All activities that occur within living cells are driven by ___________________ ___________________.

During these reactions, atoms of the _____________________ are rearranged to form the ___________________.

REACTANTS (what you start with) -------------> PRODUCTS (end result of reaction)


In your cells, chemical reactions rearrange the atoms in ____________________ (C6H12O6) molecules, making new products, and releasing ___________________.

Chemical reactions can ____________________ or ____________________ energy. (fig 5-1; 5-2)




____________________ - All of the thousands of chemical reactions occurring in the cells of an organism.

Chemical reactions need some _____________________ to get started.

___________________ ____________________ - Energy needed to start a reaction.

Ex: If you want to roll a boulder down a hill, you need to give it a push. That PUSH would be "activation energy" needed to start that boulder rolling down the hill.

Chemical reactions in cells require ________________________________ to proceed, generating activation energy necessary to start the reaction. Such high temperatures would kill cells. Solution???

Cells use ___________________, proteins that are capable of increasing the rate of a reaction by lowering activation energy. Ex: You would be lowering your activation energy needed to roll a boulder down a hill by decreasing the size of the hill. This is similar to the actions of an enzyme. (fig 5-3)




_____________________ - Makes a chemical reaction proceed faster without being used up by the reaction. Enzymes are biological catalysts.

Enzymes speed up reactions by binding with specific molecules, or _____________________ at the ____________________ of the enzyme. (fig 5-5)




Cells can control enzyme activity by altering the enzymes _____________________. Shape can be altered by binding ____________________ molecules to their surfaces.

Cells have _____________________ of enzymes, each one ____________________ to every reaction that goes on within the cell.


Factors that affect enzyme activity:



Cells require energy for:

______________________________________________________________________ and

_________________________________________________________________________________ requires considerable amounts of energy.

Energy stored in ___________________________________ is _____________________ at each step in a series of enzyme-catalyzed, linked reactions called a __________________________________________. There are _______________________ of these pathways that take place in living things.



In biochemical pathways:


When cells break down molecules, energy is:

________________ - Adenosine Triphosphate


ATP + H2O --> ADP + P + energy


When a reaction that absorbs energy in a cell is driven by the conversion of ATP -> ADP, it is called a

____________________ _____________________. These reactions occur during metabolism. (fig 5-8)





The ________________ is the ultimate source of energy for all living things.

Energy obtained from the sun is __________________________ into organisms throughout the food chain.



(fig 5-10)



_____________________, _____________________, & some ____________________ take part in a process called photosynthesis.

______________________________ - A process in which energy is captured from the sun, and used to produce ATP, energy storing carbohydrates, and other organic molecules for all other organisms on earth.

Organisms that cannot capture light directly from the sun get energy by ________________________ food, which contains carbohydrates & organic molecules.


All living things use a process called __________________________ __________________________ to obtain energy from carbohydrates & other organic molecules.

During cellular respiration, energy that was ____________________ in organic molecules is used to make ________ needed for life processes.



During photosynthesis, _____________________ captured from the sun is used to obtain ____________________, which carry the energy through a series of chemical reactions.


6 CO2 + 6H2O + light energy -> C6H12O6 + 6O2

Photosynthesis has THREE STAGES:

  1. _______________________ is captured from ________________________.
  2. The ______________________ is used to make ________________ and ___________________, an energy carrying compound
  3. ________________ & ___________________ are used to power the _________________________ of energy-rich ___________________________________ using _______________ from the air.


Stage 1: Capturing Light Energy

(fig 5-12) – The Electromagnetic Spectrum







Shorter wavelengths of light = more energy
Longer wavelengths of light = less energy
Intermediate wavelengths of light = visible light


__________________________ - Molecules that absorb light photons. When a pigment absorbs light, _____________________ of certain atoms in pigment molecules are boosted to a _______________________ _________________________ ________________________.

Ex of pigments: Retinal pigments exist in human eyes, chlorophyll pigments exist in plants.


Light -> (energy transferred) -> Electrons

__________________________ - The major pigments in plants. Absorbs mainly ____________ & ____________ photons of light, and reflects _______________ photons of light.

_________________________ - Other pigments found in plants that help gather energy for photosynthesis. These pigments absorb slightly different wavelengths of light, reflects ____________________ & ___________________ light.


Interesting fact: Chlorophyll breaks down in colder temperatures and allows colors of carotenoids to be seen in yellow and orange leaves of autumn.

Pigments for photosynthesis are located in ____________________________ of plant cells. Chlorophyll molecules are contained in disk-like membranes called ____________________________.

__________________________ - Stacks of thylakoids suspended in the fluid stroma of chloroplasts.

(fig 5-13)



What happens in Stage 1 of Photosynthesis?

(fig 5-14)


Stage 2: Using Light Energy to Make ATP & NADPH

ATP is made when protons flow through a protein channel.

(refer to fig 5-14)


These _________________________ _________________________ in the thylakoid membrane are directly responsible for providing energy to produce ________________ molecules.


Additional light energy is absorbed to make NADPH

(refer to fig 5-14)


The ________________ and ___________________ generated in Stage 2 help power Stage 3 of Photosynthesis – the building of __________________________________.

Stage 3: Building Carbohydrates

(fig 5-15)


The energy to fuel the Cycle comes from the ____________________ & ____________________ made during stage 2 of photosynthesis.


__________________________ ___________________________ is the release of energy from carbohydrates & other organic molecules.

Energy released is used to power ________________________ _______________________ in the cell.


Stage 1: Glycolysis "Splitting of glucose"


What happens during Glycolysis?


Where do these electrons and hydrogen atoms go….?

FERMENTATION occurs in the absence of O2

Electrons and hydrogen atoms carried by _______________ are attached to ______________________________ molecules.

This regenerates _____________, which enables glycolysis to continue.

In _________________________ and some _________________________, _______________________ acid is broken down into _____________ and ________________________________________________________.

In __________________________ and some _________________________, _______________________ acid is converted to _______________________ acid, which forms in muscle cells during rigorous exercise.

(fig 5.17).

Stage 2: Oxidative Respiration (AKA: Oxidative Phosphorylation)

C6H12O6 + 6 O2 6 CO2 + 6 H2O + 36 ATP


OXIDATIVE RESPIRATION occurs in the presence of O2

(fig 5-18)


What happens during Oxidative Respiration? (fig 5-19)


The KREBS CYCLE yields ATP, NADH, and CO2

The Electron Transport Chain makes more ATP


Oxidative Respiration requires oxygen because electrons stripped from pyruvic acid must have a final "home."



___________________________________________________ - Slowing or stopping of an early reaction in a series of reactions, caused by high levels of the end product of the process.

In the case of oxidative respiration, this would involve ____________________________ binding of _____________.

(fig 5-20)


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