Cell Communication and Cell Cycle

A sea otter population controls sea urchin numbers, protecting kelp forests from overgrazing.

An invasive species of plant spreads rapidly, outcompeting native species for sunlight and nutrients.

Overfishing leads to a decline in fish populations, reducing the availability of food for predatory marine animals.

A flood causes a temporary increase in nutrient deposition, leading to an algal bloom in a river ecosystem.

Polymerization

Hydrolysis

Dissolution

Conformational change

Signal transduction

Receptor-mediated response

Response

Reception

Sucrase

Ligases

Phosphatases

Kinases

Enhanced production of accessory pigments that capture wavelengths of light not absorbed by chlorophyll.

Development of thinner leaves that allow more light penetration to chloroplasts within leaf cells.

Increased sensitivity of photoreceptors that trigger developmental changes leading to larger leaves.

A mutation that disrupts chlorophyll biosynthesis reducing its capacity for capturing limited light.

It would prevent the initiation of the signaling cascade by blocking downstream relay molecules from being activated.

This would increase the specificity of the receptor for its ligand, leading to more precise cellular responses.

The mutation would enhance the response by causing continuous activation of downstream signaling pathways.

It would lead to faster degradation of the signaling molecule, thus shortening the duration of the signal.

There would be no change because kinases can also reverse their own actions.

It would lead to continuous activation of the pathway due to lack of dephosphorylation.

It would prevent the pathway from being activated at all since phosphorylation cannot occur.

The absence of phosphatase would result in faster termination of the signal.

Ca2+ and cAMP

ADP and ATP

ATP and kinases

cAMP and iP2

Gradual restoration and repair of damaged cellular components.

Fragmentation into vesicles that are subsequently engulfed by phagocytes.

Cessation of all metabolic activities due to programmed cell death mechanisms.

Activation of caspases that lead to cell dismantling.

Transports ions across the cell membrane

Amplifies the signal inside the cell

Acts as the initial ligand binding to the receptor

Binds to DNA to change gene expression