20.2: Chemical cell-cell communication

Insulin

Stimulates liver cells to store glucose as glycogen.

• number of glucose transporters in membrane increase = increased facilitated diffusion

• activates glucokinase which adds phosphate group to glucose to stop it from leaving

• inhibits activity of glucose phosphatase which removes phosphate from glucose

• activates glycogen synthase

Glucagon

triggers actions to increase blood sugar:

• activates glycogen phosphorylase which breaks down glycogen into glucose.

• inhibits activity of glycogen synthase

• activates glucose phosphatase

Plant Hormones

Can be synthesized in many locations and often play multiple regulatory roles, unlike animal hormones.

Ethylene

A gas involved in fruit ripening.

Brassinosteroids

Most similar to animal hormones; a type of steroid. - promotes stem growth alongside auxins and gibberellins

Abscisic acid (ABA)

Promotes seed dormancy and is antagonistic to gibberellins. Also causes stomata to close to reduce transpiration

Stomata

Pores on the surface of leaves that allow for carbon dioxide intake and water vapor release.

Guard cells

Specialized cells surrounding the stomata that control their opening and closing.

Drought Response Genes

Promote longer-term responses to drought, affecting plant growth and cellular stability.