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A&P > Cellular Organization > Flashcards

Cellular Organization Flashcards

1
Q

What is the plasma membrane

A

Forms cells flexible selectively permeable outer surface. Separates outside and inside cell environments. Regulates flow into and out of cell. Plays key roll in cellular communication.

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2
Q

What is cytoplasm?

A

Consists of all cell contents b/w plasma membrane and nucleus. Consists of cytosol(fluid portion aka intRAcellular fluid- water, solutes, suspended particles) and organelles (w/ diff shapes and functions)

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3
Q

What is the nucleus?

A

A LRG organelle that houses most of cell DNA. Each singular Chromosomes that lie in nucleus (1 single molecule of DNA associated wi
/ several proteins) contains thousands of heriditary units called genes that control cell structure & function

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4
Q

What is the function of the plasma membranes fluid mosaic model?

A

It is a molecular arrangement of continually moving sea of fluid lipids that contains a mosaic of many diff. Proteins. Some proteins float freely in the fluid lipids while others are anchored . It allows passage of several types of lipid-soluble molecules but act as barrier against entry or exit of charges or polar substances. Some of the proteins in the membrane allow passage of polar molecules or ions. Other proteins act as signal receptors.

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5
Q

What is the plasma membranes lipid bilayer?

A

Basic structural framework of plasma membrane that has two back to back layers made up of 3 types of lipid molecules (phospholipids, cholesterol and glycolipids-75% are phospholipids). The bilayer happens bcuz the lipids are amphipathic( have both polar and non polar parts). For phospholipids the phosphate “head” is hydrophilic and then non-polar “tails” are hydrophobic hydrocarbon chains. These phospholipids orient themselves the same w/ hydrophilic head facing out and the hydrophobic tails point towards each other making a no polar, hydrophobic region of membrane interior.

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6
Q

What are integral proteins?

A

Proteins that extend into or thru the lipid bilayer. Firmly embedded. Most are transmembrane proteins (span the entire lipid bilayer and protrude into both cytosol and extra cellular fluid.

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7
Q

What function do ion channels do?(integral protein in membrane)

A

Forms pores that allow specific ions such as potassium (K+) to flow in or out of cell. Most are selective (only one type of ion can pass)

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8
Q

What do carriers (integral protein in membrane) do?

A

Selectively move a polar substance or ion from one side of membrane to other. Aka transporters.

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9
Q

What do receptors do? (Integral protein in membrane)

A

Serve as cellular recognition sites specific to a type of molecul. Ex: insulin receptors that bind to hormone insulin.

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10
Q

What is a ligand?

A

A specific molecule that binds to a receptor is called a ligand to that receptor.

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11
Q

What are some other functions of integral proteins in cellular membrane?

A

Enzymes- catalyze specific Chen rx’s in or out cell.
Linkers- anchor proteins in membrane or neighbouring cells. Or to protein filaments in a out cell.
Glycoproteins and glycolipidsoften serve as cell-identity markers.

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12
Q

What is membrane fluidity dependent on?

A

of double bonds in fatty acid rials of the lipids that make up bilayer and on amount of cholesterol present. No redouble bonds makes more kinks

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13
Q

What is the plasma membranes lipid bilayer?

A

Basic structural framework of plasma membrane that has two back to back layers made up of 3 types of lipid molecules (phospholipids, cholesterol and glycolipids-75% are phospholipids). The bilayer happens bcuz the lipids are amphipathic( have both polar and non polar parts). For phospholipids the phosphate “head” is hydrophilic and then non-polar “tails” are hydrophobic hydrocarbon chains. These phospholipids orient themselves the same w/ hydrophilic head facing out and the hydrophobic tails point towards each other making a no polar, hydrophobic region of membrane interior.

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14
Q

What are integral proteins?

A

Proteins that extend into or thru the lipid bilayer. Firmly embedded. Most are transmembrane proteins (span the entire lipid bilayer and protrude into both cytosol and extra cellular fluid.

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15
Q

What function do ion channels do?(integral protein in membrane)

A

Forms pores that allow specific ions such as potassium (K+) to flow in or out of cell. Most are selective (only one type of ion can pass)

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16
Q

What do carriers (integral protein in membrane) do?

A

Selectively move a polar substance or ion from one side of membrane to other. Aka transporters.

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17
Q

What do receptors do? (Integral protein in membrane)

A

Serve as cellular recognition sites specific to a type of molecul. Ex: insulin receptors that bind to hormone insulin.

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18
Q

What is a ligand?

A

A specific molecule that binds to a receptor is called a ligand to that receptor.

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19
Q

What are some other functions of integral proteins in cellular membrane?

A

Enzymes- catalyze specific Chen rx’s in or out cell.
Linkers- anchor proteins in membrane or neighbouring cells. Or to protein filaments in a out cell.
Glycoproteins and glycolipidsoften serve as cell-identity markers.

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20
Q

What is membrane fluidity dependent on?

A

of double bonds in fatty acid rials of the lipids that make up bilayer and on amount of cholesterol present. More double bonds makes more kinks in tail which increases membrane fluidity by preventing lipid molecules from packing tightly in membrane.

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21
Q

What is the lipid bilayer of plasma membrane highly permeable to?

A

Highly permeable to nonpolar molecules (like O2, CO2 and steroids). Somewhat permeable to small, uncharged polar molecules such as H2O and urea. I permeable to ions and LRG, uncharged polar molecules such as glucose. The more hydrophobic or lipid soluble a substance is, the greater the membrane allows that substance in.

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22
Q

What is a concentration gradient?

A

A diff. In concentration of a chemical from one place to another. There may be more ions or molecules in the cytosol than in the extra cellular fluid or vice versa. Ex: O2& NA+ are more concentrated in extra cellular fluid than in cytosol- opposite of CO2 molecules and K+.

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23
Q

What is the electrical gradient?

A

A diff. B/w electrical charges b/w two regions. Typically, inner surface of plasma membrane is more negatively charged and outer surface is more positive. When this occurs across the plasma membrane it is called a membrane potential.

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24
Q

What are some examples of passive transport processes?

A

Diffusion, facilitated diffusion, channel mediated facilitates diffusion, carrier-mediated facilitated diffusion, osmosis,

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25
Q

What are some examples of active transport processes?

A

Active transport, primary active transport,secondary active transport, vesicles ( endocytosis, phagocytosis, exocytosis, transcytosis)

26
Q

What is diffusion?

A

A passive process in which the random mixing of particles in a solution occurs because of the particles kinetic energy.both solutes (dissolved substances) and solvent (liquid that does he dissolving) go thru diffusion. If solute is in high concentration in one area of solution and low in another, solute molecules will move/diffuse towards area of lower concentration. Ie: move down their concentration gradient until they reach equilibrium.

27
Q

What factors influence the diffusion rate if substances across plasma membranes?

A
  1. )Steepness of concentration gradient( higher rate of diffusion w/ greater diff. In concentration b/w two sides of membrane.
  2. ) temperature.( higher temp= faster rate of diffusion.
  3. ) mass of the diffusing substance.( the larger the mass of diffusing particle,the slower it diffuses. Smaller go quicker.
  4. ) surface area( larger the membrane surface= faster rate of diffusion. Ex:emphysema, reduces surface area of lungs and slows rate of O2 diffusion.
  5. )diffusion distance( greater the distance which diffusion must occur =longer it will take. Ex: in pneumonia fluid collects in lungs which increases distance O2 must travel to reach bloodstream.
28
Q

How do no polar, hydrophobic molecules move across the lipid bilayer? (Such as:oxygen, carbon dioxide, nitrogen gases, fatty acids, steroids, and fat-soluble vitS/ADEK

A

Simple diffusion.

29
Q

What is simple diffusion?(

A

A passive process where substances move freely thru lipid bilayer of plasma membrane w/out help of membrane transport proteins.

30
Q

How do small, uncharged polar molecules pass they lipid bilayer?(water,urea, small alcohols)

A

Simple diffusion

31
Q

How type of diffusion is used in the transfer oxygen and carbon dioxide b/w blood and body cells as well as air and blood w/ lungs?

A

Simple diffusion

32
Q

What solutes use facilitated diffusion?

A

Solutes that are too polar or highly charged to move across lipid bilayer by simple diffusion can pass membrane by this passive process where an integral protein assists a specific substance across membrane.(channel or carrier)

33
Q

How does channel mediated facilitated diffusion work?

A

A solute moves down concentration gradient across lipid bilayer thru membrane channel. Most are ion channels, integral transmembrane proteins that allow passage of small,inorganic ions that are too hydrophilic to penetrate non polar interior of L.bilayer.
Sometimes channels are “plugged”/gated when a certain part of channel changes shape in order to open/close. Some randomly open close and other are regulated by chemicals or electrical changes.

34
Q

What are some of the most abundant ion channels that use facilitated diffusion?

A

k+ potassium ions and chloride Cl- are most abundant, followed by na+ or Ca2+.

35
Q

How does carrier mediated facilitated diffusion work?

A

A carrier aka a transporter moves a solute down its concentration gradient across plasma membrane . No energy required (passive process) solute binds to specific carrier on one side & is released on the other side after carrier undergoes a change in shape.carrier binds on side that has higher solutes until equilibrium.

36
Q

What is a carrier transport maximum?

A

max # of carriers occupied available in plasma membrane. Depends on rate at which facilitated diffusion can occur. If this occurs even an increase in concentration gradient won’t increase rate of facilitated diffusion. .(like a totally saturated sponge) ie: carrier mediated facilitated diffusion exhibits saturation.

37
Q

What are some examples of substance that move across L. Bilayer by means of carrier mediated facilitated diffusion?

A

Glucose, fructose, galactose & some vitamins. Glucose binds to carrier proteins called glucose transporter (aka GluT) on outside surface of membrane.transporter than changes shape and glucose passes thru and then released by transporter on other side

38
Q

What is osmosis?

A

Type of diffusion in which there is a net Mvmt of a solvent thru a selectively permeable membrane. It Is a passive process. Solvent/water moves from area of higher water concentration to area of lower water concentration. In other words, water moves they selectively permeable membrane from area of lower SOLUTE concentration to an area of high SOLUTE concentration. Water molecules pass thru plasma membrane by simple diffusion or via aquaporins (water channel integral membrane proteins) for this to work.

39
Q

What is hydrostatic pressure?

A

Pressure exerted on side of the membrane-forces water molecules to move back into the arm w/less water d/t osmosis.

40
Q

What is osmotic pressure?

A

The solution with the impermeable solute exerts a force (osmotic pressure). Os mimic pressure of a solution is equal to the concentration of the solute particles that cannot cross the membrane. The higher the solute concentration the higher the solutions osmotic pressure.

41
Q

What is tonicity?

A

A measure of th solutions ability to change the volume of cells by altering their water content

42
Q

What is isotonic?

A

Any solution in which a cell maintains its normal shape and volume

43
Q

What happens to a cell (rbc ) in a hypotonic solution?

A

Hemolysis for RBC- lysis for any other cell. In hypotonic solution the concentration of solutes is lower than in that of the cytosol of the cell. Water rushes in faster than it leaves and the cell ruptures.

44
Q

What happens to a cell

In a hypotonic solution?

A

In this case the solution has a higher sconce traction of solutes than does the cytosol inside the RBC. In this car water molecules move output the cells faster than they enter, causing cells to shrink. This is called crenation.

45
Q

What is active transport?

A

Some polar or charges solutes must enter or leave the cells and they can’t cross the plasma membrane passively bcuz they would need to
Move UP against concentration gradient. This process requires energy for carrier proteins to move solutes across membrane against the gradient.

46
Q

What are the two sources of cellular energy that can be used to drive active transport?

A

1.) energy obtained from hydrolysis of ATP is the primary source in primary active transport 2.) energy stored in an ionic concentration gradient is the source of secondary active transport.

47
Q

What solutes are actively transported across the plasma membrane?

A

Several ions(na+, k+, h+, ca2+, I-) Cl-), amino acids, and monosaccharides.( some of these also can cross using facilitated diffusion when proper carriers or channels are present)

48
Q

What is primary active transport?

A

Energy derived from hydrolysis of ATP changes the shape of a carrier protein, which pumps. A substance across a plasma membrane against concentration gradient. Normal cells spend 40% of the ATPį it generates on primary active transport. Most prevalent one expels sodium ions from cells and brings potassium in.(sodium m-. potassium pump). This particular pump keeps maintain low concentration of na+ in cytosol by going against concentration gradient. Forces k+ into cells against gradient as well. Na and k slowly leak back across membrane down their electrochem gradient thru passive transport or secondary active transport.

49
Q

What is secondary active transport?

A

The energy stored in a na+ or H+ concentration gradient is used to drive other substances across the membrane against its own concentration gradient. ( both of these are established by primary active transport so secondary active transport indirectly uses energy from hydrolysis ATP). In this method, a carrier protein simultaneously binds to na+ or other and then changes shape so that BOTH can cross membrane together.

50
Q

What is a symporter? Antiporter?

A

If these transporter move 2 substances in same direction. Anti porters move 2 substances in diff. Directions.

51
Q

Explain vesicles

A

Vesicles, such as during endocytosis and exocytosis,require energy and is an active form of transport.

52
Q

What is endocytosis?

A

3 types: receptor mediated endocytosis, phagocytosis, and bulk phase endocytosis. Receptor mediated kind is very specific and cell take up specific Ligands.

53
Q

What is phagocytosis?

A

A form of endocytosis I which cell engulfs leg solid particles. (Worn out cell, bacteria, viruses) phagocytes cells do phagocytosis- called macrophages& neutrophils. Extends pseudopods to surround particles outside cell.

54
Q

What is bulk phase endocytosis?aka pinocytosis

A

A form of endocytosis in which tiny droplets of extra cellular fluid are taken up. No receptor proteins. Plasma membrane folds inwards and pinches off and enters cell. . Particularly prominent in absorptive cells such as kidneys and intestines.

55
Q

What is exocytosis?

A

Releases materials from a cell. All cells perform exocytosis but especially prominent in secretory cells that liberate digestive enzymes, hormones, mucus, secretions AND nerve cells that Rls substances called neurotransmitters. Secretory vesicles form in cell and fuse e/ membrane & Rls substances into extra cellular fluid.

56
Q

What is transcytosis?

A

Transport by vesicles of substances into, across and out of a cell.it is an active process.vesicles undergo endocytosis on one side of cell, move across and then undergo exocytosis on other side

57
Q

What is cytosol?

A

Aka intRAcellular fluid. It’s the fluid portion of the cytoplasm that surrounds organelles. Constitutes 55% of total cell volume. Made up of mostly water- then some diff types of dissolved and suspended component. Lots of Chem rx’s occur here. Ex: enzymes that catalyze glycolysis(10 steps that produce 2 ATP from 1 molecule of glucose)

58
Q

What is the cytoskeleton

A

Network of protein filament a that extends throughout the cytosol. (Smallest -> biggest = micro filaments, intermediate filaments, micro tubules)

59
Q

What are micro filaments? What are they composed of? What are their fx?

A

Thinnest element of cytoskeleton. Composed of actin and myosin. Most prevalent in cells edges. Fx as generating Mvmt and provide mechanical support. Help w/ support of micro villi.

60
Q

What are intermediate filaments?

A

Medium sized. V. Strong. Made of several proteins.found in parts of cell that undergo mechanical stress. Stabilize positions of organelles

61
Q

What are micro tubules? Composed of?

A

Largest of the cytoskeleton components. Long, unbranched, hollow tubes composed of protein tubular. Creation of these begins in centrosome. Help determine cell shape. Also fx for Mvmt of organelles such as secretory vesicles (cilia and flagella)

62
Q

What’s a centrosome?

A

Located near nucleus, consists of 2 components : a pair of centrioles and peri centriole material

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