Biology Chap. 4

Flashcards on key vocabulary terms related to cell biology, protein structure, and function based on the lecture notes.

Protein Shape

The shape of a protein determines its function.

Confirmation

The specific shape of a protein that is influenced by local conditions.

Local Conditions

Environmental factors like temperature and pH that affect protein interactions and structure.

Cell

The smallest unit of a living organism that is still considered alive.

Volume to Surface Area Ratio

The relationship between the volume of a cell and its surface area, critical for cell function and size.

Phospholipid Bilayer

A double layer of phospholipids that forms the fundamental structure of cell membranes.

Hydrophilic Heads

The water-attracting part of phospholipids that interacts with the aqueous environment inside and outside cells.

Hydrophobic Tails

The water-repelling part of phospholipids that faces inward in the bilayer to avoid water.

Rough Endoplasmic Reticulum (RER)

Has ribosomes; modifies and transports proteins.

Smooth Endoplasmic Reticulum (SER)

A membrane structure that has no ribosomes; makes lipids, detoxifies, stores ions (calcium).

Golgi Apparatus

An organelle involved in modifying, sorting, and packaging proteins for secretion.

Lysosome

An organelle that contains digestive enzymes for breaking down waste and cellular debris.

Zymogen

An inactive enzyme precursor that becomes active through a specific biochemical change.

Nucleus

The membrane-bound organelle that contains the cell's genetic material (DNA).

Ribosome

Cellular machinery responsible for synthesizing proteins.

Transport Vesicle

A small membrane-bound sac that transports materials within the cell.

Endomembrane System

A series of membranes within eukaryotic cells that divides the cell into functional and structural compartments.

Cell Membrane (Plasma Membrane)

A biological membrane that separates and protects the interior of the cell from the external environment. Main component is the phospholipid bilayer.

Eukaryotic Cells

Complex cells that contain a nucleus and organelles, typically larger than prokaryotic cells.

Prokaryotic Cells

Simpler cells that lack a nucleus and membrane-bound organelles.

Why are cells so small?

Cells are small to maximize surface area-to-volume ratio, allowing efficient exchange of materials (like nutrients, gases, and waste) with the environment.

What can pass through the plasma membrane easily?

Small, nonpolar molecules (like O₂ and CO₂); some small polar molecules (like water) can pass through slowly.

What cannot easily pass through the membrane?

Large molecules and charged ions; they require transport proteins or energy (active transport).

Prokaryotic Cell

DNA, Ribosomes, plasma membrane, cell wall, capsule (sometimes), flagella

Plant Cell

Nucleus, chloroplast, large central vacuole, cell wall, mitochondria, ER, golgi, ribosomes, cytoskeleton elements

Animal Cell

Nucleus, no cell wall or chloroplast, small vacuoles, lysosomes and peroxisomes, mitochondria, ER, golgi, ribosomes, cytoskeleton elements, extracellular matrix

Nucleus

Control center of the cell; stores DNA.

Nuclear Envelope

Double membrane that surrounds the nucleus; has pores for transport.

Chromatin

DNA + proteins (histones); the form DNA is in when not dividing. In nucleus.

Nucleolus

Dense area in the nucleus; makes ribosomal RNA (rRNA).

Ribosome

Made of rRNA and protein; synthesize proteins.

Vacuole

Stores substances; large central vacuole in plants maintains pressure.

Peroxisome

Breaks down fatty acids and detoxifies; produces hydrogen peroxide.

Chloroplast

Site of photosynthesis; contains chlorophyll; only in plants.