lesson 1: Introduction
Key words:
-DNA
-Double Helix
-Nitrogenous bases
-Chromosome
-Homologous chromosomes
Genetics is the study of an organism's DNA. DNA is a molecule that lives inside the nucleus of pretty much every cell in the body. It codes for any living thing's heritable characteristics. Half of the offspring's DNA comes from each parent. DNA codes for things like eye color, susceptibility to disease, gender, blood type, and (some) personality traits.
DNA is in a double-helix structure, like a twisted ladder. The long parts are made up of phosphates and sugars. The 'rungs' are the four nitrogenous bases: adenine, guanine, thymine and cytosine. Adenine attaches only to thymine. Guanine attaches only to cytosine. Organisms are unique because of different arrangements and numbers of each of these pairs.
If you stretched all the DNA in all of your cells combined, the resulting string would be about twice the diameter of the Solar System! That means DNA is difficult to stuff into a tiny little nucleus. That's where histones come in, twisting your DNA into shapes called chromosomes.
In diploid organisms (such as rabbits and humans), we have two 'copies' of each chromosome. These are called homologs. Homologs are similar in that they have the exact same genes in the same respective regions. Each gene can have variant forms, called alleles. For example, a gene that determines color could have an allele for blue or an allele for red. For this reason, homologs are not truly genetically identical - they may have different variant forms of any given gene.
Rabbits have 21 pairs of autosomal (regular) chromosomes, and 1 pair of sex chromosomes (X and Y) which determine gender and sex-linked characteristics. Therefore, they have 22 pairs of homologous chromosomes, or 44 individual chromosomes (which can be described as chromatids for ease of understanding).
-DNA
-Double Helix
-Nitrogenous bases
-Chromosome
-Homologous chromosomes
Genetics is the study of an organism's DNA. DNA is a molecule that lives inside the nucleus of pretty much every cell in the body. It codes for any living thing's heritable characteristics. Half of the offspring's DNA comes from each parent. DNA codes for things like eye color, susceptibility to disease, gender, blood type, and (some) personality traits.
DNA is in a double-helix structure, like a twisted ladder. The long parts are made up of phosphates and sugars. The 'rungs' are the four nitrogenous bases: adenine, guanine, thymine and cytosine. Adenine attaches only to thymine. Guanine attaches only to cytosine. Organisms are unique because of different arrangements and numbers of each of these pairs.
If you stretched all the DNA in all of your cells combined, the resulting string would be about twice the diameter of the Solar System! That means DNA is difficult to stuff into a tiny little nucleus. That's where histones come in, twisting your DNA into shapes called chromosomes.
In diploid organisms (such as rabbits and humans), we have two 'copies' of each chromosome. These are called homologs. Homologs are similar in that they have the exact same genes in the same respective regions. Each gene can have variant forms, called alleles. For example, a gene that determines color could have an allele for blue or an allele for red. For this reason, homologs are not truly genetically identical - they may have different variant forms of any given gene.
Rabbits have 21 pairs of autosomal (regular) chromosomes, and 1 pair of sex chromosomes (X and Y) which determine gender and sex-linked characteristics. Therefore, they have 22 pairs of homologous chromosomes, or 44 individual chromosomes (which can be described as chromatids for ease of understanding).