“I find the harder I work, the more luck I seem to have.” 12/2/2018 Title: Biology 12/6/06 Objectives: To assess knowledge of chapter 5 and begin learning about cell division. Class Topics All chapter 5 corrections are to be handed in before the bell rings Chapter 5 Test Begin Chapter 6 “I find the harder I work, the more luck I seem to have.” Thomas Jefferson Sunday, December 02, 2018 5:41 AM

Class Assignments Chapter 5 Test 12/6/06 Read 118-129 12/8/06 12/2/2018 Class Assignments What By When Chapter 5 Test 12/6/06 Read 118-129 12/8/06 W.S. 6.1 12/8/06 Due this class period Due next class period Due in the future

Grade Sheet 1A – SR p. 61 - 5 pts Measurement W.S. – 10 pts 12/2/2018 Grade Sheet 1A – SR p. 61 - 5 pts Measurement W.S. – 10 pts 3A SR p. 42 – 6 pts 4A – SR p. 47 – 5 pts 2A – Measurement W.S. – 10 pts SR p. 80 – 5 pts

12/2/2018 Posttest Activities Read 118-129

Chromosomes Made from DNA Formed from chromatin 12/2/2018 Chromosomes Made from DNA Genetic material that directs activities and determines characteristics Formed from chromatin Right before mitosis Chromatin coils up into rods

Eukaryotic Cell Reproduction (Mitosis) 12/2/2018 Eukaryotic Cell Reproduction (Mitosis) Each chromosome (at this point) is made up of 2 identical chromatids Joined strands of identical duplicated genetic material Joined at centromere Chromatids separate and each cell has identical information Formed in S phase of cell cycle Chromosome Number in Various Organisms & Chromosome Structure From: http://www.rothamsted.bbsrc.ac.uk/ notebook/courses/guide/chromo.htm

From: http://www.accessexcellence.org/RC/VL/GG/nucleosome.html 12/2/2018 From: http://www.accessexcellence.org/RC/VL/GG/nucleosome.html

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12/2/2018 Sets of chromosomes Each human somatic cell has 23 pairs of chromosomes (46 total) Homologous chromosomes Each pair is called homologous Similar in size, shape and genetic content Not identical! One from each parent

Sets of chromosomes Somatic cells Gametes Fertilization Diploid (2n) 12/2/2018 Sets of chromosomes Somatic cells Diploid (2n) 2 sets of chromosomes (46 total) Homologous pairs Gametes Haploid (n) 1 set of chromosomes (23 total) Sperm and egg If an organism has haploid number ___ of chromosomes, how many are in a diploid cell? Fertilization Two haploid gametes join to form a zygote (2n) Fertilized egg

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Numbers of chromosomes 12/2/2018 Numbers of chromosomes Karyotype Table 1 (p. 121)

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“Geographer of the Male Genome” 12/2/2018 Chromosomes 23 homologous pairs 22 pairs of autosomes (44 total) Numbered chromosomes 1 pair of sex chromosomes (2 total) Contain genes to determine gender???? X chromosome – needed, many genes Y chromosome – genes used to determine male gender Male XY Female XX Father determines gender of child Sperm contains X or Y chromosome “Geographer of the Male Genome”

Changes in chromosome number 12/2/2018 Changes in chromosome number Monosomy Having 1 less chromosome (45) Autosomes = lethal Sex = XO – Turner syndrome YO - lethal Trisomy Having 1 more chromosome (47) Abnormalities occur Trisomy 21 = Down syndrome Caused by nondisjunction failure of chromosomes to separate

Down Syndrome Occurs most often in “older” mothers Characteristics 12/2/2018 Down Syndrome Occurs most often in “older” mothers +37 years 1 in 290 births +45 years 1 in 46 births Characteristics Short stature, round face, “slanted eyes”, varying degrees of mental capacity Prenatal testing Amniocentesis Chorionic villi testing

From: http://www.criduchat.asn.au/criduchat/what.htm#Diagram%201 12/2/2018 Mutation (Handout) Changes in chromosome structure Deletion Cri du chat syndrome 5p deletion Translocation 14-21 Another cause of Down Syndrome From: http://www.criduchat.asn.au/criduchat/what.htm#Diagram%201

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