New User Special Price Expires in

Let's log you in.

Sign in with Facebook


Don't have a StudySoup account? Create one here!


Create a StudySoup account

Be part of our community, it's free to join!

Sign up with Facebook


Create your account
By creating an account you agree to StudySoup's terms and conditions and privacy policy

Already have a StudySoup account? Login here

Biology 1020 -- Chapter 12

by: Brittney Champagne

Biology 1020 -- Chapter 12 BIOL 1020 (Dr. Overturf)

Brittney Champagne
GPA 4.0

Preview These Notes for FREE

Get a free preview of these Notes, just enter your email below.

Unlock Preview
Unlock Preview

Preview these materials now for free

Why put in your email? Get access to more of this material and other relevant free materials for your school

View Preview

About this Document

These notes cover chapter 12 -- The Cell Cycle.
Principles of Biology (Dr. Overturf)
Dr. Overturf
Class Notes
Biology, Cell
25 ?




Popular in Principles of Biology (Dr. Overturf)

Popular in Biology

This 5 page Class Notes was uploaded by Brittney Champagne on Thursday September 22, 2016. The Class Notes belongs to BIOL 1020 (Dr. Overturf) at University of Louisiana at Monroe taught by Dr. Overturf in Fall 2016. Since its upload, it has received 113 views. For similar materials see Principles of Biology (Dr. Overturf) in Biology at University of Louisiana at Monroe.


Reviews for Biology 1020 -- Chapter 12


Report this Material


What is Karma?


Karma is the currency of StudySoup.

You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!

Date Created: 09/22/16
Chapter 12 — The Cell Cycle Key Roles of Cell Division Cell division — • Reproduction (unicellular organisms) • Growth and development (multicellular organisms) Tissue renewal (fully grown cells) • Cell cycle — • The life of a cell from the time it is first formed until its own division to two daughter cells • Passes down crucial genetic information 12.1 Most cell division results in genetically identical daughter cells DNAmolecules are packaged into chromosomes. Each chromosome has one long DNAstrand. Each DNAstrand carries several hundred to a few thousand genes, the units of information that specify an organism’s inherited traits. Chromatin — • The entire complex of DNAand proteins • The building material of chromosomes. One piece of chromatin will likely consist of two long strands of DNAplus proteins. • The nuclei of human somatic cells each contain 46 chromosomes, made up of two sets of 23 (one set inherited from each parent). In order for human chromosomes to be correctly counted, it had to be discovered how to use a hypotonic solution to swell nuclei. Distribution of Chromosomes during Eukaryotic Cell Division Sister chromatids — joined copies the original chromosome Each sister chromatid has a centromere. Centromere — region in which chromatids remain attached to one another until anaphase • 2 chromatids for every centromere 2 centromeres for every chromosome • Centrosome — microtubules of the spindle assemble here during mitosis (in both plant and animal cells); the microtubule organizing center 12.2 The mitotic phase alternates with interphase in the cell cycle Eukaryotic cell divison: • Mitosis — the division of genetic material in the nucleus • Cytokinesis — division of the cytoplasm In some cells, mitosis occurs without cytokinesis, resulting in cells with more than one nucleus. Phases of the Cell Cycle 1. Mitotic (M) phase (mitosis and cytokinesis) 2. Interphase (cell growth and copy of chromosomes) • 90% of the cell cycle • G1 phase (first gap) S phase (synthesis) • • G2 phase (second gap) Steps of Mitosis: 1. Prophase — • Centrioles beginning to move apart (in animal cells) • Chromosomes coil and condense during mitosis in order to allow the chromosomes to move without becoming entangled and breaking. Spindle formation • • Separation of the spindle poles • Mitotic spindle — made of microtubules; control chromosome movement during mitosis 2. Prometaphase — Nuclear envelope fragments • • dinoflagellates and diatoms — groups of eukaryotic organisms in which the nuclear envelope remains intact. • Microtubules invade nuclear area Chromosomes continue to condense • • Kinetochore develops by the combination of microtubules • Spindle microtubules that do not attach to kinetochores maintain the region of overlap of microtubules in the cell’s center 3. Metaphase — • Centrosomes are at opposite poles of the cell • Chromosomes align at middle (metaphase plate) 4.Anaphase — Separation of sister chromatids • • For anaphase to begin, cohesion must be cleaved enzymatically. • Movement of the chromosomes during anaphase would most likely be affected by something that prevents shortening of microtubules. How they move: The chromosomes are “reeled in” by the contraction of spindle • microtubules, and motor proteins of the kinetochores move the chromosomes along the spindle microtubules. • ATP as an energy source is required for motor proteins to function in the movement of chromosomes toward the poles of the mitotic spindle. 5. Telophase — • Chromatids become chromosomes • Nuclear membrane forms around new chromosomes Spindle breaks down • Cytokinesis:ACloser Look Cytokinesis — Begins in late anaphase • • Formation of a cleavage furrow; pinches the cell in two • Cleavage furrow — a groove in the plasma membrane between daughter nuclei In animal cells, cleavage occurs; in plant cells, a cell plate forms. • • Golgi-derived vesicles — responsible for cytokinesis in plant cells but NOT in animal cells. Binary Fission in Bacteria Binary fission — process for prokaryotes to reproduce • In binary fission, the chromosome replicates (beginning at the origin of replication) and the two daughter chromosomes move apart • Plasma membrane pinches inward, dividing the cell in two. Using cell division rather than binary fission allows for the orderly segregation of multiple • chromosomes. • Actin and tubulin — involved in both binary fissionAND eukaryotic mitotic division The Evolution of Mitosis Prokaryotes evolved before eukaryotes; therefore, mitosis probably evolved from binary fission. 12.3 The eukaryotic cell cycle is regulated by a molecular control system The frequency of cell division varies with the type of cell and results from regulation at the molecular level. The Cell Cycle Control System Cell cycle control system — • Driven by specific chemical signals in cytoplasm • Directs sequential events similarly to a clock • Regulated by both internal and external controls and checkpoints The Cell Cycle Clock: Cyclins and Cyclin-Dependent Kinases Cdk (cyclin dependent kinases) — • Protein maintained at constant levels throughout the cycle & requires cyclin to become catalytically active • Present throughout the whole cell cycle • Enzyme that attaches phosphate groups to other proteins MPF (maturation-promoting factor) — • Triggers the cell’s passage past the G2 checkpoint into mitosis • Turns itself off by activating a process that destroys cyclin components • The cyclin component of MPF is destroyed toward the end of the M phase. The decline of MPF activity at the end of mitosis is due to the degradation of cyclin. • Cyclin — • Protein synthesized at specific times during the cell cycle Associates with a kinase to form catalytically active complex • • Involved in the regulation of the cell cycle • Shows fluctuations in concentration during the cell cycle Activation of a Cdk molecule happens when it is in sufficient concentration • • Destruction of cyclin is initiated by the activity of its complex and causes the decrease in amount of cyclin Stop and Go Signs: Internal and External Signals at the Checkpoints Internal: G1 Checkpoint — • The cell is first committed to continue the cell cycle after this checkpoint Cells will not begin anaphase until all chromosomes are properly attached to the spindle at • the metaphase plate (middle), assuring that daughter cells will have the correct number of chromosomes. M Phase Checkpoint — Allows separase enzyme cleaves cohesins and allows chromatids to separate. • External: Growth factors are released by certain cells and cause others to divide. PDGF — released by platelets in the vicinity of an injury • • Density dependent inhibition — crowded cells will stop dividing • Anchorage dependence — must be attached to a substratum • Density dependent inhibition and anchorage dependence check the growth of cells at an optimal density All cell cycle checkpoints are similar because they activate or inactivate other proteins. Loss of Cell Cycle Controls in Cancer Cells Cancer cells — Continue to divide even when they are tightly packed together Transformation — Normal cell is converted to a cancerous cell Cancer cells not eliminated by immune system collect to form tumors. Benign tumor — abnormal cells stay at original site Malignant tumor — • Invades surrounding tissues and can metastasize (export cancer cells to other parts of the body) • Cells from an advanced malignant tumor most often have very abnormal chromosomes, and often an abnormal total number of chromosomes. This is because chromosomal abnormal cells can still go through cell cycle checkpoints. In order to find which cells are malignant, one must karyotype samples to look for unusual • size and number of chromosomes.


Buy Material

Are you sure you want to buy this material for

25 Karma

Buy Material

BOOM! Enjoy Your Free Notes!

We've added these Notes to your profile, click here to view them now.


You're already Subscribed!

Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'

Why people love StudySoup

Jim McGreen Ohio University

"Knowing I can count on the Elite Notetaker in my class allows me to focus on what the professor is saying instead of just scribbling notes the whole time and falling behind."

Anthony Lee UC Santa Barbara

"I bought an awesome study guide, which helped me get an A in my Math 34B class this quarter!"

Bentley McCaw University of Florida

"I was shooting for a perfect 4.0 GPA this semester. Having StudySoup as a study aid was critical to helping me achieve my goal...and I nailed it!"

Parker Thompson 500 Startups

"It's a great way for students to improve their educational experience and it seemed like a product that everybody wants, so all the people participating are winning."

Become an Elite Notetaker and start selling your notes online!

Refund Policy


All subscriptions to StudySoup are paid in full at the time of subscribing. To change your credit card information or to cancel your subscription, go to "Edit Settings". All credit card information will be available there. If you should decide to cancel your subscription, it will continue to be valid until the next payment period, as all payments for the current period were made in advance. For special circumstances, please email


StudySoup has more than 1 million course-specific study resources to help students study smarter. If you’re having trouble finding what you’re looking for, our customer support team can help you find what you need! Feel free to contact them here:

Recurring Subscriptions: If you have canceled your recurring subscription on the day of renewal and have not downloaded any documents, you may request a refund by submitting an email to

Satisfaction Guarantee: If you’re not satisfied with your subscription, you can contact us for further help. Contact must be made within 3 business days of your subscription purchase and your refund request will be subject for review.

Please Note: Refunds can never be provided more than 30 days after the initial purchase date regardless of your activity on the site.