Introduction to metabolism (Miss Dawson) Flashcards
What is metabolism ?
The sum of all chemical processes necessary to make possible the characteristics of living cells/organisms.
Organisms need to survive, grow and reproduce. What does this require ?
Energy, carbon source and “reducing power”.
What is the difference between autotrophs and heterotrophs ?
Autotrophs are organisms that can produce their own food from the substances available in their surroundings (inorganic sources of C and e-) using light (photosynthesis) or chemical energy (chemosynthesis).
Heterotrophs cannot synthesize their own food and rely on other organisms — both plants and animals (organic sources of C and e-) — for nutrition.
What is the difference between phototrophs and chemotrophs ?
Chemotrophs are organisms that obtain energy by the oxidation of electron donors in their environments. These molecules can be organic (chemoorganotrophs) or inorganic (chemolithotrophs). Phototrophs use solar energy.
How does the giant tube worm R. Pachyptila, a chemoheterotroph, survive in hydrothermal vents at depths which the sunlight can’t reach ?
R. Pachyptila lives in a symbiotic relationship with chemolitotrophic bacteria inside them.
Tube worms have no digestive tract, but the bacteria convert oxygen (provided by the tube worm), hydrogen sulfide, carbon dioxide, etc. into organic molecules on which their host worms feed.
Are humans chemo/phototrophs ?
Auto/heterotrophs ?
Chemoheterotrophs. We eat food ! Carbohydrates (glucose), fats lipids, and protein.
Is fuel oxidation catabolism or anabolism ?
Why ?
Catabolism, we are breaking down complex molecules into simpler ones (e.g. respiration of glucose). These reactions remove e- and Hs and add Os. They release NRG and are therefore energetically favourable (-ve delta G).
Is biosynthesis catabolism of anabolism ?
Why ?
Anabolism, we are building a complex molecule with more simple ones (e.g. DNA synthesis). These are reductive reactions: e- and Hs added, Os removed. Anabolic reactions require NRG and thus don’t happen spontaneously (+ve delta G).
How can endergonic reactions (+ve delta G) be pushed forward ?
By enzymes coupling these reactions to more exergonic reactions.
How does ATP store NRG ?
It it’s 2 high NRG phosphoanydride bonds.
What are two very important coenzymes in metabolism regulation ?
NAD(P)H/NAD(P) : NADH (oxidized form) is primarily used during catabolism and NAD+ (reduced form) during anabolism.
FADH2/FAD : FADH2 (oxidized form) is primarily used during catabolism and FAD (reduced form) during anabolism. Unlike NADH, FADH2 is never found in solution and is always associated a protein.
What are key organs/tissues involved in metabolism ?
How do they use/store energy ?
The brain: normally runs on glucose, can use tone bodies during starvation
Skeletal muscle: when glucose is plentiful, it stores glycogen for its own use
The liver: when glucose is plentiful, make oxygen and fat. Release fuel during fasting and exercise
Adipose tissue: when fat is plentiful, stores fat. Releases it during facing and exercise.
What are the three main metabolic states ?
How do key organs function in these different states ?
Fed state: liver uses excel fuel to make glycogen and fat, tissues can take up glucose, adipose tissue takes up and stores fat
Exercice: muscle fuel use increase, adipose tissue releases fatty acids, liver releases glucose
Fasting state: liver release glucose and ketone bodies,adipose tissue releases fat acids, most tissues switch to fat use
