Unit 2: The Cell

What are all living things made from?

All living things are made from cells.

What is used to study cell organelles?

Microscopes.

What are the two main types of cells?

Prokaryotic (bacteria, archaea) and Eukaryotic (e.g., plants, animals).

Where is DNA stored in eukaryotic cells versus prokaryotic cells?

Eukaryotic cells store DNA in a nucleus, while prokaryotic cells store it in a nucleoid.

What do both prokaryotic and eukaryotic cells have?

Cytoplasm and a plasma membrane.

Why is the surface area-to-volume ratio important for cells?

A larger surface area allows for faster diffusion, impacting the cell's efficiency.

What is unique about the internal structure of eukaryotic cells?

They have extensive internal membranes dividing the cell into compartments.

What is the main component of most biological membranes?

A double layer of phospholipids and other lipids.

Where are most of the genes housed in eukaryotic cells?

In the nucleus.

What is the role of the nucleolus?

It synthesizes RNA from DNA genes.

What are ribosomes made of, and what is their function?

Made of ribosomal RNA and protein; they synthesize proteins.

What is the difference between free and bound ribosomes?

Free ribosomes are in the cytosol; bound ribosomes are attached to the ER or nuclear envelope.

What organelles are part of the endomembrane system?

The nuclear envelope, ER, Golgi apparatus, lysosomes, vesicles, vacuoles, and plasma membrane.

How are components of the endomembrane system connected?

Through direct continuity or transfer via vesicles.

What are the two types of ER and their functions?

Smooth ER synthesizes lipids, detoxifies, and stores calcium; Rough ER helps make proteins for secretion.

What is the role of the Golgi apparatus?

It sorts and ships products from the ER.

What do lysosomes do in the cell?

They digest macromolecules and recycle cellular material through autophagy.

What are mitochondria and chloroplasts responsible for?

Mitochondria perform cellular respiration; chloroplasts perform photosynthesis.

What theory explains the origin of mitochondria and chloroplasts?

Endosymbiotic theory.

What is the cytoskeleton, and what does it do?

It is a network of fibers that maintains cell shape and assists in movement.

What property does the plasma membrane have regarding permeability?

Selective permeability, allowing only certain substances to pass.

What is the fluid mosaic model?

A model describing the dynamic nature of cell membranes.

What are the main functions of membrane proteins?

Transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, and attachment to cytoskeleton and ECM.

What is diffusion?

Movement of substances from higher to lower concentration.

How does osmosis differ from diffusion?

Osmosis is the movement of water across a membrane from low to high solute concentration.

What is active transport, and what is an example?

Movement against the concentration gradient using energy; example: sodium-potassium pump.