Chapter 8 Review 8-1: Chromosomes 8-2: Mitosis 8-3 Meiosis Take a moment to write down the most important question you have about one of the topics covered in chapter 8.

Chromosome Structure DNA strand Gets wrapped around many histone proteins (aka histones) forming a coil. Coils are coiled up even more to form a supercoil, which is then packaged even more to make a chromosome.

What’s the big idea? Most of the time, DNA is uncoiled, so that it can perform its function of providing instructions to the cell. Only during cell reproduction does DNA get tightly packed into chromosomes

Parts of a chromosome The 2 chromatids that make up a chromosome are called sister chromatids, which are extremely similar to each other.

Dogs Have 78 Chromosomes! Every specie of organisms has a characteristic number of chromosomes. 78 Dog Adder’s Tounge Fern 1,262 46 48 Humans chimps

Autosomes and Sex Chromosomes Human and animal chromosomes are categorized as autosomes or sex chromosomes. Sex Chromosomes determine and organisim’s sex. All of the others are called autosomes Typical human male 44 autosomes, 1 X sex chromosome 1 Y sex chromosome Typical human female 44 autosomes, 2 X sex chromosomes

Homologus Chromosomes Every cell contains two copies of each autosome. To put it another way, autosomes come in pairs. These two chromosomes are called HOMOLOGUS CHROMOSOMES. Genes for eye color are found at The same location on both Chromosomes. The gene for brown Eyes I got from my dad is in exactly The same location on one chromosome As the gene for blue eyes I got from my Mom on the other homologus Chromosome. Specific genes are found in the Same location on each homolugus Chromosome. Consider me for example…

Diploid vs. Haploid Most of the cells in your body (and in all mammals) are DIPLOID, meaning they have 2 copies of all of your DNA

Haploid Cells Some cells (like animal reproductive cells – sperm and eggs) have only 1 copy of each chromosome. They are haploid.

The Cell Cycle The cell cycle is like a cell’s life cycle.

Mitosis Mitosis is the process of a cell making two identical “daughter” cells.

Mitosis vs Meiosis Mitosis = normal cell division. Meiosis = gamete production. Remember: My toeses do mitosis.

Meiosis: Chromosomes are copied Cell divides twice. (PMAT) 2n x 2 / 2 / 2 = 1n Produces haploid gametes Don’t forget crossing over!

Self-Assessment: Chapter 8 8-1-1 Chromosomes are made up of: A. RNA and histone proteins B. DNA and histone proteins C. DNA and phospholipids D. Histone proteins only

8-1-2: What is the function of the Y-chromosome in male humans? A. It carries very important genes B. It is a sex chromosome, so it determines gender C. Both A & B D. None of the above

8-2-1: During which phase of mitosis do chromosomes first become visible? A. Telophase B. Metaphase II C. Prophase D. G0

8-2-2: The process of cytokinesis happens in slightly different ways in plant and animal cells. In plant cells, a(n) ____________ forms, while in animal cells, a(n) _____________ can be seen. A. Xerophile; ribosome B. Cell plate; cell membrane C. Cell plate; cleavage furrow D. Cell wall, endoplasmic reticulum

8-3-1 Which of the following best describes meiosis? A. A single cell division results in two daughter cells B. Two cell divisions result in four diploid cells C. Two cell divisions result in four haploid cells D. Two haploid cells fuse to form one diploid cell

8-3-2: During meiosis a process known as crossing over A. Always occurs between different chromosomes B. Can exchange DNA between homologous chromosomes C. Never happens D. Produces gametes with an incorrect number of chromosomes

Remember those Questions? Take a look at the question you wrote down at the beginning of the period. Did it get answered?