anaerobic resp student version

8/13/2019 Anaerobic Resp Student Version

1/22

Topic 3: Chemistry of Life

Anaerobic Respiration


2/22


Glycolysis allows organisms to obtain

energy in the absence of oxygen

Glycolysis yields 2 AT and 2 !A"# Cells possess a limited s$pply of !A"%

&f glycolysis contin$es witho$t a

mechanism to oxidi'e !A"# bac( into!A"%) that step will be halted in glycolysis


3/22

*rganisms ha+e e+ol+ed se+eral ways of

recycling !A"% to allow glycolysis to

contin$e when oxygen is not present

,$(aryotes primarily $se two main methods:

-. ,thanol /ermentation2. Lactic Acid /ermentation



4/22

/ermentation: transferring the hydrogen

atoms of !A"# are transferred to certain

organic molec$les instead of the electrontransport chain

/ermentation


5/22


6/22

!A"# is oxidi'ed by acetaldehyde to form

!A"%

This forms ethanol 0the alcohol $sed in

alcoholic be+erages1

This process allows !A"% to be recycled

and glycolysis to contin$e

,thanol /ermentation


7/22

The prod$cts are 2 AT) 2 !A"%) ethanol

and C*2

,thanol and C*2are released from the cell

as waste prod$cts



8/22


9/22

ractical ses:

,thanol fermentation is carried o$t byyeast to lea+en bread

east cells ferment gl$cose from starchand release C*

2and ethanol

The C*2gas b$bbles ca$se

the bread to rise and the

ethanol e+aporates away

when the bread is ba(ed



10/22

ractical ses:

&n wine ma(ing) yeast cells

ferment s$gars fo$nd incarbohydrate4rich fr$it 5$ices)

s$ch as grape 5$ice

east cells die as a res$ltof ethanol acc$m$lation



11/22

/looded plants $ndergo ethanol

fermentation in the roots and may die if

oxygen is not ret$rned to the roots

This is why it is important not to o+erwater

ho$se plants



12/22

nder normal conditions) animals) s$ch ash$mans) cataboli'e gl$cose by aerobicrespiration

"$ring stren$o$s exercise) m$scle cellsbrea(down gl$cose molec$les faster thanthey can be s$pplied with oxygen

nder these conditions) aerobicrespiration slows down and lactatefermentation begins

Lactic Acid /ermentation


13/22

!A"# prod$ced d$ring glycolysis

transfers its hydrogen atoms to pyr$+ate

This regenerates !A"% and allows

glycolysis to contin$e

This res$lts in a change of pyr$+ate to

lactic acid or lactate



14/22


15/22

The acc$m$lation of lactic acid in m$scletiss$e ca$ses stiffness) soreness) andfatig$e

Lactic acid is transported thro$gh thebloodstream from the m$scles to the li+erto be bro(en down

6hen +igoro$s exercise ceases) lacticacid is oxidi'ed bac( to pyr$+ate tocontin$e thro$gh the 7rebs Cycle ifoxygen is present



16/22

,xtra oxygen is re8$ired to cataboli'e

lactate to C*2and #

2*

!eeding extra oxygen to do so is calledoxygen debt

anting after stren$o$s acti+ity is the

body9s way of paying; the oxygen debt



17/22

"id o$ 7now

anaerobic resp student version

Documents