University:
High School
Course:
High School Biology
Academic year:

2022
Views:

93

Pages:

10
Author:

Aisha Costa

Chromosomes • How is it made? 1. Get cells from blood or amniotic fluid 2. Chemically treated to stop them in metaphase and stain 3. The chromosomes are then photographed 4. Chromosomes are cut out 5. Arranged in pairs from largest to smallest 6. Chromosomes are numbered in 23 sets #1-Chromatin #2 Chromosome Scatter #3 Karyotype Chromosomes Abnormalities 1. Nondisjunction (NOT-COMING-APART) Chromosomes fail to separate during anaphase of Meiosis 2. Mutations: changes in chromosome structure Nodisjunctions • What if a chromosome is missing? • Monosomy –Most do not survive to be born –If a chromosome is missing the condition is called – EX: Turner’s Syndrome (XO) Nondisjunctions • What if a cell has an extra chromosome? • Trisomy –The condition in which a cell has an extra chromosome is called trisomy –Example: Trisomy 21 (Down Syndrome) Nondisjunction Chromatids do not Separate in Anaphase II NORMAL TRISOMY MONOSOMY Mutations • Deletion part of the chromosome breaks off • Duplication: part of the chromosome is repeated Cancer • Mutations in genes that control normal cell division can lead to cancer. Increasing your risk • Sun without sun block • Smoking or being around 2nd hand smoke • Working with known cancer causing chemicals. • Eating foods with preservatives such as nitrates • Cooking Foods in plastics that contain dioxin Proto-Oncogenes are normal genes that code proteins involved in a cell's normal growth Oncogenes tell cells to make proteins that cause excessive cell growth and division. *Oncogenes are Mutant Forms of Proto-Oncogenes* Tumor Suppressor Genes • Normal genes whose ABSENCE can lead to cancer. Why don’t we all get cancer? • Genes come in pairs, one from each parent • A defect in one copy will not cause cancer because the other normal copy is still functional.