Biochemistry Review Flashcards
Carbohydrates
Sugar molecules that provide energy, store energy, spare protein, and prevent ketosis
- Glucose energy is stored as glycogen, with the majority of it in the muscle and liver.
- The liver uses its glycogen reserve as a way to keep blood-glucose levels within a narrow range between meal times.
- The presence of adequate glucose in the body spares the breakdown of proteins from being used to make glucose needed by the body.
- Adequate glucose also prevents ketosis which can make the blood too acidic.
3 types:
- Sugars (simple carbs)
- Starches (complex carbs)
- Fibers (complex carbs)
Made of C, H and O
- 1:2:1
Energy Production:
- Most cells prefer glucose as energy source (brain ONLY uses glucose)
- ~70% of glucose from digestion is put back into the blood for tissue use by the liver
- Cells that require energy remove glucose from blood using transport protein in their membrane
- Energy from glucose comes from chem bonds btw Carbon atoms; cells in our body break the bond and use energy for cellular respiration
Energy Storage:
- Excess glucose stored as glycogen in muscles and liver
- 1 molecule of glycogen contains >50,000 glucose units (highly branched)
- When glycogen reserve is used up, body relies on lipids and proteins as fuel source (hitting the wall)
- ~1/4 total glycogen storage is in the liver
- Liver uses glycogen reserve to keep blood-glucose levels within a narrow range btw meals.
- When liver’s glycogen supply is exhausted, glucose is made from amino acids obtained from the destruction of proteins (gluconeogenesis)
Fats and Lipids
Lipids function as an energy reserve, regulate hormones, transmit nerve impulses, cushion vital organs, and transport fat-soluble nutrients
- Excess energy from food is stored as adipose tissue in the body
- Lipids contain the same elements as carbohydrates: C, H and O
- However, lipids are mainly made of hydrocarbon chains (or rings) and contain fewer polar hydroxyl groups (-OH).
- This makes most lipids nonpolar hydrophobic molecules
- In the stomach fat is separated from other food substances.
- In the small intestines bile emulsifies fats while enzymes digest them.
- The intestinal cells absorb the fats.
- Long-chain fatty acids form a large lipoprotein structure called a chylomicron that transports fats through the lymph system.
Proteins
Proteins are macromolecules composed of amino acids
- Contains C, H, O and N
- Each amino acid contains a central C, Amino group (H-N-H), Carboxylic acid group (O=C-OH) and a side chain (R)
- The building of a protein consists of transcription, translation, and protein folding
- SHAPE determines FUNCTION; A change in the amino acid sequence will cause a change in protein shape
Electrostatic (IMF)
The electrostatic force is the force of attraction or repulsion between two charged particles
- Strong interaction btw ions
- H2O has a large dielectric constant
- Stabilizes zwitterion formation
Polarizability (IMF)
Measures distortion of electron cloud by other nuclei and electrons
- A measure of how easily an electron cloud is distorted by an electric field
Dipole Moment (IMF)
Asymmetric electron distribution gives partial charge to atoms
London Dispersion Forces (IMF)
Attraction due to induced dipole moments
- Force increases with dipole moment
Dipole-Dipole Interaction (IMF)
Positive end of one dipole is attracted to the negative end of another dipole
- Strength increases with dipole moment
Hydrogen Bonding (IMF)
Enhanced dipole interaction btw H and long-pair of neighboring S, N, or O (SNO)
- Gives structure to liquid water
- Solubilizes alcohols, fatty acids, amines, sugars and AA’s
Hydrophobic
- Repelled by polar group
- Insoluble in H2O
- Affinity for nonpolar
- HydroPHOBIC = LipoPHILIC
e.g. alkanes, alkenes, arenes
Hydrophilic
- Repelled by nonpolar group
- Soluble in H2O
- Affinity for polar
- HydroPHILIC = LipoPHOBIC
e.g. alcohols, amines, carboxylic acid
Amphipatic
(of a molecule, especially a protein) having both hydrophilic and hydrophobic parts.
- BOTH polar and nonpolar functionality
- common for most biochemical molecules
- fatty acids, AA’s and nucleotides
