Cell Biology Basics

Life Processes

• Seven essential life processes: homeostasis, metabolism, nutrition, excretion, growth, response to stimuli, and reproduction

Atypical Cells in Eukaryotes

• Atypical cells in eukaryotes: red blood cells, phloem sieve tube elements, skeletal muscle cells, and aseptate fungal hyphae
• Red blood cells are enucleated, lacking a nucleus, allowing them to be smaller and more flexible
• Phloem sieve tube elements have large pores for sap to pass through, and their nucleus and most cell contents break down during development
• Skeletal muscle cells are multinucleated, with long cylindrical fibers formed from the fusion of individual cells
• Aseptate fungal hyphae lack septa and cell membranes between cells, resulting in a large multinucleate structure

Cell Specialization

• In multicellular organisms, cells become specialized to form different cell types
• Each cell does a small number of functions extremely efficiently
• Different cell types interact to achieve complex functions

Differentiation

• Every cell in a multicellular organism is a clone of an original parent cell (except gametes)
• All cells that come from this will have identical DNA
• Certain cells will express specific genes, while others will express other genes

Stem Cells

• Stem cells are unspecialized cells with two key properties: self-renewal and potency
• When a stem cell differentiates and becomes specialized, it cannot change again
• Stem cells are limited in availability

Types of Stem Cells

• Three types of stem cells: totipotent, pluripotent, and multipotent
• Totipotent stem cells can form any cell type and divide into new organisms
• Pluripotent stem cells can form any cell type
• Multipotent stem cells can form a number of closely related cell types

Cell Membranes

• Cell membranes enclose the cellular contents, separating them from the external environment
• Cell membranes have two properties: semi-permeability and selectivity
• Cell membranes have two major components: phospholipids and proteins

Phospholipids

• Phospholipids have a polar head (glycerol and phosphate) and two nonpolar tails (fatty acids)
• The head is hydrophilic, and the tails are hydrophobic, making phospholipids amphipathic molecules
• Phospholipids spontaneously form bilayers in water, with tails forming the center and heads on the outside

Membrane Proteins

• The phospholipid bilayer is embedded with proteins, forming a mosaic
• Membrane proteins can be integral (permanently attached to the bilayer) or peripheral (attaching to the membrane surface)
• Membrane proteins serve a variety of functions: junctions, enzymes, transport, recognition, anchorage, and transduction

Glycosylation

• Phospholipids and proteins can have carbohydrate chains added to them, forming glycolipids and glycoproteins
• The carbohydrate extends to the extracellular side of the membrane and can function for adhesion and recognition

Membrane Transport

• Simple diffusion occurs in cells for particles that can pass between the phospholipids
• Osmosis is the movement of water into and out of cells, which is possible through aquaporins, water channel proteins
• Facilitated diffusion occurs through channel proteins for large, charged, or polar molecules
• Active transport requires energy (ATP) and moves particles from low to high concentrations

Cell Compartmentalization

• Eukaryotic cells are compartmentalized, with discrete organelles that are specialized to carry out specific tasks
• Each organelle is separated from the rest of the cell, allowing for greater efficiency and organization

This quiz covers the fundamental concepts of cell biology, including homeostasis, metabolism, nutrition, and more. Test your understanding of the basic functions of cells and their organelles.