Lecture 5-10 Flashcards
1
Q
Name the characteristics of lipids
A
- vary widely in structure
- defined by at least partially insoluble in water
2
Q
What is the function of lipids
A
- energy storage (triglycerides)
- biomembrane composition: phospholipids and glycolipids
- chemical signaling (steroids)
3
Q
What are the monomers of lipids for membrane lipids
A
- fatty acids
- backbone molecule (glycerol)
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
5
Q
What makes a triglyceride solid/liquid at room temp
A
Degree of saturation of the lipid
6
Q
1st
A
7
Q
How can fatty acids vary in a phospholipid?
A
- length
- saturation of tail
8
Q
What does it mean to be amphipathic?
A
- a molecule consisting of a hydrophobic and hydrophilic group.
9
Q
Describe the structure and function of steroids
A
- used as circulating hormones or as membrane components
- consistent of a steroid ring steroids
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
11
Q
Why is transverse diffusion so slow?
A
- polar (hydrophilic) heads need to move through the hydrophobic tail region.
12
Q
How does the level of saturation effect fluidity of the membrane
A
- Highly saturated: increases fluidity
- Less saturated: decreases fluidity
13
Q
How does the tail length of fatty acids affect fluidity of the cell membrane?
A
- Short chains: increases
- long chains: decrease
14
Q
How does the number of cholesterol molecules effect membrane fluidity at low temps
A
- high: increases
- low: decreases
15
Q
How does the number of cholesterol molecules effect membrane fluidity at high temps
A
- high number: decreases
- low number: increases
16
Q
What is a nucleoside?
A
- the base and the sugar in the nucleotide
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
18
Q
What are the pyrimidines?
A
- uracil
- cytosine
- thymine
19
Q
What are the purines?
A
- adenine
- guanine
20
Q
What are the purines?
A
- adenine
- guanine
21
Q
What is the difference in structure between ribose and deoxyribose?
A
- on C 2’, deoxyribose has ONE LESS OXYGEN than ribose
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
What are the monomers of proteins
What bonds formed between amino acids?
- amino acids
- peptide bonds
26
How is a peptide bond formed?
- from the N to C direction
- from a condensation reaction, between the N and C of adjacent amino acids
27
What is it called if it is a polypeptide with a purpose?
- proteins
28
What are the 4 categories amino acids can be put in
- uncharged but polar
- non polar
- basic (positively charged) - proton acceptor
- Acidic (negatively charged) - proton donor
29
What is the primary structure of a protein?
- linear sequence of amino acids
30
What is the secondary structure?
- 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
Describe the structure of keratin
- very rich a helical structure
- coiled coils
32
What is a prion
- misfolded proteins which induce normal versions (the wild type) of that protein to fold the same incorrect way.
33
How can prions cause disease?
- misfolded protein comes out of solution, which creates plaques when proteins precipitate
- causes transmissible spongiform encephalopathies (TSEs) eg: mad cow disease
34
Describe aspects of the tertiary structure
- unique 3D structure
- final configuration of some proteins
- due to interactions between R groups with each other and backbone
35
What type of bonds can be formed in a tertiary structure?
- 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
How does water influence a protein?
- it contorts the protein so that its hydrophilic R groups are on the outside and hydrophobic R groups are on the inside
37
Describe aspects of the quaternary structure
- multiple polypeptide chains Held together.
38
What are the relative stabilities of bimolecular forces? (Most stable - least stable)
- disulfide linkages: covalent
- ionic bonds: easily made and broken
- hydrogen bonds
- hydrophobic clusters
- Van der Vaals
39
What does denaturing mean?
- removal or activation of stabilizing forces that makes it go back to the primary structure, but NO peptide bonds are broken.
40
What do molecular chaperones do?
- prevent incorrect folding of a protein
41
What do you call reactions that require energy?
- Biosynthetic or anabolic
- linking together of smaller molecules into larger ones like condensation reactions
42
What do you call reactions that release energy?
- catabolic/spontaneous
- breaks down larger molecules into smaller ones like hydrolysis reactions.
43
What is meant by spontaneous? (In biology terms)
- a reaction that releases energy, much of which is lost through heat.
44
Key points about enzymes (2)
- 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
What is delta G
- difference in E between reactants and products
46
How does substrate binding to active site decrease Ea (4)
- 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
What is a exergonic reaction?
- a reaction that has a -delta G
48
What is an endergonic reaction?
- has a positive delta G
49
Describe irreversible inhibition
- 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
Describe competitive inhibition
- 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
Describe non competetive inhibiton
- 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
What is Km?
- the concentration of substrate which permits the enzyme to achieve HALF of Vmax (the max rate of reaction)
53
What effect does competetive inhibition effect Km?
- Vmax stays the same
- Km increases
54
What effect does non competetive inhibition have on Km and Vmax?
- Km stays the same.
- lowers Vmax
