Question of the Day 3-7 When are sister chromatids formed? When are they separated? When are homologous pairs separated?

Question of the Day 3-8 What is cancer? What causes cancer?

Today How Cancer Grows Quiz make ups 3-7 How Cancer Grows Quiz make ups Read Section 8.3 in the Owl Book and answer #s 1-6 on page 156

Question of the Day 3-9 What is a haploid cell (there are multiple correct answers)?

Question of the Day 1. What are the four stages of mitosis in order? 3-10 1. What are the four stages of mitosis in order?

Announcement 3-10 Plan for the Unit # 6 Test at the end of next week (Thursday 3-17 or Friday 3-18)

Control of Cell Division Cell division in eukaryotes is controlled by many proteins. Contact Inhibition = when normal cells come in contact with one another, growth stops

Cancer Cancer may result if cells do not respond to proteins and/or contact inhibition. Contact Inhibition - Cancer cells do not stop dividing when they come in contact.

Cancer = uncontrolled cell growth causes = mutated DNA (genetic or environmental)

Mitosis vs. Meiosis  Mitosis produces 2 daughter cells while meiosis produces 4 daughter cells  Mitosis produces diploid cells while meiosis produces haploid cells

Mitosis Review Genetically – how similar are the daughter cells in mitosis? They are identical When is the DNA copied for the new cell? S phase of interphase What are two things make up chromosomes? DNA and histones (protein) What is the middle part of the chromosome? Centromere What gets separated during mitosis? Sister chromatids NOT homologous pairs

Meiosis Objectives Compare the end products of meiosis with those of mitosis. Summarize the events of meiosis I. Explain crossing-over and how it contributes to the production of unique individuals. Summarize the events of meiosis II. Compare spermatogenesis and oogenesis. Define sexual reproduction. 12

Assignment #s 1-6 on page 156 – Owl Book

Poster Contest Due Friday 3-11 3-8 Topics: The S-phase of Interphase Prophase Metaphase Anaphase Telophase Cytokinesis The chromosome Creativity Slogan / Title Aesthetically pleasing Accurately descriptive and understandable MAKE SURE YOU GET A CHECKLIST FOR YOUR TOPIC!!!

Important vocab. review What does DIPLOID mean? Cells having 2 homologous copies of each chromosome (homologous pairs) What does HAPLOID mean? Number of chromosomes in a sex cell (half the number in a diploid cell) What are sister chromatids? Identical copies of the same chromosome

Important vocab. review What is are sister chromatids? Identical copies of the same chromosome When does the cell produce the copy of the chromatid? S phase of interphase

Important vocab. review What are homologous chromosomes? Chromosomes that carry genes for same traits (though variation of the trait may differ) Allele – variation of a trait Trait = flower color Alleles = genes for either white or purple flowers

Formation of Haploid Cells Meiosis – the process of making sex cells. makes sperm and eggs Four new haploid cells result (gametes) Meiosis is broken down into Meiosis I and Meiosis II. 18

Question of the Day 3-14 How is meiosis different from mitosis (there is more than one correct answer)?

Announcement 3-14 Plan for the Unit # 6 Test on Friday 3-18

Reviewing Objectives Describe the structure of a chromosome. How is a prokaryotic chromosome different than a eukaryotic chromosome? How many chromosomes do you have? How are diploid and haploid cells different?

Reviewing Objectives cell division in prokaryotes = ??? What happens during interphase? 4 stages of mitosis in order = ??? How is cytokinesis in animal cells different from cytokinesis in plant cells? How is cell division controlled? What happens if it is not?

Meiosis I:  crossing over takes place  homologous chromosomes get separated  2 new haploid cells result

Meiosis II:  sister chromatids get separated (like in mitosis)  2 new haploid cells result from each of the cells from meiosis I (total 4 new cells)

During meiosis… Synapsis – pairing of homologous chromosomes – this did not occur in mitosis

Formation of Haploid Cells Crossing-over – when portions of homologous chromosomes exchange genes Results in genetic recombination. Genetic recombination – Regrouping of genes in an offspring that results in a genetic makeup that is different from the parents 26

Crossing Over

Crossing Over

Types of Reproduction Asexual Reproduction = genes identical to parents PRO: Offspring well adapted to survival Need only one parent Fast CON: If susceptible to a disease, may kill off the entire population (b/c all genes are the same)

Why is genetic recombination important? Sexual Reproduction PRO: Leads to genetic diversity from parents Not all members will die from a disease (leads to species evolution) CON: Need two parents Takes longer

Poster Contest Due Friday 3-14 3-14 Topics: The S-phase of Interphase Prophase Metaphase Anaphase Telophase Cytokinesis The chromosome Creativity Slogan / Title Aesthetically pleasing Accurately descriptive and understandable MAKE SURE YOU GET A CHECKLIST FOR YOUR TOPIC!!!

Error in Meiosis Nondisjunction - when a set of homologous chromosomes do not separate Means "not coming apart" Results in gametes with incorrect chromosome #