Human Biochemistry Flashcards
What is metabolism?
The sum total of the metabolic reactions reactions in the body
Give two units that convey energy value of its food content.
calories, joules
What is a bomb calorimeter?
Measures the heat of combustion reactions
What is the formula for energy?
mass (g) x specific heat capacity x temperature change
If given the mass of food and the volume of water and temperature change, how do you calculate the energy value of the food in kjg^-1?
First solve for energy using the q=mct. Then divide q by the mass in grams of the food.
List major functions of proteins in the body.
Structural Hormones Immunoproteins Transport Enzyme Energy
Describe the structural role of proteins.
Make up the building blocks for our body. Makes up our structure.
Example:
Keratin - in hair and fingernails
Collagen - connective tendons in skin and tendons
Myosin - contractile action in muscles to bring about movement
Describe proteins as enzymes.
They are catalysts that lower the activation energy. This increases the rate of reaction.
Ex. Lactase hydrolyzes lactose into glucose and galactose.
Describe proteins as hormones
They control and regulate bodily functions by sending chemical messages into the blood stream.
Ex. Insulin - signals the cells to bring glucose from the blood stream into the cell.
Describe proteins as immunoproteins.
act as antibodies which help destroy foreign proteins in the blood
Describe proteins in their transportation roles.
move specific molecules throughout the body.
ex: hemoglobin- carries oxygen from the lungs to all respiring cells.
Name the functional groups of amino acids.
Central carbon is surrounded by a hydrogen, a amino group, a R group and a carboxylic acid.
How are amino acids characterized?
They are classified according to the chemical nature of their R group.
..Wait. What are amino acids?
Amino acids have properties similar to ionic compounds. ie- they are crystalline compounds with high melting points. Have a much greater solubility in water than in non polar solvents.
What’s the significance of AA’s having properties similar to ionic compounds?
Suggests that AAs exists as dipolar ions, or commonly known as zwitterions.
What is a zwitterion?
A group of atoms with a positive and negative charge.
How does a zwitterion form?
Result of internal acid-base reaction in an amino acid.
The H+ is transferred from the -COOH group and added to the NH2 group to form NH3.
Ok. Why is a zwitterion important?
It allows the protein to be amphoteric. duh.
Since amino acids are amphoteric they are able to act as…
buffers. Helps maintain pH in our body.
In terms of pH, characterize a positive. neutral, and negative ion.
Positive ion - low pH
Neutral ion - at its isoelectric point, no net pH, least soluble at this point
Negative Ion - higher pH
How do amino acids link together?
Through a condensation reaction between the acid group of one amino acid and the amino group of another amino acid. Water is eliminated. This bond is known as a peptide bond.
What is the primary structure of a protein?
The amino acid sequence. Sets foundation for the formation of following structures.
What is the secondary structure of proteins?
Regular hydrogen bonding. Hydrogen bonding can occur between amino acid molecules to produce alpha helix (spiral) or the beta pleated sheet.
Describe te a-helix spiral.
It’s a spiral. Flexible and elastic because the hydrogen bonds break easily. “intra-chain” h-bonds
Good example is in keratins.
Describe the b-pleated sheet.
Composed of “side-by-side” polypeptides. “inter-chain” h bonds.
Flexible, not elastic.
What is the tertiary structure of proteins?
Refers to the 3D shape created due to the interactions between the R groups of amino acids. This 3D shape is called conformation.
Compare and contrast fibrous and globular proteins.
Fibrous - tough, insoluable
Globular - water soluble.
Name some interactions that occur between R groups in the tertiary structure.
- Hydrophobic interactions - between non-polar side chains.
- Hydrogen bond - between polar
- Ionic bond - between side chains carrying a charge
- Disulfide bridges - between sulfide atoms in the amino cysteine
