Introduction to Molecular Biology

A specific location on a chromosome where a gene resides.

A branch of biology focusing on the structure and function of essential macromolecules like proteins and nucleic acids. It explores life at the molecular level.

Different forms of the same gene.

The DNA that makes up the human genome can be divided into segments called genes, each carrying instructions for a specific protein.

The genetic makeup of an individual, represented by the alleles they possess.

The process by which information within a gene is used to create a functional product, ultimately resulting in a protein.

The observable physical characteristics of an individual, determined by their genotype.

The central dogma describes how genetic information flows from DNA to RNA, then to protein. This is the fundamental process of how genetic information is used to produce functional proteins.

The study of genes: their structure, function, and inheritance.

An individual with two identical alleles for a specific trait.

The passing of traits from parents to their offspring.

An individual with two different alleles for a specific trait.

The tendency for offspring to differ from their parents, resulting in a diverse population.

A change in the DNA sequence that can be passed on to offspring.

A trait that requires only one copy of the mutated gene for it to be expressed.

Small sections of DNA that code for specific traits. These are passed down from parents to offspring.

The process where DNA strands unwind and separate due to heat or alkali conditions, without breaking the phosphodiester bonds.

When separated DNA strands are cooled slowly under specific conditions, they re-join as the complementary base pairs form hydrogen bonds.

The pairing of a single DNA or RNA strand with a complementary sequence on another strand.

The circular DNA molecule found within the mitochondrial matrix.

The genetic code used by mitochondria differs slightly from the genetic code used by nuclear DNA.

Mitochondria, the organelles responsible for cellular energy production, are inherited solely from the mother.

Mitochondrial DNA changes (mutations) at a rate (about 5-10 times) higher than the nuclear genome.

The process of DNA replication that occurs in mitochondria.

Deoxyribonucleic acid (DNA) is a large molecule that stores genetic instructions for an organism. It's composed of two long strands of nucleotides, twisted into a double helix shape.

Ribonucleic acid (RNA) is another nucleic acid that plays a crucial role in protein synthesis. It's a single-stranded molecule involved in copying and transferring genetic information from DNA to ribosomes, where proteins are made.

DNA contains deoxyribose sugar, while RNA contains ribose sugar. DNA uses thymine (T) as a base, while RNA uses uracil (U) instead of thymine.

The structure of DNA consists of two long strands of nucleotides, each nucleotide containing a phosphate group, a deoxyribose sugar, and a nitrogenous base. The bases pair up specifically: adenine (A) with thymine (T), and guanine (G) with cytosine (C). These base pairs are connected by weak hydrogen bonds, while the sugar and phosphate form the backbone of the strands.

DNA's double helix structure is essential for its function in storing and transmitting genetic information. The two strands are complementary, meaning the sequence of bases on one strand determines the sequence of the other. This allows for accurate replication of DNA, ensuring that offspring inherit correct genetic instructions.

DNA was first observed by Friedrich Miescher in 1869, but its structure wasn't determined until 1953, thanks to the work of Watson and Crick.

James Watson and Francis Crick, along with Rosalind Franklin's X-ray diffraction data, provided the model for the three-dimensional structure of DNA in 1953. This model showed DNA's double helix shape and explained how it stores and transmits genetic information.

Gregor Mendel, known as the "father of genetics", performed experiments with plants in the 1850s, revealing principles of inheritance. This laid the foundation for later research on DNA and its role in heredity.

Genes are segments of DNA that carry the instructions for building and maintaining an organism. They provide the blueprint for specific proteins, which are the workhorses of cells. The sequence of bases in a gene determines the amino acid sequence of the protein it codes for. This, in turn, determines the function of the protein.

Chromatin is the complex of DNA and proteins found in the nucleus of eukaryotic cells. It's not a solid structure but is organized into a dynamic network of fibers. DNA is tightly wound around proteins called histones, which help to package and condense the DNA to fit within the nucleus. During cell division, chromatin becomes even more condensed into visible structures called chromosomes.

Chromosomes are thread-like structures that carry genetic information in the form of DNA. They are made up of tightly packaged chromatin and become visible during cell division. Humans normally have 23 pairs of chromosomes, meaning they have 46 total. Each chromosome contains many genes, which are the units of inheritance.

DNA replication is the process by which a DNA molecule is copied to produce two identical DNA molecules. It occurs during cell division to ensure that each new daughter cell receives a complete set of genetic information. This process involves the unwinding of the DNA double helix and the synthesis of new complementary strands using the existing strands as templates.

Messenger RNA (mRNA) is a type of RNA that carries the genetic code from DNA in the nucleus to the ribosomes in the cytoplasm. Here, it serves as a template for protein synthesis. mRNAs are translated by ribosomes into proteins, according to the genetic code.

Ribosomal RNA (rRNA) is a type of RNA that is a key component of ribosomes. Ribosomes are the molecular machines that synthesize proteins. rRNA provides the structural framework of the ribosome and is involved in the catalytic activity of protein synthesis.

Transfer RNA (tRNA) is a type of RNA that transports amino acids to ribosomes during protein synthesis. Each tRNA molecule has a specific anticodon that binds to a complementary codon on mRNA, ensuring that the correct amino acid is added to the growing polypeptide chain. This process is crucial for translating the genetic code into the amino acid sequence of a protein.