Chapter 9-Cellular Respiration/Notes

I.Chemical Pathways

➪Food serves as a source of raw materials for molecular synthesis and energy

Chemical Energy and Food

➪1 g glucose when burned in the presence of O2 releases 3811 calories of heat energy.

➪A ______is the amount of energy needed to raise the temperature of 1 g water 1 degree C.

➪The calorie used on food labels is a kilocalorie,or 1000 calories

➪Cells don’t “burn” glucose.Instead,they gradually release the energy from glucose and other food compounds.

➪Begins w/ ______-a pathway that releases a small amount of energy.If O2 is present,it turns to 2 other pathways that release a lot of energy and if O2 is not present,glycolysis is followed by another pathway.

➪Final steps of cellular respiration takes place in the ______

Overview of Cellular Respiaration

➪In the presence of O2,Glycolysis is followed by the Krebs cycle and the electron transport chain

➪Glycolysis,electron transport chain and Kreb’s cycle make up______-the process that releases energy by breaking down glucose and other food in the presence of O2

➪Glycolysis equation______

➪Requires O2 ,food and gives off CO2 ,water and energy

➪The cell has to find a way trap these little bits of energy to make ATP.

Glycolysis= process in which one molecule of glucose is broken in ½ ,producing 2 molecules of ______,a 3-C compound

ATP Production

➪2 molecules of _____ used @ beginning/4 molecules ATP are produced @ end-net gain of 2 molecules

NADH Production

➪4 high energy molecules are removed and passed onto electron carrier ______-nictotinamide adenine dinucleotide-these accept a pair of high energy electrons making ______and it passes

electrons onto next molecule.Energy is passed from glucose to other pathways.

➪Process is fast so ATP is produced –a lot in a short amount of time.

➪Does not require O2

➪A problem:when a lot of ATP is made from glycolysis-NAD+ fills w/electrons and w/o NAD+,glycolysis stops

Fermentation

➪Follows glycolysis if O2 is not present

➪______releases energy from food molecules by making ATP in the Absence of O2.

➪Cells convert NADH to NAD+ by passing electrons to ______acid.This coverts NADH back to carrier NAD+,allowing glycolysis to continue

➪Called______because it does not require O2.

1)Alcoholic Fermentation

➪Used by______

➪Ethyl alcohol and CO2 are made as waste

Pyruvic acid + NADH-- alcohol + CO2 + NAD+

➪Causes bread dough to rise due to _____

2)Lactic Acid Fermentation

➪Fermentation that uses pyruvic acid produced to convert to lactic acid

➪Regenerates NAD+ so glycolysis can continue

➪Pyruvic acid + NADH-- lactic acid + NAD+

➪Produced in muscles during rapid exercise when the body cannot supply enough ___ to the tissues.(for ATP production)

➪Causes a painful burning sensation

➪Unicellular organisms also produce lactic acid as a waste during fermentation…..eg .prokaryotes in yogurt production,buttermilk,sauerkraut…

II. The Kreb’s Cycle and Electron Transport

•At the end of Glycolysis,90 % of chemical energy available in glucose is still unused,locked in high energy electrons of ______

•O2 becomes a powerful electron acceptor

•Called ______because these pathways require O2

A. The Kreb’s Cycle

–During the Kreb’s Cycle,pyruvic acid is broken down into ______in a series of energy-extracting steps

–Because ______is the 1st compound formed,it is also called ______.

–1) Begins when pyruvic acid produced by glycolysis enters the ______.

–1 C-atom pyruvic acid becomes part of CO2 and gets released into the air.

–2) Citric acid is broken down into a 4-C molecule,more CO2 is released,and ______are transferred to energy carriers

–For each turn of the cycle,a molecule similar to ADP is converted into a molecule similar to ATP.

–Electron carrier NAD+ changes to ______

–Electron carrier FAD(flavine adenine dinucleotide) changes to ______What happens to each of the Kreb’s Cycle Products?

–

–CO2 released is the source of all CO2 you exhale

–______produced directly can be used for cellular activities

–In the presence of O2,high-energy electrons from electron carriers are used to make large amounts of ATP

Kreb’s Cycle

B.Electron transport

•Kreb’s Cycle produces high-energy electrons passed to NADH and FADH2

•These electrons are passed from the electron carriers to ______,which uses high energy electrons from Kreb’s cycle to convert ADP into ATP

1)High energy electrons are passed from NADH and FADH2 are passed along electron transport chain

•In eukaryotes,the chain is composed of carrier proteins in the inner membrane of the mitochondrion.

•In prokaryotes,the same chain is in the ______

•At the end of the chain,an enzyme combines these electrons w/H+ ions and O2 to form ______

•O2,then ,serves as the final electron acceptor of the electron transport chain,getting rid of wastes(low energy electrons and H+ ions.)

•2) Every time 2 high energy electrons transport down the transport chain,their energy is used to transport H+ across the membrane…..H+ ions build up in the intermembrane space making it positive…. and the other side is negative.

•3) How does the cell use the charge difference?....The inner membranes of mitochondria contain protein spheres called ATP synthase….As H+ ions escape into the proteins,the enzyme rotates,adding phosphate to low energy ADP to make _____.

On the average,each pair of high energy electrons moves down the chain,providing enough energy to make 3 ATP from 3 ADP.

C) THE TOTALS:

–Glycolysis makes 2 ATP for each glucose molecule

–w/o O2,that’s all the energy extracted

–w/ O2,the Kreb’s Cycle and the transport chain make 34 more ATP(36 molecules total,counting glycolsis)----18 x as much

–These 36 molecules of ATP are 38% the total energy in glucose…actually efficient

–The other 62 % is released as ______---one reason why you feel warmer after exercise

D)ENERGY AND EXERCISE

•Glycolysis covers a few seconds of a runners run

•Next –lactic acid fermentation produces ATP w/o O2 present

•At end of race,runner breathes extra to use O2 to help rid body of lactic acid

•For long term energy(eg. Cross-country running),cellular respiration releases a continual supply of ATP

•Muscles store ______that help out w/ about 20 min. of activity

•After that,stored fats are broken down

E. Comparing Photosynthesis & Cellular Respiration

–______deposits energy by making glucose

–______withdraws energy by breaking down glucose

–Photosynthesis removes CO2 from atmosphere and cellular respiration puts it back.

–Photosynthesis releases ____ into atmosphere and Cellular Respiration uses it to release energy from food.

–Cellular Respiration happens in eukaryotes and some prokaryotes and______only happens in plants ,algae and some bacteria.