cell membrane and cytoplasm

No nuclear envelope

No membrane bound organelles

No cell wall and no cytoskeleton

Smaller than eukaryotic cells

Subcellular compartment or large macromolecular complex, often membrane

enclosed but doesn’t have to be, so long as it has a distinct structure, composition, and function

DNA enclosed in nuclear envelope (nucleus and cytoplasm(surrounds nucleus) is divided into 2 main compartments

Internal membrane bound organelles

Cytoskeleton and no cell wall

Chloroplasts

Cell wall made of cellulose

A soluble substance derived from a mold or bacterium that inhibits the growth of other microorganisms, many times by fitting in the active site of an enzyme

They target either bacterial enzymes that have no eukary counterpart or bacterial enzymes (like in protein synthesis) whose structure is different enough from their eukaryotic counterparts such that the antibiotic kills bacteria but not you

light is focused on a specimen by a glass condenser lens; the image is then magnified by an objective lens and an ocular lens, for projection on the eye, digital camera, digital video camera, or photographic film

a beam of electrons (top of the  microscope) is used instead of light, and electromagnets are used instead of glass lenses. The electron beam is focused on the specimen by a condenser lens; the image is magnified by an objective lens for projection on a digital detector, fluorescent screen, or photographic film **better at resolving smaller objects

photo taken by means of a microscope

**prokaryotes are .2-2 microns in diameter

**eukaryotes are 10-100 microns in dimeter

Phospholipids

Cholesterol

Proteins

**cell membranes range from 7.50nm in thickness so they can only be viewed under an electron microscope

Polar head group

Linkage derived from glycerol

2 nonpolar fatty acid tails

**can be saturated and unsaturated, in humans phospholipids contain 1 saturated and one unsaturated FA tails

** saturated straight unsaturated kink

Phosphatidylcholine

Sphingomyelin (linkage derived from sphingosine not glycerol)

Phosphatidylserine(only phosphor with negative charge and gives itself a special function

Phosphatidylethanolamine

**all major classes of phospholipids are synthesized on smooth ER

Form a lipid bilayer by putting hydrophilic head groups next to water and bury hydrophobic tails away from water

**water above and below bilayer prevents membrane lipids from escaping from bilayer, but the phospholipids move around and change places with one another spontaneously or move laterally, rotate, or flex.

**it is not energetically favored to drag large hydrophilic head group through the hydrophobic center of the bilayer

Speed at which movements occur (to phospholipids, cholesterol, or proteins)

**composition of membranes affect fluidity

• Membrane traffic in cell, membranes have to be fluid enough to change their shape and be able to bud off a vesicle
• Be fluid enough to have a vesicle fuse with a target membrane and have its lipid and membrane components spread out in the bilayer after fusion

One smaller polar head group and one fatty acid tail Cholesterol molecules immobilize the first few


 

hydrocarbon groups of the phospholipid molecules but the smaller polar head group allows cholestersol to flip easily between 2 bilayers and will be distributed equally in every membrane

Tends to “stiffen” cell  membranesThis makes the lipid bilayer less deformable and decreases its permeability to small water soluble molecules

**Cholesterol is absolutely essential for every membrane in every cell in your body, you don’t ingest it, your body will synthesize it on SER (cells needed a lot of membrane cholesterol or steroid hormones have more SER), it is also a precursor for steroid hormones

**Bacteria and plant cells do not contain cholesterol*, this is why bacteria need a cell wall to maintain rigidity of membrane

Warm temperature, cholesterol restrains movement of phospholipids (high cholesterol decrease fluidity)

Cool temperature maintain fluidity by preventing tight packing

**membranes are composed of lipids with embedded proteins 1:1 ratio

Integral membrane proteins – embedded in membrane need detergent to remove

Peripheral membrane proteins – only help to membrane by ionic interactions with membrane proteins or lipids, can be washed away with high salt rinse

Glycophorin – human red blood cell protein has a single transmembrane alpha helix (2 copies form dimer)

Bacteriorhodopsin – a light driven proton pump from the plasma membrane of a purple bacterium has 7 transmembrane helices

Porin – nonselective channel protein from the outer membrane of a bacterium or mitochondria

**aa in transmembrane domain are hydrophobic

Alpha helix containing about 20 AA is required to completelty transverse a membrane

These amino acids need to have hydrophobic side chains to be able to cross the hydrophobic interior of the bilayer

Both lipids and proteins may be mobile or fluid in the plane of the membrane

BUT Transmembrane proteins will also not flip spontaneously (like phospholipids) between leaflets of the bilayer because of all the charge

Membranes composed of just phospholipids spontaneously repel large and/or hydrophilic molecules

Use regulated ion channels to control which ions cross membranes

Transport of molecules – channels and pumps

Cell signaling – cell membrane bound receptors, enzymes, and proteins

Phagocytosis, pinocytosis, receptor medited endocytosis

Cell to cell communication – due to presence of carbohydrates

Attachment to cytoskeleton and extracellular matrix

Compartmentalization – segregates one part of the cell from other

A protein spanning the membrane may provide hydrophilic channel across that is selective for a particular solute

One transport protein shuttles a substance from one side to the other by changing shape by hydrolyzing ATP as an energy source to pump across membrane

Diseases caused by disturbed function of ion channel subunits or the proteins that regulate them

Congenital – resulting in mutation or mutations in the encoding genes

Acquired – often resulting from auto immune attack on an ion channel

Is a transmembrane protein with 12 transmem domains that transports chloride ions into and out of epithelial cells into the lumen

Repeated chest infections cause progressive loss of lung function and major cause of premature death and is caused by mutations in CFTR

Normal cell lining respiratory tract secrete proteins into lumen of airway, with defective CFTR the chloride imbalance within cell causes cell to secrete less water, cells swell, tissue damage, secretions become thick, the secretions clog up respiratory tract and trap bacteria leads to lung infections

Receptor (membrane protein) may have a binding site with a specific shape that fits the shape of a chemical messenger (i.e hormone). The signaling molecule (external messenger) may cause the protein to change shape allowing it to relay a message inside usually by binding to a cytoplasmic protein.

A signaling molecule can bind to the receptor which can activate one or more intracellular signaling pathways with series of signaling proteins. One or more of the intracell signaling proteins can alter the activity or effector proteins and thereby the behavior of the cell

Sphingomyelin

Glycolipids

Cholesterol

**they float around but fluidity within is diminished

Sphingomyelin has 2 saturated FA tails, causes less fluidity in lipid raft

Need 24-25 hydrophobic AA to cross lipid raft, transmem proteins with longer domains cluster in lipid rafts as well as signaling proteins

Rafts may contain incomplete signaling pathways that are activated when a receptor or other molecule is recruit into the raft

Rafts can limit signaling by physical sequestration  (being kept apart) of signaling components to block nonspecific interactions or by suppressing the intrinsic activity of signaling proteins within rafts

 

Singal transduction in lipid rafts occurs more rapidly and efficiently because of close proximity of interaction proteins. Different signaling rafts allow for separation of specific signaling molecules from each other

During endocytosis, segment of plasma mem buds inward toward the cytosol so the exoplasmic face is inside facing the vesicle lumen while the cytosolic face is on the outside. During exocytosis, an intracellular vesicle fuses with plasma membrane and the exoplasmic face connects with the extracellular medium. Whatever is facing what will eventually end there once the process is complete

Lipid raft protein coating that forms the organelle caveola in most cell types but are abundant in endothelial cells lining blood capillaries

It also carries macromolecules from blood stream across capillary endothelial cell and into the extracellular fluid and vice versa. Can pinch off and bring a macromolecule into the cell one type of endocytosis that is not clathrin-mediated

**if the vesicles go all the way across the cell and fuse with the other side its call transcytosis, caveolae do this

are attached to glycoproteins lipids (glycolipids) and play a key role in cell-cell recognition

Ability of a cell to distinguish neighboring cells from each other

Important in organ and tissue development

Basis for rejection of foreign cells by immune system

Nonliving material secreted by cells that fills spaces between the cells in tissue, protecting them and holding them together

May be semifluid or regidy and hard as in bone

Is composed mainly of proteins (i.e collagens, elastin, glycoproteins,fibronectin,laminins and osteoporins

Contents of a Contents of a cell that are contained within its plasma membrane but, in the case of eukaryotic cells, outside the nucleus

Contents of the main compartment of the cytoplasm excluding membrane bounded organelles such as endoplasmic reticulum and mitochondria

**70% of cell volume, gelatinous substance, consists of cytoskeleton filaments, organic molecules, free proteins like enzymes, fatty acids, sugars and AA, salts and water. Contains ribosomes, proteasomes, and nonmembrane bound cytoplasmic inclusions

Fat droplets

Lipofuscin granules

Glycogen rosettes

Not membrane bound

Composed of accumulated metabolites or other substances and are oftem transitory components of the cytoplasm

Nonmotile with no metabolic activity

Not an organelle since they don’t do anything

Stored E source

Aggregates of a carbohydrate polymer in which glucose is stored

Not surrounded by membrane

Liver cells and skeletal muscles are 2 major glycogen storage sites