Molecular Biology Lecture Notes

These flashcards cover key concepts from molecular biology lectures, focusing on DNA structure and replication, gene expression, mutations, and biotechnological methods.

What are nucleic acids?

Polymers of nucleotides.

What is DNA?

Deoxyribonucleic acid.

What is RNA?

Ribonucleic acid.

What are the components of a nucleotide?

Sugar base (deoxyribose or ribose), phosphate group, nitrogenous base.

What are purines?

Nitrogenous bases with a double ring structure, specifically adenine (A) and guanine (G).

What are pyrimidines?

Nitrogenous bases with a single ring structure, specifically thymine (T), cytosine (C), and uracil (U).

What is the base pairing rule in DNA?

C pairs with G; A pairs with T; A pairs with U in RNA.

What is the structure of DNA?

Double-stranded, wound in a double helix, with complementary nitrogenous base pairs.

Who contributed to the understanding of DNA's double helix structure?

James Watson, Francis Crick, and Rosalind Franklin.

What does it mean for DNA strands to be antiparallel?

Each strand has a 3’ end and a 5’ end, oriented in opposite directions.

What is the semiconservative model of DNA replication?

Half of the parent DNA molecule is maintained in each daughter molecule.

What initiates DNA replication?

Proteins binding to the origin of replication (ori) to unzip the DNA strands.

What enzyme is responsible for linking DNA nucleotides?

DNA polymerase.

What is the leading strand in DNA replication?

The strand synthesized continuously towards the replication fork.

What is the lagging strand in DNA replication?

The strand synthesized in short pieces away from the replication fork, known as Okazaki fragments.

What role does DNA ligase play in DNA replication?

It links Okazaki fragments together into a continuous strand.

What is the replication fork?

The point where parental DNA strands are separated for replication.

What is a mutation?

Any change to the genetic information in a cell.

What is a silent mutation?

A mutation that does not change which amino acid is coded for.

What is a missense mutation?

A mutation where the nucleotide substitution changes the amino acid coded for.

What is a nonsense mutation?

A mutation that changes an amino acid codon into a stop codon.

What is a frameshift mutation?

The addition or deletion of a nucleotide that alters the reading frame of the genetic message.

What can cause mutations?

Spontaneous errors during DNA replication or exposure to mutagens.

What are operons?

A series of genes regulated as a single unit for coordinated expression.

What is the lac operon?

The operon that codes for enzymes needed for lactose breakdown.

What is a repressor protein?

A protein that inhibits transcription by binding to an operator.

What is X inactivation?

The process by which one of the two X chromosomes in female mammals is inactivated.

What is gene expression?

The process by which genetic information flows from genes to proteins.

What is transcription?

The synthesis of RNA using the DNA sequence as a template.

What is translation?

The synthesis of protein using the instructions from mRNA.

What is alternative RNA splicing?

The process that allows different mRNA molecules to be produced from a single RNA transcript.

What is genomic analysis?

The comparative analysis of different genomes to gain insight into evolutionary relationships.

What is PCR?

Polymerase Chain Reaction, a method used to amplify DNA.

What is gel electrophoresis?

A technique used to separate macromolecules based on size and charge.

What are the components needed for translation?

Processed mRNA, ribosomes, transfer RNA (tRNA), enzymes, and chemical energy (ATP).

What is a codon?

A sequence of three nucleotide bases that specifies one amino acid.

What is the genetic code?

The set of rules by which information encoded in genetic material is translated into proteins.

What distinguishes eukaryotic and prokaryotic transcription?

In prokaryotes, transcription and translation occur in the cytoplasm; in eukaryotes, they occur in the nucleus and cytoplasm.

What is methylation?

The addition of methyl groups to DNA, often affecting gene expression.

What is gene regulation?

The processes that control the expression of genes in cells.