Genetic Material Flashcards
What is DNA
-DNA (Deoxyribonucleic Acid) is an organic molecule carrying hereditary material.
-Found in all prokaryotic and eukaryotic cells.
-Responsible for genetic inheritance and protein production.
How is bacterial DNA different from eukaryotic DNA
-Bacteria: Single circular DNA strand in the nucleoid region.
-Eukaryotes: DNA is membrane-bound in the nucleus
Who discovered DNA and its structure?
-DNA was discovered by Friedrich Miescher in 1869.
-Double helix structure identified by Watson and Crick in 1953.
What is the structure of DNA?
-Double helix, twisted ladder structure
-Made of nucleotides (sugar, phosphate group, nitrogen base).
-Bases pair as A-T and C-G.
What are the components of DNA?
-Sugar (deoxyribose): Forms the backbone.
-Phosphate group: Links nucleotides.
-Nitrogen bases: Adenine (A), Thymine (T), Guanine (G), Cytosine (C).
What are the nitrogen bases in DNA and their classifications?
-Purines: Adenine (A), Guanine (G).
-Pyrimidines: Cytosine (C), Thymine (T), Uracil(U)
What are nucleotides and nucleosides?
-Nucleotides: Nitrogenous base + sugar + phosphate group.
-Nucleosides: Nitrogenous base + sugar (no phosphate group)
What is the role of nucleotides in metabolism?
-Provide energy (e.g., ATP, GTP).
-Participate in cell signaling (e.g., cAMP, cGMP).
-Act as enzyme cofactors (e.g., NAD, FAD).
DNA Polymerase
-Polymerase I: DNA repair.
-Polymerase II: Primer extension and proofreading.
-Polymerase III: In vivo DNA replication.
Helicase
Unzips DNA by breaking hydrogen bonds.
Ligase
Joins Okazaki fragments on discontinuous strands.
Primase
This enzyme helps in the synthesis of RNA primer complementary to the DNA template strand.
Endonucleases
These produce a single-stranded or a double-stranded cut in a DNA molecule.
How does DNA coil and organize?
-DNA coils into chromosomes.
-Humans have 23 pairs of chromosomes.
What is the genetic code?
A set of rules cells use to translate DNA or mRNA sequences into proteins with the help of ribosomes, tRNA, and codons.
What is a codon?
A sequence of three nucleotides in DNA or RNA that specifies an amino acid or a stop signal.
What does “non-ambiguous and universal” mean in the genetic code?
-Non-ambiguous: Each codon codes for only one amino acid.
-Universal: The code is the same across almost all organisms.
What are start and stop codons?
Start codon: AUG (methionine).
Stop codons: UAG, UAA, UGA (do not code for amino acids).
What does “commaless” mean in the genetic code?
Codons are read sequentially without spaces or punctuation between them.
What does “nonoverlapping” mean in the genetic code?
Each nucleotide belongs to only one codon and is not reused in another codon.
What is the polarity of the genetic code?
Codons are read in the 5′ → 3′ direction, determining the sequence of the encoded protein
What is RNA?
RNA (ribonucleic acid) is a nucleic acid with a single helical strand that helps convert DNA instructions into functional proteins.
How does RNA differ from DNA?
RNA has ribose sugar, uses uracil (U) instead of thymine (T), and forms a single helix.
What are the three roles of RNA?
-Carries instructions from DNA to ribosomes.
-Delivers amino acids to ribosomes.
-Makes up ~50% of ribosome structure.
What is mRNA and its function?
mRNA carries genetic instructions from DNA to ribosomes for protein synthesis and is small enough to pass through nuclear pores.
What is rRNA and its role?
rRNA forms ~50% of ribosomes and facilitates protein synthesis by binding with proteins.
What is tRNA and its function?
tRNA transports amino acids from the cytoplasm to ribosomes for protein assembly, as instructed by mRNA.
What does RNA enable DNA to do?
RNA allows DNA to act as genetic instructions despite being confined to the nucleus.
