- describe the biological arrangement of human organism
cells are the structural units of all living things, from one-celled organisms such as amoe- bas to complex multicellular organisms such as humans, dogs, and trees.
The human body contains 50 to 100trillion of these tiny building blocks.
For cells, “headquarters,” or the control center, is the nucleus.
nucle = kernel
Genetic material, or deoxyribonucleic acid (DNA), is a blueprint that contains all the instructions needed for building the whole body
The nuclear boundary is a double membrane barrier called the nuclear envelope.
At various points, the two layers of the nuclear envelope fuse, generating openings called nuclearpores
nuclear membrane encloses a jellylike fluid called nucleoplasm
Nucleolus is an area within the nucleus where ribosomes are manufactured.
When a cell is not dividing, its DNA is carefully wound around proteins called histones to form a loose network of “beads on a string” called chromatin
chromatin threads coil and condense to form dense, rodlike bodies called chromosomes
chromo = colored, soma = body
plasma membrane is a fragile, transparent barrier that contains the cell contents and separates them from the surrounding environment
Fluid Mosaic Model - The model that describes the structure of the plasma membrane.
“sugar-proteins” are called glycoproteins
the cell surface is a fuzzy, sticky, sugar-rich area called the glycocalyx
Tight junctions
- impermeable junctions that encircle the cells and bind them together into leakproof sheets.
Desmosomes
- are anchoring junctions scattered like rivets along the sides of adjacent cells.
Gap Junction
- function mainly to allow communication between two neighboring cells
connexons - hollow cylinders composed of proteins that connects two cells
Cytoplasm - the cellular material outside the nucleus and inside the plasma membrane; the site of most cellular activities
Cytosol - semitransparent fluid that suspends the other elements
Inclusions - chemical substances that may or may not be present, depending on the specific cell type.
Organelles - specialized cellular compartments that are the metabolic machinery of the cell.
Mitochondria - usually depicted as tiny, lozenge-like or sausage-shaped organelles
Ribosomes - are tiny, bilobed, dark bodies made of proteins and one vari- ety of RNA called ribosomal RNA
Endoplasmic Reticulum - a system of fluid-filled tunnels (or canals) that coil and twist through the cytoplasm
Endoplasmic Reticulum - a mini circulatory system for the cell because it provides a network of channels for carrying substances
RoughER
- synthesizes proteins and secretes it
Smooth ER - functions in lipid metabolism (cholesterol and fat synthesis and breakdown) and detoxification of drugs and pesticides.
Golgi Apparatus - appears as a stack of flattened membranous sacs that are associated with swarms of tiny vesicles
Lysosomes - membranous “bags” containing powerful digestive enzymes. Because lysosomal enzymes are capable of digesting worn-out or nonusable cell structures and most foreign substances that enter the cell,
Peroxisomes - membranous sacs containing powerful oxidase enzymes that use molecular oxygen (O2) to detoxify a number of harmful or poisonous substances
Free radicals - highly reactive chemicals with unpaired elec- trons that can damage the structure of proteins and nucleic acids.
peroxisomes = peroxide bodies
catalase - converts excess hydrogen peroxide to water
Cytoplasm - elaborate network of protein structures extends throughout the cytoplasm
Microfilaments - involved in cell motility and in producing changes in cell shape
Intermediate filament - the strong, stable, ropelike structure; provide internal guy wires to resist pulling forces on the cell