Page 12 - Chapter 3: Cells and Tissues

f. Protein participate in gluconeogenesis

Protein can be converted to glucose in the liver; the glucose can
then be used as fuel or used to regulate blood glucose.

g. Ammonia Is associated with protein catabolism
Proteins contain nitrogen. The catabolism of protein generates
ammonia, NH 3.
h. Ammonia is toxic to the body, especially the brain. The liver
converts the ammonia to urea. The urea is eliminated in the
urine.

5. Protein synthesis and the genetic code

a. The three parts of a nucleotide
The three parts are sugar, phosphate group, and a base.

b. Purines and pyrimidines.

The purines are adenine and guanine. The pyrimidines are
cytosine, thymine, and uracil.

c. Bases can form pairs (base-pairing)
DNA: adenine pairs with thymine; cytosine pairs with guanine.
RNA: cytosine pairs with guanine; adenine pairs with uracil.
d. Differentiate between base-pairing and base-sequencing.

In base pairing, two bases bond in order to link strands of DNA
or RNA. Base-sequencing refers to the series of three bases
(along a strand of DNA or RNA) that codes for a particular
amino acid.

e. Base-pairing in DNA.
Two strands of DNA are held together by base-pairing. The
adenine pairs with thymine, while cytosine pairs with guanine.

f. Base-pairing is used in the formation of mRNA.
The double-stranded DNA opens up, exposing the genetic code
(base-sequencing). The mRNA reads the code by base-pairing
with the exposed DNA strand. The mRNA carries the code to
the ribosomes where protein is synthesized.

g. Example: If a strand of DNA reads: CGGATACATTCGAAA. What

is the sequence of the complimentary strand of DNA? What is
the sequence of the mRNA?

Answer. DNA: GCCTATGTAAGCTTT; mRNA: GCCUAUGUAAGCUUU
h. Difference between the function of mRNA and tRNA