BIOL 1103 Unit #2

metabolism

controls the release of energy from chemical reactions

Cell’s metabolism

the sumtotal of chemical reactions occurring in one cell

unit of metabolism

calories

calorie

the amount of energy required to raise the temperature of gram of water by one degree kelvin or celsius

metabolic rate

the number of calories you intake must be equal to the output

factors that influence metabolic rate

gender, genetics, size etc.

catabolic

release of energy (large molecules are broken down)

anabolic

consume energy (making large molecules)

energy

the capacity to do work

kinetic energy

energy of motion

potential energy

energy from location or structure (ei. chemical bonds)

first law of thermodynamics

energy cannot be created or destroyed in the universe

second law of thermodynamics

energy conversion increases the disorder of the universe

entropy (S)

measures disorder

high order =

low entropy (working cells)

low order =

high entropy

what inputs energy for the earth?

the sun

spontaneous reaction

energetically favoured, will yield some energy as a product

nonspontanous reactions

will require energy to perform and are not energetically favoured

free energy (delta G)

the portion of the system’s energy that can perform work

enthalpy

the total energy of a system

exergonic reaction

energy is released, spontaneous, free energy is negative, ex. cellular respiration

endergonic reaction

requires energy, non-spontaneous, free energy is positive, ex. photosynthesis, products contain more potential energy than reactants

energy coupling

energy released from exergonic reactions is used to drive forward endergonic reactions, usually using the ATP stored in molecules

ATP releases energy by

breaking of a phosphate group and becoming ADP

how is ATP broken down

hydrolysis

what happens to the phosphate group from ATP

inorganic phosphate ion

How is ATP formatted in cytoplasm

ADP and phosphate ions lay around and ATP is formed upon demand

Is ATP a renewable source?

yes

What needs to be present for ATP formation?

enzymes

activation energy

reactions must overcome this energy to have the reaction go forward

transition state

unstable, bonds will want to break and have the reaction go to completion

how do reactions usually overcome activation energy?

heat energy

what lowers activation energy?

enzymes

do enzymes affect the amount of energy released?

no, just lower activation energy

do enzymes increase rate of reaction?

yes

active site

spot on enzyme where the substrate makes a connection

what happens when a substrate gets close to active site?

enzyme will change its shape to hold onto the substrate (induced fit)

how do active sites attract substrates?

they specific characteristics

do substrates always bond with enzymes?

they bump into enzymes in the cytoplasm but it must be the right orientation

Initiation

when the reactants come together in the active site

Transition

binding induces transition state by changing the shape of the enzyme breaking bonds

Termination

enzymes release substrates as products and returns to its orignal shape

limiting factors of enzymes

time, amount of enzymes vs. substrates

what factors affect enzymes productivity?

temperature, pH, presence of cofactors/ coenzymes

do enzymes require cofactors or coenzymes?

yes, they bind to the protein affecting rate of reaction

competitive inhibitors

block the active site on enzymes from natural substrates reducing productivity

noncompetitive inhibitors

binds somewhere other than the active site and changes the shape of the enzyme preventing natural substrate from binding

allosteric site

site other than the active site on an enzyme

activator molecule

binds to an allosteric site and stabilizes the enzyme allowing for the substrate to bind (allows ones that put enzyme in inactive state)

how do drugs act

as enzyme inhibitors; other examples, pesticides, poisions

feedback inhibition

regulates metabolic processes by having the product bind to enzyme preventing further reactions to go forward

redox reaction

transfer of electrons

oxidation

loss of electrons

reduction

gain of electrons

carriers of electrons

NADH and FADH2

glycolysis

1st stage: breaks one molecule of glucose into 2 pyruvates

Pyruvate Oxidization

pyruvate is oxidized producing Acetyl CoA which can enter the citric acid cycle

Oxidative Phosphorylation

electron transport chain breaks bonds and released energy

where does glycolysis take place?

cytoplasm

3 stages of cellular respiration

glycolysis, pyruvate oxidization, oxidative Phosphorylation

substrate level phosphorylation

enzymes transfer phosphate ion from substrate to ADP

energy investment phase

2 ATP molecules are used to put glucose in a high energy/ unstable state

energy payoff phase

products include 4 ATP, 2 NADH, 2 pyruvate

where does most of the energy lie after glycolysis?

in the pyruvate molecules

stages of glycolysis

substrate level phosphorylation, energy investment phase, energy payoff phase

where does pyruvate oxidation occur?

mitochondria matrix

products of pyruvate oxidation

2 CO2 and 2NADH

where is most of the energy at the end of pyruvate oxidation?

2 NADH molecules

citric acid cycle

completes the oxidation of glucose

output of citric acid cycle

6 NADH

2 FADH2

2 ATP

photosynthesis

endergonic reaction ; has light and dark reactions

autotrophs

make their own food via photosynthesis

chemoautotrophs

make their own food not with photosynthesis

heterotrophs

depend on consuming organic molecules as food source

where does photosynthesis take place?

chloroplasts

where are chloroplasts located?

anywhere the plant is green; in the mesophyll

what type of reaction is photosynthesis?

redox reaction

light reaction

at the presence of light; water is split and electrons are released

transmittance

how much light passes through

where do light reactions take place?

in chloroplast thylakoid membranes