signal transduction

In the glucose Na+ transport pump, sodium moves from a _____ concentration to a _____ concentration.

low; high

What classification of membrane transport describes the sodium-glucose pump?

Secondary transport

How does an enzyme interact with its substrate to facilitate a reaction?

It changes the shape of the substrate.

What determines whether a signal transduction event results in a long-term change in the cell?

Whether transcription or translation in DNA is impacted.

List four examples of chemical signals processed by cells.

Nutrients, wastes, ions, and hormones.

What are three examples of physical stimuli that can act as cellular signals?

Light, sound, and temperature.

What is the initial event required to trigger a cell's response to a signal?

Ligand binding causes the receptor protein to change shape.

What specific biochemical activity is often triggered by the shape change of an activated receptor?

Kinase activity

In signal transduction, what is the purpose of having more than one responder molecule in a cell?

To amplify the signal.

Term: Mitogen

Definition: A substance that binds to a receptor to stimulate cell division.

What is the immediate result of a mitogen binding to its receptor according to the provided pathway?

The receptor phosphorylates itself.

In the mitogen pathway, what must be exchanged for RAS to become active?

GDP is exchanged for GTP.

Which protein is directly bound and activated by activated RAS?

MAP3K

What is the specific enzymatic function of activated MAP3K?

It is a protein kinase that phosphorylates MAP2K.

Activated MAP2K serves as a protein kinase to phosphorylate which molecule?

MAP kinase (MAPK)

Where does MAP kinase travel once it has been activated by phosphorylation?

Into the nucleus

What is the final cellular outcome of the MAP kinase pathway entering the nucleus?

Changes in gene expression, including the stimulation of cell division.

How do transmembrane proteins facilitate signal transduction?

By converting an extracellular signal into intracellular signals.

Signal transduction allows cells to respond to their environment by moving, surviving, dividing, growing, or _____.

differentiating

What are the three general stages of signal transduction mentioned in the text?

Binding of ligand, transduction via second messenger, and amplification.

List three common examples of second messengers.

cAMP, Calcium, and G protein.

How many subunits compose a G protein?

3 subunits

In its inactive form, a G protein is bound to which molecule?

GDP

What triggers the exchange of GDP for GTP in a G protein?

The activation of the G protein by binding with a receptor.

The insulin receptor is composed of which two distinct sites?

Alpha and beta sites

To which specific site of the insulin receptor does insulin bind?

The alpha site

What do anchor proteins interact with to provide structural integrity to the cell?

The extracellular matrix (ECM)

What is the extracellular matrix (ECM)?

An organized network of material produced and secreted by cells.

List four main functions of the Extracellular Matrix (ECM).

Cell adherence, communication, mechanical support/shape, and acting as a barrier/filter.

The mitochondrial matrix contains which three specific components according to the notes?

DNA, ribosomes, and hormones.

What percentage of ATP production in animal cells is attributed to substrate-level phosphorylation?

Around 12%

What percentage of ATP production in animal cells is attributed to oxidative phosphorylation?

Around 88%

What is the role of oxygen in the process of oxidative phosphorylation?

It acts as the final electron acceptor.

Where does Stage 1 of aerobic respiration, glycolysis, take place?

In the cytosol

Which molecule is necessary for the Krebs cycle to occur following pyruvate oxidation?

Acetyl CoA

What is the primary carbon-based waste product of the Citric Acid (Krebs) cycle?

Carbon dioxide (CO2)

What are the two high-energy electron carriers produced during the Citric Acid Cycle?

FADH2 and NADH

When $NADH$ loses electrons to become NAD^+, the molecule is being _____.

oxidized

Where are electrons pumped during the oxidation stage of oxidative phosphorylation?

The intermembrane space

Why do electrons require specific transporters to move across the mitochondrial membrane?

Because they cannot pass through the membrane themselves due to their charge.

How many protons are required by ATP synthase to produce one molecule of ATP?

3 protons

What is the relationship between ligand binding and receptor shape?

Ligand binding causes the receptor protein to change its shape.

The process where one molecule activates another in a sequence is called a _____.

cascade

What determines the length of a cellular message's impact?

The message length can vary; long-term changes involve transcription or translation.

During G protein activation, the exchange of _____ for _____ is different from simple hydrolysis.

GDP; GTP

What is the function of mitochondrial cristae (the folded inner membrane)?

To provide a surface for ATP production via aerobic respiration.

In the context of aerobic respiration, what is the state of $NADH$ when it has 'gained' electrons?

Reduced

What are the four main stages of oxidative phosphorylation mentioned in the text?

Oxidation of carriers, pumping protons to intermembrane space, electron transport to oxygen, and ATP synthesis via ATP synthase.