METABOLISM Metabolism Sum of all the chemical processes

METABOLISM

Metabolism � Sum of all the chemical processes that occur in an organism.

� Metabolic Pathway –series of linked chemical reactions that occur in a cell and produce specific products.

Photosynthesis � Autotrophs take sunlight energy and convert it to chemical energy. � Occurs in chloroplasts of plant cells.

� Energy is immediately captured by two molecules: � ATP � NADPH

ATP � Adenosine Triphosphate � Energy storage molecule that plant cells use to make carbohydrates.

� Heterotrophs uses energy released from hydrolysis of complex molecules and store as ATP. � Cycle between ATP and ADP is primary energy exchange mechanism in cells. � ATP carries energy from macromoleucles to energy requiring processes in cells. � ATP is hydrolyzed to ADP, and energy is released to power cell activities.

ATP-ADP CYCLE

Catabolism � Breaks down molecules and forms ATP � Ex-digestion of carbohydrates - begins in mouth where amylase is secreted by salivary glands. Chyme is passed through esophagus, stomach, and small intestines where enzymes complete the hydrolysis of carbohydrates to form gluc � ose and other monosaccharides.

� Fat digestion occurs only in small intestine. Broken down into fatty acids and glycerol. � Protein digestion occurs in stomach and small intestine. Broken down into amino acids.

� Products of digestion are absorbed by small intestines and into blood stream where molecules are transported to cells.

In Cells � Glycolysis breaks down glucose into pyruvate. � Pyruvate enters mitochondria and then is fed into the Krebs Cycle. � In Krebs cycle, NADH and ATP are produced. � The catabolism of 1 glucose molecule can make up to 36 ATP. (40% efficient)

ANABOLISM � Makes larger molecules and uses ATP. � Energy released during catabolism powers the synthesis of new molecules. � Anabolic processes are how cells produce molecules needed for growth and repair. � ATP energy is needed it make lipids, polysaccharides, proteins, and nucleic acids.

GLYCONEOGENESIS � An important anabolic pathway, where glucose is produced from non-carbohydrate substances.