Intro to Genetics Genetic Lingo & Cell Organization

Cell Organization  Many parts of the cell interact to make sure that every cell has a copy of the genetic information Chromosomes Chromosomes Nucleolus Nucleolus Nucleus Nucleus Ribosomes Ribosomes

Genetic Material  Our genetic material is arranged in chromosomes Each chromosome has genes that code for specific characteristics in the organism Each chromosome has genes that code for specific characteristics in the organism Chromosomes are made of DNAChromosomes are made of DNA

Chromosomes  Difficult to see during normal cell activity We observe them during cell division (metaphase) We observe them during cell division (metaphase) They condense and coil and become visibleThey condense and coil and become visible  A chromosome contains 2 copies of the same genes Each chromatid contains one copy of the genes Each chromatid contains one copy of the genes The chromatids are held together by the centromereThe chromatids are held together by the centromere

DNA  Deoxyribonucleic Acid Structure is called a double helix Structure is called a double helix It is also like a twisted ladder It is also like a twisted ladder The backbone (side of ladder) is called the ‘sugar- phosphate’ backboneThe backbone (side of ladder) is called the ‘sugar- phosphate’ backbone It is made of a ‘deoxyribose sugar’ & a phosphate group It is made of a ‘deoxyribose sugar’ & a phosphate group The middle of the helix (ladder rungs) are made of base pairsThe middle of the helix (ladder rungs) are made of base pairs

DNA Bases  DNA has 4 bases Adenine Adenine Cytosine Cytosine Guanine Guanine Thymine Thymine  A & T always pair (base-pair)  C & G always pair (base-pair) Video: DNA StructureVideo: DNA Structure  What is a nucleotide?

DNA to Chromatids DNA Histones Nucleosome Chromatin Fibres Chromatin Chromatid Every 200 base pairs, DNA is wrapped around 8 histones - histones are proteins – how do they attract DNA? DNA wound around 8 histones creates a structure called a nucleosome Nucleosomes coil further into chromatin fibres Chromatin fibres coil into what is called chromatin Chromatin wraps up into a chromatid