Bell Ringer 1- What is the basic/ smallest unit of life Cells

The Cell Cycle  The entire life cycle that a cell goes through

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Gap 1 Phase (G1)  G= Growth!!!  Cell goes through its normal functions

Checkpoint 1: G1  Enough nutrients?  Large enough?  DNA damaged?  Signals from nearby cells telling them division is needed

Synthesis Phase (S)  Synthesis= combining parts to make whole  DNA duplication occurs

Gap 2 Phase (G2)  REMEMBER G= Growth  Normal cell functions continue

Checkpoint 2  Large enough?  DNA damaged?

Mitosis (M)  Cell undergoes division  CYTOKINESIS

Length of Cell Cycle  S, G2, and M stages for all human cells takes about 12 hours.  Length of G1 depends on the cell

Rate of Division Cell typeLength of time Red blood120 days LymphocytesOver one year Other white10 hours Platelets10 days Bone25-30 years BrainLifetime Colon3-4 days Skin19-34 days Spermatozoa2-3 days Stomach2 days

G0 stage  Given to cells when they are not likely to divide  Brain and nerve cells remain in this stage!

Limitation to cell size  Too small?  Not enough organelles  Too big?  Decreased surface area: inadequate exchange of materials

Suitable cell size  Is maintained through coordination of growth and division

Bell Ringer 2- What is the purpose of Mitosis? To create more cells

Cell Division Mitosis

Chromosomes  Are made of DNA  Each duplicated chromosome consists of sister chromatids attached at a centromere

Interphase  Interphase – time for growth and regular cell activity.  Most of a cells life is spent in Interphase  During the synthesis stage of Interphase the chromosomes start to replicate.

Interphase

Mitosis  The division of somatic or regular cells.  Its divided into 4 phases.  Remember Interphase is NOT part of Mitosis.

Mitosis Stages  Prophase  Metaphase  Anaphase  Telophase

Prophase  Chromatin condenses into chromosomes  Centrioles separate and a spindle fiber begins to form  Nuclear membrane breaks down

Metaphase  Chromosomes line up in the middle of the cell.  Each chromosome is connected to a spindle fiber.

Metaphase

Anaphase  Sister chromatids separate into individual chromosomes.  They move apart to opposite ends of the cell.

Anaphase

Telophase  Chromosomes begin to uncoil  Nuclear membranes begin to reform

Telophase

Cytokinesis  The cytoplasm pinches in half.  Each daughter cell has an identical set of duplicate chromosomes

Cytokinesis

Bell Ringer 3- 3-How do the football players lined up at midfield, the goal posts & the midfield line compare to the structures of a cell during mitosis?

Regulating the Cycle  Cells respond to internal and external events to control the process of cellular division.  Proteins are used as regulators.

External Factors  Growth Factors: proteins that stimulate cell division and are released by other cells.  Example: Platelets release sticky GF that form clots to stop bleeding.

Internal Factors  External Factors bind to the cell and trigger internal factors.  Kinases and Cyclins help the cell advance to the different stages of the cell cycle

Other Regulators  Apoptosis: Programed cell death   Baby development: Webbed fingers

Why regulate cell division?  Uncontrolled cell growth is CANCER!  As a result, they form masses of cells called tumors that can damage surrounding tissues.

Asexual Reproduction  Creating of offspring from a single parent  Genetically identical  Mostly Prokaryotes  Reproduction= Binary Fission

Asexual Advantages  More efficient in environments that do not change  If not broken/ Don’t fix

Asexual Disadvantages  In changing environments offspring willall respond in the same way  Why would this be bad?

Brain POP  Asexual Reproduction Asexual Reproduction Asexual Reproduction

Cell Differentiation  Unspecialized cells develop into mature forms and functions (specialized)  Examples? winter-11.html

Brain POP  Cancer Cancer

Mitosis Real Cells: Matching  07/resources/htmls/animated_biology/uni t2/bio_ch05_0157_ab_mitgame.html 07/resources/htmls/animated_biology/uni t2/bio_ch05_0157_ab_mitgame.htmlwww.classzone.com/cz/books/bio_ 07/resources/htmls/animated_biology/uni t2/bio_ch05_0157_ab_mitgame.html

Ticket out the door Some anticancer drugs prevent microtubules from forming spindle fibers. Why do you think these drugs might be effective treatments for cancer?

Bell Ringer 4- When cells become specialized and have a certain function Cell Differentiation

How to remember the stages  “I Playfully Meow at the Cat”  Interphase  Prophase  Metaphase  Anaphase  Telophase  Cytokinesis

Cells  Somatic cells= body cells  Gametes= sex cells:  ova or eggs= Female  spermatozoa or sperm= Male

Human Body Cells  46 chromosomes  23 pairs

Human Body Cells  Genetically identical unless mutation  Homologous Chromosomes= onefrom mother & one from father

Human Body Cells  Autosomes= Chromosome pairs 1-22  Not related to sex of an organism

Human Sex Cells  Sex chromosomes= directly related to development of sexual characteristics  23 rd pair  XX= female  XY= male

Sexual Reproduction  Sexual Reproduction= fusion of two gametes: mixture of two parents  Fertilization= two gametes come together

Body vs. Sex Cells  Body cells (somatic) are Diploid (2n)  Sex cells (gametes) are Haploid (1n)

Meiosis  Meiosis= nuclear division that divides a diploid cell into haploid cells.

Gamete Formation  In males, meiosis results in 4 sperm cells  In females, meiosis results in 1 egg cell and three polar bodies, which are not used in reproduction.

Bell Ringer 5- What type of sex chromosomes make up a male; XX or XY? XY

Meiosis Division of Sex Cells

Meiosis Stages  Meiosis usually involves 2 stages  Meiosis I  Meiosis II

Prophase I  Chromosomes pair with its corresponding homologous chromosome to form a tetrad= 4 chromosomes.  Crossing-over= chromosomes overlap and exchange portions of their chromatids.

Prophase I introduction-to-dna-and-chromosomes-text-and-audio/

Metaphase I  Spindle fibers attach to the chromosomes

Metaphase I

Anaphase I  Spindle fibers pull the homologous chromosomes toward opposite ends of the cell.

Anaphase I

Telophase I & Cytokinesis  Nuclear membranes form.  The cell separates into 2 cells.  How many chromosomes in each cell?

Telophase I

Prophase II  Each cell has half the number of chromosomes as the original cell.

Prophase II

Metaphase II  The chromosomes line up similar to metaphase in mitosis.

Metaphase II

Anaphase II  Sister chromatids separate and move to opposite ends of the cell.

Anaphase II

Telophase II  Meiosis II results in 4 haploid cells.

Telophase II

Mitosis vs Meiosis MitosisMeiosis Results in 2 Diploid Cells (2N) 4 Haploid Cells (N) Cells are Genetically Identical Genetically Different Occurs in Somatic (Body) Cells Sex Cells

How many?  How many chromosomes does the somatic human cell have?  After Mitosis?  After Meiosis I?  After Meiosis II?

Bell Ringer 6-When does crossing over occur? Meiosis- Prophase 1

Mitosis vs Meiosis MitosisMeiosis Results in 2 Diploid Cells (2N) 4 Haploid Cells (N) Cells are Genetically Identical Genetically Different Occurs in Somatic (Body) Cells Sex Cells

Bell Ringer  Quietly STUDY for mitosis/ meiosis Test!!!