Chapter 3 - Nucleic acids and DNA replication Flashcards
What are nucleic acids?
Large polymers formed from nucleotides, contains elements C, H, N, O and phosphorus
What are nucleotides?
The monomers used to form nucleic acids (made from pentose monosaccharide)
Describe the structure of an individual nucleotide
- Pentose monosaccharide w 5 C atoms
- A phosphate group (PO4)2- molecule that is acidic and negatively charged
- A complex complex organic molecule containing one or two carbon rings
How are nucleotides linked together?
By condensation reaction to form a polynucleotide
What are phosphodiester bonds?
Covalent bonds formed between phosphate group of one nucleotide and hydroxyl group of another
Forms long strong phosphodiester bond
Where is the covalent bond in the nucleotide
The 5th carbon with phosphate, bonds to the carbon 3 forms phosphodiester bond
What is deoxyribose nucleic acid?
A sugar with one fewer oxygen atoms than ribose (DNA)
What are the two different groups of nucleotides?
Pyrimidines- Smaller bases (single carbon ring) Thymine and cytosine
Purines- Larger bases (double ring structure) Adenine and guanine
How many bonds have does A&T form and C&G and what is this pairing known as
A&T form 2 hydrogen bonds
C&G form 3 hydrogen bonds
Complementary base pairing
Why is DNA made to be antiparallel?
Because the two strands of DNA are arranged to run in opposite directions
Runs from 5’ to 3’ on left and 3’ to 5’ on right strand
What role does RNA play?
In the transfer of genetic information form DNA to the protein that make up the enzymes and tissues of the body
Why is DNA transcribed to RNA
Because the DNA is too large to leave nucleus for protein synthesis
A short section of the DNA molecule is transcribed into mRNA
What are the differences in RNA and DNA nucleotides?
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- Thymine base is replaced by uracil
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What is the genetic code?
The sequence of bases in DNA are the instructions for the sequences of amino acids in the production of proteins
What is the idea of non-overlapping?
Each nucleotide is only part of one triplet of bases (one codon, not 2 codons) so that the codons are read one at a time
