Chapter 7 Flashcards
Metabolism
- metabolism is the buildup and breakdown of nutrients within the cell
- these chemical reactions provide energy and create substances that sustain life
Catabolism
- breaks down complex molecules; provides energy and building blocks for anabolism; exergonic
- cats break things down
Anabolism
- uses energy and building blocks to build complex molecules; endergonic
- ants build things up
Metabolic pathways
- sequences of enzymatically catalyzed chemical reactions in a cell
- determined by enzymes
- enzymes are encoded by genes
- enzymes act on specific substrate and lower the activation energy
- enzymes are biological catalysts
- catalysts speed up chemical reactions without being altered
Enzymes
- enzymes are biological catalysts:
- increase the rate of chemical reactions
- do not become part of the products
- are not consumed in the process
- do not create a reaction
Enzymes and chemical reactions
- substrates contacts the enzyme’s active site to form an enzyme-substrate complex
- substrate is transformed and rearranged into products, which are released from the enzyme
- enzyme is unchanged and can react with other substrates
Components of holoenzyme
The makeup of enzymes
- many protein enzymes are complete in themselves
- apoenzymes are inactive if not bound to nonprotein cofactors (inorganic ions or coenzymes)
- binding of apoenzyme and its cofactor(s) yields holoenzyme
- some are RNA molecules called ribozymes
The 4 factors that influence enzyme activity
- temperature
- pH
- substrate concentration
- inhibitors
How factors influence enzyme activity in general
- high temperature and extreme pH denature proteins
- if the concentration of a substrate is high (saturation), the enzyme catalyzes at its maximum rate
inhibitors - competitive
fill the active site of an enzyme and compete with the substrate
inhibitors - noncompetitive
- interact with another part of the enzyme (allosteric site) rather than the active site in a process called allosteric inhibition
aerobic respiration
- a series of reactions that converts glucose to CO2, and allows the cell to recover significant amounts of energy
- utilizes glycolysis, the Krebs cycle, and the respiratory chain
- relies on free oxygen as the final electron and hydrogen acceptor
- characteristic of many bacteria, fungi, protozoa, and animals
- 36-38 ATP
- oxygen takes the las electron so you can have ATP
anaerobic respiration
- used by strictly anaerobic organisms and others who are able to metabolize with or without oxygen
- involves the same three pathways as aerobic respiration: glycolysis, Krebs cycle, and the electron transport chain
- uses NO3-, SO4^2-, CO3^-3, and other oxidized compounds as terminal electron acceptors
- 2-36 ATP
fermentation
- incomplete oxidation of glucose
- only go through glycolysis
- oxygen is not required
- organic compounds are terminal electron acceptors
- 2 ATPs
Making ATP where there is no oxygen, making the glycolysis cycle repeat
Alcoholic fermentation uses yeasts
Lactic acid fermentation uses lactic acid in the body (2 pyruvate -> 2 lactate)
After pyruvic acid: the fermentation strategy
- the incomplete oxidation of glucose or other carbohydrates in the absence of oxygen
- uses organic compounds as the terminal electron acceptors
- yields a small amount of ATP
- use by organisms that do not have an electron transport chain
- other organisms can repress the production of electron transport chain proteins when oxygen is lacking in their environment
- they can revert to fermentation
Factors that influence enzymatic activity
Substrate concentration
- a grade or money is a substrate and the more you have the better
- maximum is typically 4 -> you are dependent on your substrate concentration
- the concentration of your substrate can affect your activity
What does a competitive inhibitor do to an active site
A competitive inhibitor is something that binds to the active site. The activity of the enzyme then goes down because the competitive inhibitor attached to the active site which blocks and slows down the process of the binding of substrates on the active sites
Strategies of metabolism: ATP and energy transfer
- ATP has three phosphate groups
- removal of terminal -PO3^2- group by hydrolysis gives adenosine diphosphate -ADP
Substrate-level phosphorylation
- ATP generated when high-energy PO4^- is added to ADP and generates ATP
Differences between the aerobic and anaerobic metabolic pathways
- While aerobic metabolism generates more ATP and relies on oxygen, anaerobic metabolism does not need oxygen but only creates two ATP molecules per glucose molecule. However, anaerobic and aerobic metabolism are both required to produce cellular energy
- anaerobic metabolism can only use glucose and glycogen, aerobic can use those plus break down fats and proteins
Similarities between the aerobic and anaerobic metabolic pathways
- both use glycolysis and glycogen
- both take place in most cells
- both start with glucose as a substrate and oxidize to release energy (use of glucose as an energy source
- both go glycolysis to pyruvate to kreb’s to ETS
Where are aerobic, anaerobic, and fermentation found
Aerobic - higher animals and plants
Anaerobic - micro-organisms, rarely in higher organisms
Fermentation - bacteria and some higher animals (sometimes in muscle cells in humans)
Fermentation
- the metabolic process that extracts energy from the carbohydrates by the cation of enzymes in the absence of oxygen
What types of organisms need no oxygen - fermentation
Yeast
Sometimes bacteria
Archaea
Sometimes muscle cell
Lose electrons =
Gain electrons =
Oxidized
Reduced
