Cells
What are the basic building blocks of all living things?
Cells
What is the main function of the nucleus in a eukaryotic cell?
Stores DNA and allows transcription into mRNA
What type of transport moves molecules down their concentration?
Passive transport
What are the three main reasons cells communicate?
Reproduction, development, and recognition
What is energy in biological terms?
The ability to do work and cause specific changes
What is the role of an enzyme in a chemical reaction?
It lowers the activation energy to speed up the reaction without being used up.
A nucleus and membrane-bound organelles
What are the two types of endoplasmic reticulum and what are the functions of each?
Smooth ER: synthesizes lipids and stores calcium
Rough ER: synthesizes proteins
What is the main difference between active transport and passive transport?
Name the three main types of signaling and their distances
Paracrine (local)
Synaptic (very local)
Endocrine (long distance)
What is the difference between kinetic and potential energy?
Kinetic is energy of movement
Potential is store energy
Where does the substrate bind on an enzyme?
At the enzyme's active site
Why can eukaryotic cells be larger than prokaryotic cells?
Because they have specialized compartments called organelles.
What is the job of the Golgi apparatus?
Modifies, sorts, and packages proteins into vesicles
How does the sodium-potassium pump move ions, and why does it require ATP?
It moves 3 Na⁺ out and 2 K⁺ in against their concentration gradients. ATP provides the energy to drive this transport and change the proteins shape.
What are ligands in cellular communication?
Molecules that bind specifically to receptors to trigger a cellular response
What is metabolism?
All chemical reactions in an organism
What happens when the enzyme-substrate complex forms?
The reaction occurs, products are formed, and the enzyme is released to act again.
Where is DNA located in prokaryotic cells?
In the nucleoid
What are lysosomes used for?
Digest food and recycle defective organelles
What type of transport brings solid particles into the cell?
Phagocytosis
What are the three steps of cell signaling?
Reception
Transduction
Response
How are catabolic and anabolic pathways different?
Catabolic pathways break down molecules and release energy
Anabolic pathways build molecules and require an input of energy
How does competitive inhibition affect an enzyme?
A molecule blocks the active site so the substrate cannot bind.
Why are small cells more efficient than large cells?
Because small cells have a larger surface area-to-volume ratio, which allows faster nutrient and gas exchange.
Which organelles have their own DNA?
Mitochondria and chloroplasts
What type of transport brings liquids into the cell?
Pinocytosis
What happens when a ligand binds to a G-protein coupled receptor?
The receptor activates the G-proteins allowing them to be phosphorylated and then split into subunits that trigger cellular responses.
What does a negative ΔG indicate?
Reaction is exergonic and spontaneous
How does a noncompetitive inhibition affect an enzyme?
A molecule binds somewhere else on the enzyme, changing its shape so the substrate cannot bind.
What part of the cell controls what enters and leaves?
The plasma membrane
What is the central vacuole in plant cells used for?
Stores water and help maintain turgor pressure
What is receptor mediated endocytosis?
Endocytosis where specific molecules (ligands) bind to receptors and trigger vesicle formation.
How do cell surface ion channel receptors work?
Ligand binding opens the channel, allowing ions to enter and trigger a response.
What does a positive ΔG indicate?
Reaction is endergonic and non-spontaneous
How does an enzyme lower the activation energy of a reaction?
By stressing chemical bonds and brining substrates together in the correct orientation.
Name three features that all cells have in common
DNA, ribosomes, and cytoplasm
What are the structures called that allow direct cytoplasmic communication between neighboring cells?
Gap junctions in animal cells and plasmodesmata in plant cells
A vesicle fuses with the cell membrane to release contents outside the cell.
What is apoptosis and give an example of why it is important.
Cells between fingers die to form individual digits
On a reaction graph, how do the reactants and products compare for exergonic and endergonic reactions?
Exergonic: reactants have more free energy than products (ΔG < 0)
Endergonic: products have more free energy than reactants (ΔG >0)
What is the structure of ATP and how does it release energy for cellular work?
ATP is made of adenosine plus three phosphates. The bonds between the negatively charged phosphates are unstable and breaking them releases energy (–7.3 kcal/mol) that the cell uses for work.