Download A Getting-It-On Review and Self

A Getting-It-On Review and Self-Test
Nucleic Acids
The great variety of proteins found in any organism does not arise by
chance. The substances that direct the course of protein synthesis are
known as (1)
. The two major types are known by
abbreviations, (2)
and (3)
. There are several
major differences between these types of nucleic acids. RNA contains the
sugar (4)
, while DNA contains (5)
. DNA is a
double-stranded (6)
, while RNA is only (7)
stranded. In addition, one of the pyrimidine bases is different. DNA
contains the base (8)
and RNA contains (9)
. The
term nucleoside refers to either the purine or pyrimidine base joined with
a (10)
molecule. There are (11)
such
nucleosides, each with a specific abbreviation. So that A stands for
(12)
, dG stands for (13)
, T stands for (14)
, and dU stands for (15)
. In nucleic acids, the actual
building blocks are phosphate esters of nucleosides. These molecules are
called (16)
. There are specific abbreviations. AMP stands
for (17)
, ADP for (18)
, and ATP for (19)
. These last two nucleotides are extremely important biological
compounds as easily obtainable chemical energy resides in their
hydrolyzable (20)
bonds. When ATP is hydrolyzed to ADP
and inorgainic phosphate via an enzyme catalyzed reaction, a
considerable amount of energy is released.
In the double-stranded helix of DNA, it has been found that (21)
pairing occurs between purine and pyrimidine bases, dAMP pairs with
(22)
and dG pairs with (23)
. The genetic information
contained in the cell’s genes is found to be the exact sequence of
nucleotides along the DNA strands. When DNA replicates itself during
normal cell division called (24)
, the two daughter cells have
the same double-stranded DNA sequences as the original cell. During sex
cell production, called (25)
, only half of the genes or DNA
sequences are present in the new cells. When fertilization takes place the
zygote has a normal complement of genes, half from the mother and half
from the father. Each gene, which directs the synthesis of one protein,
contains what is termed the genetic code. Each codon, for a specific
amino acid, is composed of (26)
nucleotides in sequence. The
intermediate compound, which carries the information from the nucleus
(site of the DNA) to the ribosomes (site of protein synthesis), is a type of
ribonucleic acid called (27)
. The ribonucleic acid, which
brings various amino acids to the ribosomes, is called (28)
and has the shape of a (29)
. Each loop of a particular t-RNA
has a purpose.
2
If, for some reason, the DNA structure is changed or a breakdown occurs
in the protein synthesis process, a (30)
may occur. Most
severe cases result in an organism’s death, but sometimes the organism
survives. For example sickle cell anemia results from (31)
change(s) in an amino acid in one chain of hemoglobin.
32.
Match the term on the left with a phrase or term on the right.
(1)
(2)
(3)
(4)
guanine
cytosine
transfer RNA
uracil
(5) messenger RNA
(6) ribosomal RNA
(7) adenine
(8) thymine
(9) genome
a. purine base
b. cause cells to become cancerous
c. pyrimidine base
d. carries genetic info from DNA
to ribosomes
e. condons for the start of protein
synthesis
f. brings amino acids to the
ribosomes for incorporation into
protein
g. nucleotide that is primary source
of energy for protein synthesis
h. part of structure at which protein
synthesis occurs
i. sum of all hereditary material in a
cell
(10) oncogenes
(11) AUG and GUG
(12) ATP
33.
Using the table below, for each codon in the following mRNA, write
the amino acid sequence that would be placed in the protein.
mRNA: GGG AGU CCC GCG
3
ANSWERS
(1) nucleic acids
(2) DNA
(3) RNA
(4) ribose
(5) deoxyribose
(6) helix
(7) single
(8) thymine
(9) uracil
(10) sugar
(11) 10
(12) adenosine
(13) deoxyguanosine
(14) thymidine
(15) deoxyuridine
(16) nucleotides
32.
(1) a
(2) c
(3) f
(4) c
(5) d
(6) h
(7) a
(8) c
(9) i
(10) b
(11) e
(12) g
33.
—Gly—Ser—Pro—Ala—
(17)
(18)
(19)
(20)
(21)
(22)
(23)
(24)
(25)
(26)
(27)
(28)
(29)
(30)
(31)
adenosine monophosphate
adenosine diphosphate
adenosine triphosphate
phosphate
complementary
dT
dC
mitosis
meiosis
3
messenger RNA
transfer RNA
cloverleaf
mutation
1