Nucleic Acids Flashcards
(29 cards)
What are the two types of nucleic acids used in cells?
DNA (deoxyribonucleic acid) and RNA (ribonucleic acid)
What are two primary functions of nucleic acids?
Pass genetic information between generations
Code for protein production
What does it mean that DNA is the genetic material of all living organisms?
All living organisms use DNA to store and transmit genetic information.
What is the implication of all life using DNA as genetic material?
Universal genetic code implies common ancestry; DNA sequences can show evolutionary relationships.
Why don’t RNA viruses falsify the idea that DNA is the genetic material of all living things?
Viruses aren’t made of cells and aren’t considered living.
What are the 3 components of a nucleotide?
Nitrogenous base
5-carbon sugar (ribose or deoxyribose)
Phosphate group
What forms the sugar-phosphate backbone of nucleic acids?
Covalent bonds between the 5′ phosphate of one nucleotide and the 3′ carbon of the sugar of another
What nitrogenous bases are found in DNA and RNA?
DNA: Adenine, Thymine, Cytosine, Guanine
RNA: Adenine, Uracil, Cytosine, Guanine
What base pairs form in DNA and RNA?
DNA: A-T (2 H-bonds), C-G (3 H-bonds)
RNA: A-U (2 H-bonds), C-G (3 H-bonds)
What is meant by complementary base pairing?
Specific nitrogenous bases pair using hydrogen bonds: A-T/U, C-G.
What does ‘antiparallel’ mean in DNA?
DNA strands run in opposite directions: one 5′ to 3′, the other 3′ to 5′.
Differences between DNA and RNA?
DNA: deoxyribose, double-stranded, A-T, C-G
RNA: ribose, single-stranded, A-U, C-G
Where are DNA and RNA found in cells?
Eukaryotes: DNA in nucleus, mitochondria, chloroplasts; RNA in nucleus, cytoplasm, ribosomes
Prokaryotes: Both in cytoplasm (DNA in nucleoid)
Role of base pairing in DNA replication?
Ensures accurate copying: each parent strand is a template for a complementary daughter strand.
Role of base pairing in transcription?
DNA template strand is used to make complementary RNA (A-U, C-G).
Role of base pairing in translation?
mRNA codon pairs with complementary tRNA anticodon to place correct amino acid.
Why is there limitless diversity in DNA base sequences?
4 bases can combine in any order and length = infinite combinations.
Define “universal” in the context of the genetic code.
All living things use the same genetic code for translating DNA into proteins.
Why does conservation of the genetic code support common ancestry?
It’s unlikely that all life independently evolved the same code—more logical they inherited it.
What is the directionality of DNA/RNA strands?
Strands have a 5′ end (phosphate) and a 3′ end (sugar). DNA is antiparallel
What are purines and pyrimidines?
Purines: double-ring bases (A, G)
Pyrimidines: single-ring bases (C, T, U)
Which bases are purines and which are pyrimidines?
Purines: Adenine, Guanine
Pyrimidines: Cytosine, Thymine, Uracil
What stabilizes the DNA helix?
Hydrogen bonding between purines and pyrimidines (A-T = 2 bonds, G-C = 3 bonds)
What is a nucleosome?
DNA wrapped around an octamer of histone proteins, with linker DNA and H1 protein.
