4 3 Signal Transduction Illustrative Examples Period 2

4. 3 Signal Transduction Illustrative Examples Period 2

Epinephrine stimulation of glycogen breakdown in mammals By Julia Sochur and Kyra Cvitanich ● ● Signal transduction: the binding of a molecular “signal” that initiates a cellular response Transduction pathway: the process of transforming a signal to a response in the cell Epinephrine- (aka adrenaline) a hormone that facilitates fight or flight mode Epinephrine starts glycogen breakdown Glucose is needed for immediate energy and to maintain blood sugar levels

Julia Sochur and Kyra Cvitanich Occurs in two places: the liver and muscle cells Liver: Epinephrine binds to a receptor on the outside of a liver cell and the G protein can bind with the adenylate cyclase, which allows ATP to bind to the complex. The adenylate cyclase breaks down ATP into a second messenger molecule called c. AMP. The second messenger then causes the activation of a protein kinase which activates phosphorylase, which is an enzyme that catalyzes the breakdown of glycogen to glucose. Muscles: Leads to the phosphorylation of two metabolic enzymes. This addition of a phosphate group changes the behavior of the enzyme. The phosphorylation of glycogen phosphorylase (GP) makes it active, which breaks down glycogen to glucose. The phosphorylation of glycogen synthase stops the creation of more glycogen molecules as the need if for it to be broken down, not made

Liver Cell Muscle Cell

Signal transduction is the transmission of molecular cells from exterior to interior Chris L. and Nicolas L. Vocab Apoptosis: the programmed death of cells Phenotype: the physical appearance of an organism due proteins Cytokinesis: the division of the cytoplasm in cell

Correct Signal Two Identical Cells Mitosis Chris L. and Nicolas L. But with a change of Phenotype And Growth

Wrong/Mutated Signal Apoptosis Mitosis DE A D DE AD Multinucleated Cell Mutated Cells Chris L. and Nicolas L. CANCER

What is signal transduction? ● Transmission of molecular signals from a cell’s exterior to its interior ○ Results in change in gene expression or cell function ○ Can alter phenotype of a cell Erica Wan Sarah O’Malley

How do mating pheromones in yeast trigger a response? ● ● ● Pheromone: chemical substance that affects behavior/physiology of the species that excretes it Mating pheromone binds to the Ste 2 or Ste 3 receptor of a yeast cell Activates the heterotrimeric G protein to induce Erica Wan mating gene expression Sarah O’Malley

How/why are the pheromones released? ● ● ● Through meiosis, four haploid cells are produced ○ 2 “a” cells, 2 “��” cells “A” cells secrete type �� mating factors ○ Bind to “��” cell receptors “��” cells secrete type a mating factors ○ Bind to “a” cell receptors Erica Wan Sarah O’Malley

What response do these pheromones produce? ● ● ● Cell begins to grow in the areas where pheromones are bound to the receptors ○ Shmoo An “��” and “a” cell’s shmoos will begin to gro towards each other Eventually, the shmoos touch ○ The two haploid cells join to create 1 complete diploid cell Erica Wan Sarah O’Malley

Overall… ● ● The molecular mating signals (pheromones) are released into the environment Cells receive these signals, begin to undergo gene expression in response ○ Produce proteins to grow and join together, creating a new cell Erica Wan Sarah O’Malley

THE SRY GENE Sex-chromosomes XY: males XX: females The SRY(Sex-determining region y) gene is a testis determining factor In Y chromosome on short branch During fetal development Sry in animals, SRY in humans By: Melissa Qin Alexis Soriano

MUTATIONS IN THE SRY • Types of mutations • Removal • Substitutions • Insertion • Disorders of Sexual Development(DSD) • Mutations during early embryonic development • Changes genotype and phenotype • Swyer Syndrome (XY/XXY) • Appear women but are infertile • Cannot go through menstrual cycle By: Melissa Qin Alexis Soriano

What is Ethylene? - - A gas known as “ the fruit-ripening” hormone Enzyme function is increased in the fruit when ethylene is present Ex: ethylene makes cell membranes permeable so the enzymes can do their job

How does Ethylene work? - - - When picking a fruit to change color, become soft and juicy, and sweet fragrance Because ethylene is released into the environment, it can be used to signal ripening in surrounding fruit Ethylene can easily diffuse across membranes and is produced near its site of action Once ethylene reaches a certain concentration, the cells begin to release CO 2 rather than O 2 → peak ripeness

How to control Ethylene - - - To prevent fruits from ripening, 1 -methyl-cyclo-propene, a synthetic compound, can be used to block the ethylene from triggering the fruit to ripen Warehouses store fruits in cold temps and by using charcoal filters to absorb any ethylene made To get fruits to ripen right before they are given to customers, warehouses release ethylene into their warehouses

Ethylene Signal Transduction - - - Ethylene is perceived by two receptors that become inactivated upon ethylene binding Without ethylene, the receptors activated CTR 1, a negative regulator of ethylene responses Amplification of the initial ethylene signal also occurs during transduction

What are HOX Genes? • Hox genes, a subset of homeobox genes, are a group of related genes that specify regions of the body plan of an embryo along the head-tail axis of animals. Layman’s term: they lay out the body of the organism. • The general purpose in the sense that they are similar in many organisms; it doesn't matter if it's a mouse's head or a fly's head that is being built, the same gene directs the process.

Just an image • Just an image

Correlation to Cell Signaling • Activation requires cell aggregation in addition to RA. This suggests that HOX-PBX complexes may repress transcription under some conditions. • Treatment with the deacetylase inhibitor trichostatin A not only relieves repression but also converts the HOX-PBX complex to a net activator of transcription. • Russell Chuang and Andrew S.