The Molecular Basis of Inheritance

These flashcards cover vocabulary related to the molecular basis of inheritance, specifically focusing on DNA structure, replication, and repair, as discussed in the lecture.

Gene

A segment of DNA that is responsible for the physical and inherited characteristics or traits of an organism.

Chromosome

A thread-like structure made up of DNA and proteins that contains many genes.

DNA

Deoxyribonucleic acid, the molecule that carries the genetic instructions for life.

Transformation

The process by which a cell takes up DNA from its environment, resulting in a change in genotype and phenotype.

Bacteriophage

A virus that infects bacteria, consisting of DNA or RNA surrounded by a protein coat.

Lysis

The breaking down of the membrane of a cell, resulting in the death of the cell.

Antiparallel strands

The opposite direction of the two strands of DNA, running in 5' to 3' and 3' to 5' directions.

X-ray crystallography

A method used to study the fine structure of molecular biology, often used by Rosalind Franklin.

Nucleotide

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

Nitrogenous base

The key molecule in the DNA structure that pairs with its complementary base (A, T, G, C).

Purine

A type of nitrogenous base that has a double-ring structure, specifically adenine (A) and guanine (G).

Pyrimidine

A type of nitrogenous base that has a single-ring structure, specifically cytosine (C) and thymine (T).

RNA

Ribonucleic acid, which plays roles in coding, decoding, regulation, and expression of genes.

DNA replication

The process by which DNA makes a copy of itself, occurring before cell division.

Semiconservative replication

The model of DNA replication in which each strand serves as a template for a new strand, resulting in two DNA molecules with one old strand and one new strand.

Primase

An enzyme that synthesizes a short RNA primer to start DNA replication.

DNA polymerase

An enzyme that synthesizes new DNA strands by adding nucleotides to an existing strand.

Okazaki fragments

Short segments of DNA synthesized on the lagging strand during DNA replication.

Leading strand

The DNA strand that is synthesized continuously in the same direction as the replication fork.

Lagging strand

The DNA strand that is synthesized in short segments away from the replication fork.

Helicase

An enzyme that unwinds the DNA double helix at the replication fork.

Single-strand binding proteins (SSB proteins)

Proteins that stabilize single-stranded DNA and prevent it from re-annealing during replication.

Topoisomerase

An enzyme that relieves the strain ahead of the replication fork by breaking and rejoining DNA strands.

Deoxyribonucleoside triphosphate (dNTP)

A nucleotide that carries energy to synthesize DNA during replication, consisting of a base, sugar, and three phosphate groups.

Pyrophosphate

A molecule released during the addition of a nucleotide to a growing DNA strand, providing energy for the reaction.

DNA ligase

An enzyme that joins Okazaki fragments on the lagging strand by forming covalent bonds.

Proofreading

The process by which DNA polymerase checks and corrects mistakes made during DNA replication.

Mismatch repair

A DNA repair mechanism that removes and replaces incorrectly paired nucleotides.

Nucleotide excision repair (NER)

A DNA repair process that removes damaged DNA and replaces it with the correct nucleotides.

Telomeres

Repeated DNA sequences at the ends of chromosomes that protect them from shortening during replication.

Telomerase

An enzyme that extends telomeres, allowing for continued cell division.

Chromatin

The complex of DNA and protein found in eukaryotic cells; can be loosely or tightly packed.

Nucleosome

The basic unit of DNA packaging in eukaryotic cells, consisting of DNA wrapped around histone proteins.

Euchromatin

Loosely packed form of chromatin that is accessible for transcription.

Heterochromatin

Tightly packed form of chromatin that is generally not transcribed.

Histone proteins

Proteins that help package DNA into nucleosomes and regulate gene expression.

Gene expression

The process by which information from a gene is used to synthesize a functional gene product, often a protein.

Replication fork

The Y-shaped structure that forms when DNA is being unwound during replication.

Cell cycle

The series of events that take place in a cell leading to its division and duplication.

Mitosis

The process of cell division that results in two identical daughter cells.

Meiosis

The process of cell division that produces gametes, resulting in four genetically different cells.

Phenotype

The observable characteristics or traits of an organism, which result from the interaction of its genotype with the environment.

Genotype

The genetic constitution of an organism; the specific alleles present.

Mutation

A change in the DNA sequence that can lead to variations in traits.

Natural selection

The process by which organisms better adapted to their environment tend to survive and produce more offspring.

Biological evolution

The change in the inherited traits of a population from generation to generation.