RNA functions as the reader that decodes this flash drive. This reading process is multi-step and there are specialized RNAs for each of these steps. Below, we look in more detail at the three most important types of RNA. The nitrogen bases in DNA are the basic units of genetic code, and their correct ordering and pairing is essential to biological function. The four bases that make up this code are adenine A , thymine T , guanine G and cytosine C.
Bases pair off together in a double helix structure, these pairs being A and T, and C and G. RNA molecules, by comparison, are much shorter 3. Eukaryotic cells, including all animal and plant cells, house the great majority of their DNA in the nucleus, where it exists in a tightly compressed form, called a chromosome 4.
This squeezed format means the DNA can be easily stored and transferred. In addition to nuclear DNA, some DNA is present in energy-producing mitochondria, small organelles found free-floating in the cytoplasm, the area of the cell outside the nucleus.
The three types of RNA are found in different locations. If it receives the correct signal from the ribosome, it will then hunt down amino acid subunits in the cytoplasm and bring them to the ribosome to be built into proteins 5. Ribosomes are formed in an area of the nucleus called the nucleolus, before being exported to the cytoplasm, where some ribosomes float freely.
Other cytoplasmic ribosomes are bound to the endoplasmic reticulum, a membranous structure that helps process proteins and export them from the cell 5.
Louis, MO We are open Saturday and Sunday! Subject optional. Email address: Your name:. Example Question : High School Biology. Possible Answers: Ribose. Correct answer: Deoxyribose. Explanation : DNA stands for "deoxyribonucleic acid. Report an Error. Which of the following might you find in the backbone of DNA?
Phosphate group II. Hexose sugar III. Possible Answers: I only. Correct answer: I only. Example Question 3 : Dna Structure. Possible Answers: Phosphodiesterase is needed to break the bonds between the phosphate group on the 5' carbon of one sugar and hydroxyl group on the 3' carbon of the adjacent sugar. Correct answer: Phosphodiesterase is needed to break the bonds between the phosphate group on the 5' carbon of one sugar and hydroxyl group on the 3' carbon of the adjacent sugar.
Explanation : A DNA molecule is made up of multiple nucleotides that are connected by phosphodiester bonds. Example Question 4 : Dna Structure. Possible Answers: The two strands are antiparallel and the 5' end on both strands contain a phosphate group.
The two strands are parallel and the 5' ends on both strands contain a phosphate group. Correct answer: The two strands are antiparallel and the 5' end on both strands contain a phosphate group. Explanation : In the nucleus, DNA is always found as a double-stranded molecule. Example Question 5 : Dna Structure. The RNA backbone has uracil instead of thymine. The sugar in the RNA backbone has an extra hydroxyl group.
Correct answer: The sugar in the RNA backbone has an extra hydroxyl group. Explanation : RNA and DNA are both types of nucleic acids; therefore, both molecules are made from nucleotide monomers. Example Question 6 : Dna Structure.
Possible Answers: Positive. Correct answer: Negative. Explanation : Given the backbone of DNA, with the phosphate group attached to the deoxyribose via a phosphodiester bond, DNA is negatively charged. Example Question 7 : Dna Structure. Which of these can be found in the DNA backbone: I. Ribose III. Deoxyribose IV. Phosphodiester bond.
Explanation : The backbone of DNA consists of a phosphate group and a deoxyribose. Example Question 8 : Dna Structure. Possible Answers: A phosphate group, 5-C sugar, and a nitrogenous base make up a nucleotide.
The bond between the phosphate and 5-C deoxyribose sugar in DNA is called a phosphodiester bond. The two strands of DNA are connected by phosphodiester bonds. In DNA, adenine pairs with thymine, and cytosine pairs with guanine. Correct answer: The two strands of DNA are connected by phosphodiester bonds.
Explanation : The two strands of DNA are actually connected by hydrogen bonds H-bonds between the nitrogenous bases. Example Question 9 : Dna Structure. Possible Answers: Phosphate only. Correct answer: Phosphate-sugar. In prokaryotes, the DNA is not enclosed in a membranous envelope. The entire genetic content of a cell is known as its genome, and the study of genomes is genomics. In eukaryotic cells but not in prokaryotes, DNA forms a complex with histone proteins to form chromatin, the substance of eukaryotic chromosomes.
A chromosome may contain tens of thousands of genes. Many genes contain the information to make protein products; other genes code for RNA products. The other type of nucleic acid, RNA, is mostly involved in protein synthesis. The DNA molecules never leave the nucleus but instead use an intermediary to communicate with the rest of the cell. Each nitrogenous base in a nucleotide is attached to a sugar molecule, which is attached to one or more phosphate groups.
The nitrogenous bases, important components of nucleotides, are organic molecules and are so named because they contain carbon and nitrogen. They are bases because they contain an amino group that has the potential of binding an extra hydrogen, and thus, decreasing the hydrogen ion concentration in the environment, making it more basic. Adenine and guanine are classified as purines. The primary structure of a purine is two carbon-nitrogen rings. Each of these basic carbon-nitrogen rings has different functional groups attached to it.
In molecular biology shorthand, the nitrogenous bases are simply known by their symbols A, T, G, C, and U. The difference between the sugars is the presence of the hydroxyl group on the second carbon of the ribose and hydrogen on the second carbon of the deoxyribose so deoxyribose is "missing" an -OH group.
The phosphodiester linkage is not formed by simple dehydration reaction like the other linkages connecting monomers in macromolecules: its formation involves the removal of two phosphate groups. A polynucleotide may have thousands of such phosphodiester linkages.
Chargaff had observed that for any given species, the abundance of A was the same as T, and G was the same as C.
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