1. Genetics Unit 1

2. Objectives 4.1 – 4.2 Review of 2.5 Readings Orange book: pg. 81 – 90, pg. 38-43 Green book:

3. Remember that chromosomes consist of both DNA and histone proteins which are packed together in a specific way. In most organisms chromosomes are paired, one being inherited from the mother (maternal chromosome) and the other being inherited from the father (paternal chromosome) Humans have 23 pairs of chromosome, 22 pairs being homologous and the 23 rd pair being the sex chromosomes.

4. A gene is a factor that controls a specific characteristic (trait). Genes are heritable, meaning they are passed from parent to offspring Various forms of a gene are referred to as alleles. Ex) allele for eye color may code for blue, green, brown, etc… Alleles for the same gene occupy the same locus (position) on a chromosome

6. Mutation A random change in genetic material Point mutation – involves one base pair of a gene  Substitution – one nucleotide is replaced with another Silent Missense Nonsense  Insertion/Deletion – causes a “frameshift” in how the sequence of DNA is read.

7. Mutations occur  Spontaneously  Due to chemical mutagens

8. A Karyotype: A karyotype of a photo of chromosomes arranged according to size and shape based on location of the centromere.

9. Making a Karyotype Cells are extracted from an unborn baby via amniocentesis or chorionic villus sampling. Fetal cells grown in the lab