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MCB 150 > Lecture 5-10 > Flashcards

Lecture 5-10 Flashcards

1
Q

Name the characteristics of lipids

A
  • vary widely in structure
  • defined by at least partially insoluble in water
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2
Q

What is the function of lipids

A
  • energy storage (triglycerides)
  • biomembrane composition: phospholipids and glycolipids
  • chemical signaling (steroids)
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3
Q

What are the monomers of lipids for membrane lipids

A
  • fatty acids
  • backbone molecule (glycerol)
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4
Q

What does it mean if a lipid is:
- saturated
- unsaturated

A
  • saturated: does not contain any C=C double bonds
  • unsaturated: contains C=C double bonds
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5
Q

What makes a triglyceride solid/liquid at room temp

A

Degree of saturation of the lipid

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6
Q

1st

A
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7
Q

How can fatty acids vary in a phospholipid?

A
  • length
  • saturation of tail
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8
Q

What does it mean to be amphipathic?

A
  • a molecule consisting of a hydrophobic and hydrophilic group.
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9
Q

Describe the structure and function of steroids

A
  • used as circulating hormones or as membrane components
  • consistent of a steroid ring steroids
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10
Q

In what ways do phospholipids move within the membrane?

A
  • flex (very rapid) - rotating in place
  • transverse diffusion (very slow) - moving
  • Lateral shift (rapid) -moving within the leaflet
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11
Q

Why is transverse diffusion so slow?

A
  • polar (hydrophilic) heads need to move through the hydrophobic tail region.
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12
Q

How does the level of saturation effect fluidity of the membrane

A
  • Highly saturated: increases fluidity
  • Less saturated: decreases fluidity
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13
Q

How does the tail length of fatty acids affect fluidity of the cell membrane?

A
  • Short chains: increases
  • long chains: decrease
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14
Q

How does the number of cholesterol molecules effect membrane fluidity at low temps

A
  • high: increases
  • low: decreases
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15
Q

How does the number of cholesterol molecules effect membrane fluidity at high temps

A
  • high number: decreases
  • low number: increases
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16
Q

What is a nucleoside?

A
  • the base and the sugar in the nucleotide
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17
Q

What are the differences between RNA and DNA?

A
  • DNA:
  • Deoxyribose sugar
  • has the thiamine base
    RNA:
  • has a ribose sugar
  • has the uracil base
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18
Q

What are the pyrimidines?

A
  • uracil
  • cytosine
  • thymine
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19
Q

What are the purines?

A
  • adenine
  • guanine
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20
Q

What are the purines?

A
  • adenine
  • guanine
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21
Q

What is the difference in structure between ribose and deoxyribose?

A
  • on C 2’, deoxyribose has ONE LESS OXYGEN than ribose
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22
Q

What are DNA monomers?

A
  • deoxyribonucleoside triphosphates (dNTPs)
  • n stands for the nitrogenous base (eg dGTP for guanine in that nucleotide)
23
Q

What are RNA nucleotides?

A
  • ribonucleoside triphosphate (NTP)
24
Q

What are some functions of proteins? (4)

A
  • act as enzymes
  • structure (keratin)
  • defense (antibodies)
  • movement (actin/myosin)
25
Q

What are the monomers of proteins
What bonds formed between amino acids?

A
  • amino acids
  • peptide bonds
26
Q

How is a peptide bond formed?

A
  • from the N to C direction
  • from a condensation reaction, between the N and C of adjacent amino acids
27
Q

What is it called if it is a polypeptide with a purpose?

A
  • proteins
28
Q

What are the 4 categories amino acids can be put in

A
  • uncharged but polar
  • non polar
  • basic (positively charged) - proton acceptor
  • Acidic (negatively charged) - proton donor
29
Q

What is the primary structure of a protein?

A
  • linear sequence of amino acids
30
Q

What is the secondary structure?

A
  • first level of folding
  • stabilized by hydrogen linkages between peptide linkages
  • independent of R groups
  • a helixes and b pleated sheets as main types
31
Q

Describe the structure of keratin

A
  • very rich a helical structure
  • coiled coils
32
Q

What is a prion

A
  • misfolded proteins which induce normal versions (the wild type) of that protein to fold the same incorrect way.
33
Q

How can prions cause disease?

A
  • misfolded protein comes out of solution, which creates plaques when proteins precipitate
  • causes transmissible spongiform encephalopathies (TSEs) eg: mad cow disease
34
Q

Describe aspects of the tertiary structure

A
  • unique 3D structure
  • final configuration of some proteins
  • due to interactions between R groups with each other and backbone
35
Q

What type of bonds can be formed in a tertiary structure?

A
  • H bonds between polar side chins
  • H bonds between hydrophilic side chins and backbone
  • ionic bond between acidic and basic amino acid
  • hydrophobic clustering of non-polar side chains
  • disulfide linkages
  • Van Der Waals forces
36
Q

How does water influence a protein?

A
  • it contorts the protein so that its hydrophilic R groups are on the outside and hydrophobic R groups are on the inside
37
Q

Describe aspects of the quaternary structure

A
  • multiple polypeptide chains Held together.
38
Q

What are the relative stabilities of bimolecular forces? (Most stable - least stable)

A
  • disulfide linkages: covalent
  • ionic bonds: easily made and broken
  • hydrogen bonds
  • hydrophobic clusters
  • Van der Vaals
39
Q

What does denaturing mean?

A
  • removal or activation of stabilizing forces that makes it go back to the primary structure, but NO peptide bonds are broken.
40
Q

What do molecular chaperones do?

A
  • prevent incorrect folding of a protein
41
Q

What do you call reactions that require energy?

A
  • Biosynthetic or anabolic
  • linking together of smaller molecules into larger ones like condensation reactions
42
Q

What do you call reactions that release energy?

A
  • catabolic/spontaneous
  • breaks down larger molecules into smaller ones like hydrolysis reactions.
43
Q

What is meant by spontaneous? (In biology terms)

A
  • a reaction that releases energy, much of which is lost through heat.
44
Q

Key points about enzymes (2)

A
  • will only speed up rates of existing reaction, not make a reaction happen which won’t happen.
  • do not effect position of equilibrium, only speed up rate of forward reaction.
45
Q

What is delta G

A
  • difference in E between reactants and products
46
Q

How does substrate binding to active site decrease Ea (4)

A
  • acting as a template for substrate orientation
  • stressing the substrate and stabilizing the transition state
  • providing a favorable micro environment
  • participating directly in the catalytic reaction.
47
Q

What is a exergonic reaction?

A
  • a reaction that has a -delta G
48
Q

What is an endergonic reaction?

A
  • has a positive delta G
49
Q

Describe irreversible inhibition

A
  • permanently bind to or modify active site of enzyme, changing conc of original substrate or inhibitor has no effect.
  • only can make more of that enzyme to overcome this - have to increase enzyme conc to overcome this.
50
Q

Describe competitive inhibition

A
  • inhibitor molecule binds to active site instead of substrate
  • prevents substrate from being converted into products.
  • can be overcome by increasing substrate conc or reducing inhibitor molecule conc
51
Q

Describe non competetive inhibiton

A
  • an inhibitor moleule binds to a second active site (allosteric site) on the enzyme, which modifies the shape of the original active site, preventing substrate from being converted to products
  • increasing substrate conc has no effect, but can reduce inhibitor conc.
52
Q

What is Km?

A
  • the concentration of substrate which permits the enzyme to achieve HALF of Vmax (the max rate of reaction)
53
Q

What effect does competetive inhibition effect Km?

A
  • Vmax stays the same
  • Km increases
54
Q

What effect does non competetive inhibition have on Km and Vmax?

A
  • Km stays the same.
  • lowers Vmax

MCB 150 (8 decks)

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