enzymes and metabolic reactions. how do reactions occur in cells? –molecules are in constant...
TRANSCRIPT
![Page 1: ENZYMES and METABOLIC REACTIONS. How do reactions occur in cells? –Molecules are in constant motion –Collisions between molecules allow reactions to occur](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e585503460f94b519e3/html5/thumbnails/1.jpg)
ENZYMES and METABOLIC REACTIONS
![Page 2: ENZYMES and METABOLIC REACTIONS. How do reactions occur in cells? –Molecules are in constant motion –Collisions between molecules allow reactions to occur](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e585503460f94b519e3/html5/thumbnails/2.jpg)
ENZYMES and METABOLIC REACTIONS
• How do reactions occur in cells?– Molecules are in constant motion– Collisions between molecules allow
reactions to occur
![Page 3: ENZYMES and METABOLIC REACTIONS. How do reactions occur in cells? –Molecules are in constant motion –Collisions between molecules allow reactions to occur](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e585503460f94b519e3/html5/thumbnails/3.jpg)
ENZYMES and METABOLIC REACTIONS
• How do reactions occur in cells?– Molecules are in constant motion– Collisions between molecules allow
reactions to occur
• How do we speed up reactions in cells?
![Page 4: ENZYMES and METABOLIC REACTIONS. How do reactions occur in cells? –Molecules are in constant motion –Collisions between molecules allow reactions to occur](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e585503460f94b519e3/html5/thumbnails/4.jpg)
ENZYMES and METABOLIC REACTIONS
• Enzymes– Are protein catalysts that allow chemical
reactions to take place in our body without increasing the temperature
– End with the suffix ‘-ase’
![Page 5: ENZYMES and METABOLIC REACTIONS. How do reactions occur in cells? –Molecules are in constant motion –Collisions between molecules allow reactions to occur](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e585503460f94b519e3/html5/thumbnails/5.jpg)
ENZYMES and METABOLIC REACTIONS
• Enzymes– Are protein catalysts that allow chemical
reactions to take place in our body without increasing the temperature
– End with the suffix ‘-ase’– Examples: urease, amylase, sucrase
![Page 6: ENZYMES and METABOLIC REACTIONS. How do reactions occur in cells? –Molecules are in constant motion –Collisions between molecules allow reactions to occur](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e585503460f94b519e3/html5/thumbnails/6.jpg)
Catalysts
• Control the speed of reactions without changing the products formed– By reducing the activation energy
![Page 7: ENZYMES and METABOLIC REACTIONS. How do reactions occur in cells? –Molecules are in constant motion –Collisions between molecules allow reactions to occur](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e585503460f94b519e3/html5/thumbnails/7.jpg)
![Page 8: ENZYMES and METABOLIC REACTIONS. How do reactions occur in cells? –Molecules are in constant motion –Collisions between molecules allow reactions to occur](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e585503460f94b519e3/html5/thumbnails/8.jpg)
Catalysts
• Control the speed of reactions without changing the products formed– By reducing the activation energy– Tunnel vs. Climbing a mountain
• Remain unchanged and can be used over and over
• Often only needed in small amounts
![Page 9: ENZYMES and METABOLIC REACTIONS. How do reactions occur in cells? –Molecules are in constant motion –Collisions between molecules allow reactions to occur](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e585503460f94b519e3/html5/thumbnails/9.jpg)
Enzymes…
• Work on molecules called the substrate– Can be anything
![Page 10: ENZYMES and METABOLIC REACTIONS. How do reactions occur in cells? –Molecules are in constant motion –Collisions between molecules allow reactions to occur](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e585503460f94b519e3/html5/thumbnails/10.jpg)
Enzymes…
• Work on molecules called the substrate– Can be anything
• Are substrate-specific
![Page 11: ENZYMES and METABOLIC REACTIONS. How do reactions occur in cells? –Molecules are in constant motion –Collisions between molecules allow reactions to occur](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e585503460f94b519e3/html5/thumbnails/11.jpg)
Enzymes…
• Work on molecules called the substrate– Can be anything
• Are substrate-specific
• Alter the substrate in some way
• Examples:
![Page 12: ENZYMES and METABOLIC REACTIONS. How do reactions occur in cells? –Molecules are in constant motion –Collisions between molecules allow reactions to occur](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e585503460f94b519e3/html5/thumbnails/12.jpg)
Substrate approaches an enzyme
The enzyme-substrate complex is formed
Reaction is complete. Enzyme remains unchanged.
Products are formed.
![Page 13: ENZYMES and METABOLIC REACTIONS. How do reactions occur in cells? –Molecules are in constant motion –Collisions between molecules allow reactions to occur](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e585503460f94b519e3/html5/thumbnails/13.jpg)
Enzymes Models
• Where the substrate joins the enzyme is called the active site
• ‘Lock and Key Model’– The active site of an
enzyme is a perfect match to a specific substrate
![Page 14: ENZYMES and METABOLIC REACTIONS. How do reactions occur in cells? –Molecules are in constant motion –Collisions between molecules allow reactions to occur](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e585503460f94b519e3/html5/thumbnails/14.jpg)
Enzymes Models
• ‘Induced-Fit Model’– The active site
changes shape slightly when the E-S complex join together
– Makes a tighter fit
![Page 15: ENZYMES and METABOLIC REACTIONS. How do reactions occur in cells? –Molecules are in constant motion –Collisions between molecules allow reactions to occur](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e585503460f94b519e3/html5/thumbnails/15.jpg)
Factors that Affect Enzymes
• What happens at cooler temperatures?
1. Temperature– Reaction rates
increase as temperature increases
– Peaks at ~ 37 - 40°C then drops rapidly
– Why?• E.g. egg frying
![Page 16: ENZYMES and METABOLIC REACTIONS. How do reactions occur in cells? –Molecules are in constant motion –Collisions between molecules allow reactions to occur](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e585503460f94b519e3/html5/thumbnails/16.jpg)
Factors that Affect Enzymes2. pH
– Enzymes function within an optimal pH range• Stomach pH• Small intestine pH
![Page 17: ENZYMES and METABOLIC REACTIONS. How do reactions occur in cells? –Molecules are in constant motion –Collisions between molecules allow reactions to occur](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e585503460f94b519e3/html5/thumbnails/17.jpg)
Factors that Affect Enzymes
3. Concentration of Substrate Molecules– Reaction rate increases as the substrate
concentration increases up to a point– Animation link– The limiting factor in the reaction may be
the amount of substrate or the amount of enzyme available
![Page 18: ENZYMES and METABOLIC REACTIONS. How do reactions occur in cells? –Molecules are in constant motion –Collisions between molecules allow reactions to occur](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e585503460f94b519e3/html5/thumbnails/18.jpg)
Factors that Affect Enzymes4. Inhibitor molecules
– Molecules that attach to the enzyme and reduce its ability to bind substrate
– There are two types of inhibitors:
a. Competitive inhibitors
b. Non-competitive inhibitors
![Page 19: ENZYMES and METABOLIC REACTIONS. How do reactions occur in cells? –Molecules are in constant motion –Collisions between molecules allow reactions to occur](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e585503460f94b519e3/html5/thumbnails/19.jpg)
4. Inhibitor molecules
a. Competitive inhibitors• Attach to enzyme’s active site• Shape is similar to substrate• Compete with the substrate• Often the end product of the reaction
E.g. drugs and poisons
- CO
- Cyanide
![Page 20: ENZYMES and METABOLIC REACTIONS. How do reactions occur in cells? –Molecules are in constant motion –Collisions between molecules allow reactions to occur](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e585503460f94b519e3/html5/thumbnails/20.jpg)
4. Inhibitor molecules
a. Non-competitive inhibitors• Attach elsewhere on the enzyme (not the active site)• Attachment changes the 3D shape of enzyme• Reaction still occurs, but is inhibited
![Page 21: ENZYMES and METABOLIC REACTIONS. How do reactions occur in cells? –Molecules are in constant motion –Collisions between molecules allow reactions to occur](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e585503460f94b519e3/html5/thumbnails/21.jpg)
Regulation of Enzyme Activity
• Feedback Inhibition– Animation– Turns the path ‘off’– Prevents accumulation of products– Final product of pathway interferes with an
enzyme by binding with allosteric (regulatory) site and altering the active site
![Page 22: ENZYMES and METABOLIC REACTIONS. How do reactions occur in cells? –Molecules are in constant motion –Collisions between molecules allow reactions to occur](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e585503460f94b519e3/html5/thumbnails/22.jpg)
Regulation of Enzyme Activity
• Precursor Activity– Animation– Turns the path ‘on’– A substrate binds with the last enzyme in a
path improving the fit of the E-S complex– Binds to the allosteric site– Speeds up the final product formation
![Page 23: ENZYMES and METABOLIC REACTIONS. How do reactions occur in cells? –Molecules are in constant motion –Collisions between molecules allow reactions to occur](https://reader035.vdocuments.mx/reader035/viewer/2022062516/56649e585503460f94b519e3/html5/thumbnails/23.jpg)
Regulation of Enzyme Activity
• Both feedback inhibition and precursor activity are called allosteric activity
• Handout