DNA Flashcards
(22 cards)
What are the three main components of a nucleic acid monomeric unit?
A nitrogenous base, a sugar scaffold (deoxyribose in DNA or ribose in RNA), and a phosphate group.
What is the difference between a nucleoside and a nucleotide?
A nucleoside consists of a sugar and a base, while a nucleotide includes a sugar, a base, and a phosphate group.
What are the nitrogenous bases found in DNA?
Adenine (A), Thymine (T), Guanine (G), and Cytosine (C).
uracil in RNA
What type of bond holds the complementary bases in DNA together?
Hydrogen bonds.
Describe the structure of DNA.
DNA is a double helix with two complementary, anti-parallel strands that form a right-handed helix.
What role do hydrophobic interactions and hydrogen bonds play in DNA structure?
They stabilize the double helix structure of DNA.
In which direction is DNA synthesized?
DNA is synthesized in the 5’ to 3’ direction.
What is the significance of the major and minor grooves in DNA?
They facilitate interactions with certain DNA-binding proteins.
How is eukaryotic DNA packaged within the cell nucleus?
It is packaged into chromatin, where DNA is wrapped around nucleosomes made up of histone proteins.
What is the role of histone H1 in DNA packaging?
Histone H1 helps in winding DNA and spacing nucleosomes.
What is the nucleosome, and what is its composition?
The nucleosome is the core unit of chromatin, composed of an octamer of histone proteins (H2A, H2B, H3, and H4).
What enzyme unwinds the DNA double helix during replication?
helicase
Explain the concept of “semi-conservative replication” in DNA.
each strand of the original DNA serves as a template for the synthesis of a new complementary strand, resulting in two daughter strands each containing one parental strand.
What enzyme synthesizes new DNA strands during replication?
DNA polymerase delta (Pol δ).
What is the role of DNA polymerase alpha (Pol α) in replication?
It synthesizes a short RNA primer required to initiate DNA synthesis.
What is the difference between the leading and lagging strands in DNA replication?
The leading strand is synthesized continuously toward the replication fork, while the lagging strand is synthesized in short segments away from the fork.
How are the short segments on the lagging strand joined together?
DNA ligase.
What are the four basic genetic processes involved in macromolecular synthesis?
DNA Replication - the process of copying DNA to produce two identical molecules.
Transcription - the synthesis of RNA from a DNA template.
Translation - the process of synthesizing proteins from RNA.
Gene Regulation - the mechanisms that control the expression of genes.
How does DNA replication ensure fidelity?
ase Pairing Rules: Specific pairing (A-T and C-G) reduces errors.
Proofreading Activity: DNA polymerase has exonuclease activity that allows it to remove incorrectly paired nucleotides during replication.
Repair Mechanisms: Post-replication repair systems identify and correct any remaining errors.
what are the different ways of gene regulation
Transcription Factors: Proteins that enhance or inhibit transcription by binding to specific DNA sequences.
Epigenetic Modifications: Chemical changes to DNA or histones that affect gene activity without altering the DNA sequence.
Acetylation: The addition of acetyl groups to histones, which relaxes chromatin structure, making DNA more accessible for transcription. Acetylation typically enhances gene expression.
Methylation: The addition of methyl groups to DNA or histones, which can suppress gene expression by making DNA less accessible.
Feedback Mechanisms: Regulatory pathways that adjust gene expression in response to internal and external signals, helping maintain cellular homeostasis.
What is gene regulation, and how does acetylation play a role in it?
refers to the processes that control the expression of genes, including:
Acetylation: The addition of acetyl groups to histones, which relaxes chromatin structure, making DNA more accessible for transcription. Acetylation typically enhances gene expression.
