DNA Structure, Replication, and Gene Expression

Flashcards covering the key concepts and vocabulary related to DNA structure, replication, and gene expression.

Nucleotide

The basic building block of DNA and RNA, composed of a sugar, a phosphate group, and a nitrogenous base.

Base Pairing Rules

Rules describing how nucleotides pair in DNA; Adenine (A) pairs with Thymine (T) and Cytosine (C) pairs with Guanine (G).

Helicase

An enzyme that unwinds the DNA double helix during replication.

DNA Polymerase

An enzyme that adds new nucleotides to a growing DNA strand during replication.

Semi-Conservative Replication

The method of DNA replication in which each new DNA molecule consists of one old strand and one new strand.

Mutation

A change in the DNA sequence that can be harmful, beneficial, or neutral.

Central Dogma of Molecular Biology

The framework describing the flow of genetic information from DNA to RNA to protein.

Transcription

The process of synthesizing RNA from a DNA template.

Translation

The process of synthesizing proteins from mRNA.

Codon

A sequence of three nucleotides on mRNA that codes for a specific amino acid.

Start Codon

The codon (AUG) that signals the ribosome to begin translation.

Stop Codon

One of three codons (UAA, UAG, UGA) that signal the end of translation.

Gene Regulation

The process that controls when and how genes are expressed, affecting protein production.

What is the base-pairing rule for DNA?

The base-pairing rule states that adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G) in DNA.

Describe the steps of DNA replication.

1. Unwinding: The DNA double helix is unwound by helicase.
2. Priming: RNA primers are synthesized.
3. Elongation: DNA polymerase adds new nucleotides complementary to the template strand.
4. Completing: The process continues until the entire molecule is replicated.

What are the three types of RNA, and what are their functions?

1. mRNA (messenger RNA): Carries genetic information from DNA to the ribosome.
2. tRNA (transfer RNA): Transfers amino acids to the ribosome during protein synthesis.
3. rRNA (ribosomal RNA): Forms the core of the ribosome's structure and catalyzes protein synthesis.

How does transcription differ from translation?

Transcription is the process of synthesizing RNA from a DNA template, while translation is the process of synthesizing proteins using the information encoded in mRNA.

What is the significance of the genetic code being universal?

The universality of the genetic code means that the same codons translate into the same amino acids across different species, indicating a common evolutionary origin.

How does gene regulation influence protein production?

Gene regulation controls the timing and amount of protein produced, allowing cells to respond to changes in the environment or to developmental signals.

What are the roles of mRNA, tRNA, and rRNA in translation?

1. mRNA provides the template with codons for amino acid sequence.
2. tRNA brings specific amino acids to the ribosome and matches them to codons on mRNA.
3. rRNA is a structural component of ribosomes and catalyzes peptide bond formation.