ucleic Acids: DNA & RNA Practice Exam Guide Questions With Answers A+ Score.

Nucleic Acid - correct answer A polymer (long repeating chain) of nucleotides - covalently bonded together. Deoxyribonucleic Acid (DNA) - correct answer Usually a double helix made up of 2 chains of deoxyribonucleotides. Ribonucleic Acid (RNA) - correct answer Usually a singe-stranded chain of ribonucleotides. Nucleotides - correct answer These are the building blocks of nucleic acids. The contain a central sugar ring (containing an oxygen and several carbons), 1 to 3 phosphate groups (made up of a phosphorous atom and 4 oxygen atoms) and a nitrogenous base. Nucleoside - correct answer This is made up of a sugar and a base, it doesn't contain the phosphate groups. Nitrogenous Bases - correct answer Split into two groups, pyrimidines which contain one ring and purines which contain two rings (one 5 membered and one 6 membered). Pyrimidines - correct answer Cytosine and Thymine Purines - correct answer Adenine and Guanine Base Pairs - correct answer A bonds with T (with 2 hydrogen bonds) and C with G (with 3 hydrogen bonds - hence stronger). This enables the formation of the double helix. Deoxynucleotide Triphosphates (dNTPs) - correct answer These are made up of a deoxyribose sugar, a nucleotide base and a triphosphate. This forms the basis of DNA. Adenine Deoxynucleotide Triphosphate - correct answer Deoxy-adenosine triphosphate (dATP) Guanine Deoxynucleotide Triphosphate - correct answer Deoxy-guanosine triphosphate (dGTP) Cytosine Deoxynucleotide Triphosphate - correct answer Deoxy-cytidine triphosphate (dCTP) Thymine Deoxynucleotide Triphosphate - correct answer Deoxy-thymidine triphosphate (dTTP) Phosphodiester Bonds - correct answer These bonds link deoxynucleotides to form DNA chains through condensation reactions (3' hydroxyl (OH) of one reacts with the 5' phosphate (OH in PO4) of the other). These bonds can only be made at the end of the chain. Sugar-Phosphate Backbone - correct answer Created by multiple phosphodiester bonds and adds structure to the molecule. Primary Structure of DNA - correct answer The sequence of a single DNA chain. Directionality - correct answer Thus means that one end of the DNA molecule is different to the other end. DNA has this because there is a free 5' end (not linked to another nucleotide) and a free 3' OH group at the other end of the molecule. Chargaff's Rule - correct answer Percentage of A = Percentage of T and percentage of G = percentage of C. In a double-stranded DNA molecule. Secondary Structure of DNA - correct answer The double helix structure formed between two DNA chains bonded with hydrogen bonds between the base pairs. Antiparallel Strands - correct answer The DNA strands in a double-helix run in opposite directions (one is 5' to 3' and the other is 3' to 5'). Differences Between DNA and RNA - correct answer 1 - RNA is single-stranded 2 - RNA contains ribose instead of deoxy-ribose 3 - RNA contains uracil (U) instead of thymine (T). Ribose - correct answer This has two OH groups, one on the 2' and one on the 3' carbons (deoxy-ribose only has one on the 3' carbon). The 3' OH is still used for phosphodiester bond in ribose. Difference Between Uracil and Thymine - correct answer Thymine (in DNA) has a methyl group attached to the ring structure whereas uracil (in RNA) doesn't. Primary Structure of RNA - correct answer Similar to that of DNA, the sequence of nucleotide bases. Secondary Structure of RNA - correct answer When long enough, RNA doesn't act as a single strand, but instead folds up on itself and forms base pairs with itself (internal base pairing) to produce a different structure. Messenger RNA (mRNA) - correct answer Codes for cellular proteins. Transfer RNA (tRNA) - correct answer Involves in bringing amino acids to the ribosome. Ribosomal RNA (rRNA) - correct answer Structural RNAs that contribute to the ribosome. Small Nuclear RNA (snRNA) - correct answer Involved in mRNA splicing in the nucleus. MicroRNA (miRNA) - correct answer Small RNAs that regulate mRNA translation. Short Interfering RNA (siRNA) - correct answer Small RNAs that promote mRNA degradation. Piwi Interacting RNA (piRNA) - correct answer Regulate development in germ cells (sperm and egg and their precursors). Long Non-Coding RNA (lncRNA) - correct answer Long RNA molecules that regulate gene expression, chromatin and chromosome structure and cell development.