1 24 12 portion of DNA tha codes for a protein or part of a protein Alternate forms of a gene Ex eye color position on the chromosome where we find the gene or allele Gene Allele Locus Point mutation change in one base of DNA o ATTCGG ATTGGG point mutation o Silent mutation where amino acid isn t changed Sickle Cell Anemia is a result of point mutation 2 alpha chains 2 beta chains 146 amino acids in these 3x146 bases in the DNA 1 change can cause a much larger change o Variation comes from this Chromosomes Your DNA o In humans it is packaged into 46 chromosomes 23 pairs o Half from each parent Chromosome 1 is longest They all have the same length same banding same centromere position same information aside from variation of alleles Centromere Constriction that divides chromosome P arm shorter arm Q arm longer arm Each chromosome carries the same information for its position as everyone else s Ex 1 has eye color for everyone 22 is shortest Autosomes Sex chromosomes chromosomes 1 22 23rd pair either XX female or XY male Mother always gives X male has chance to give X or Y o Apes have 48 chromosomes This is because our chromosomes are the same ones with some stuck together o Fruit flies have 8 easy to study o Minnow 100 o Fern 250 o Shows that number of chromosomes does NOT show complexity of species o Our autosomes are Homologous chromosomes they are always the same o There is hardly any information on the Y chromosome Determines if you ll have hairy ears Also has coding for SRY gene SRY gene codes for TDF protein Testus determining Factor o TDF o In the embryo there is a bi potential gonad that can become o When TDF is introduced to this they form testicles o Androgens are produced which causes rest of body to be male testicles or ovaries testosterone is one Cell Division o Mitosis simple cell division for somatic cells First step is DNA replication o Miosis ovaries testes DNA is normally in a loose unwound state called Chromatin It only condenses to where you can see it before cell division DNA splits attracts bases again and forms new DNA and chromosomes are doubled Cell splits and doubled DNA and chromosomes go into new cell and both are now identical complex replication responsible for making eggs and sperm and only occurs in DNA replication still occurs for 46 double stranded chromosomes Homologous chromosomes find each other They share information and change This is called crossing over or Recombination This means that none of the chromosomes you make are like the ones you were given from your parents This adds variation to genetics because there is a 1 in 8 million chance that two eggs sperm are genetically similar where 46 double stranded chromosomes split into 2 cells Reduction Division with 23 double stranded chromosomes 1 23 These two cells split again into 4 genetically unique cells with 23 single stranded chromosomes In females this only happens in the embryonic stage In males once this happens testosterone gives the cells tails making them sperm Females put all the cytoplasm and nutrients and good stuff into one cell the egg and the other three become Polar Bodies they aren t used for anything Nondisjunction the incorrect number of chromosomes chromosomes fail to replicate and you get eggs sperm with Aneuploids Responsible for 50 of miscarriages incorrect pairing of chromosomes Most autosomal aneuploids aren t compatible with life Some are extra 21st chromosome Down s Syndroe Lots of sex chromosome aneuploids