signal transduction

what is false regarding primary structure of proteins?

• it is a sequence of amino acids in the polypeptide chain

• it is the overall shape of the protein

• it is held together by covalent bonds

• a change in the primary structure could lead to loss of structure and function of the protein

it is the overall shape of the protein

classify this enzyme

lyase

which hormone shown is a protein

C

which hormone shown is a steroid?

D

what is signal transduction?

a signal outside of the call that interacts with cell receptors which in turn triggers changes in the cell

why is signal transduction important to human health?

diseases, medicine

what are the 5 steps of signal trasnduction?

1. environmental change causes a production/release of a primary messenger (signal)

2. reception (primary messenger binds to the receptor)

3. transduction (receptor binding triggers conformational change in receptor)

4. response (activation of effectors)

5. termination of response (return to baseline)

what is a type of primary signals

hormones, pheromones, growth factors, neurotransmitters, cytokines

which hormone shown is a short polypeptide?

B

what can hormones be?

peptides, polypeptides, steroids, amino acid derivatives

Three major hormones (that we will learn about)

Insulin, Glucagon, Epinephrine

what type of primary messenger affects cells that are nearby?

neurotransmitters

compare/ contrast growth factor vs. hormone

Both act as primary messengers that bind to specific surface receptors. Hormones can work much more quickly while growth factors are slow acting.

what type of primary messenger has long term effects?

growth factor

what is a secondary messenger? why are they important?

small molecules that change in concentration in response to enviornmental signals and can move through the cell.

they diffuse throughout the cell to influence processes in the cell.

common secondary messengers in signal transduction

cyclic nucleotide, metal, sugar alcohol, lipid

what is the name of the molecule that is made in large abundance upon signal transduction

secondary messenger

compare/ contrast primary vs. secondary messenger

both are generally biomolecules that are required for signal transduction.

A primary messenger is produced in response to an environmental signal and acts outside the target cell by binding to a receptor on the cell surface. A secondary messenger is produced inside the cell after the reception and transduction of the signal.

nutritionally speaking, which of the following does NOT contain much carbohydrate or glucose?

corn, grapes, bread, or cheese

cheese

insulin structure

secondary: alpha helices connected with loops and turns

tertiary: a few disulfides, compact globular, 1 domain

quaternary: hetero-dimer

what is insulin

protein hormone made by your pancreas, which circulates through your bloodstream. It tells your cells to take up the glucose in the blood.

what is a kinase

a protein that phosphorylates a substrate, using ATP as a donor

does an insulin receptor have an alpha chain, beta chain or both?

they have both. this is called a dimer (specifically a hetero dimer). the alpha chain contains the extracellular insulin binding site. the beta chain contains the transmembrane domain and intracellular tyrosine kinase.

which signal is involved in the immune system?

cytokine

which of the following is NOT true about secondary messengers?

• examples include Ca2+, dicylglycerol, and cAMP

• they are made in high abundance upon transduction

• they can be found in the cytosol or membrane

• they phosphorylate other proteins to amplify the signal

they phosphorylate other proteins to amplify the signal (no kinases do that)

which enzyme makes the secondary messenger for insulin signaling?

PI3K (makes PIP3 from PIP2)

which of the following is not an enzyme?

• insulin receptor

• IRS-1

• PDK1

• Akt

IRS-1 (adaptor protein)

what is crosstalk and why is it important?

instances in which one or more components of one signal transductio pathway affects another.

important for cells to integrate information from multiple signaling pathway.

insulin signaling causes a lot of cellular responses. Which of the following does not make sense as a response to insulin?

• activates storage of glucose as glycogen

• activate breakdown of glucose

• activate synthesis of glucose from smaller precursor molecules

• activate the movement of glucose transporter to the cell surface

activate synthesis of glucose from smaller precursor molecules

diabetes

blood glucose levels are high and can stay high after eating food

what is type 1 diabetes

can’t make insulin since beta cells in the pancreas are destroyed by immune cells.

you have to monitor diet

autoimmune disease (rare)

what is type 2 diabetes?

more than 90% of cases and diagnosed later in life

insulin is made and the receptor is functional but tissue do not respond (insulin resistance)

how does Ozempic work to control Type 2 diabetes?

It stimulates insulin secretion

prevents the liver from overproducing and releasing too much sugar

slows how quickly food leaves the stomach → more full → eat less → weight loss

what are examples of 2 medicines that affect signal transduction?

birth control and viagra

with birth control, primary messengers (hormones) are given to stimulate the signal transduction process to prevent ovulation

viagra interferes with a signaling pathway , leading to increased blood flow

compare/ contrast type 1 and type 2 diabetes

both have an impairment of the insulin signaling pathway.

Type 1 does not make insulin while Type 2 makes insulin and the receptor is functional but the tissue does not respond.

what is the difference between pheromones and hormones?

Pheromones act externally to influence behavior between members of the same species while hormones act internally to regulate physiological processes within a single organism