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Section: 2.1 Name: Opening Activity: Latin Root Word Review of Old Information: None New Information: Notes - Chromosomes and the Cell Cycle Why cell division? A.Necessary for the __________ of organisms. B.Necessary for every cell in organism to have the ___________ instructions to survive. C.Genetic instructions passed through __________ in _______________. DNA. A. Cell reproduction begins with _______. B. DNA is a long, thin molecule stores _________ information! C. Found in _____________ of eukaryotic cells. What are chromosomes A.Rod-shaped structures of coiled ________ and ___________. B.____________: proteins in chromosomes that help DNA form its double helix shape. C.____________: proteins that control activities of DNA I. Chromosome Structure a. ______________ – condensed DNA that can be found in the nucleus of the cell during cell division – visible! i. Remember, Chromatin is uncondensed DNA and cannot be seen. b. The DNA in a chromosome can be found wrapped around proteins known as _______________ c. Chromosomes have two halves known as ______________________. d. The ________________________ holds the two halves of the chromosome together. e. Sex Chromosomes – Chromosomes that determine the sex of an organism i. In humans, the sex chromosomes are ______________________ 1. Women have two X chromosomes 2. Men have an X chromosome and a Y chromosome f. _________________________ – any non-‐sex chromosome i. __________________________________________ – the two copies of each autosome g. __________________________ – a photo of the homologous chromosomes found in humans h. ______________________ – Have both sets of homologous chromosomes i. Each chromosome has a pair ii. In humans this means ________chromosomes i. ______________________ – have just one set of homologous chromosomes i. Each chromosome doesn’t have it’s pair ii. In humans this means ________ chromosomes The Cell Cycle and Cancer: A.Cell division occurs during the ___________________ B.It is the repeating set of events that make up the life cycle of a cell. C.Divided into __________ phases: 1._____________: time between cell divisions 2.Cell Division: consists of two stages a._______________: division of nucleus. b._______________: division of cytoplasm of the cell. Stages of Interphase 1. G Phase: _____________________. 1 2. S Phase: ____________________. 3. G Phase: growth and ________________ for cell division (organelles develop) 2 ***G Phase: used by some cells to exit cell cycle; usually occurs after G Phase; examples include mature nerve cells. 0 1 CANCER Cancer is a disease of the ____________. Some of the body’s cells divide uncontrollably and _______________ form. Some Tumors are cancer others are not ___________________ ¨Cells in a tissue overgrow ¨Resulting defined mass: ________________ (neoplasm) -________________, e.g., moles 1. _________ growth 2. Expands in the same tissue; does ________ spread 3. Cells look nearly normal -________________ 1. ___________ growth 2. Invades surrounding tissue and ________________(becomes cancerous) 3. Cell differentiation usually poor Cancer cells do not divide normally ¨Cancer cells don’t necessarily divide faster than normal cells; more cancer cells are ___________________ than dying ¨Cancer cells do not respond to _____________; loss of ____________ inhibition 1. Leads to a disorganized mass; cells may have extensions 2. ___________: makes a cancer malignant Cancer usually involves several genes ¨______________________ -In ________________ cells -Code for proteins involved in the ____________ of cell division -If altered, may form ____________ -_____________, do not cause malignant cancer -Require other mutations, including one in a tumor suppressor gene ¨_______________________ -_________ cell growth and _________; __________ cancer formation -May prevent expression of ____________________ -p53: codes for a regulatory protein that turns off cell division when the cell is stressed or damaged 1. If mutated, runaway ____________________ 2. More than _________ of cancers has a mutated or missing p53 gene Factors that may lead to cancer… Treatment for cancer cells… Activity: Read pages 145 through 147 and answer the following questions 1. Draw the structure of a chromosome labeling the DNA, centromere, chromatid. 2. Describe the difference between a chromosome and a DNA molecule? 3. _____During cell division, the DNA in a eukaryotic cell is tightly packed and coiled into structures called a. centromeres b. histones c. haploids d. chromosomes 4. _____Between cell divisions, the DNA in a eukaryotic cell is uncoiled and spread out; in this form it is called a. chromatid b. chromatin c. histone d. nonhistone 5. _____The chromosomes of most prokaryotes consist of proteins and a. a single circular DNA molecule b. a single linear DNA molecule c. a pair of linear DNA molecules joined in the center d. a pair of homologous, circular DNA molecules 6. What are homologous chromosomes? 7. Humans have 46 chromosomes in all cells except sperm and egg cells. How many of these chromosomes are autosomes? 8. Compare chromosomes and chromatids.
