CELL RESPIRATION & METABOLISM LECTURE 5

FOR AN OVERVIEW OF CELLULAR RESPIRATION, CLICK HERE (2 min).HERE Cellular respiration includes aerobic and anaerobic respiration. This lecture is about anaerobic respiration. But, before you begin, you should get an overview of cellular respiration. “Anaerobic” = “without oxygen” “Aerobic” means “with oxygen.” Aerobic respiration produces about 20 times more ATP than Anaerobic respiration. But anaerobic respiration provides the ATP we need if we need short bursts of energy. Click here. here

A Metabolic Pathway is… series of enzyme-controlled reactions leading to a product each new substrate is the product of the previous reaction SOME REACTIONS ARE ENDERGONIC; OTHERS ARE EXERGONIC Cellular Respiration consists of metabolic pathways..

Your “Metabolism” When food is broken down, energetic electrons are released. NADH catches the electrons. NADH releases the electrons so that ATP can be made. Metabolism is all of the reactions in the body that involve energy transformation ANABOLISM & CATABOLISM = METABOLISM

OVERVIEW

Glucose GLUCOSE IS A simple sugar (C 6 H 12 O 6 ) Atoms held together by covalent bonds IN GLYCOLYSIS : One 6-carbon glucose is oxidized to form two 3- carbon PYRUVATE molecules

Glycolysis Occurs in Two Stages Energy-requiring steps – ATP energy activates glucose and its six-carbon derivatives Energy-releasing steps – The products of the first part are split into three- carbon pyruvate molecules – ATP and NADH form

Energy-Requiring Steps 2 ATP invested Energy-Requiring Steps of Glycolysis glucose PGAL P P ADP P ATP glucose-6-phosphate P fructose-6-phosphate ATP fructose1,6-bisphosphate PP ADP IN THE CYTOSOL 2 ATP ARE REQUIRED FOR GLYCOLYSIS

Energy-Releasing Steps ADP ATP pyruvate ADP ATP pyruvate H2OH2O P PEP H2OH2O P P 2-phosphoglycerate P ADP ATP P 3-phosphoglycerate ADP ATP P 3-phosphoglycerate NAD + NADH PiPi 1,3-bisphosphoglycerate PP NAD + NADH PiPi 1,3-bisphosphoglycerate PP PGAL P P IN THE CYTOSOL 4 ATP + 2 NADH ARE PRODUCED IN GLYCOLYSIS

Use and Expenditure of Energy in Glycolysis ENERGY IS ADDED TO GLUCOSE

FADH is also an electron carrier and it works just like NADH Q: WHAT IS THE PURPOSE OF NADH? A: NADH RECEIVES ELECTRONS IN A REDOX REACTION

Redox Reactions transfer energy A compound that gains an electron is “reduced” A compound that gives up an electron is “oxidized” Energy is carried in the form of electrons! Remember this?

ATP carries potential energy Phosphate groups ATP Energy PPP P PP Hydrolysis Adenine Ribose H2OH2O Adenosine diphosphate Adenosine Triphosphate + + ADP What is ATP review: For a 3 minute review of ATP, click HEREHERE

Glycolysis: Net Energy Yield Energy requiring steps: 2 ATP invested Energy releasing steps: 2 NADH formed 4 ATP formed Net yield is 2 ATP and 2 NADH and 2 pyruvate molecules

FERMENTATION Pyruvate is converted to LACTIC ACID NADH is produced NADH can be used for glycolysis to help make 2 ATP (just a little).

LACTIC ACID FERMENTATION LACTIC ACID – causes soreness in skeletal muscle Note: the heart only respires aerobically. RBCs only use lactic acid fermentation because they lack mitochondria. Click HERE for an explanationHERE