A1.2 - nucleic acids (2b) Flashcards
what is a dna nucleotide?
a DNA monomer composed of a phosphate group, pentose sugar and base joined by covalent bonds
what are the 4 different bases?
- adenine
- cytosine
- guanine
- thymine or uracil (in RNA)
what are the 2 types of genetic material?
where are they located?
DNA is the genetic material of all living organisms
- some viruses use RNA as their genetic material but viruses are not considered to be living
why are multiple bases required?
multiple bases are required as the bases form the foundation of the genetic code
what is a pentose sugar?
a pentose sugar contains 5 carbon atoms
what is the name of the pentose sugar found in DNA and RNA?
DNA - deoxyribose
- it has one less O than ribose
RNA - ribose
what structures are formed by joining nucleotides in the backbone of DNA and RNA?
sugar–phosphate bonding makes a continuous chain of covalently bonded atoms in each strand of DNA or RNA nucleotides, which forms a strong “backbone” in the molecule
- the pentose sugar of one nucleotide is covalently bonded to the phosphate group on the next nucleotide
how are nucleotides joined together?
nucleotides are joined by condensation reactions between monomers to form a polymer
- this forms a strong covalent bond between the pentose sugar on one nucleotide and the phosphate group of another nucleotide
- a molecule of water is released
what is the structure of DNA?
DNA is a double helix made of two antiparallel strands of nucleotides with the strands linked by hydrogen bonding between complementary base pairs
what are differences between the structures of DNA and RNA?
DNA:
- double stranded
- deoxyribose sugar
- adenine, thymine, guanine, thymine
- helical structure
RNA:
- single stranded
- adenine, thymine, guanine, uracil
- ribose sugar
- variety of forms: mRNA, rRNA, tRNA
what is DNA?
DNA is a long-term hereditary storage molecules for all living organisms
what is mRNA?
messenger RNA is synthesized using one gene as a template, in a process called transcription, and it then leaves the nucleus and brings the genetic information to the ribosome
what is rRNA?
ribosomal RNA are components of ribosomes, which carry out translation
what is tRNA?
transfer RNA brings the correct amino acid to add to a growing chain of amino acids at the ribosome, during translation
what is ATP?
adenosine triphosphate (ATP) is a single-nucleotide nucleic acid comprised of adenine, ribose and three phosphate groups
- ATP is used as a short-term store of chemical energy
what is complementary base pairing?
specific bases only pair with each other due to hydrogen bonding
- A and T/U
- G and C
how does complementary base pairing allow genetic information to be replicated?
replicated - separating strands of DNA and allowing free DNA nucleotides to base pair with unmatched nucleotides forms an exact cope of the molecule
how does complementary base pairing allow genetic information to be expressed?
expressed - separating strands of DNA and allowing free RNA nucleotides to base pair with unmatched nucleotides forms an RNA copy of one strand of DNA which can be used by ribosomes for protein synthesis
how is DNA diverse and how does it contribute to its role?
- molecules can have any length and any base sequence
- allows DNA to store huge amounts of data in the genetic code with great economy, contributing to diversity of organisms
what evidence is there for a universal common ancestor?
- universal genetic code - same codons code for the same amino acids in all organisms
- conservation of genetic code - life on earth has evolved from a common ancestor
