Cytology: Cell Size Limitation and Components

Cell Biology

• The ability of a solution to affect the fluid volume in a cell is referred to as its tonicity.
• Insulin is transported across endothelial cells through a process called transcytosis.
• White blood cells engulf bacteria through phagocytosis.
• cAMP activates enzymes called kinases, which regulate other enzymes by adding phosphate groups to them.
• Hepatocytes have large amounts of smooth endoplasmic reticulum for detoxifying drugs or other chemicals.
• The cytoskeleton provides structural support, determines the shape of a cell, and directs the movement of substances through a cell.
• Microvilli increase a cell's surface area, cilia act as sensory "antennae" in many cells, and flagella provide motility to a sperm cell.

Cellular Transport

• Na+-K+ ATPase is a countertransport antiport carrier that always requires energy.
• Facilitated diffusion does not require energy and can transport molecules down a concentration gradient.
• The greater the concentration gradient, the faster the diffusion rate.

Cell Structure and Function

• The nucleus and the mitochondrion are surrounded by a two-layer membrane.
• In the plasma membrane, glycolipids and glycoproteins face toward the outside, while peripheral proteins face toward the cytoplasm.
• Most human cells range from 10 to 15 micrometers in diameter, and the limit to how large a cell can get is the relationship between the cell's volume and surface area.
• The three basic components of a cell are cytoplasm, nucleus, and plasma membrane.
• Phospholipids are the most abundant molecules in the plasma membrane.

Cell Signaling and Communication

• Membrane proteins that bind to signals by which cells communicate are called receptors.
• The term selectively permeable refers to a membrane that allows some things to pass through it, but not others.

Osmosis and Filtration

• Osmosis is the process by which hydrostatic pressure forces water and small solutes through narrow clefts between capillary cells.
• The number of particles of a solute in a solution is described by its osmolarity.

Test your knowledge on cytology, the study of cells, by answering questions about the factors that limit cell size and the three basic components of a cell. Explore concepts related to cell size, components, and limitations.