecule used to carry foreign genetic material into another cell e.g. plasmids and artificial chromosomes
When are artificial chromosomes preferable over plasmids as vectors
when larger fragments of DNA are required to be inserted
What are restriction endonuclease enzymes used for
recognising specific nucleotide base sequences and cutting specific genes out at those sequences leaving sticky ends
+
recognising specific nucleotide base sequences and cutting open plasmids at those sequences
How are complementary sticky ends produced
when the same restriction endonuclease is used to cut open the plasmid and cut out the gene from the chromosome
How are complementary DNA sequences sealed into place
DNA ligase enzymes
What do recombinant plasmids and artificial chromosomes contain
restriction sites, regulatory sequences, an origin of replication and selectable markers
Restriction sites contain ….
target sequences of DNA where specific endonucleases cut
What do regulatory sequences do
controls gene expression
What does the origin of replication do
allows self replication of the plasmid/artificial chromosome
What do selectable marker genes do
ensure that only microorganisms that have taken up the vector grow in the presence of the selective agent eg antibiotic resistance genes
Genes may be introduced to a genetically engineered micro-organisms genome to ….
to prevent its survival in the external environment as a safety mechanism
Recombinant yeast cells may be used instead of bacteria because ….
bacteria may be unable to produce an active form of protein due to an inability to correctly fold polypeptides
