the smallest structural and functional unit of all living organisms. It is often described as the basic building block of life.
CELL
2 main categories of cell
PROKARYOTES AND EUKARYOTES
Refers to the structural units that make up living organisms. Each cell has specialized
functions and contains components necessary to perform and perpetuate these functions.
CELLULAR ORGANIZATION
Basic Components of Human Cells
PLASMA MEMBRANE
NUCLEUS
CYTOPLASM WITH ORGANELLES
A semipermeable outer boundary that separates the intracellular contents from the
extracellular environment.
➢ Provides a flexible physical barrier to protect the cell.
➢ Regulates and facilitates substance exchange through selective permeability, endocytosis,
and exocytosis.
➢ Establishes electrochemical gradients essential for cellular activity.
➢ Contains receptors for signal transduction allowing the cell to respond to environmental
signals.
➢ Hosts cell surface glycoproteins and glycolipids which contribute to cell recognition and
interaction.
PLASMA MEMBRANE
The control center of the cell and the largest organelle.
➢ Contains deoxyribonucleic acid (DNA) and is the site of DNA replication and transcription.
➢ Controls chemical reactions and directs reproductive processes.
➢ Stains deep purple with Wright stain due to nucleic acids.
NUCLEUS
Composed of long DNA molecules folded with histone and nonhistone proteins.
CHROMATIN WITHIN THE NUCLEUS
2 forms of chromatin
HETEROCHROMATIN and EUCHROMATIN
Darkly stained, condensed, transcriptionally inactive; more abundant in mature cells.
HETEROCHROMATIN
Diffuse, uncondensed, genetically active; where DNA transcription into mRNA occurs.
EUCHROMATIN
Double phospholipid bilayer membrane.
■ Inner membrane surrounds the nucleus, outer membrane continuous with the endoplasmic reticulum.
■ Contains nuclear pore complexes that allow molecule exchange between nucleus and cytoplasm.
NUCLEAR ENVELOPE
One or several per nucleus.
■ Site of ribosomal RNA (rRNA) production and ribosome subunit assembly.
■ Disassemble as blood cells mature and decrease protein synthesis.
NUCLEOLI
The cellular material between the plasma membrane and the nucleus.
➢ Contains organelles that perform distinct functions to sustain the cell.
➢ Houses the cytoskeleton, which provides structure, shape, and facilitates movement.
CYTOPLASM
Sites of protein synthesis.
RIBOSOMES
2 types of endoplasmic reticulum
SMOOTH ER
ROUGH ER
Studded with ribosomes, synthesizes membrane-bound proteins.
ROUGH ER
Synthesizes lipids, detoxifies substances, stores and releases calcium.
SMOOTH ER
Modifies, sorts, and packages proteins and lipids for transport
GOLGI APPARATUS
Produce ATP via oxidative phosphorylation, contain their own DNA.
MITOCHONDRIA
Contain enzymes for digestion of cellular debris
LYSOSOMES
Microfilaments: Support cell shape and motility.
➢ Intermediate Filaments: Provide strength.
➢ Microtubules: Involved in cell shape, movement, and mitosis.
CYTOSKELETON
Near the nucleus, composed of centrioles.
➢ Organizes mitotic spindle fibers for cell division.
CENTROSOMES
the ordered series of events that a cell goes through to grow and divide into two daughter cells.
CELL CYCLE
the phase where the cell prepares for division, encompassing about 90% of the cycle.
INTERPHASE
