1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 18 Patterns of Chromosome Inheritance Lecture Outline Part 1 Human Biology Sylvia S. Mader Michael Windelspecht

2 Patterns of Chromosome Inheritance

3 Points to ponder What is the structure of chromosomes? What is the cell cycle and what occurs during each of its stages? Explain what mitosis is used for, what cells undergo mitosis, and the 4 stages of mitosis. Explain the 2 divisions of meiosis. What is meiosis used for and what cells undergo meiosis? Compare and contrast mitosis and meiosis. Compare and contrast spermatogenesis and oogenesis. What are trisomy and monosomy? What most often causes changes in chromosome number? What are the syndromes associated with changes in sex chromosomes? Explain the 4 changes in chromosome structure.

4 Chromosomes: A review Humans have 46 ______________ that are in 23 pairs within a cell’s nucleus. –Pairs of chromosomes are called ___________ chromosomes. –Autosomes are the ___ pairs of chromosomes that control traits unrelated to gender. –__________________ are the 1 pair that contains the genes that do control gender Chromosomes

5 Chromosomes: A review Cells (___________) that have 46 (2n) paired chromosomes are called __________. Cells (__________) that have only 23 (n) unpaired chromosomes are called ________ Chromosomes

6 What is a karyotype? 18.1 Chromosomes Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The 46 chromosomes of a male sister chromatids centromere sex chromosomes in males homologous autosome pair © CNRI/SPL/Photo Researchers, Inc. Figure 18.1 A karyotype of human chromosomes.

7 2 parts 1.Interphase G 1 stage – cell doubles its __________; cell grows in size S stage – _______________ occurs G 2 stage – proteins needed for division are synthesized 2.Cell division (mitosis and cytokinesis) _________ – nuclear division __________ – cytoplasmic division 18.2 The Cell Cycle The cell cycle

8 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. G1G1 growth G2G2 S M Cytokinesis Telophase Anaphase Metaphase Prophase Interphase growth and DNA replication growth and final preparations for division Figure 18.2 Stages of the cell cycle The Cell Cycle

9 Control of the cell cycle Checkpoints can delay the cell cycle until certain conditions are met. There are 3 major checkpoints. –G 1, if passed, the cell is committed to divide. –G 2 cycle pauses to verify DNA replication. –M cycle pauses to verify spindle assembly and chromosome attachment The Cell Cycle

10 Figure 18.3 Control of the cell cycle The Cell Cycle Control of the cell cycle Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. G 2 (growth and final preparations for division) M Cytokinesis G 2 checkpoint Mitosis checkpoint. Mitosis will occur if DNA has replicated properly. Apoptosis will occur if the DNA is damaged and cannot be repaired. G 1 checkpoint Cell cycle main checkpoint. If DNA is damaged, apoptosis will occur. Otherwise, the cell is committed to divide when growth signals are present and nutrients are available. M Telophase Anaphase Metaphase Prophase Interphase S (growth and DNA replication) G 1 (growth) M checkpoint Spindle assembly checkpoint. Mitosis will not continue if chromosomes are not properly aligned. G0G0 G1G1 G2G2

11 Chromosome structure in mitosis Chromosomes contain both DNA and proteins (collectively called ___________). Chromosomes that are dividing are made up of 2 identical parts called _________________. The sister chromatids are held together at a region called the ____________ Mitosis

12 Chromosome structure in mitosis 18.3 Mitosis Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. centromere duplicated chromosome sister chromatids replication division chromosome

13 The spindle in mitosis ______________ – the microtubule organizing center of the cell ______ – an array of microtubules at one of the poles (ends of the cell) ___________ – short cylinders of microtubules that assist in the formation of spindle fibers 18.3 Mitosis

14 The spindle in mitosis 18.3 Mitosis Figure 18.7 The mitotic spindle. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. centrioles in centrosome chromosomes spindle fibers aster pole