VCE Biology Question Thread

[grannysmith]

can somebody elaborate on how enzymes speed up chemical reactions? Like what happens with the chemical bonding etc

Enzyme catalyse or speed up chemical reactions by lowering the activation energy of the reaction. They achieve this by influencing the stability of the bonds within the reactants; in anabolic reactions, they facilitate the formation of the product by essentially binding the reactants together, while in catabolic reactions, they facilitate the breakdown of bonds within the reactant.

[RazzMeTazz]

Is it correct to say that all catabolic reactions are exergonic and all anabolic reactions are endergonic?

Thanks!

[millie96]

thank you oddly!

also, do we need to know much detail as to why factors such as pH and temperature increase enzyme activity (until a point of denaturing)? E.g. why does an increasing temperature cause an increase in enzyme activity? Does the heat energy increase collisions?

[RazzMeTazz]

Is a metabolic pathway the same thing as a biochemical pathway?

[grannysmith]

Is it correct to say that all catabolic reactions are exergonic and all anabolic reactions are endergonic?

Yes

thank you oddly!

also, do we need to know much detail as to why factors such as pH and temperature increase enzyme activity (until a point of denaturing)? E.g. why does an increasing temperature cause an increase in enzyme activity? Does the heat energy increase collisions?

Definitely; often you'll be required to interpret graphs, which an understanding of the factors influencing enzyme activity is necessary.

Is a metabolic pathway the same thing as a biochemical pathway?

Yes

[millie96]

yes but how much detail do we need to go into?

can someone please explain why  increasing temperature (before passing optimal point) actually increases enzyme activity? does it have to do with heat energy and collisions?

[RazzMeTazz]

Is the enzyme catalase an intracellular or extracellular enzyme?

[alchemy]

can someone please explain why  increasing temperature (before passing optimal point) actually increases enzyme activity? does it have to do with heat energy and collisions?

Denatures the enzymes. Therefore, the substrate molecules no longer have an active site to bind to.

[millie96]

Is the enzyme catalase an intracellular or extracellular enzyme?

intracellular

[alchemy]

Is the enzyme catalase an intracellular or extracellular enzyme?

Good question. Amylase is an extracellular enzyme. It's secreted from salivary glands in the mouth and the pancreas. Therefore, evidently it is secreted into the body from the cells where it was made.

[millie96]

Denatures the enzymes. Therefore, the substrate molecules no longer have an active site to bind to.

sorry if I'm unclear with my question - but I'm asking about why increasing temperature increases enzyme activity, before it reaches the optimal temp and denatures.

For example, why would enzyme activity increase as a result of a change from 5degrees to 20deg?

[grannysmith]

sorry if I'm unclear with my question - but I'm asking about why increasing temperature increases enzyme activity, before it reaches the optimal temp and denatures.

For example, why would enzyme activity increase as a result of a change from 5degrees to 20deg?

Increase in temperature increases the kinetic energy of the enzymes and substrates, which in turn increases the number of collisions between the molecules, thereby the formation of enzyme-substrate complexes increases. In turn, the rate of the reaction increases.
Yes, increases.

Edited

[millie96]

perfect thank you!

[auds]

Haha, seems like so many of us have enzyme-related questions x]

Does anyone know if exergonic reactions still need addition of energy at the beginning, given that they actually release energy ?? ;x

[grannysmith]

Haha, seems like so many of us have enzyme-related questions x]

Does anyone know if exergonic reactions still need addition of energy at the beginning, given that they actually release energy ?? ;x

To an extent, yes. Consider cellular respiration; although it is deemed an exergonic reaction, 2 ATP molecules are required to drive the Krebs cycle, which produces a net total of 2 ATP.
I guess you could generalise exergonic reactions as producing a net amount of energy.

Edit: Refer below