AY Honors/Biochemistry/Answer Key

Biochemistry

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1. Define the following terms:

a. Carbohydrates

A carbohydrate is a molecule that is present in living organisms consisting of carbon, hydrogen, and oxygen atoms.

b. Lipid

Lipids are a group of molecules that include fats, waxes, sterols, Vitamin A, Vitamin D, Vitamin E, Vitamin K, monoglycerides, diglycerides, triglycerides, phospholipids. Lipids store energy, used in binding protein targets, and structural components of the cell membrane.

c. Fatty acid

Fatty Acids are carboxylic acids with a long hydrocarbon chain. They can be saturated or unsaturated.

d. Protein

Proteins consist of one or more long chains of amino acid residues. They are large biomolecules. Proteins have a lot of functions in organisms such as DNA replication, catalyzing metabolic reactions, responding to stimuli, and transporting molecules from one to another.

e. Peptide

A peptide is a compound consisting of two or more amino acids that are linked in a chain. They are short chains of amino acids.

f. Enzyme

Enzymes are biological molecules that act as catalysts. They accelerate the chemical reactions.

g. Amino acid

Amino Acids are used by cells in the body to build proteins.

h. Nucleic acid

Nucleic acids can be DNA, RNA, mRNA, and TRNA. They help replicate cells, and build proteins.

j. Triglyceride

A triglyceride is an ester which is a formation of carboxylic acid and alcohol. Triglycerides are the main body fat in mammals and vegetable fat.

5. Explain how the glucose pathway occurs.

It is a metabolic pathway that results in the generation of glucose from certain non-carbohydrate carbon substrates; eg protein breakdown products (certain amino acids), glycerol from breakdown of triglycerides (lipids) and from other steps in metabolism including pyruvate and lactate.

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6. Which human cells depend only on this pathway for energy?

brain cells

7. Which molecule links the glucose pathway and the Krebs Cycle?

oxaloacetate is an intermediate in both these biochemical pathways. it is also involved in the urea cycle, the glyoxylate cycle, amino acid synthesis, and fatty acid synthesis.

13. What are essential and non-essential amino acids?

Essential Amino Acids

There are amino acids that cannot be made by the human body. They only come from food. There are 9 types of Essential Amino Acids. They are isoleucine, leucine, histidine, lysine, methionine, phenylalanine, threonine, valine, tryptophan

Non-Essential Amino Acids

Our bodies make these amino acids. There are 4 types: asparagine, alanine, glutamic acid, aspartic acid.

15. What compounds are formed by the binding of amino acids? What are the main functions of these compounds?

Amino Acids forms proteins. They are organic compounds when combined that help build cells. When proteins from the Amino Acids break down they leave Amino Acids. The body uses the amino acids to break down food, grow, repair cells and skin cells. They can be stored and used for energy.