Class Notes (836,373)
Canada (509,756)
York University (35,328)
Biology (2,253)
BIOL 1500 (75)
all (14)


4 Pages
Unlock Document

BIOL 1500
All Professors

Biology Chapter 6 Notes: Chromosomes and Cell Division • Telomere: cell reproduction "counter" and human cells divide about 50 times • Some chromosomes are circular, some are linear; • Binary fission (division of 2): asexual reproduction of prokaryotic cell division; daughter cells inherit their DNA from a single parent cell; DNA is carried in a single, circular chromosome; begins with replication (DNA duplicates itself); DNA molecule unwinds from its coiled-up configuration; the DNA strand splits apart and free-floating nucleotide bases attach; the cell elongates and pinches into two • Eukaryotic chromosome: made of more than just DNA; the long linear DNA strand is wrapped around proteins called histones (keeps DNA from getting tangled) Cell Cycle • eukaryote cells: somatic cells are cells forming the body of the organism and gametes are reproductive sex cells • Two phases to the somatic cell cycle: cells grow and prepare to divide during interphase and divide during the mitotic phase Interphase • Gap 1: cell grows and performs all cellular functions (making proteins, getting rid of waste, etc); cells that divide infrequently (neurons, heart muscle cells) spend most of their time in Gap 1 • DNA synthesis: cells begin to prepare for cell division; every chromosome creates an exact duplicate of itself by replication; before replication, each chromosome has become a pair of identical long linear strands, held together near the centre (region where chromosomes are in contact is called centromere) • Gap 2: cells continue to grow and prepare for cell division; differs from Gap 1 because genetic material has now been duplicated; Gap 2 usually shorter than Gap 1 Mitosis • nucleus of parent cell duplicates; followed by cytokinesis • DNA replication: Unwinding of coiled double-stranded DNA molecule and Rebuilding of double stranded DNA with an enzyme connecting the complementary base pairs • Purpose: enable existing cells to generate new, identical cells for Growth and Replacement • Apoptosis: Cells that must be replaced die on purpose 1. Prophase: nuclear membrane breaks down; sister chromatids (replicated chromosomes) condense; spindle fiber forms 2. Metaphase: sister chromatids line up at the centre of the cell 3. Anaphase: the sister chromatid pairs are pulled apart by the spindle fibrers; one full set of chromosomes from each chromatid goes to each side of the cell 4. Telophase: chromosomes begin to uncoil; nuclear membrane is reassembled around them 5. Cytokinesis: cytoplasm and organelles duplicate and are divided into approximately equal parts Out of Control Cell Division • Cancer: unrestrained cell growth and division and can cause serious health problems • Loses their "contact inhibition" • Cancer cells can divide indefinitely • Benign vs. malignant; metastasis is the process cancer cells separate from a tumor and invade the circulatory system Meiosis • Fertilization: fusion of two reproductive cells • Outcomes: 1. Redu
More Less

Related notes for BIOL 1500

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.