Topic

These flashcards cover key concepts of DNA structure, organization, manipulation, and related processes in molecular biology.

Nucleotide

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

Deoxyribonucleic acid (DNA)

The molecule that carries the genetic instructions for life, composed of nucleotides.

Pentose sugar

A five-carbon sugar molecule; in DNA, this is deoxyribose.

Phosphate

A chemical group consisting of a phosphorus atom bonded to four oxygen atoms; part of the nucleotide structure.

Nitrogenous base

The part of a nucleotide that can vary; includes adenine, guanine, cytosine, and thymine in DNA.

Purine

A category of nitrogenous bases with a two-ring structure; includes adenine and guanine.

Pyrimidine

A category of nitrogenous bases with a one-ring structure; includes cytosine and thymine.

Phosphodiester bond

The covalent bond between the phosphate group of one nucleotide and the hydroxyl group of another, forming the backbone of DNA.

Polarity

The directional property of a DNA strand; determined by the orientation of the phosphodiester bonds.

Double helix

The structure formed by two strands of DNA wound around each other.

Complementary base pairing

The specific pairing of nitrogenous bases (adenine with thymine and guanine with cytosine) held together by hydrogen bonds.

Hydrogen bonding

Weak bonds that form between nitrogenous bases, stabilizing the DNA structure.

Antiparallel strands

The orientation of the two strands of DNA running in opposite directions (5' to 3' and 3' to 5').

Genome

The complete set of genetic material in an organism.

Chromosome

A structure containing genetic information, made of DNA and proteins.

Gene

A segment of DNA that encodes a functional product, typically a protein.

Bacterial chromosome

A circular DNA molecule found in prokaryotic cells, localized in the nucleoid region.

Eukaryotic chromosome

Linear DNA structures found in eukaryotic cells, contained within the nucleus.

Nucleosome

The basic unit of DNA packaging, consisting of a segment of DNA wrapped around a core of histone proteins.

Chromatin

The complex of DNA and proteins that forms chromosomes within eukaryotic cells.

Histones

Positively charged proteins around which DNA is wound to form nucleosomes.

Linker DNA

The short stretches of DNA between nucleosomes in chromatin.

Supercoiling

The winding of DNA that allows it to fit within the cell by making it compact.

Plasmid

Extrachromosomal DNA that can replicate independently of chromosomal DNA, often found in bacteria.

Restriction endonucleases

Enzymes that cut DNA at specific sequences, used in molecular cloning.

Recombinant DNA

A DNA molecule made from two or more different sources, often created in laboratory settings.

Molecular cloning

The creation of multiple copies of a DNA sequence, typically by inserting it into a vector.

CRISPR-Cas9

A genome editing technology that allows for precise modifications in DNA.

Genome editing

The process of making targeted alterations to the genome of an organism.

Cas9

An endonuclease enzyme that cuts DNA, part of the CRISPR-Cas system.

Guide RNA

A synthetic RNA molecule that directs Cas9 to the specific site of DNA to be edited.

Nuclear DNA

DNA that is located in the nucleus of eukaryotic cells, organized into chromosomes.

Anti-phage defense systems

Mechanisms that bacteria use to protect themselves from viral infections, including restriction endonucleases and CRISPR-Cas systems.

Spacer acquisition

The process by which short sequences of viral DNA are incorporated into the CRISPR array of a bacterial genome.

CRISPR RNA (crRNA)

The RNA derived from the CRISPR array that guides Cas9 to the target DNA sequence.

Non-homologous end joining (NHEJ)

A method of DNA repair that directly joins the ends of DNA fragments without requiring a homologous template.

Homology-directed repair (HDR)

A method of DNA repair that uses a homologous sequence as a template for accurate repair.

Transcription

The process of synthesizing RNA from a DNA template.

Bacteriophage

A type of virus that specifically infects bacteria.

Biological cloning

The process of creating genetically identical organisms or cells from a single biological entity.

Clone

A genetically identical copy of an organism or cell.

Bacterial DNA organization

The structure and arrangement of DNA in bacteria, typically localized in the nucleoid.

Histone tails

The flexible extensions of histone proteins that play a role in chromatin structure and gene regulation.

Nucleoid

The region in prokaryotic cells where the chromosomal DNA is located.

Looping

A process by which DNA is stabilized and compacted through interactions with proteins.