Tour of the cell, membrane structure and fuction

The difference between microscopes and their functions.

Electron microscope: focuses beam of electrons through the specimen or onto its surface.

Light microscope: visible light is passed through the specimen and then through glass lenses.

Brightfield stained : stained with various dye enhances contrast>

Phase-contrast: density within the specimen are amplified to enhance contrast in unstained cell.(useful for living unpigmented cells).

Brightfiled unstained :light passes straight thought specimen, unless naturally pigmented.

Differential interference contrast: the location of a specific molecule in the cell can be label by fluorescent dyes or antibiotics.

Scanning electron microscopy (SEM) : show a 3D image of the surface of a specimen and is very helpful for detailed study of the topography.

Transmission electron microscopy (TEM): Shows a section through a tracheal cell, revealing its internal structure.

Membranes and everything to their function and structure

Membrane structure:

The plasma membrane main purpose is to to allow the passage of oxygen, nutrients, and wastes to help the whole cell.

The hydrophobic parts in the phospholipids and membrane proteins are found in the interior of the membrane, on the other hand the hydrophilic parts are in contact to aqueous solutions on the opposite side.

Carbohydrate side chains may be attached to proteins or lipids on the outer surface of the plasma membrane.

The plasma membrane is made up of a double layer bilayer of phospholipids with multiple proteins that are emended in it.

Passive Transport (no energy)

The spontaneous movement of a substance down its concentration gradient from high to low (Diffusion).

Facilitated diffusion

Osmosis

Simple diffusion

Dialysis

Crossses through and between phospholipids.

Protein that speeds up the movement of water and solute across a membrane down its concentration gradient. Ion channels facilitate the diffusion of ions through a membrane. Proteins can undergo changes in shape that translocate bound solutes across a membrane.

Process in which molecules of a solvent tend to pass through a semipermeable membrane from a less concentrated solution into a more concentrated one.

Active transport (energy)

Na/k

Bulk transport

Cotransport : when a membrane protein allows the downhill diffusion of one solute drive the uphill transport of the other.

Electrochemical gradient drives ions across a membrane as they can have chemical gradient and a electric gradient.

Exocytosis: transport vesicles migrate to the membrane. and brings things out. Endocytosis : cell that takes in macromolecules by forming vesicles.

Prokaryotes and Eukaryotes:

Eukaryotes

Prokaryotes

Fimbriae: attachment structure on the surface of several prokaryotes.
Flagella: locomotion organelles

Nucleoid: Region where the cells DNA is located (not enclosed by a membrane)

Ribosomes: complexes that synthesize proteins. Plasma membrane: membrane enclosing the cytoplasm.

Cell walls rigid structure outside the plasma membrane .Glycocalyx outer coating of many is made up capsule or a slime layer.

Cytoplasm in the region between the membrane and nucleus.

DNA is a nucleus that is bounded by a double membrane.

Membrane-bound organelles.

Cellular membrane are fluids mosaics of lipids and proteins

The unsaturated hydrocarbon tails of some phospholipids keep membranes fluid at a lower temperatures , while cholesterol helps membranes resist charges in fluidity.

Phospholipids move sideways whit in the membrane.

Membrane proteins and lipids are synthesized in the endoplasmic reticulum and modified in the ER and Golgi apparatus.

Cell Fracnation

importance: helps the study and identification of over the different components of a cell .Definition: The process used to separate cellular components while preserving individual functions of each component.

Surface area and volume ratio

Larger organisms do not have cells any smaller organisms instead they just have more.

multicellular is better than just a bigger cell because as a cell increases in size, its volume grows proportionally more than its surface area.

Surface area is large enough to accommodate the volume helps explain the microscopic size of cell.

Organelles structure and fuctions

Animal cell

plant cell

Mitrochondrion

Nucleus

Plasma membrane

Golgi apparatus

Wall of adjacent cell

Peroximome

Chloloplast

Cytoskeleton "microfilaments, intermediate flaments and microtubulus"

Ribosomes

Cell wall

Plamodesmata

Central vacuole

Nucleous

Nuclear envelope

Chromatin

Outer layer that protects and maintains the shape from mechanical changes: made of cellulose , and other polysaccharides.

cytoplasmic channel through cell walls that connect the cytoplasm of adjacent cells.

Microvilli

Mitochondrion

Centrosome

Golgi apparatus

Flagellum

Plasma membrane

Cytoskeleton

Endoplasmic reticulum

Peroxisome

Lysosome

Ribosomes

Nucleus

Nucleolus: Non membranous structure in production of ribosomes a nucleus has once or more nucleoli.

Nuclear envelope: double membrane enclosing the membrane , perforated with pores continuous with ER.

consist of DNA

network of membranes sacs and tubes: active in memebrane

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