DNA Structure and Function

DNA Structure and Function

• Genes are composed of DNA, a chemical that contains genetic material passed down through generations.
• DNA is found in the nucleus of almost every cell in the human body, except for red blood cells.

DNA as a Blueprint

• DNA is a unique code that defines every structure and function in an organism, and is passed down from generation to generation.
• Each species has its own unique DNA, while individuals within a species have fine variations of the existing DNA.

Key DNA Terms

• Ribonucleic acid (RNA): a complementary copy of DNA that carries genetic messages from the nucleus to the cytoplasm.
• Karyotype: the arrangement of a complete set of chromosomes in pairs of decreasing size.
• Bivalent chromosome: a chromosome with two identical strands, formed during DNA replication, often represented by an 'X' shape.
• Chromatid: a single strand of a bivalent chromosome.
• Genetic code: the sequence of nucleotides in DNA that is inherited from parents.
• Uracil: one of the four nitrogen bases of RNA.
• Transcription: the formation of complementary RNA from DNA.

Chromosomes and DNA Relationship

• Each cell in the human body (except red blood cells) contains 46 chromosomes, made up of DNA molecules tightly wound around proteins.
• Chromosomes are often referred to by numbers according to their size, with the largest pair being number 1.
• The last two chromosomes determine the sex of an individual, with human females having two X chromosomes and males having one X and one Y chromosome.
• A single chromosome equals a molecule of DNA, and chromosomes can be single or bivalent.

Fun Fact

• If all the unwound DNA in a single cell were laid out, it would be approximately 2 meters long.

DNA and Its Structure

• Genes are made of a chemical called DNA, which is the genetic material passed down through generations.
• DNA is found in the nucleus of almost every cell in the human body, except for red blood cells.
• DNA acts as a blueprint for every structure and function in an organism, containing a unique code that can be passed down to offspring.

DNA Components

• Ribonucleic acid (RNA) is a complementary copy of DNA that carries the genetic message from the nucleus to the cytoplasm.
• Karyotype refers to the arrangement of a complete set of chromosomes in pairs of decreasing size.
• A bivalent chromosome is a pair of identical chromosomes (visualized as an 'X' shape) formed during DNA replication.
• A chromatid is a single strand of a bivalent chromosome.
• The genetic code refers to the sequence of nucleotides found in DNA that is inherited from parents.
• Uracil is one of the four nitrogen bases of RNA.

Chromosomes and DNA

• Each cell in the human body (except red blood cells) contains 46 chromosomes, which are made up of DNA molecules tightly wound around proteins.
• Chromosomes are paired and referred to by numbers according to their size, with the largest pair being number 1.
• The last two chromosomes determine the sex of an individual, with human females having two X chromosomes and males having one X and one Y chromosome.
• A simple equation to understand the relationship between DNA and chromosomes is: A single chromosome = a molecule of DNA.
• Chromosomes can be single or bivalent, with each strand of a bivalent chromosome called a chromatid.

Fun Fact

• If all the untravelled DNA in a single cell were stretched out, it would be approximately 2 meters long.