Flashcards Unit 2 2024 PDF

What is metabolism? All of the enzyme controlled chemical reactions that take place within cells. What is meant by an When small molecules are built up anabolic pathway? to form large molecules; requires...

What is metabolism? All of the enzyme controlled chemical reactions that take place within cells. What is meant by an When small molecules are built up anabolic pathway? to form large molecules; requires energy. What is meant by a catabolic When large molecules are broken pathway? down to form small molecules; releasing energy. What is an example of an Amino acids -> Proteins anabolic pathway? What is an example of a Glucose -> Carbon Dioxide and catabolic pathway? Water (in presence of oxygen) Why are irreversible steps To commit the metabolic pathway necessary in some metabolic to continuing. pathways? Why are reversible steps To ensure the concentrations of necessary in some metabolic substances remain relatively stable pathways? within the cell. Why are alternative routes If certain enzymes or substrates necessary in some metabolic are not available then the reaction pathways? can still proceed via an alternative route. What are membranes made Phospholipids and proteins out of? What are the roles of - Pumps proteins in the membranes? - Pores - Enzymes How are genes and Genes need to be expressed to metabolic pathways linked? provide the enzymes for metabolic pathways (enzymes are proteins). How can gene expression be By the presence or absence of controlled? particular signal molecules – repressors (stop expression) or inducers (start expression). What is an enzyme? A biological catalyst that speeds up chemical reactions by lowering the activation energy required for the reactions to proceed. Made of proteins. What are the properties of - Speed up chemical reactions catalysts? by lowering activation energy required for reactions to take place - Remain unchanged by reactions What are the properties of - Work with specific substrates enzymes? which show an affinity for the active site and have a shape which is complementary to the active site. - Work in the induced fit model because the active sites are dynamic and flexible What is activation energy? The energy required for the  reaction to start. What is meant by the When the substrate binds to the “induced fit model”? enzyme the active site changes shape slightly to fit more closely around the substrate. What is meant by “affinity”? Chemical attraction between molecules Why are enzymes specific? They only work on substrates which have a high affinity for the active site; they only work on substrates with a shape which is complementary to the active site of the enzyme. Which factors can affect the - Temperature rate of enzyme activity? - pH - Substrate concentration - Presence of inhibitors What is an inhibitor? A substance which decreases the rate of an enzyme controlled reaction. What is a competitive An inhibitor which works by inhibitor? binding to the active site of the enzyme because it has a similar shape to the substrate. How can the effects of a By increasing the substrate competitive inhibitor be concentration. overcome? What is a non-competitive An inhibitor which works by inhibitor? binding to the enzyme at a site away from the active site which causes the active site to change shape. How can some enzymes be Binding of an activator which activated? makes it take on its active shape. What is end-product As the concentration of the end inhibition? (Sometimes product builds up it can bind to the known as feedback first enzyme in the pathway thus inhibition) slowing down the pathway. As the concentration of end-product drops, the rate of the reaction can speed up again. How is end-product It prevents the build up of end inhibition useful? products and the wasteful breakdown of intermediates. What is cellular respiration? A series of enzyme controlled reaction which results in the release of energy from food and regenerates the supply of ATP. What is aerobic respiration? Respiration which occurs in the presence of oxygen. What is fermentation? Respiration which occurs without oxygen. What is the summary Glucose + oxygen -> carbon dioxide equation for aerobic + water + 38 ATP respiration? What is the summary Glucose -> Pyruvate -> Lactate equation for fermentation in animals ? What is the summary Glucose -> Pyruvate -> Carbon equation for fermentation in dioxide + ethanol plants and yeast? What is ATP? A high energy chemical compound with three phosphates. What is ADP? A low energy chemical compound with two phosphates. How is ATP generated in the ADP is joined to Pi to create ATP cell? which results in energy being stored by ATPsynthase (enzyme). What happens when ATP is Energy is released. broken down? How is it that organisms As ATP is broken down more ATP is have a fixed quantity of ATP constantly regenerated. at all times in their bodies? What is phosphorylation? The addition of phosphate to a molecule– acts as a transfer of energy and makes the molecule more reactive. What is the first stage of Glycolysis respiration? Where does the first stage Cytoplasm of respiration take place? What happens in Glycolysis? Glucose -> Pyruvate NAD -> NADH because DEHYDROGENASE (enzyme)release electrons and hydrogen ions from the intermediates 2 ATP used in energy investment phase  4 ATP made in energy payoff phase What is the second stage of Citric acid cycle aerobic respiration known as? Where does the second Matrix of the mitochondria stage of aerobic respiration take place? What happens in the second Pyruvate -> Acetyl group + Carbon stage of aerobic respiration? dioxide. Releases hydrogen ions and electrons so NAD -> NADH. Acetyl group combines with coenzyme A to make Acetyl coenzyme A. Acetyl group reacts with oxaloacetate to make citrate – coenzyme A is recycled. Series of enzyme controlled steps leads to regeneration of oxaloacetate from citrate. During this further NADH are produced. Carbon Dioxide molecules are given off. This cycle happens twice per glucose molecule (once for each pyruvate) What is required for the Oxygen second stage of aerobic respiration to occur? What is the final stage of Electron transport chain aerobic respiration? Where does the final stage The inner membrane of the of aerobic respiration take mitochondria, proteins which place? make up the electron transport chains are found here. What is the role of NADH in They deliver electrons and the final stage of aerobic hydrogen ions to the electron respiration? transport chain. What is the function of the They provide the energy to pump electrons in the final stage hydrogen ions across the of aerobic respiration? membrane. What is the function of the The hydrogen ions flow back into hydrogen ions in the final the matrix of mitochondria causing stage of aerobic respiration? ATP synthase to produce ATP from ADP + Pi. What is the function of Acts as the final hydrogen and oxygen in the final stage of electron acceptor. Combines with aerobic respiration? hydrogen and electrons to form water. Which enzyme is responsible ATP synthase for the synthesis of ATP molecules? Which enzyme removes Dehydrogenase hydrogen and electrons from molecules during respiration? What is meant by metabolic The quantity of energy used per rate? unit time. How can metabolic rate be By measuring the oxygen uptake, measured? heat production or carbon dioxide  production. Which pieces of equipment Respirometer or calorimeter. can be used to measure metabolic rate? Where does blood enter the Atrium heart? Where does blood leave the Ventricle heart? What do we call the Single circulatory system circulatory system of a fish? What do we call the Incomplete double circulatory system of amphibians (and reptiles)? What do we call the Complete double circulatory system of mammals and birds? Why are incomplete double There is mixing of oxygenated and systems less efficient than deoxygenated blood in incomplete complete double? systems so cells are not receiving the maximum quantity of oxygen. How many chambers does a 2 fish heart have? How many chambers does 3 – Two atriums, one ventricle an amphibian heart have? How many chambers do bird 4 – Two atriums, two ventricles. and mammal hearts have? What is a conformer? An organism which cannot control its metabolic rate and its internal environment is dependent on its external environment. What is a disadvantages of - Narrower range of ecological being a conformer? niches What is an advantage of Lower metabolic costs. being a conformer? What is a regulator? An organism which can control its internal environment using physiological mechanisms. What is an advantage of Can exploit a wider range of being a regulator? ecological niches What is a disadvantage of Higher metabolic costs. being a regulator? Give an example of a Any fish, reptile, amphibian or conformer? invertebrate Give an example of a Any bird or mammal regulator? What is homeostasis? Maintaining a stable internal environment. What is negative feedback When a change from the optimum control? conditions is detected by receptors a corrective mechanism is switched on to bring the conditions back to the optimum. The corrective mechanism is then switched off. What is a receptor? Something which detects change in a condition. What is an effector? Something which brings about a change in response to messages from receptors. How are messages sent Nerve impulses or hormones. between receptors and effectors? Why do organisms need to 1. To ensure that enzymes have maintain stable body optimum conditions to temperatures? maintain high metabolic rates. 2. To ensure high diffusion rates of substances. Which part of the brain The hypothalamus. detects changes in blood / body temperature? What is a thermoreceptor Detects changes in blood and where are they found? temperature, found in hypothalamus. How does the hypothalamus Nerve impulses receive and send signals? What are the effectors in - Sweat glands thermoregulation? - Skin arterioles/capillaries - Hair erector muscles - Skeletal muscles Describe the mechanisms Sweat glands: increase sweat which bring body production, heat energy is used to temperature back to normal evaporate the water from the body when it experiences high lowering the body temperature. temperatures. Skin arterioles: vasodilation – arterioles widen increasing blood flow closer to the surface of the skin, more heat is lost by radiation.  Metabolic rate: decreases. Describe the mechanisms Skin arterioles: vasoconstriction– which bring body arterioles narrow decreasing blood temperature back to normal flow closer to the surface of the when it experiences low skin so less heat is lost by temperatures. radiation. Hair erector muscles contract, hairs stand on end so more insulating air trapped increasing body temperature. Skeletal muscles: shivering which produces heat Metabolic rate: increases What do we call conditions Adverse conditions which are beyond an organism’s tolerable limits for its normal metabolic rate? What is dormancy? A period where organisms have a reduced metabolic rate. What is predictive When organisms become dormant dormancy? before the onset of adverse conditions. What is consequential When organisms become dormant dormancy? after the onset of adverse conditions. What is hibernation? A form of predictive dormancy that helps an organism survive cold temperatures. What happens to organisms - Rate of metabolism decreases during dormancy? - Heart rate and breathing rate decreases - Body temperature decreases What is aestivation? A form of consequential dormancy that helps an organism survive hot temperatures / drought. What happens to organisms - Rate of metabolism decreases during aestivation? - Heart rate and breathing rate decreases - Body temperature decreases Rate of metabolism decreases What is daily torpor? A period of time where an organism’s metabolic rate is greatly reduced in every 24 hour cycle. What is migration? The regular movement by members of a species from one place to another. Why do organisms migrate? To avoid periods of metabolic adversity like food shortages or low temperatures. Which specialised - Ringing / banding techniques can be used for - Electronic tagging studying migration? - Colour marking - Using transmitters which send GPS signals What is innate behaviour? Behaviour which is inherited and inflexible. What is learned behaviour? Behaviour which is gained by experience and is flexible. Which type of behaviour is Innate behaviour thought to play a primary role in migration? Why are microorganisms - They are easy to culture used in industry - They reproduce and grow quickly - They produce many different useful products - They are generally highly adaptable and make use of a wide variety of substrates - Their metabolism can be easily manipulated What is meant by growth A mixture of chemicals which medium? microorganisms are grown in / on. What is found in a growth Energy source and supply of raw medium? materials that can be used to make complex molecules needed for their growth. What forms of growth Broth (liquid) / Agar (solid) media are there? Why are culture conditions To avoid contamination by other kept sterile? microorganisms. What is the name for the Aseptic technique technique which allows us to keep conditions sterile? Which abiotic factors must Temperature we control when working Oxygen concentration with microorganisms? pH What is a fermenter vessel? A large vessel which can be used to culture large quantities of microorganisms. What is generation time / The time needed for a population doubling time? to double in number. What are the four phases of Lag phase, log/exponential phase, growth in microbes? stationary phase, death phase. What happens in the lag Little change in cell number as cells phase? adjust to new growth medium and begin to induce enzymes required to metabolise their substrate. What happens during the The cells multiply at the maximum log / exponential growth rate as long as there are no limiting phase? factors. What happens during the The cells death rate equals the stationary growth phase? birth rate. Nutrients begin to run out and secondary metabolites start to build up. What happens during the Substrates and nutrients run out death phase? and / or toxic metabolites build up to a concentration which leads to the death of the cells. The death  rate now exceeds the birth rate. What is meant by a viable Number of cells which are alive cell count? and capable of reproduction. What is meant by total cell Number of cells dead or alive. count? What is secondary Phase where secondary metabolism? metabolites which are not necessary for growth but may provide an ecological advantage to the organism are produced (e.g. antibiotics). When does secondary During the stationary phase metabolism occur? How can wild strains of 1. Mutagenesis micro-organisms be 2. Recombinant DNA technology improved? Why may we want to Ability to grow on low-cost improve a micro-organism? nutrients Ability to vastly overproduce target compounds Allow easy harvesting of target product What is mutagenesis? Increasing the rate of mutations using a mutagenic agent. Examples of mutagenic - Ultraviolet light agents? - X-Rays - Mustard gas What are the problems with They are often genetically unstable strains which have been so can undergo reverse mutations improved by mutagenesis? and revert back to their original state. What is recombinant DNA Transfer of genetic material from technology? one organism to another What is recombinant DNA? DNA which contains host DNA and DNA from another source. What is a restriction An enzyme which cuts DNA into endonuclease? fragments at particular sequences. What is a restriction site? A genetic sequence which is recognised by a restriction endonuclease When are restriction 1. To remove the required DNA endonucleases used? from the donor 2. To open the plasmids which will receive the DNA What is meant by When the cut ends of DNA overlap complementary sticky ends? and match together What is DNA ligase? The enzyme used to seal DNA fragments back together What is a vector? Something which is used to carry DNA from the genome of one organism to the genome of another (e.g. plasmid) What are the same So that the stick ends of the gene restriction endonucleases and the plasmid are used to cut the gene and the complementary. plasmid? What must be present in a - Restriction site vector for it to be effective? - Origin of replication - Regulatory sequence - Selective marker gene - Safety gene What is the origin of The genes which control the replication replication of the plasmid a What is the function of To allow us to know if the marker genes? recombinant gene has been taken up by the bacteria. E.g. only bacteria with the required gene will have a marker gene for antibiotic resistance so only bacteria which survive on that antibiotic have taken up the new gene. What is a limitation of using They don’t fold prokaryotes (bacteria) to proteins/polypeptides correctly. produce eukaryotic proteins in recombinant DNA technology? How can we overcome this Use eukaryotes like yeast as they limitation of prokaryotes in fold proteins/polypeptides recombinant DNA correctly. technology?