U1 KA 5-8

• what is the genome of an organism

  its entire hereditary information encoded in DNA
• what is the genome made up of

  genes and other DNA sequences that do not code for proteins
• what happens in genomic sequencing

  the sequence of nucleotide bases can be determined for individual genes and entire genomes
• how can computer programs can be used to identify base sequences

  by looking for sequences similar to known genes
• what is required to compare sequence data

  computer and statistical analyses (bioinformatics)
• use of analysing an individual's genome

  to predict the likelihood of developing certain diseases
• what is pharmacogenetics


  the use of genome information in the choice of drugs
• how can an individual's personal genome sequence be used in pharmacogenetics

  to select the most effective drugs and dosage to treat their disease (personalised medicine)
• what are metabolic pathways

  metabolic pathways are integrated and controlled pathways of enzyme-catalysed reactions within a cell

  - metabolic pathways can have reversible steps, irreversible steps and alternative routes
• what are anabolic reactions

  anabolic reactions build up large molecules from small molecules and require energy
• what are catabolic reactions

  catabolic reactions break down large molecules into smaller molecules and release energy
• how are metabolic pathways controlled

  by the presence or absence of particular enzymes and the regulation of the rate of reaction of key enzymes
• what is induced fit

  occurs when the active site changes shape to better fit the substrate after the substrate binds

  - this decreases the activation energy required for a reaction
• the affinity of the substrates/products for the active site

  the substrate molecules have a high affinity for the active site and the subsequent products have a low affinity allowing them to leave the active site
• effect of increase in substrate conc. on rate of chemical reactions

  - increase in reaction rate as more substrate molecules and active sites involved

  - point at which substrate conc. has no effect

  - enzyme conc. has become limiting factor
• effect of substrate and product concentration on the direction of enzyme reactions

  some metabolic reactions are reversible and the presence of a substrate or the removal of a product will drive a sequence of reactions in a particular direction
• what are competitive inhibitors

  competitive inhibitors bind at the active site preventing the substrate from binding
• how to reverse competitive inhibition

  increase substrate concentration
• what are non-competitive inhibitors

  non-competitive inhibitors bind away from the active site but change the shape of the active site preventing the substrate from binding
• can you reverse non-competitive inhibition by increasing substrate conc.

  no
• how does feedback inhibition work

  occurs when the endproduct in the metabolic pathway reaches a critical concentration

  - the end-product then inhibits an earlier enzyme, blocking the pathway, and so prevents further synthesis of the end-product.
• what is glycolysis


  breakdown of glucose to pyruvate in the cytoplasm
• why is ATP required in glycolysis

  ATP is required for the phosphorylation of glucose and intermediates during the energy investment phase of glycolysis
• energy pay-off stage of glycolysis

  the use of ATP earlier leads to the generation of more ATP during the energy pay-off stage and results in a net gain of ATP
• how is acetyl CoA formed

  in aerobic conditions pyruvate is broken down to an acetyl group that combines with coenzyme A forming acetyl coenzyme A
• where does the citric acid cycle occur

  matrix of the mitochondria
• citric acid cycle process

  - the acetyl group from acetyl coenzyme A combines with oxaloacetate to form citrate

  - during a series of enzyme-controlled steps, citrate is gradually converted back into oxaloacetate which results in the generation of ATP and release of carbon dioxide
• function of dehydrogenase enzymes


  dehydrogenase enzymes remove hydrogen ions and electrons and pass them to the coenzyme NAD, forming NADH

  - occurs in both glycolysis and the citric acid cycle
• what happens to the hydrogen ions and electrons from NADH

  they are passed to the electron transport chain on the inner mitochondrial membrane
• what is the electron transport chain


  a series of carrier proteins attached to the inner mitochondrial membrane
• process of the electron transport chain

  ATP synthesis

  - electrons are passed along the electron transport chain releasing energy

  - this energy allows hydrogen ions to be pumped across the inner mitochondrial membrane

  - he flow of these ions back through the membrane protein ATP synthase results in the production of ATP

  - finally, hydrogen ions and electrons combine with oxygen to form water
• the role of ATP in the transfer of energy

  ATP is used to transfer energy to cellular processes which require energy
• what happens to muscle cells during vigorous exercise

  the muscle cells do not get sufficient oxygen to support the electron transport chain

  - under these conditions, pyruvate is converted to lactate

  - lactate accumulates and muscle fatigue occurs

  - the oxygen debt is repaid when exercise is complete

  - this allows respiration to provide the energy to convert lactate back to pyruvate and glucose in the liver
• during anaerobic respiration, how is NAD regenerated and why

  - the conversion of pyruvate to lactate involved the transfer of hydrogen ions from NADH (produced during glycolysis) to pyruvate in order to produce lactate

  - this regenerates the NAD needed to maintain ATP production through glycolysis
• slow-twitch muscle fibres


  - contract relatively slowly, but sustain contractions for longer

  - rely on aerobic respiration to produce ATP

  - many mitochondria

  - a large blood supply

  - a high concentration of the oxygen-storing protein myoglobin

  - major storage fuel is FATS
• what activities are slow-twitch muscle fibres useful for

  endurance activities such as long-distance running, cycling or cross-country skiing
• fast-twitch muscle fibres


  - contract relatively quickly, over short periods

  - generate ATP through glycolysis only

  - fewer mitochondria

  - lower blood supply compared to slow-twitch muscle fibres

  - the major storage fuel is GLYCOGEN
• what sport are fast-twitch muscle fibres good for

  sprinting and weightlifting
• mixture of slow-twitch and fast-twitch muscle fibres (+ athetes)


  most human muscle tissue contains a mixture of both slow- and fast-twitch muscle fibres

  - athletes show distinct patterns of muscle fibres that reflect their sporting activities