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Cell Membrane and Cell Functions

What are carrier proteins?
carrier proteins are proteins embedded in the cell membranes, they help release and input molecules that are too large to enter in simple diffusion. their shape enables them to be semi-permeable meaning that they know which molecules can enter and which cannot
Define isotonic
(used of solutions) having the same or equal osmotic pressure. (when the flow of water entering the cell is equal to the flow of water leaving the cell)
How are phospholipids important in the cell membrane?
phospholipids are the lipids that form the phospholipid bi-layer that is the cell wall. the hydrophilic heads point to the cytoplasm and the ECF while the hydrophobic fatty acid tails point in. they are the main component of the cell membrane allow the cell to diffuse particles. this is because the head to head repulsion of the polar heads causes gaps for important nutrients to get in, and waster to leave.
Define facilitated diffusion
process that moves materials from high to low concentration with the help of protein channels; does not require energy. carrier and channel proteins help allow objects to large to fit into the cell membrane enter it.
Why is oxygen always entering the cell? And why is carbon dioxide always leaving?
cellular respiration. oxygen is needed to preform cellular respiration seeing as it is one of the reactants, because of this it is always being diffused into the cell. carbon dioxide is one of the products of cellular respiration and is not needed in the cell, thus it is released into the ECF
Define cytoskeleton
a microscopic network of actin filaments and microtubules in the cytoplasm of many living cells that gives the cell shape and coherence
What is the difference between a glycolipid and a glycoprotein?
both are sugars in the form of glycogen, hence the "glyco" in the name. however, glycolipids are attached directed to the phospholipid and glycoproteins are attached to a integral protein.
What is endocytosis and exocytosis?
endocytosis and exocytosis is the taking in and expelling of nutrients and waste in the body. Endocytosis means taking in and exocytosis means shoving out (haha ok I made that up). during endocytosis, the nutrient, or bacteria in the case of white blood cells, is taken in by having the cell mold around it until a vesicle is formed and the cell membrane reseals. exocytosis is when the products in the vacuole have been digested by enzymes and are now waste. the vacuole moves to the cell membrane and molds with it. returning the phospholipids to the bi-layer, and the waste to the ECF
integral protein
Typically a transmembrane protein with hydrophobic regions that extend into and often completely span the hydrophobic interior of the membrane and with hydrophilic regions in contact with the aqueous solution on either side of the membrane (or lining the channel in the case of a channel protein).
What is the ECF?
The extracellular fluid, this is the liquid coating the outside of all cells. It is filled with vital nutrients that enter the cell and waste products that have left the cell.
Surface Recognition Protein
Surface recognition proteins are proteins that are studded in the cell membrane. These proteins help identify cells as "selfs" (so they are considered safe) rather than enemies and harmful to the body.
How does a carrier protein work?
A carrier protein is another protein in the phospholipid bilayer. It helps proteins in and waste out during facilitated diffusion. It only accepts certain substances to large to get through the phospholipid bilayer. When it touches the protein, the active site on it changes the shape accepting the substance.
Does simple diffusion move with or against the concentration gradient?
With. It moves from an area of high concentration to an area of low concentration.
Why is cholesterol important in the cell?
Cholesterol helps keep the cell fluid under extreme temperature conditions. It allows the cell to maintain fluid in cold rather than freezing and fluid in heat rather than boiling.
Brownian Motion
the chaotic movement of colloidal particles, caused by collision with particles of the solvent in which they are dispersed
What is diffusion affected by?
Diffusion is affected by:
diffusion of molecules through a semipermeable membrane from a place of higher concentration to a place of lower concentration until the concentration on both sides is equal
What would happen to a cell in a hypotonic solution?
In a hypotonic solution, the solvent outside the cell is greater than inside the cell, (like in distilled water), this would cause an animal cell to undergo cytolysis and a plant cell to undergo turgor pressure.
region of the membrane where sugar chains of the proteins are located. Can act as an adhesion layer to other cells.
What is the difference between a channel and a carrier protein?
A carrier protein is an integral protein in the cell which aids in facilitated, it accepts large uncharged particles like glucose. When the molecule touches the active site, the protein changes shape accepting it in and through the bilayer to the cytoplasm. A channel proteins accepts charged particles that would not be able through the bilayer in any other case.
What are the four functions of proteins?
Structural support, help maintain the shape of the cell, recognition: the cell has recognition proteins on it that allows it to recognize other cells as selfs, communication: receptor proteins can receive information via traveling molecules like hormones, and Transport: carrier and channel proteins accept cells
What is active transport?
When molecules are moved against the concentration gradient, so from an area of low concentration to an area of high concentration.
What is the difference between phagocytosis and pinocytosis?
Phagocytosis can also be described as cell eating and pinocytosis cell drinking. In the former, the cell literally moves around the particle, like a pathogen for example, that is too large to be taken in by a protein. The cell ingests it in a food vacuole. In pinocytosis the cell ingests dissolved particles in the ECF in a similar way to phagocytosis.
What makes the cell membrane fluid?
The phospholipids, because the heads are polar they repel each other, meaning that this repulsion keeps them in constant motion. This allows the membrane to stay fluid. The cholesterol in the cell membrane also keeps the cell from freezing and boiling.
Why do we need the cell membrane to be fluid
so small particles can diffuse in via simple diffusion.
If you don't have cholesterol in your diet, how does your cell membrane manufacture it?
The body can build cholesterol from other substances i.e. carbohydrates or lipids, because all are organic compounds they have essentially the same elements in them.
Kinetic Molecular Theory
1. All matter is made of particles
2. They are in constant motion
What is cytolysis?
Cytolysis is when an animal cells are put in a hypotonic solution. This means that more water is entering the cell than leaving the cell. The cell may burst because there is too much water in it
What is an isotonic environment?
This means that the concentration of solvent is equal in and out of the cell. This happens in the blood in our bodies.
What is plasmolysis?
Plasmolysis is when there a higher concentration of solute outside of the cell meaning that it causes the cell to shrivel. Plasmolysis only happens in plants
What is an example of diffusion?
In the lungs there is a higher concentration of oxygen than in the blood, the oxygen diffuses into the blood stream.
Does active transport occur spontaneously?
No. It requires energy from the cell to undergo this procedure.
Can diffusion occur in non-living things?
Yes, for example spraying perfume it diffuses from an area of [high] to an area of [low]
How does a membrane from a vesicle reform with the cell membrane?
During exocytosis when the vesicle has waste in it, it moves to the edge of the membrane and reforms to the main membrane
What moves against the concentration gradient
exocytosis, endocytosis, and active transport- with transport proteins
Concentration Gradient
a difference in the concentration of a substance across a distance
What molecules need facilitated diffusion?
Glycogen, Glucose, Amino and Drugs
the process by which an organism's internal environment is kept stable in spite of changes in the external environment. Important during changes to keep the cell normal this is because digestive enzymes only function at a certain pH.
What happens when cells get polluted?
The oil goes in between the phospholipid bilayer and dissolves because like dissolve like and separates the two layers causing the cell to die. Also small non-charged particles can enter that are not good for the cells.
How do cells survive in a fresh water environment?
Contractile vacuoles pump water out of the cell.
What are two examples of helpful exocytosis?
endocrine glands secrete enzymes and hormones, and pancreatic cells secrete insulin
What is a property of the cell that helps it form vacuoles?
Its self sealing properties.
What breaks down the nutrients in vacuoles?
Lysosomes which produce digestive enzymes.
Membrane Receptors
Membrane receptors allow hormones into the cell, they match to the hormone and then impocket until they form a vesicle. They allow things based on their shape, size and charge.
when polymer has been broken into monomers <-- hydrolysis
what are pseudopods?
Fake foots that are formed when a cell engulfs a large particle, especially by leukocytes
a capsule made up of a fuzzy coat of sticky sugars