Quiz 3 Flashcards
(34 cards)
What if substances are too big for a transport proteins?
Big molecules must use the bulk transport mechanism, which involves the formation of vesicles. The membrane is flexible and can bend into different shapes including the pinching off vesicles. This requires energy.
What is endocytosis?
The importing of substances, there is three types; Phagocytosis, which is cell eating when the membrane bends around and pinches off this is for large food particles, Pinocytosis which is cell drinking with little water droplets and everything dissolved in them and Receptor mediated which involve receptors to import specific things.
What is a receptor?
A specific membrane protein, receptors receive chemical signals form the outside of the cell which involves a physical interaction b/w the ligand and receptor. Each receptor only binds to one specific type of ligand structure.
What is receptor-mediated endocytosis?
Receptors bind to a substance that the cell needs to uptake. Cathrin binds to these receptors on the inside of the cell;gathering them and the membrane into a pit shape that eventually becomes a vesicle. Cathrin is then released, the particle is used/consumed and the receptors are their way back to the membrane.
What is clathrin?
Clathrin is a coat protein that helps facilitate vesicle formation. It is three proteins in a quaternary structure that associate with e/o and bind to active receptors and brings other clathrin.
What is an example of receptor mediated endocytosis?
Fat delivery to cells. Lipoproteins transport fat to cells via the blood stream. there is a surface layer of phospholipid and cholesterol so fat doesn’t clog the bod with a core of triglycerides. Specific proteins associate with the fat droplet and the receptors of the cell recognize the apoprotein and promote endocytosis.
What is a LDL?
A low density lipoprotein, low in density but high in cholesterol, this lipoprotein is referred to as “bad” cholesterol
What is a HDL?
A high density lipoprotein, it is high in density due to a high protein/li[id ratio. These particles cab remove excess cholesterol form blood vessels (for transport to the liver)
What do systems that preform active transport using ATP directly mediate?
Primary active transport
What do systems that use carrier proteins by ion gradients mediate?
Secondary active transport
What are a few of the proteins used in facilitated diffusion of active transport described as?
Uniporters only transport one type of molecule, symporters transport two molecules in the same direction, antiporters transport two different molecules in the opposite direction.
What do Bacteria cell walls do?
Provide shape, protection form bursting in hypotonic environments (lysis).
What are the two types of cell walls?
Gram positive which is a very simple cell wall with an outer peptidoglycan layer and plasma membrane beneath, and gram negative which has a complex cell wall with a thin peptidoglycan layer in between two plasma membranes, this membrane is known as a lipopolysaccharide which ca cause fevers because of its endotoxin’s
What is peptidoglycan?
A thin sheet composed of; chains of a repeating disaccharide unit composed of two mono saccharides ( NAG & NAM), and small peptides attached to the NAM Subunits of the chains, bonds formed between peptides on adjacent chains cross-link the chains of gives strength to the structure.
What are components of NAG & NAM?
A peptidoglycan polymer in each with a NAM peptide on NAM with DAP in made by dehydration. Multiple strands of NAG & NAM get cross linked to form thin sheets, this cross linking is called trans peptides ion and adds strength to the layer.
What are antibiotics?
They usually affect peptidoglycan and are specific to certain types of bacteria based on their ability to target prokaryote-specific structures. Their two common targets are; prokaryotic ribosomes and prokaryotic cell walls.
How does penicillin work?
As bacteria cell grows it synthesizes more peptidoglycan. Transpeptidation reaction is catalyze by a specific enzyme.The enzyme is inhibited by penicillin and inhibition leads to a weakened peptidoglycan which works best on gram positive cells. As the cell grows peptidoglycan is not formed and eventually the cell bursts (lysis)
What is the capsule?
The capsule is secreted by the bacteria and is mostly polysaccharides that protect the cell from the environment and can be used to stick bacteria to the surface or other cells
What are the two types of Pili?
Fimbriae attach to surfaces or host cells with spikily needles that make them hard to remove. Sex Pilus which is for the transfer of DNA b/w bacteria cells to transfer plasmid
What is a taxis?
The ability to move towards towards or away from a stimulus by a bacteria in a heterogeneous environment. Chemotaxis is the movement towards or away from the chemical stimulus which is a series of runs and tumbles, the run is longer is the concentration of the attraction is higher
What is a flagella?
An external structure for movement of a cell, it is composed differently for each domain. Th bacterial flagellum rotates CCW for a run and CW for a tumble. Bacterial flagella motors are composed of many individual components
What are archaea cells walls composed of?
They have no outer membrane but various coverings surrounding the plasma membrane, there is no true peptidoglycan but related molecules exist in some species. A similar membrane is the Archaea-specific lipopolysaccharides. They generally have stronger men range, due to a number of unquiet differences other than ester in their triglycerides
What are Eukaryotic cell walls and what are they composed of?
The cell wall provides shape and function, to help plants hold themselves upright. The cell wall is made up of cellulose chains embedded in a matrix of other polysaccharides and proteins. Young plants have thin cells walls. The primary cell wall allows flexibility for growth that hardens over time. Some plants have a secondary cell wall. They also have a cell wall between adjacent cells
What is the middle lamella, and what is it composed of?
The middle lamella supersets adjacent plant cells b/w their primary cell walls. The lamella is composed of sticky polysaccharides called pectins( it glues the cell together)
