Nutrients and Energy Flashcards
why do organisms need nutrients (3)
- to obtain energy
- to obtain building blocks for development, growth, and repair
- to combat entropy
2nd law of thermodynamics
- energy tends to spontaneously disperse from being localized to becoming spread out (increased entropy)
how do we combat entropy (2)
- requires a contact input of energy
- if energy input stops, disorder gradually increases leading to death and decay
where do animals get their nutrients
- take in pre-existing organic compounds by eating other organisms
how do plants and animals differ in how they obtain energy (2)
- plants capture electromagnetic energy from sunlight
- animals capture chemical energy from food
what are the main types of nutrients (7)
- carbohydrates
- proteins
- fats
- nucleic acids (small amounts)
- vitamins
- minerals
- water
nutrient
- any substance or matter that is needed for the life and growth of living things
is oxygen a nutrient
- oxygen is not generally considered to be a nutrient, but it is required to extract most of the energy from organic nutrients
essential nutrients (2)
- nutrients that cannot be synthesized by the organism, but must be obtained from the environment
- there are macronutrients (required in large quantities) and micronutrients (micronutrients)
essential plant vs animal nutrients
- essential plant nutrients are inorganic, while essential animal nutrients are organic
are essential nutrients the same for all organisms
- no, they vary among species
vitamin C and humans
- humans cannot synthesize vitamin C, so it is required in the diet
- lack of vitamin C causes the disease “scurvy” where the connective tissues break down
essential nutrients vary among species: vitamin C (3)
- vitamin C is an essential nutrient for humans; however, it is not an essential nutrient for most other organisms because they can synthesize it themselves
- humans lack active enzyme for the last step in its synthesis
- organisms that need vitamin C as an essential nutrient likely had a diet high in fruits and no longer needed to synthesize it themselves, like their past insect eating/or other ancestors
how are nutrients used; what are the main fates of nutrients (3)
- oxidized and energy captured as ATP
- oxidized and energy released as heat
- used as building blocks for new molecules
what happens to excess carbohydrates in our diet (2)
- they are burned as fuels for energy
- they are converted to other forms (eg. fat) for storage
metabolism
- all the chemical reactions in the body
catabolic reactions (2)
- breaking down complex molecules into simpler ones
- ordered to disordered state, so energy (ATP) is released (some in the form of heat)
anabolic reactions
- building complex molecules from simple ones
- disordered to ordered, so energy (ATP) is required (but some is still lost as heat due to <100% efficiency)
how can organisms interconvert organic materials
- through metabolic biochemistry
interconversion of materials: plants
inorganic molecules (N, P) + energy from sunlight -> simple organic molecules (monosaccharides) -> complex carbohydrates -> metabolic biochemistry -> building blocks (carbs, proteins, lipids, etc)
interconversion of materials: animals
meal (other organisms) -> simpler molecules -> metabolic biochemistry -> building blocks (carbs, proteins, lipids, etc)
how could a glucose molecule provide energy required for your body to function normally
- energy of the glucose is transferred to other molecules such as ATP
how is food energy captured into ATP
- food and oxygen are turned into ATP through cellular respiration
what are the steps in energy being extracted from nutrients (3)
- break down macromolecules into simple subunits: digestive system
- breakdown/oxidize simple molecules into acetyl-CoA: glycolysis, Krebs cycle, and ETC
- complete oxidation of acetyl-CoA to H2O and CO2 to capture energy as ATP
what are the basic steps that occur in the mitochondria during cellular respiration (4)
- pyruvate is converted to acetyl-CoA
- acetyl-CoA enters the Krebs cycle to produce a small amount of ATP
- electron carriers (NADH, FADH2) are produced and carry energy
- CO2 is a by-product, composing the CO2 we breathe out
basic steps in the ETC (2)
- electron carriers (NADH and FADH2) derived from glucose carries electrons that drive the formation of proton gradients
- proton gradients are used to power ATP production
which nutrients feed into the TCA cycle
- ALL nutrients can feed into the TCA cycle
what happens when energy is converted from one form to another (2)
- inefficient metabolic processes: there is always a loss of useful energy through heat
- the total energy in the system remains the same
ectotherms (2)
- most animals: all invertebrates, most fishes, all amphibians and reptiles
- generate metabolic heat as a result of inefficient biochemical processes, but not enough to maintain their internal environment when the environmental temperature changes
endotherms (4)
- some animals: mammals, birds
- generate substantial amounts of heat internally (energetically expensive)
- allows them to maintain a relatively constant body temperature when environmental temperatures change
- has arisen independently multiple times and the mechanisms differ among groups
shivering (2)
- a method to generate excess heat
- muscle activity generates heat, so shivering can produce heat but not locomotion
non-shivering thermogenesis (3)
- uses mitochondrial metabolism to generate heat
- involved introducing inefficiencies in mitochondrial function
- uncoupling proteins (UCP) make mitochondria inefficient by introducing a pore for protons to leak through so that biochemical work (and heat production) can occur without producing ATP
where are UCP expressed in mammals
- particularly high expression in brown adipose tissue/brown fat
brown adipose tissue
- prominent in human infants
- originally thought to be only in infants, but is actually present in adults
- amount and activity of this tissue increases in the cold, but obese individuals tend to have less brown adipose tissue
other methods of thermogenesis (2)
- sea otters do not have lots of brown fat, but their skeletal muscle mitochondria have high levels of “leak”
- this generates metabolic heat which keeps them warm in cold water
how can we measure metabolism (2)
- metabolism consumes oxygen and produced carbon dioxide and heat
- measure metabolism by measuring heat production, CO2 production, or O2 consumption
measuring metabolism: heat production (2)
- estimate metabolism by measuring heat production
- called calorimetry
respiratory quotient (2)
- ration of CO2 produced relative to O2 consumed in metabolism changes depending on the fuel that is used
- allows us to estimate what fuel is being used by measuring O2 consumption and CO2 production; different fuels are used for exercise at different intensities
what factors affect metabolic rate (5)
- body size
- ingestion of a meal
- level of activity
- temperature
- age, sex, environmental oxygen, and time of day are more minor factors
effect of body size on metabolic rate (3)
- metabolic rate of large animals is greater than that of small animals
- rate per kg of body size is much lower in larger animals than in small animals
- this means that small animals must eat much more food relative to their body mass per week than large animals
how does ingestion of a meal affect metabolic rate (2)
- digesting a meal required energy and so it raises the metabolic rate
- termed the “specific dynamic action” (SDA)
how does exercise affect metabolic rate
- more exercise increases the metabolic rate
hibernation
- a long-lasting state of metabolic depression in endotherms accompanied by decreases in body temperature
effects of temperature on metabolic rate: ectotherms (2)
- metabolic rate increases with temperature up to some maximum
- body temperature changes with the temperature of the environment
