Ch 5 - Pt 3 - Nucleic Acid Flashcards
(20 cards)
Genes
1) The units of inheritance
2) Specify the amino acid sequences of polypeptides
3) Made of nucleic acid
Nucleic acids
The molecules in which hereditary information is stored and transmitted
What determines the order if amino acids in a polypeptide?
Determined by the sequence of nucleic acids in DNA and RNA molecules.
2 types of nucleic acids
1) Deoxyribonucleic acid/DNA (contains the genetic “blueprint” of an organism)
2) Ribonucleic Acid/RNA (involved in protein synthesis)
Structure of nucleic acids
Nucleic acids exist as polymers called polynucleotides made up of monomers called nucleotides
Nucleotides
The monomers that constitute each polynucleotide. Each nucleotide is made up of nucleoside and a phosphate group
Nucleoside
A nitrogenous base and a pentose sugar
Nitrogenous bases
3 pyrimidines (single 6-membered ring) and 2 purines (one 6-membered ring and one 5-membered ring).
C, T, U, A, G
T is found only in DNA
U is found only in RNA
Pentose sugars in nucleic acids
DNA nucleotides contain a deoxyribose sugar; RNA nucleotides contain a ribose sugar.
How do deoxyribose sugars and ribose sugars differ?
Deoxyribose is identical to ribose except it is missing an oxygen on the second carbon. (Ribose has OH; deoxyribose has H)
Phosphodiester linkages
The link between nucleotides and polynucleotides
Polynucleotide directionality
Polynucleotides have a 5’ end and a 3’ end
In polynucleic directionality, what group is associated with the 5’ end?
The 5’ end of a polynucleotide is associated with a phosphate group
In polynucleic directionality, what group is associated with the 3’ end?
The 3’ end of a polynucleotide is associated with a hydroxyl group
Do DNA molecules have directionality?
Yes, this directionality plays an important implications for the biological roles of DNA and RNA
Summary of DNA structure
1) Contains A, C, G, T
2) Usually double stranded
3) Has a deoxyribose pentose sugar
Summary if RNA structure
1) Contains A, C, G, U
2) Usually single stranded
3) Has a ribose pentose sugar
A DNA molecule consists of what kinds of nucleotide strands?
A DNA molecule consists of 2 “antiparallel” nucleotide strands (running in opposite directions) where one strand runs 5’ to 3’ and the other runs 3’ to 5’.
Hydrogen bonding between bases
Hydrogen bonds occur across DNA strands between purines and pyrimidines. G-C bond is stronger than A-T bonding.
What purpose does DNA’s complementarity serve?
Because the double strands of DNA are complementary, DNA serves as its own template for replication and transcription into messenger RNA (mRna).
