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MCAT Biology > Molecular Biology and Cellular Respiration > Flashcards

Molecular Biology and Cellular Respiration Flashcards

Exam Krackers MCAT Biology Lecture 1

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1
Q

Define a Lipid

A

Any biological molecule with low solubility in H2O and high solubility in nonpolar organic solvents.

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2
Q

Describe Fatty Acids (FAs)

A
  • Building blocks for most complex lipids
  • long chain of carbon with a carboxilic acid at one end.
  • longest number of carbons in humans is 24
  • oxidation of FAs release larges amt of chemical energy
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3
Q

What is the difference between saturated and unsaturated FAs?

A
  • Saturated FAs consist of only single C-C bonds
  • Unsaturated contain one or more C=C double bonds
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4
Q

Describe Triacylglycerols (aka triglycerides)

A
  • fats and oils
  • made of glycerol (3 Carbon) backbone attached to 3 FAs.
  • function in a cell to store energy, also insulation and padding
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5
Q

What are Adipocytes?

A
  • fat cells
  • cells cytoplasm contains almost nothing but triglycerides.
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6
Q

Describe Phospholipids…

A
  • has a glycerol(3 C) backbone attached to 2 FAs and 1 polar phosphate group
  • polar at the phosphate end and nonpolar at the fatty acid end
  • structural components of cellular membranes
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7
Q

Define Amphipathic

A
  • when a molecule is polar at one end and nonpolar at the other end
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8
Q

Describe Glycolipids

A
  • has a Glycerol(3C) backbone
  • similar to a phospholipid, except it has 1 or more carbohydrates attached to the glycerolin place of the phosphate group.
  • also amphipathic
  • abundantly found in membranes of myelinated cells in the nervous system
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9
Q

Describe Steroids

A
  • regulate metabolic activities
  • 4 ringed structures
  • include some hormones, vitamin D, and cholesterol
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10
Q

Describe Terpenes

A
  • include Vitamin A (important for vision)
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11
Q

Describe Eicosanoids

A
  • are released from cell membranes as local hormones to regulate BP, body temp, SM contraction… among other things
  • another class of lipids
  • 20 Cs
  • include protoglandins, -thromboxanes, leukotriens
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12
Q

Aspirin

A
  • commonly used as an inhibitor of prostaglandin synthesis.
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13
Q

lipids are transported in the blood via ______

A

lipoproteins

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14
Q

Describe Lipoproteins

A
  • has a lipid core surrounded by phospholipids and apoproteins
  • classified by their densisty, the greater the ratio of lipid to protein , the lower the density
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15
Q

What are some major classes of lipoproteins in humans

A
  • chylomicrons, VLDL(very low density lipoproteins), LDL(low density lipoproteins), and HDL(high density lipoproteins)
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16
Q

Describe Proteins

A
  • built from AAs (Amino Acids) linked together by peptide bonds
  • are polypedtides
  • most are built from the same 20 AAs
  • AAs differ from each other by side chains (R groups)
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17
Q

What are Essential AAs

A
  • the 10 AAs that that the human body does not make, they must be ingested through diet
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18
Q

Primary structure

A
  • # of polypeptides chains
  • # and sequence of AAs
  • location of disulfide bond
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19
Q

Secondary Structure

A
  • a-helix and b-pleated sheets
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20
Q

How are alpha helices and beta pleated sheets reinforced?

A

By H-bonds between the carbonyl Oxygen and the Hydrogen on the amino group

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21
Q

Tertiary Structure

A
  • peptidde chain curling up into globular shape
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22
Q

What forces contribute to formation of tertiary structure

A
  • covalent dissulfide bonds between 2 cysteine AAs on different parts of the chain.
  • ionic (electrostatic) interactons mostly between acidic and basic side chains
  • H-bonds
  • van der Waals forces
  • hydrophobic side chains pushed into the center of the glob
  • Proline –its structure does not allow it to conform to the a-helix
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23
Q

Quaternary structure

A

when 2 or more globular proteins bind together

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24
Q

What is the structure of a generic AAs.. Glycine

A

draw pic

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25
Q

Structural proteins

A
  • made from long polymers
  • maintain and add strength to cellular and matrix structure
  • an example is collagen
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26
Q

Describe Collagen

A
  • structural protein made of 3 a-helices wound around each other
  • Most abundant protein in the body
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27
Q

Glyco Proteins

A
  • proteins with carbohydrate groups attached
  • component of cellular membranes
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28
Q

Describe Carbohydrates

A
  • also called sugars and saccharides
  • made of Carbon and Water
  • empirical formula C(H2O)
  • Most common are the 5 and 6 Carbon carbohydrates (pentoses and hexoses)
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29
Q

Glucose

A
  • 6 carbon
  • animals eat the Alpha linkages (starch and Glycogen) Bacteria break doen the Beta linkages (Cellulose)
30
Q

Starch

A
  • poly saccharide
  • Alpha 1-4 linkage of Glucose
31
Q

Glycogen

A
  • polysaccharide
  • Alpha 1-4 linkage and Alpha 1-6 linkage
32
Q

Cellulose

A
  • polysaccharide
  • Beta 1-4 linkage
33
Q

What are Nucleotides composed of?

A
  • A 5 Carbon sugar
  • A Nitrogenous Base
  • A Phosphate Group
34
Q

How are nucleotides written?

A

From 5’ –> 3’

35
Q

Nucleotides from polymers to create

A

nucleic acids, DNA, RNA,

  • also composes ATP, cAMP, NADH, FADH -
36
Q

Nucleotides are joined together by

A

Phosphodiester bonds from the phosphate of one nucleotide to the 3rd Carbon of the pentose of the other nucleotide.

37
Q

Describe Minerals

A

dissolved ions inside and outside the cell

  • assist in transport of substances in/out of cells by creating an electrochemical gradient
  • can combine and solidify to give strength to a matrix ex: hydroxyapatite in bone
  • can act as cofactors assisting enzyme or protein function ex: iron is a mineral found in heme, the prosthetic group of cytochromes
38
Q

Describe Enymes

A
  • are typically globular proteins
  • act as catalyst to lower activation energy
  • increase rate of rxn by great magnitudes( thousands, trillions)
  • do not alter the equilibrium of the rxn
  • are very specific
39
Q

Vmax is proportional to ..

A

Enzyme concentration

40
Q

What is turnover number?

A

the number of substrate molecules one enzyme can convert to product in a given time when the enzyme solution is saturated.

41
Q

Describe Km (Michaelis constant)

A
  • it is the substrate concentraation at which the rxn rate is equal to 1/2 Vmax.
  • is not dependant on enzyme concentration
  • indicator of an enzyme’s affinity for its substrate
42
Q

Describe Co-factors

A
  • they can be Coenzymes, or Metal ions
  • many enzymes require a cofactor to reach their optimal activity
43
Q

Describe Coenzymes

A
  • they are organic molecules divided into co-substrates and prostetic groups
  • many coenzymes are vitamins or their derivatives
44
Q

How is Rxn rate affected by increases in

  • Temp.
  • pH
  • [substrate]
A
  • Rxn rate increase with Temp to a maximum point and then SWIFTLY decreases
  • Rxn rate increases with pH to a max rate and then decreases at the same rate
  • Rxn rate increases with increase in [substrate] towards a maximum rate.
45
Q

What Irreversible Enzyme Inhibition?

A
  • when agents (usually covalently) bind irreversible to enzymes and permanently alter their function
  • mostly highly toxic
46
Q

What is Competative Inhibition?

A
  • compete with substrate for binding( reversibly, noncovalent) at the active site
  • This type of inhibition can be overcome by increasing the [substrate]
  • Does not change Vmax
47
Q

What is Noncompetitive Inhibition?

A
  • when the inhibitior binds to an allosteric site and cause a conformation change of the enzyme
  • Do not prevent the substrate from binding
  • inhibitor can bind to a enzyme-substrate compex
  • not as specific, can act on more than one enzyme
  • Can not be over come by increase in [substrate]
  • they lower Vmax
  • they do Not lower affinity of enzyme for substrate so Km remains the same
48
Q

What are four types of Enzyme regulation?

A
  • Proteolytic cleavage
  • Reversible covalent modification
  • Control Proteins
  • Allosteric interactions
49
Q

Inactive forms of enzymes are called…

A

zymogen, or proenzyme

50
Q

Describe proteolytic cleavage

A
  • specific peptides on zymogen are cleaved the zymogen becomes irreversible actvated
  • activation can occur from change in environment (like pH, temp) or by other enzymes
51
Q

Describe Reversible covalent modification

A
  • many enzymes activated or deactivated by phosphorylation or the addition of some other modifier such as AMP.
  • hydrolysis is usually used to remove the modifier
  • phosphorylation typically occurs in the presence of a kinase
52
Q

Describe Control Proteins

A
  • protein subunits that associate with certain enzymes to activate or inhibit their activity.
  • ex: calmodulin or G-protein
53
Q

Describe Allosteric interactions

A

modification of enzyme configuration resulting from binding of activator or inhibitor to an allosteric site.

54
Q

Feedback Inhibition

A

-Negative

down stream product of a rxn comes back and inhibits enzyme activity in an earlier part of the same rxn series

  • Positive is when it activates
55
Q

Enzymes are classified into six categories

A
  1. Oxidoreductases
  2. Transferases
  3. Hydrolases
  4. Lyases
  5. Isomerases
  6. Ligases
56
Q

What is kinase?

A
  • an enzyme that phosphrylates or dephosphorylates somthing, usually to activate or deactivate it.
57
Q

Describe synthases

A
  • are lyases that catalyze the addition of one substrate to a double bond of another substrate.
  • ex: ATP synthase
58
Q

Describe ligases

A
  • also called synthetases
  • also governs an addition rxn, but requires energy from ATP or some other nucleotide.
59
Q

Whenever I see a molecule with Nitrogen think of …

A

Proteins and thus it can be denatured

60
Q

What is metabolism?

A
  • all cellular chemical rxns consists of
  • anabolism- molecular synthesis
  • catabolism- molecular degradation -
61
Q

What are the products of Glycolysis?

A
  • 2 ATP
  • 2 NADH
  • 2 Pyruvate
62
Q

Describe the process of Fermentation?

A
  • anaerobic
  • the reduction of pyruvate to ethanol or lactic acid
  • Oxidation of NADH to NAD+
  • CO2 and H2O is also released
63
Q

What is produced in each turn of the Kreb’s cycle?

A
  • 1 ATP
  • 3 NADH
  • 1 FADH2

(each glucose molecule makes 2 turns)

(Kreb’s cycle occurs in the mitochondria matrix)

64
Q

How many ATPs do NADH and FADH2 bring back respectivly?

A
  • NADH 2-3 ATPs
  • FADH2 2 ATPs
65
Q

Aerobic Respiration produces about _____ net ATPs.

A

36-38

66
Q

Oxidative Phosphorylation

A

is the metabolic pathway in which the mitochondria in cells use their structure, enzymes, and energy released by the oxidation of nutrients to move hydrogen from ADP to phosphate to reform ATP.

  • During oxidative phosphorylation, electrons are transferred from electron donors to electron acceptors such as oxygen, in redox reactions.

These redox reactions release energy, which is used to form ATP.

67
Q

Glucose + O2 –>

A

H2O + CO2

  • a combustion rxn
68
Q

What is the net ATP production from fermentation?

A
  • 2 ATPs
  • Fermentation includes the process of glycolysis which produces 2 ATP
69
Q

What are the 6 major groups of lipids?

A

FAs,

Triacylglycerols,

Phospholipids,

Glycolipids,

Steroids, and

Terpenes.

70
Q
A

MCAT Biology (6 decks)

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