Unit 11: Genetics and Genetic Engineering
Leaning Aim, A: Understand the structure and function of nucleic acids in order to describe
gene expression and the process of protein synthesis
Structure and Function of nucleic acids
A.M1 Discuss the functional role of nucleic acids in DNA (deoxyribonucleic acid) in the stages
of protein synthesis
Nucleic acids are polynucleotides, long chains of nucleotides created by monomers joined
together which store genetic information in biological systems. Deoxyribonucleic Acid and
Ribonucleic Acid are two of the main types of nucleic acids that are polymers made up of
monomers called nucleotides. Nucleotide consists of a nitrogenous base, pentose sugar and
phosphate group. In DNA, the bases are adenine,thymine,cytosine, and guanine but in RNA
(ribonucleic acid) the thymine is replaced with uracil. Nucleic acids are responsible for the
synthesis of proteins as well as the transmission of inherent characters from parent to
offspring. Transcription and Translation are two sequential processes that take place during
the synthesis of proteins. To produce mRNA, transcription takes place in the cell nucleus
using the DNA base sequence. The cytoplasm is where translation takes place, and the
mRNA carries the instructions for producing a particular protein there. The information
contained in a string of three-letter words in the mRNA is transformed during translation
into a string of amino acids, which serve as the building blocks of proteins.
The speed of chemical reactions like respiration is regulated by proteins acting as enzymes.
As part of the structure of skin, bone, and muscle, proteins also function as antibodies that
ward off infections. Proteins are made in various levels of structure, primary in which the
amino acid in a polypeptide, secondary is when the primary polypeptide fold on itself
creating an alpha helix or beta sheet, tertiary is a 3D shape with extra folding using
ioni,hydrogen,dusulfide bonds, this structure makes a functional protein like enzyme and
quaternary is when there is more than one polypeptide. Without proteins, cells would not
have the internal balance-keeping mechanisms and structures known as homeostasis. The
cytoplasm of cells contains ribosomes, which are organelles. They interpret genetic
information as instructions and put the amino acids together in the proper sequence. The
building blocks of proteins are amino acids, which are organic molecules. Through the
process of dehydration synthesis, the amino acids are joined by peptide bonds. Ribosomes
are therefore the protein manufacturing machinery of the cell. Proteins are made of
polypeptides chains. Each gene codes for a particular polypeptide. Three bases code for an
amino acid. The genetic code is read in three-letter grouping called codons. A codon is a
group of three nucleotides bases in messenger RNA that specifies a particular amino acid.
The complimentary bases on the tRNA bring the correct amino acid into place. The
anticodon on the tRNA binds to the codons. An anticodon is trinucleotide sequence that is
complementary to a corresponding codon located in messenger RNA sequence and also is
found at one end of a transfer RNA molecule. Translation occurs in a way that these
nucleotide triplets are read in successive non-overlapping fashion. No single base can take
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