DNA Structure & Chromosomal Organisation

These flashcards contain essential vocabulary and definitions related to the structure of DNA and chromosomal organisation, helping students to grasp key concepts for their exam.

DNA Structure

The arrangement of nucleotides in DNA, which forms a double helix.

Chromosome

A thread-like structure made of DNA and proteins that carries genetic information.

Nucleus

An organelle that contains the cell's genetic material in the form of DNA.

Nucleosome

A structural unit consisting of a length of DNA coiled around a core of histone proteins.

Histone proteins

Proteins around which DNA is wrapped, helping to package DNA into a compact form.

Transformation

The process through which genetic material is transferred between organisms, resulting in changes in genotype.

Semi-conservative replication

A method of DNA replication in which each new DNA molecule contains one old strand and one new strand.

Bacteriophages

Viruses that infect bacteria, used to demonstrate that DNA is the genetic material.

Chargaff's rules

Observations that in DNA, the amount of adenine equals thymine and the amount of cytosine equals guanine.

Watson and Crick Model

The model describing the double helix structure of DNA, where two strands run antiparallel and base pairs connect through hydrogen bonds.

Telomere

The end segment of a chromosome that provides stability and prevents degradation.

Centromere

The region of a chromosome where sister chromatids are joined and where the spindle fibers attach during cell division.

DNA polymerase III

An enzyme responsible for synthesizing new strands of DNA during replication.

Avery, MacLeod & McCarty experiment

Research that proved nucleic acids, not proteins, were the genetic material.

Uracil

A nitrogenous base found in RNA that replaces thymine found in DNA.

Okazaki fragments

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

Gene

A segment of DNA that contains the instructions for making a specific protein.

Ribosomal RNA (rRNA)

A type of RNA that combines with proteins to form ribosomes, the cellular machinery for protein synthesis.

Messenger RNA (mRNA)

A type of RNA that carries the genetic information from DNA to the ribosome for protein synthesis.

Transfer RNA (tRNA)

A type of RNA that transports amino acids to ribosomes during protein synthesis.