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Cell CycleMitosis & Cell Cycle Regulation

Nancy DowJill Hansen

Tammy Stundon

November 3, 2012

Gulf Coast State College Panhandle Area Educational Consortium

5230 West Highway 98 753 West Boulevard

Panama City, Florida 32401 Chipley, Florida 32428

850-769-1551 877-873-7232

www.gulfcoast.edu

Biology Partnership

(A Teacher Quality Grant)

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Pre-testQ and A board

What is Mitosis?What is Meiosis? When do they happen?

What is alike and what is different about them?

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Bell RingerMitosis Rap

"Mitosis" - Justin Bieber Baby remix!

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Florida Next Generation Sunshine State Standards

BENCHMARK • SC.912.L.16.14 Describe the cell cycle, including the process of

mitosis. Explain the role of mitosis in the formation of new cells and its importance in maintaining chromosome number during asexual reproduction. Moderate complexity

Clarifications

• Students will describe specific events occurring in each of the stages of the cell cycle and/or phases of mitosis.

• Students will explain how mitosis forms new cells and its role in maintaining chromosome number during asexual reproduction.

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Content Limits• Items may address the presence and location of

centrioles but may not require knowledge of the function of centrioles.

• Items addressing mitosis or meiosis are limited to identification of phases, structures, and major events of each phase.

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KEY CONCEPT Cells have distinct phases of growth, reproduction, and normal functions.

lung cancer cell undergoing cell division

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• Activate prior Knowledge: To get students thinking about doubling and division, have them think about baking cookies.

•Ask, if you want two batches of cookies, not just one, what do you need to do to the recipe? •Double it.

•Discuss that doubling a recipe means doubling all of the ingredients in the original recipe. Have students apply this idea to cell division.

•Ask, for cells to be functional after division, what needs to be present?

•Complete set of DNA, organelles, cytoplasm, cell membrane, cell wall if a plant.

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Preview Vocabulary:• Cycle=Latin root Circlus= circle( repeating series of

events)

• Phase =Greek origin phasis= appearance (Remind students of the phases of the moon. Each phase of mitosis has a distinctive appearance.)

• Stage=Latin word status= stand (students can think in terms of stagecoaches and stopping points, or stands, along a journey. A cell must move through the stages in the cell cycle to reach the point where it can successfully divide.)

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Recall

• Cells have 3 main jobs– make energy

• need food + Oneed food + O22

• cellular respiration & photosynthesiscellular respiration & photosynthesis• need to remove wastesneed to remove wastes

– make proteins• need instructions from DNAneed instructions from DNA• need to chain together amino acids & “finish” need to chain together amino acids & “finish”

& “ship” the protein& “ship” the protein

– make more cells• need to copy DNA & divide it up to daughter cellsneed to copy DNA & divide it up to daughter cells

Our organellesdo all those

jobs!

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The cell cycle has four main stages.• The cell cycle is a regular pattern of growth,

DNA replication, and cell division.

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• The main stages of the cell cycle are gap 1, synthesis, gap 2, and mitosis.

– Gap 1 (G1): cell growth and normal functions

• Mitosis occurs only if the cell is large enough and the DNA undamaged.

– DNA synthesis (S): copies DNA

– Gap 2 (G2): additional growth

– Mitosis (M): includes division of the cell nucleus (mitosis) and division of the cell cytoplasm (cytokinesis)

DNA REPLICATION DURING ‘S’ PHASE OF CYCLE

UNWINDINGThe coiled, double-stranded DNA molecule unwinds and separates into two strands.

REBUILDINGEach of the single strands becomes a double strand again as an enzyme connects the appropriate complementary base to the exposed base. The free nucleotides come from your food.

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2

1

2

Complementary nucleotide bases

attached

AdenineCytosineGuanineThymine

Free nucleotide

ERRORS (MUTATIONS)CAN OCCURWITH BASES

DURING DNA

Replication

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Why do Cells need to Divide?

• Single cell organisms– Asexual reproduction

• Multicellular organisms– Growth – Development – Repair

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Cells divide at different rates.• The rate of cell division varies with the need for

those types of cells.

• ~100 Trillion cells in the human body• ~100 Billion of them replicate each day

• Some cells are unlikely to divide (G0).

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Cell size is limited.• Volume increases faster than surface area.

Larger cells would either starve to death or be poisoned from the buildup of waste products.

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WHY ARE CELLS SMALL ?? BECAUSE OF SURFACE AREA- TO- VOLUME RATIO

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• Surface area must allow for adequate exchange of materials.

– Cell growth is coordinated with division.

– Cells that must be large have unique shapes.

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KEY CONCEPT Cells divide during mitosis and cytokinesis.

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Chromosomes condense at the start of mitosis.

• DNA wraps around proteins (histones) that condense it.

DNA doublehelix

DNA andhistones

Chromatin SupercoiledDNA

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Recall

• One half of a duplicated chromosome is a chromatid.

• Sister chromatids are held together at the centromere.

• Telomeres protect DNA and do not include genes.

Condensed, duplicated chromosome

chromatid telomere

centromere

telomere

•DNA plus proteins is called chromatin.

HOMOLOGUES AND SISTER CHROMATIDS

Homologues are the maternal and paternal copies of a chromosome. A sister chromatid is a chromosome and its identical duplicated version held together at a centromere.

Homologues Homologues

Maternal chromosome

Paternal chromosome

Sister chromatids

Replication (S Phase)

Centromere

Sister chromatids

Every time a cell divides, the telomere gets shorter. After a critical number of cell divisions, functional DNA is lost, which means almost certain death for the cell.

Animal cell

Functional DNAA protective cap at the end of each chromosome

TELOMERE

Nucleus

Chromosome

TELOMERES

TELOMERES HAVE BEEN COMPARED TO THE ENDS OF A SHOELACE.AFTER A LOT OF WEAR, THE END OF THE SHOELACE GETS FRAYED.

A downside to cell division:

Cell division

Cell division

Cell division

Cell death

At birth, telomeres in most human cells are long enough to support about 50 cell divisions!

TELOMERES

Functional DNA

TELOMERE A protective cap at the end of each chromosome

NOW THE CELL DOESNOT REPLACE ITSELF

WHICH CAUSES THE AGING PROCESS TO OCCUR

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Telomere Studies May Explain Rare Aging Disease in Children

• Study of children with rare case of

genetic mutation that causes drastic

early aging and death is now being

linked to short or missing Telomeres by top scientists.

PROGERIA: BORN WITH SHORTERTELOMERES---THESE ARE

HIGHLIGHTED IN YELLOW IN PIC. THE CHILD DIES OF OLD AGE.

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Parent cell

centrioles

spindle fibers

centrosome

nucleus withDNA

• Interphase prepares the cell to divide.

• During Interphase, the DNA is duplicated.

Mitosis and cytokinesis produce two genetically identical daughter cells.

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• Mitosis divides the cell’s nucleus in four phases.

– During prophase, chromosomes condense and nuclear membrane breaks down.

– centrioles ‘move’ to the poles and spindle fibers form

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• Mitosis divides the cell’s nucleus in four phases.

– During metaphase, chromosomes line up in the middle of the cell.

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• Mitosis divides the cell’s nucleus in four phases.

– During anaphase, sister chromatids separate to opposite sides of the cell.

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• Mitosis divides the cell’s nucleus in four phases.

– During telophase, the new nuclei form, spindle fibers break down and chromosomes begin to uncoil.

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• Cytokinesis differs in animal and plant cells.

– In animal cells, the membrane pinches closed.

– In plant cells, a cell plate forms.

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Mitosis in plant cells

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• Mitosis Animation

Mitosis in whitefish blastula

Mitosis in Onion root tip

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Cell Cycle Lab

15 minutes!!

See you in the See you in the Computer LabComputer Lab

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Let’s go to the Computer Lab

• Mitosis Virtual Lab – Onion Tip

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Mitosis Dance

• Jill will lead us in this dance

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Follow up

• Mitosis Dance

• Mitosis animation

• another mitosis animation

• Animating Mitosis (flipbook)

• Mitosis: Read Retrieve Connect & Use

• Mitosis Puzzle

• Cell Cycle Project

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Florida Next Generation Sunshine State Standards

Benchmark• SC.912.L.16.8 Explain the relationship between mutation, cell cycle,

and uncontrolled cell growth potentially resulting in cancer. (cognitive complexity: Moderate)

Clarifications • Students will explain how cancer (uncontrolled cell growth) may

result from mutations that affect the proteins that regulate the cell cycle.

Content Limits• Items will focus on the relationship between mutations and

uncontrolled cell growth, rather than a specific mutation that may result in uncontrolled cell growth.

• Items referring to mutation will focus on the general concepts of uncontrolled cell growth and not require specific knowledge of cancers or diseases resulting from that growth.

• Items will not assess the specific proteins associated with regulating the cell cycle.

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KEY CONCEPTCell cycle regulation is necessary for healthy growth.

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Internal and external factors regulate cell division.

• External factors include physical and chemical signals.

• Growth factors are proteins that stimulate cell division.– Most mammal cells form a single layer in a culture

dish and stop dividing once they touch other cells.

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• Two of the most important internal factors are kinases and cyclins.

• Kinases- change the activity of other molecules

• Cyclins- rapidly made and destroyed at different points in the cell cycle

• External factors trigger internal factors, which affect the cell cycle.

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– a normal feature of healthy organisms– caused by a cell’s production of self-destructive

enzymes– occurs in

developmentof infants

webbed fingers

• Apoptosis is programmed cell death.

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Cell division is uncontrolled in cancer.

• Cancer cells form disorganized clumps called tumors.

cancer cellbloodstream

normal cell

– Benign tumors remain clustered and can be removed.– Malignant tumors metastasize, or break away, and can

form more tumors.

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• Cancer cells do not carry out necessary functions.

• Cancer cells come from normal cells with damage to genes involved in cell-cycle regulation.

How cancer grows and spreads interactive

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• Carcinogens are substances known to promote cancer.

• Standard cancer treatments typically kill both cancerous and healthy cells.

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Carcinogens

PreventionPrevention

• 1. don't smoke1. don't smoke• 30% of all cancer30% of all cancer

• 2. don't sunbath/booths2. don't sunbath/booths• melanoma melanoma

• 3. avoid alcohol3. avoid alcohol• mouth, liver, larynx cancersmouth, liver, larynx cancers

• 4. avoid radiation4. avoid radiation• x raysx rays

• 5. get tested5. get tested• catch it early oncatch it early on

• 6. Diet 6. Diet • increase by 55% with obesityincrease by 55% with obesity• high fiber, Vit. A and C, broccoli, cabbagehigh fiber, Vit. A and C, broccoli, cabbage

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• HeLa Cell Activity

• Khan Academy- cancer

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Follow up

• Q & A

• Post Test