Chap 4 The Energy of Life Flashcards
What is energy?
the ability to do work
What are the different forms of energy?
kinetic
potential
What is kinetic energy?
energy in motion/movement
What is potential energy?
stored energy that is available to do work
Can energy be converted from one form to another?
yes
What is the first law of thermodynamics?
energy is never created or destroyed
What it entropy?
a measure of disorder/the randomness of the universe
What is the second law of thermodynamics?
the entropy of the universe is increasing
Why is the entropy of the universe increasing?
heat energy is constantly being lost and heat energy is disordered
What does a chemical rxn do?
rearranges atoms (break/forms bonds)
What is metabolism?
all chemical rxns in cells
In a chemical rxn does it need or release energy when forming a bond?
needs energy
In a chemical rxn does it need or release energy when breaking bonds?
release energy
Where is the energy in a compound stored?
in the chemical bonds
Most energy transformations in organisms occur in what way?
oxidation-reduction rxns
What is oxidation-reduction rxn?
transfer of electrons
What is oxidation?
atom lose electron
What is reduction?
atom gains electron
What is an electron transport chain?
series of membrane proteins participating in sequential, linked redox rxns
How much energy is released from redox reactions?
a small amount
Photosynthesis and respiration both use what?
electron transport chain
What happens to the energy released from the electron transport chain?
cells store it and use it in other rxns
What is ATP?
adenosine triphosphate - a nucleotide that temporarily stores energy
What is the cellular currency?
ATP
What is the form of energy that cells can use?
ATP
What type of energy is stored in ATP?
potential
What does ATP do?
releases stored energy
How does ATP release energy?
removing the endmost phosphate group by hydrolysis
What does the cell use the energy for?
to do work
ATP if formed during what?
cellular respiration
What is cellular respiration?
chemical rxns that release energy from sugar producing ATP from ADP
ATP is coupled with what?
chemical rxns
Reactions that break down ATP are couples with what?
rxns that require energy input
What happens when rxns are coupled together?
energy released from ATP can power the second rxn
What do enzymes do in a chemical rxn?
covert reactants into products
In relation to enzymes what is a substrate?
what enzymes act on
In relation to enzymes what are reactants?
molecules present at the start of the reaction
In relation to enzymes what are products?
molecules present at the end of the reaction
What do enzymes do to the energy in a rxn?
lower the activation energy
What is the activation energy of a rxn?
the energy required to start a reaction
Without enzymes the activation energy is…?
high
How is the activation energy lowered?
when an enzyme binds to the substrate the activation energy is lowered
Does temperature affect enzyme activity?
yes
During what temperature range are enzymes active?
55-79 degrees C
is the optimal temperature range
Do chemical factors affect enzyme activity?
yes
Where do substances enter/exit a cell?
through the membrane
Membranes form what in cells?
barriers
Solutes can enter/exit depending on what two factors?
concentration gradients
the chemical nature of the substance (polarity, charge, size)
What is a “gradient”
concentration difference
What happens when there is a gradient?
molecules diffuse until there is no more concentration gradient
maintaining a concentration gradient requires…?
energy
Is a gradient more ordered or less ordered?
more ordered (less entropy)
Is no gradient more or less ordered?
less ordered (more entropy)
Entropy tends to what?
increase
Simple diffusion does not require what?
energy
Simple diffusion is a type of what?
passive transport
When does simple diffusion occur?
when there is a concentration difference on one side of a membrane compared to the other
How do molecules diffuse?
from high concentration to low concentration
Osmosis does not require what?
energy
Osmosis is a type of what?
passive transport
Osmosis takes place when…?
there is a different concentration of water on one side of a selectively permeable membrane compared to the other
What determines the water content in animal cells?
osmosis
How does water move in and out of cells?
osmosis
Facilitated diffusion does not require what?
energy
Passive transport includes what?
facilitated diffusion
When does facilitated diffusion occur?
when membrane proteins transport substances across a cell membrane
Facilitated diffusion requires what?
membrane proteins
Active transport requires what?
energy
Active transport occurs when?
membrane proteins use cellular energy to transport substances across a cell membrane
The membrane transport protein is referred to as what?
a pump
With active transport how are substances moved?
up their concentration gradient
How are ions moved against their gradient?
the sodium-potassium pump
Where are the “pump” protein found?
the membranes of neuron and muscle cells
How do small nonpolar molecules enter/exit a cell?
passively diffuse across the membrane when there is a concentration gradient (simple diffusion e.g. osmosis and facilitated diffusion)
How to large polar molecules enter/exit a cell?
active transport into the cell regardless of gradient (membrane protein pumps)
Photosynthesis produces what?
sugar
Explain the photosynthesis rxn?
uses light energy and CO2 from the air to form glucose C6H12O6 and other carbohydrates
Sugar is a crucial what?
food source
How is sugar used?
in cellular respiration to make ATP for cells to use
What powers photosynthesis?
sunlight
What do photosynthetic organisms need to make their own sugar?
sunlight
CO2
water
Photons are what?
packets of light energy
Photosynthesizers capture photons of what?
visible light
What is the main photosynthetic pigment in plants?
chlorophyll a
Pigment does what?
absorbs energy from some wavelengths of light and reflects other wavelengths
What type of cells contain chloroplasts
mesophyll
Most photosynthetic cells contain how many chloroplasts?
40-200
Where does photosynthesis take place in eukaryotes?
chloroplasts
In how many stages does photosynthesis occur?
2 - Light rxns
- Carbon rxns
What happens in the light rxn of photosynthesis?
light energy is captured and converted to chemical energy
What happens in the carbon rxns of photosynthesis?
energy is used to produce sugar
Where does the light rxn in photosynthesis occur?
thylakoids
The light rxn in photosynthesis required what?
water
light
What is produced in the light rxn of photosynthesis?
ATP
NADPH (to carry and store energy)
What is formed as a byproduct of the light rxn of photosynthesis?
oxygen gas
What do the carbon rxns do in photosynthesis?
carbohydrates
What is the name for the carbon rxns in photosynthesis?
calvin cycle
Where do the carbon rxns in photosynthesis occur?
the stroma (liquid filled space in the chloroplasts)
What powers the calvin cycle?
ATP and NADPH
What does the calvin cycle do?
assembles CO2 molecules into carbohydrates
What do plants use sugar for?
respiration to make ATP
build complex sugars/polysaccharides
Plants use different what?
carbon fixation pathways
Carbon fixation pathways are plant what?
adaptations
What type of plants do well in cool moist weather?
C3
What type of plants do well in hot dry weather?
C4
CAM
Organisms need what?
food
oxygen
Cells use energy in food to make what?
ATP
What would happen to cells without ATP?
they would die
What is the process that makes ATP?
cellular respiration
What is the form of energy cells are able to use?
ATP
What do cells use ATP for?
do work
power chemical rxns
Aerobic cellular respiration is a series of what?
chemical rxns
What are the reactants of aerobic cellular respiration?
glucose
oxygen
What are the products of aerobic cellular respiration?
CO2
water
ATP
Why do we need to breathe air?
it is required for cellular respiration
Where does oxygen travel to when we breathe?
Mitochondria
What exits the mitochondria during cellular respiration?
CO2
What are the three main pathways for cellular respiration?
Glycolysis
Krebs cycle
electron transport chain (ETC)
What happens in glycolysis?
glucose in split in half forming pyruvate. some energy is transferred to electrons, some used to form ATP
What happens in the Krebs Cycle?
a derivative of pyruvate is oxidized, CO2 is released. more energy is transferred to electrons
What happens in the electron transport chain?
energy from electrons id used to form ATP.
What is the final electron acceptor in cellular respiration?
oxygen
Cellular respiration relies on what type of reactions?
redox
What do the pathways of aerobic respiration do?
release energy by oxidizing glucose and reducing oxygen
Where is the most ATP produced?
mitochondria
What are the key ATP-generating processes?
krebs cycle
electron transport chain
Does the redox respiration rxn release or take up energy?
release energy
