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MBB231 > Midterm 1 (Chapters 1-4) > Flashcards

Midterm 1 (Chapters 1-4) Flashcards

1
Q

Cell theory

A
  1. All living things are composed of cells,
  2. All cells come from pre-existing cells,
  3. Cells are the structural unit of life
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2
Q

Model organisms

A

relatively simple, fast generation time, large number of offspring, easy to manipulate in lab, inexpensive to breed. E. coli, yeast, nematodes, mustard plant, zebra fish, mouse, fruit fly

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3
Q

Size

A

viruses are smaller than cells, proteins are smaller than viruses

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4
Q

Covalent bonds

A

pairs of electrons are shared between pairs of atoms. Strong bonds are not super useful in proteins since it takes a lot of energy to break

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5
Q

Nonpolar covalent bonds

A

equal sharing of electrons

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6
Q

Polar covalent bonds

A

unequal sharing of electrons

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7
Q

Ionic bonds

A

electrostatic attraction between two oppositely charged ions

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8
Q

Hydrogen bonding

A

weak attractive interaction between an electronegative atom and a hydrogen atom that is covalently linked to a second electronegative atom

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9
Q

Electronegativity

A

an indication of an atom’s ability to attract an electron (they are electron deficient). The more electronegative, the greater the ability of an atom to attract an electron.

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10
Q

Properties of water as a solvent

A

molecules that contain polar bonds and that can form hydrogen bonds with water dissolve readily in water

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11
Q

Hydrophobic effect

A

nonpolar molecules and nonpolar portions of molecules tend to aggregate in water. Nonpolar molecules are forced into aggregates to reduce exposure to water.

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12
Q

Functional groups

A

often behave as a unit and give organic molecules their physical properties, chemical reactivity, and solubility in aqueous solution.

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13
Q

Amphipathic

A

a molecule or protein having both hydrophobic and hydrophilic components

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14
Q

Macromolecules

A

large, highly organized molecules that form the structure and carry out the activities of the cell. 4 major categories: proteins, nucleic acids, polysaccharides, lipids

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15
Q

Building blocks of the cell -> larger units of the cell

A

Sugars -> polysaccharides.
Fatty acids -> fats, lipids, membranes.
Amino acids -> proteins.
Nucleotides -> nucleic acids

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16
Q

Glucose

A

forms a ring structure in our bodies. Double bonded O is found at C1, with CH2OH group at C6.

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17
Q

Anomeric carbon

A

carbon derived from the carbonyl carbon (the ketone or aldehyde group) of the open chain form of the carbohydrate molecule. Numbered as C1. can open and mutarotate in solution. When the anomeric carbon of a monosaccharide participates in a glycosidic bond it can no longer mutarotate and is in a fixed position

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18
Q

Identifying anomeric carbon

A

draw a line through the plane. If the OH group is above the plane it is in the beta position. Below the plane, it is alpha position.

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19
Q

Glycosidic bonds

A

monosaccharides that are linked together by covalent bonds. Formed between two OH groups on two separate monosaccharides, or a monosaccharide and another molecule. Always involve the hydroxyl of an anomeric carbon. Always generates a beta glycosidic linkage when it happens in the cell.

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20
Q

Disaccharide

A

2 monosaccharides linked by a glycosidic bond

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21
Q

N-glycosidic bond

A

when an anomeric carbon reacts with a nitrogen, always beta

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22
Q

O-glycosidic bond

A

when an anomeric carbon reacts with a hydroxyl - can be alpha or beta

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23
Q

Polysaccharides

A

polymers of sugars joined by glycosidic bonds.

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24
Q

Amylose

A

linear polymer, with alpha(1 -> 4) links between glucose monomers

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25
Q

Amylopectin and glycogen

A

branched polymer alpha(1 -> 4) linkages plus alpha (1 -> 6) linkages. Branched starches.

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26
Q

Glycoproteins

A

one or more oligosaccharides covalently joined to a protein. O-linked - oligosaccharide in a glycosidic bond with a serine or threonine hydroxyl. N-linked - oligosaccharide in an N-glycosidic bond to the amide nitrogen of an Asparagine residue

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27
Q

Cellular lipids

A

fats (triacylglycerols - TAGs), steroids, phospholipids. Amphipathic, long, unbranched hydrocarbon chains with a single carboxyl group at one end.

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28
Q

Fats (Triacylglycerols)

A

glycerol linked by ester bonds to three fatty acids

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29
Q

Fatty acids

A

differ in their length and presence of double bonds. Cis double bonds insert a bend into a hydrocarbon chain which reduces Van Der Waal interactions, thereby decreasing melting point.

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30
Q

Phospholipids

A

two fatty acid chains attached to a glycerol backbone which is bonded to a phosphate group (polar head group). Have two different properties: one end with a phosphate group (hydrophilic), the other end has two fatty acid tails (hydrophobic)

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31
Q

Peptide bond formation

A

carboxyl group + amino group in a dehydration reaction

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32
Q

Hydropathy index

A

the more negative the index = less soluble = more hydrophilic, will not be happy in the hydrophobic core. More positive = more soluble = more happy in the hydrophobic core. Polar charged will likely be on the surface, otherwise will likely be found inside the protein.

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33
Q

Protein structure

A

Primary - describes the unique order in which amino acids are linked together to form a protein.
Secondary - coiling or folding of a polypeptide chain that gives the protein its 3D shape (alpha helix, beta sheets).
Tertiary - comprehensive 3D structure of the polypeptide chain of a protein.
Quaternary - refers to the structure of a protein macromolecule formed by interactions between multiple polypeptide chains (assembled subunits)

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34
Q

Domain

A

a substructure produced by any part of a polypeptide chain that can fold independently into a stable structure that generally has a specific function.

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35
Q

Quaternary structure in a table

A

proteins that have more than 1 polypeptide chain has a quaternary structure. Largest protein is the one with the largest molecular weight.

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36
Q

Molecular chaperones

A

class of proteins that help other intracellular proteins fold. Proteins that bind and stabilize unfolded or partially folded polypeptides thereby preventing these proteins from aggregating and degrading.

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37
Q

Chaperonins

A

directly facilitate the folding of the proteins

38
Q

Biomembranes

A

composed of lipids, proteins, carbohydrates arranged in a bilayer, but in different proportions and different specific lipids, proteins, carbs.

39
Q

3 major lipids in cell membranes

A

phosphoglycerides, sphingolipids, cholesterol

40
Q

Phosphoglycerides

A

glycerol backbone, phosphate group, head group, 2 fatty acids

41
Q

Sphingolipids

A

instead of glycerol backbone, there is a sphingosine backbone and a fatty acid chain.

42
Q

Sphingomyelin

A

is the only one with a phosphate

43
Q

Cerebroside

A

sphingolipid with one sugar

44
Q

Ganglioside

A

sphingolipid with multiple sugars

45
Q

Cholesterol

A

complex molecule with OH group, rings. Amphipathic

46
Q

Ceramide

A

building block of sphingolipids

47
Q

Phospholipids

A

lipids with a phosphate group

48
Q

Phosphoglycerides

A

phospholipids built on a glycerol backbone. Phosphatidylserine has a net negative charge.

49
Q

Membrane biosynthesis

A

Step 1 - acyl transferases add two fatty acids to glycerol - 3 phosphate to produce phosphatidic acid.
Step 2 - a phosphatase removes the phosphate leaving DAG (diacylglycerol).
Step 3 - the addition of a head group

50
Q

Membrane lipids (sphingolipids)

A

sphingosine, ceramide, sphingomyelin

51
Q

Sphingosine:

A

an amino alcohol that contains a long hydrocarbon chain

52
Q

Ceramide

A

sphingosine linked to a fatty acid

53
Q

Sphingomyelin

A

phosphorylcholine added to a ceramide. The only sphingolipid that that is a phospholipid and a sphingolipid.

54
Q

Glycolipid

A

a carbohydrate added instead of a phosphorylcholine

55
Q

Glycoprotein and glycolipid orientation

A

found in the exoplasmic face of the plasma membrane. Sugar groups added in the lumen of the golgi

56
Q

Membrane proteins

A

integral proteins, peripheral proteins, lipid-anchored membrane proteins

57
Q

Integral proteins

A

penetrate and pass through lipid bilayer. Are amphipathic.

58
Q

Peripheral proteins

A

located entirely outside of bilayer on either the extracellular or cytoplasmic side

59
Q

Lipid-anchored membrane proteins

A

Proteins are covalently bound to a membrane anchored lipid.

60
Q

Types of lipid-anchored membrane proteins

A

acylation, prenylation

61
Q

Prenylation

A

lipid anchor is built from 5 carbon isoprene units attached to a carboxyl terminal cysteine. On the cytosol side of the membrane. Always faces interior of cell.

62
Q

Acylation

A

generally attached to an internal cysteine, serine, or an amino terminal glycine. protein is covalently attached to a fatty acyl group.

63
Q

GPI

A

attached to C-terminus of a protein during post-translational modification. Always faces outside of the cell. Attaches to a phosphatidylinositol which is attached to sugar units and an ethanolamine phosphate which attaches to the protein.

64
Q

Transmembrane domain

A

a string of about 20 mostly nonpolar amino acids that span the lipid bilayer as a helix.

65
Q

Hydropathy plot

A

anything above the 0 point is hydrophobic and will be found in the membrane. Below 0 is hydrophilic and will be outside of the membrane.

66
Q

Fluidity

A

membranes function only in the fluid state. HOT: don’t want kinks in the membrane, want straight chained fatty acids, decrease fluidity. COLD: want more fluidity, more kinks in the membrane, adding double bonds = more fluid

67
Q

Factors affecting fluidity

A

phospholipid content, length of and degree of saturation of fatty acyl chains, temperature, sterol content.

68
Q

Lipid rafts

A

cholesterol and sphingolipids pack together to form lipid rafts that float within the more fluid and disordered environment (or may be anchored). They provide a favourable environment for cell-surface receptors and GPI-anchored proteins and sequester proteins involved in cell signalling

69
Q

Bilayer thickness

A

bilayers with sphingomyelin and sphingomyelin and cholesterol are similar thickness, and are thicker than bilayers composed of phosphatidylcholine and phosphatidylcholine and cholesterol. Phosphatidylcholine and cholesterol are thicker than just phosphatidylcholine.

70
Q

Protein mobility

A

proteins can move. When 2 different membrane proteins are coloured and combined, they begin to mix. They will fully mix after a period of time, a result of protein movement.

71
Q

Lipid mobility

A

lipids can move. Phospholipid can move laterally within the same leaflet. To flip-flop, the hydrophilic head must pass through the hydrophobic centre.

72
Q

FRAP

A

fluorescence recovery after photobleaching. Can measure the diffusion rates of proteins. Label proteins with fluorescent dye, photobleach a spot with a laser, watch the protein recovery (proteins fill spot that was bleached)

73
Q

Passive transport

A

spontaneous movement down concentration gradient. No energy expended. Contains simple diffusion and facilitated diffusion.

74
Q

Active transport

A

against concentration gradient, requires an input of free energy (pumps)

75
Q

Simple diffusion

A

small molecules such as oxygen, CO2, ethanol. Have to be small and nonpolar enough to cross membrane without the aid of transport proteins. Movement of a solute from a region of higher concentration to lower concentration.

76
Q

Facilitated diffusion

A

requires a protein to get the molecule across the membrane.

77
Q

Membrane potential:

A

will influence charged molecules. Cytoplasmic side of membrane is usually negative relative to outside. Draws positive molecules in and drives negative molecules out.

78
Q

Glucose uptake graph

A

high Km/Kt is more able to bring glucose levels in the body down. Calcium is important in signal transduction. low Kt = transports less glucose but picks up glucose more readily. high Kt = transports more glucose but requires more glucose to be present as it has a lower affinity

79
Q

Carrier proteins

A

transport either one or two solutes. One solute = facilitated transport, 2 solutes = indirect active transport

80
Q

Uniport

A

transports a single molecule at a time down its concentration gradient

81
Q

Coupled transport

A

two solutes are transported at the same time. Either antiport or symport.

82
Q

Antiporter

A

simultaneously transports two molecules in opposite directions. One molecule moves down its concentration, and the other moves up.

83
Q

Symporter

A

simultaneously transports two different molecules in the same direction. One molecule moving down its concentration gradient and one molecule moves up.

84
Q

P class pumps

A

two identical catalytic alpha subunits that contain an ATP binding site. perform active ion transport across biological membranes

85
Q

P class pumps: Na+/K+ ATPase (pump)

A

Na+ concentration in the cytosol is much lower than extracellular fluid. K+ concentration in the cytosol is much higher than extracellular fluid. Na+ is always pumped out of the cell, K+ always pumped into the cell. Maintains intracellular sodium and potassium concentrations in animal cells which maintains osmotic balance and stabilizes cell volume.

86
Q

Ca2+pumps

A

P class pump that keeps intracellular Ca2+ concentrations low. Unidirectional pump from cytosol to lumen of SR.

87
Q

Glucose-Na+ symporter and glucose uniporter

A

work together to get glucose from the digestive system into the body. Sodium goes with its concentration gradient, glucose goes against its concentration gradient. The two types of transporters are kept segregated in the plasma membrane by tight junctions.

88
Q

Voltage-gated channels

A

conformational state depends on the difference in ionic charge on the two sides of the membrane

89
Q

Ligand-gated channels

A

conformational state depends on the binding of a specific molecule and can be either open or closed after ligand binding

90
Q

Mechano-gated (stress gated) channels

A

conformational state depends on mechanical forces that are applied to the membrane (ie. stretch tension)

MBB231 (10 decks)

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