metabolic pathways

What is a metabolic pathway?

A series of chemical reactions occurring within a cell that converts a substrate into a product, often involving enzymes.

What are catabolic pathways?

Metabolic pathways that break down complex molecules to release energy stored in chemical bonds.

What are anabolic pathways?

Metabolic pathways that construct complex molecules from simpler ones, requiring energy.

characteristics of multistep pathways

• highly regulated by specific enzymes for each step

  • allow response to environmental changes

  • avoids futile cycles

• each reaction takes place in specific organelles

what does flow of material depend on for multistep pathways

• supply of substrates

• removal of products

• pathway enzyme activities

How does free energy exchange occur between anabolic and catabolic pathways?

Catabolic pathways release energy that is used to drive anabolic pathways, allowing for cellular processes.

What is the role of ATP in metabolism?

ATP acts as a universal energy currency, transferring free energy between reactions.

What is feedback inhibition?

A regulatory mechanism where the end product of a metabolic pathway inhibits the pathway's first committed step.

What is feed-forward activation?

Activation of an enzyme later in a pathway by an intermediate metabolite earlier in the pathway.

What is the difference between single and multistep pathways?

Single pathways release energy all at once, while multistep pathways release energy in smaller, manageable quantities.

What is the significance of enzymes in metabolic pathways?

Each reaction in a metabolic pathway is catalyzed by specific enzymes that ensure regulation and efficiency.

What is the committed step in a metabolic pathway?

The first step in a pathway that is specific to that pathway and regulates its rate.

inhibition of activation from other pathways

metabolites from related pathways inhibit or activate a key enzyme on the pathway

What are allosteric regulators?

Molecules that bind to the site other than the active site of an enzyme, causing a conformational change that affects enzyme activity.

covalent modification definition, purpose and example

• addition or removal of a group

• enzyme can be rapidly and reversibly altered

• protein phosphorylation by protein kinase

• protein phosphotase removes the phosphate groups

What is the thermodynamic significance of delta G?

If delta G is less than 0, the reaction is spontaneous; if more than 0, it is non-spontaneous.

What is a coupled reaction?

An enzyme-catalyzed reaction where the free energy released by an exergonic reaction is used to drive an endergonic reaction.

What characterizes autotrophic organisms?

Autotrophic organisms obtain energy directly from the environment through processes like photosynthesis.

What characterizes heterotrophic organisms?

Heterotrophic organisms derive energy from the breakdown of complex organic molecules from other organisms.

What is the molecular structure of ATP?

ATP consists of adenosine (adenine + ribose) and three phosphate groups, magnesium lowers overall charge to -2

What is the significance of the phosphoanhydride bond in ATP?

These bonds store substantial energy; upon hydrolysis, they release energy used for cellular work.

What process uses large negative delta G reactions to synthesize ATP?

Catabolic pathways, where energy is released from the breakdown of molecules.

How does ATP hydrolysis influence biosynthetic pathways?

Hydrolysis of ATP can drive biosynthetic pathways, allowing reactions with positive delta G to occur.

What is the specific bond between adenosine and the alpha phosphate?

The bond is called a phosphoester bond.

What occurs when water is added back to phosphates in ATP?

Hydrolysis generates a significant release of free energy.