Metabolism - 2 Flashcards
Energy Balance
Defintion:
Energy intake = internal heat produced + external work + internal work + energy storage
Energy balance
Definition:
Energy Input
Energy in ingested food, cells capture portion in high-energy bonds of ATP
Definition:
Energy expended when skeletal muscles are contracted to move objects or to move body in relation to the environment
External work
Defintion:
Energy Output
energy from nutrients that is not used to perform work, transformed into thermal energy or heat
What percent of chemical energy in food is harnessed to do biological work?
25% - remainder is converted to heat (a lot is used to maintain body temperatures
Definition:
Internal work
all other forms of biological energy expenditure that do not accomplish mechanical work outside the body (skeletal muscle used for postural maintenance, shivering, heartbeat - things that are necessary to sustain life)
What is the most effective way to change metabolic pool in the body?
Food energy
What are the 3 possible states of energy balance?
- neutral
- positve
- negative
Defintion:
Energy Input = Energy output. (body weight remains constant)
Neutral energy balance
Definition:
Energy input is greater than energy output. Energy not used is stored primarily as adipose (body weight increases)
Positive Energy Balance
Definition:
Negative energy balance.
Energy input is less than energy output. Body must use stored energy to supply energy needs (body weight decreases)
Definition:
Total amount of energy we need to expend (both internal and external work) in order to perform a given task.
Metabolic rate
What is the equation for metabolic rate?
Energy expenditure/unit of time
Definition:
Basal metabolic rate (BMR)
Minimal internal energy expenditure we need to maintain in order to meet the basic physiological functions of our body
What conditions does a person need to be under in order to perform a calorimetry assessment to determine BMR?
- person should be at physical rest
- person should be at mental rest
- done at comfortable room temperature
- no food consumed within 12 hours
What factors influence metabolic rate?
- thyroid hormones levels (primary determinant of BMR)
- sympathetic stimulation (epinepherine/norepinepherine)
- exercise (post exercise BMR stays high)
- daily activities
- sex/gender (male have higher BMR)
- age (babies use more energy/weight than adults)
Definition:
Set of life sustaining chemical processes that enables organisms transform the chemical energy stored in molecules into energy that can be used for cellular processes
Metabolism
Is your brain or you bones more metabolically active?
Brain
Definition:
Cellular process that build complex molecules.
Anabolic reaction
Definition:
Catabolic reaction
Cellular process that breaks down complex molecules
Definition:
Exothermic reaction
Reaction that releases energy
Definition:
Reactions that require energy to proceed
Endothermic
T/F: all chemical reactions that take place inside cells are a part of our cellular metabolism
True
What energy stored in chemical bonds can be harnessed to perform work for biological processes?
The potential energy stored within chemical bonds
Fill in the blank:
All reactions in our body require a certain amount of _______ energy?
activation
What do enzymes do when they act as catalysts?
Lower the activation energy required for a certain chemical reaction to occur which increases the reaction rate
T/F: Enzymes are able to control multiple different types of chemical reactions.
False! One enzyme can only control a single type of chemical reaction. if an enzyme is not active the entire pathway will stop working
Why are enzymes fundamental for cell functionality?
Enzymes determine which chemical reactions a cell can carry out and the rate at which they can proceed
T/F: Specific molecules can regulate enzymes in order to promote or inhibit certain chemical reactions.
True
Definition:
Competitve Inhibition
An inhibitor molecule is similar enough to a substrate that it can bind to the enzymes active site to stop it from binding to the substrate, therefore competing with the substrate to bind to the enzyme
Definition:
An inhibitor molecule binds to the enzyme at a location other than the active site (allosteric site). Substrate can still bind to the enzyme but the inhibitor changes the shape of the enzyme so it is no longer in optimal position to catalyze the reaction.
Non-competitive inhibition
T/F: Noncompetitive inhibitor is sensitive to substrate concentration
False! It is not sensitive to substrate concentration
Are allosteric inhibitors the only molecules that bind to allosteric sites?
No
Definitions:
Allosteric activators.
Bind to allosteric sites and increases reaction rates by inducing conformational change that increases the affinity of the enzymes active site for its substrate.
Many enzymes only work if bound to non-protein helper molecules called _______
cofactors and coenzymes
What are the most common coenzymes?
Dietary vitamins
What does binding to cofactors and coenzymes promote?
optimal conformation and function
Definition:
Feedback inhibition
When a reaction product is used to regulate its own further production
How is feedback inhibition used to regulate enzyme activity in metabolism?
By using the products of the enzymatic reactions further enzyme activity is inhibitied
T/F: Metabolic reactions proceed according to cellular demands.
True
How does metabolism maintain chemical equilibriuma nd meet cellular needs?
Some metabolic products inhibit the enzymes in the chemical pathway while some reactants activate them.
