Nucleic acids Flashcards
(55 cards)
What is DNA?
Deoxyribonucleic acid, the hereditary material in living organisms.
DNA carries coded instructions for development and functioning.
What is the structure of a nucleotide?
A molecule consisting of a five-carbon sugar, a phosphate group, and a nitrogenous base.
Nucleotides are the monomers of nucleic acids.
What are the two phosphorylated nucleotides mentioned?
ADP (adenosine diphosphate) and ATP (adenosine triphosphate).
ATP is used to drive most energy-requiring metabolic processes.
What is a polynucleotide?
A large molecule containing many nucleotides.
Polynucleotides are formed by the linking of nucleotides through phosphodiester bonds.
What is the shape of the DNA molecule?
Double helix, due to coiling of the two sugar-phosphate backbone strands.
The double helix configuration is right-handed.
What is the difference between a nucleotide and a nucleoside?
A nucleotide consists of a pentose sugar, a nitrogenous base, and a phosphate group; a nucleoside consists of only a pentose sugar and a nitrogenous base.
Example: Adenosine is a nucleoside, AMP is a nucleotide.
How do hydrogen bonds contribute to the structure of DNA?
Hydrogen bonds join the two antiparallel DNA strands through complementary base pairing.
Adenine pairs with thymine, and guanine pairs with cytosine.
What are the four nitrogenous bases in DNA?
Adenine, guanine, thymine, and cytosine.
These bases determine the genetic information carried by DNA.
What is the significance of antiparallel strands in DNA?
The two strands run in opposite directions, which is crucial for DNA replication and transcription.
This refers to the orientation of the sugar-phosphate backbones.
Fill in the blank: Adenine always pairs with _______ by means of two hydrogen bonds.
Thymine
Fill in the blank: Guanine always pairs with _______ by means of three hydrogen bonds.
Cytosine
What type of bond is formed between the phosphate group and the sugar in a nucleotide?
Phosphodiester bond.
These bonds are broken during the breakdown of polynucleotides.
True or False: A purine always pairs with a purine in DNA.
False
A purine always pairs with a pyrimidine.
What are the components of coenzyme NADP?
Adenine nucleotides.
NADP is used in photosynthesis.
What is the role of ATP in biochemical pathways?
ATP is an energy-rich end-product used to drive most energy-requiring metabolic processes.
It is formed from ADP and inorganic phosphate.
What is the significance of the sugar-phosphate backbone in DNA?
It forms the upright part of the DNA molecule, resembling a ladder.
The backbone is formed by the covalent bonds between the sugar and phosphate groups.
Fill in the blank: Each DNA nucleotide consists of a phosphate group, a five-carbon sugar called ________, and one of four nitrogenous bases.
Deoxyribose
What are the roles of nucleotides in metabolism?
Regulate metabolic pathways and serve as components of coenzymes.
Examples include ATP, ADP, AMP, NAD, and FAD.
What is the sugar-phosphate backbone in DNA?
A structural framework of DNA consisting of alternating sugar (deoxyribose) and phosphate groups
The sugar-phosphate backbone supports the nucleotide bases that are attached.
In eukaryotic cells, where is the majority of DNA found?
In the nucleus
The DNA is organized into chromosomes.
How is DNA organized in prokaryotic cells?
DNA is in a loop within the cytoplasm and is not enclosed in a nucleus
This DNA is described as naked and does not wind around histone proteins.
What is the role of helicase in DNA replication?
Catalyses the breaking of hydrogen bonds between nitrogenous base pairs
This allows the DNA strands to separate.
Define semi-conservative replication.
A process where each new DNA molecule consists of one old strand and one new strand
This method conserves one original strand in each new molecule.
What is the function of DNA polymerase?
Catalyses the addition of new nucleotide bases to the growing DNA strand
It uses a single strand of DNA as a template.
