NUCLEICACIDSDNA UNIT 11: GENETICS AND GENETIC
LEARNING AIM A: UNDERSTAND THE
ENGINEERING
STRUCTURE AND FUNCTION OF
IN ORDER TO DESCRIBE GENE EXPRESSION AND
THE PROCESS OF
NUCLEIC ACIDS
PROTEIN
SYNTHESIS.
The nucleic acid is the storage and expression of genetic the human body•
infomation. It is the "insu-uction"for every characteristicand protein in the STRUCTURE AND FUNCTION OF NUCLEIC ACIDS.
The structure of it determines which genetic characteristic it is responsible is arranged in
for; it also determines the order in which a nucleotide OF DNA AND VARIOUS NUCLEIC ACID
are A.PI EXPLAIN THE STRUCTURE AND FUNCTION
nucleic acid polymer chain. They store genetic information and information for the synthesis of polynucleoddes•
proteins. Nucleic acids are
large molecules found inside the nucleus of a cell. Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are both nucleic acids HISTORY OF DNA
1866 —Gregor Mendel
HOW ARE NUCLEOTIDES PRODUCED? publishes his work on heredity
Nucleotides are produced by a condensation reaction beovveenthe hydroxyl functional group 4 of peas.
be compact and
(OH) of the sugar and the hydrogen atom of hydroxyl group on the phosphate and water is Structed in a helix so that it can 1944 —Experiments by
removed during the reaction; this is when the nitrogenous bases react and carry out a is able to be stored in the nucleus. Oswald Avery et al, show
condensation reaction as the hydroxyl functional group of carbon 1 on the sugar reacts with 3' evidence of DNA as the
a hydrogen atom on the base. carrier of genetic information.
HOW DO NUCLEOTIDES COMBINE?
combine to make a polynucleotide.The phosphate group of one nucleotide forms a 1950 —Erwin Chargaffs tules
phosphodiester bond by covalent bonds, with the hydroxyl (OH) group attached to the of base pairing are published.
carbon 3 sugar Of the next nucleotide. These produced a very strong sugar-phosphate t 952 —Rosalind Franklin and
5-carbon sugar) Maurice Wilkins obtain X-Ray
A nucleotide consists of three components: sugar such as pentose monosaccharide (a z
diffraction image of DNA.
phosphate groups and a nitrogenous base
1953 —James Watson and
ORGANIC NITROGENOUS BASES. [All carbon, hydrogen, oxygen, and nitrogen]
Francis Crick determine and
PYRIMIDINE: (simple Hng structure) publish paper on structureof
DNA double helix.
Thymine (I) is found only in DNA
Uracil (U) is only found in RNA. 196t —Genetic code is cracked
• Cytosine(C) by Marshall Nirenberg.
COMPLEMENTARY BASE PAIRING
PURINE: (double ring structures)
a & = two hydrogen bonds
• Adenine (A)
• Guanine (G)
& = three hydrogen binds.
h BASES :
essential proteins.
used to build organisms and produce
DNA: DNA stores genetic code,
nucleotides. Therefore, each strand is
helix. Polymers made from repeating units called
It is a Double condensation reaction, which will remove
nucleotide is linked to the next by
called a polynucleotide. Each makes 1 strand of DNA, the second
as a phosphodiester bond.
water. The bond form is known base pairing. The five
direction, the bases also add, complementary
strand is arranged in an antiparallel side of the DNA strands.
pHrne ends and 4 ends are used to determine each