Metabolism - refers to all of the chemical reactions that occur within a cell.
Mutation -accidental changes in the genetical material of cells.
Cells Classification
Prokaryotes and Eukaryotes
Prokaryotes - do not have complex system of membranes and organelles; bacteria and archaea
Eukaryotes - more complex cells, containing true nucleus.
Cell Membrane - Enclosed and keep the cell intact; Composed of large molecules of proteins and phospholipids; Like a “skin”; Regulates passage of substances in and out; Selective permeability
Cytoplasm - semi-fluid, gelatinous nutrient matrix; contains the “organelles”
Nucleus - command center or what controls the functions of the entire cell.
Nucleoplasm – gelatinous matrix or base material of the nucleus
Nuclear membrane – “skin” around the nucleus, contains holes
Chromosomes – consist of linear DNA molecules where GENES are located
Endoplasmic Reticulum - Highly convoluted system of membranes that are interconnected to form a transport network tubules and flattened sacs within the cytoplasm.
Ribosomes - 18 to 22 nm in diameter; consists of rRNA; play important part in protein synthesis
Golgi Apparatus - Packages newly synthesized proteins into small, membrane-enclosed vesicles for storage within the cellar export outside the cell (exocytosis).
Lysosomes - –contain lysozyme and other digestive enzymes that break down foreign material taken in by the cell
Peroxisomes - where hydrogen peroxide is both generated and broken down
Mitochondria - Where most of the ATP (energy carrying molecules) are formed by cellular respiration
Plastids - Contains various photosynthetic pigments
Chloroplasts – one type of plastid, contain a green, photosynthetic pigment called chlorophyll
Cytoskeleton - system of fibers present throughout the cytoplasm; Strengthen, support and stiffen the cell, giving its shape.
Microtubules - slender, hallow tubules (tubulins)
Microfilaments – Slender, thread-like contractile structures which facilitate cell contraction
Cell Wall - External structures that provide rigidity, shape, and protection.
Cellulose -polysaccharide, present in algae and plants
Chitin - present in fungi and exoskeleton of arthropods
Flagella – relatively long, thin structure, the organelle of locomotion.
Cilia - tend to be more shorter (hair-like), thinner and more numerous
Prokaryotic Cell Structure
Chromosome (Bacterial Nucleoid) - Consists of a single, long, super coiled, circular DNA molecule; Serves as the control center of the bacterial cell.
Prokaryotic Cell Structure
Plasmid - Small, circular molecules of double-stranded DNA that are not part of the chromosome; Extrachromosomal DNA; May contain 10 to hundred genes; May or may not be present in bacterial cell.
Cytoplasmic Particles - Many tiny particle in the bacterial cytoplasm; Most of these are clusters of ribosomes-polyribosomes or polysomes
Bacterial Cell Wall (Prokaryotic) - Rigid exterior cell wall that defines the shape of bacteria.
Bacterial Cell Wall
Consist of a complex macromolecule known as Peptidoglycan (murein) – only found in bacteria
Gram positive bacteria - thick layer
Gram negative bacteria- thinner layer
Gram Stain - The most widely used procedure for staining bacteria; Developed over a century ago by Dr. Hans Christian Gram
Steps in Staining
Crystal Violet
Iodine (Mordant)
Alcohol (Decolorizer)
Safranin (Counterstain)
Glycocalyx - Slimy, gelatinous material produced by the cell membrane and secreted outside the cell wall.
SLIME LAYER- not highly organized and is not firmly attached to the cell wall. Enables certain bacteria to glide along solid surfaces