bio lecture 2

What is ECC?

Excitation-contraction coupling.

What are the 3 major ATP-consuming proteins during muscle contraction?

Myosin ATPase, SERCA pump, and Na⁺/K⁺ ATPase.

What does myosin ATPase do?

Powers muscle contraction.

What does SERCA do?

Pumps Ca²⁺ back into the sarcoplasmic reticulum and promotes muscle relaxation.

What does the Na⁺/K⁺ pump do?

Helps restore ion gradients and repolarize the muscle membrane.

What are the 3 major sources of ATP during muscle activity?

Phosphocreatine, glycolysis, and mitochondrial oxidative phosphorylation.

What is ATP?

A molecule used as an energy currency and as a molecular building block.

What happens when ATP is broken down?

ATP → ADP + Pi, releasing usable energy.

Why is ATP important for signaling?

ATP provides the phosphate used during protein phosphorylation.

What does phosphorylation mean?

Adding a phosphate group to a protein.

What can phosphorylation do to a protein?

Increase or decrease its activity.

What is AMPK?

An energy sensor and signal transducer.

What activates AMPK?

An increase in AMP.

Why does AMP increase during exercise?

Because ATP is being used and broken down during increased energy demand.

What does AMPK do?

Phosphorylates downstream proteins to help restore energy homeostasis.

What is one important AMPK target?

Acetyl-CoA carboxylase (ACC).

What happens when AMPK phosphorylates ACC?

Fatty acid oxidation increases.

What is the easiest way to think about AMPK?

It's the cell's energy sensor that responds when energy availability is becoming low.

What is a signal?

Information received by a cell.

What is a sensor?

A molecule that detects the signal.

What is a transducer?

Something that converts the signal into another form.

What is an effector?

A molecule that produces the final cellular response.

Give the AMPK example of signal transduction.

AMP ↑ → AMPK senses it → AMPK phosphorylates targets → energy supply increases.

What is the Central Dogma?

DNA → RNA → Protein

What is transcription?

DNA → RNA.

What is translation?

What is a codon?

A group of 3 bases in mRNA that specifies an amino acid.

What molecule carries amino acids to the ribosome?

tRNA.

What is the role of the ribosome?

It reads mRNA and builds a protein.

According to the lecture, how many ATP equivalents does translation cost per amino acid?

3 ATP equivalents.

For the lecture's 1,500-nucleotide gene/500-amino-acid example, what is the total energy cost?

4,500 ATP equivalents.