Biology Int 2 Section 2 revision.ppt

7/24/2019 Biology Int 2 Section 2 revision.ppt

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Cells & Enzymes

Enzymes

Made of proteinPresent in

all living cells

Converts substrates

into products

Biological

catalysts

Increase the rate of

chemical reactionsRemain unchanged

by chemical reaction


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ProductSubstrate

Chemical Reactions

chemical reaction ta!es place "hen one or

substances is chemically changed into one or more

different substances#

Chemical reactions ta!e place in cells all the time#

Enzyme

Catalase

$ydrogen

pero%ideater ' o%ygen

Manganese

dio%ide

Catalyst


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Catalysts

catalyst is a substance "hich speeds up a chemicalreaction( "ithout itself being changed by the

reaction#

)# hen a catalyst is present( less energy is neededto get the chemical reaction started#

*# hen a catalyst is present( the speed of the

chemical reaction is faster#

+# lthough a catalyst helps a chemical reaction to

happen( it is unchanged at the end of the reaction#


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Biological Catalysts

,he biological catalyst present in the cytoplasm ofplant and animal cells that speeds up the brea!do"n

of hydrogen pero%ide is called C,-SE#

$ydrogen

pero%ide.%ygen ' "ater

catalase


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*#* /ature of Enzymes

,he biological catalyst present in the cytoplasm ofplant and animal cells that speeds up the brea!do"n

of hydrogen pero%ide is called C,-SE#

Catalase cannot speed up any other reaction# It is

SPECI0IC to this reaction#

Catalase$ydrogen

pero%ideater ' o%ygen


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.ne Enzyme 1 .ne Reaction

,here are thousands of different enzymes in yourbody#

hy are there so many different enzymes2

Each enzyme has its o"n uni3ue protein structure

and shape( "hich is designed to match or

C.MP-EME/, its substrate#


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-oc! & 4ey $ypothesis

n enzyme only acts on one type of substance( or substrate#

,herefore( the enzyme is said to be SPECI0IC to its one substrate#

,he shape of the active site 5binding site6 of the enzyme( matches the

shape of the substrate# llo"ing the t"o molecules to bind during the

chemical reaction#

,his theory of enzyme action is called the 7loc!8and8!ey9 hypothesis#


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M.:IE


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*#+ =sing a Control

hy is it necessary to include a control e%perimentin an investigation2

controlis an e%periment that allo"s a

comparison "ithin an investigation in order toensure that the conclusions dra"n from the results

are valid#


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*#+ =sing a Control

.nly one variable should be altered in aninvestigation( this is said to be the altered variable#

It is important to ensure that all other potential

variables are !ept the same in the investigation(

these are called the controlled variables#

hat "as the altered variable in the last

investigation you carried out2

hat "ere the controlled variables in the last

investigation you carried out2


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Enzymes involved in brea!do"n reactions

Catalase$ydrogen pero%ide ater ' .%ygen

mylase

Starch Maltose

-ipase0at 0atty acids ' >lycerol

PepsinProtein mino acids


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*#? Synthesis reactions

>lucose is used by

leaves as energy

source or transportedto root for storage#

-eaves ma!e glucose#

Roots convert glucose

into >8)8P#

Phosphorylase

converts >8)8P into

starch#


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phosphorylase

glucose-1-phosphate starch

hat is phosphorylase2

Phosphorylase is an enzyme that synthesises starch#

hat is substrate of phosphorylase2

>lucose8)8phosphatehat is the product2

Starch


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phosphorylase

glucose-1-phosphate starch

mylase catalyses the brea!do"n of starch toproduce maltose#

$o" is starch produced2


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*#@ Effect of $igh ,emperature

/otes on ;enaturation /otes on .ptimum temp

A Optimum conditionsare the conditions

at "hich an enzymes "or!s best

A Rate of reactions may be affected by

temperature and p$


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*#@ Effect of $igh ,emperature

/otes on ;enaturation/otes on

.ptimum temp

hat happens to the activity of an enzyme at high

temperatures2


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Movie

Effect of p$ on enzymes

hen the p$ changes out"ith optimal conditions( the shape

of the active site of the enzyme alters and the enzyme is

denatured#


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Effect of p$ on enzyme activity

Most enzymes "or! best at a p$ close to neutral 5p$6( but

there are some e%ceptions# Pepsin( an enzyme found in thestomach( has an optimum p$ of *#


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Enzyme Substrate Product5s6 ;egradationor synthesis2

mylase Starch Maltose ;egradation

Catalase $ydrogenpero%ide

.%ygen and"ater

;egradation

Pepsin Protein mino acids ;egradation

Phosphorylase >lucose8)8

phosphate

Starch Synthesis

-ipase 0at mino acids ;egradation

Enzyme Summary

Biology Int 2 Section 2 revision.ppt

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