Image from: Image by Riedell CELL GROWTH & DIVISION 10-1 & 10-2

Reasons why cells divide 1. _____________________ As cell grows bigger demand on DNA “genetic library” becomes too great Ex: Small town library has 1000 books. As town grows and more people borrow books, there may be a waiting list to read the most popular titles DNA OVERLOAD

Reasons why cells divide 2. _____________________ As cell grows bigger demand for transport across membrane is too great Material exchange can’t keep up

BIGGER CELLS NEED MORE FOOD and OXYGEN, but CAN’T TRANSPORT IT FAST ENOUGH or IN BIG ENOUGH QUANTITIES!

3.To Grow-Multicellular organisms grow mainly by increasing cell number More cells, not bigger cells Reasons why cells divide Image by Riedell

Now we know why cells divide, let’s talk about how What do you think will have to happen before a cell can divide into identical copies? What is the most important thing that needs to be copied?

SPREAD OUT IN NON-DIVIDING CELLS SCRUNCHED UP IN DIVIDING CELLS CHROMATIN CHROMOSOMES DNA CAN BE:

DNA in PROKARYOTES BACTERIAL DNA is CIRCULAR HAVE ONE CHROMOSOME NO NUCLEUS; ATTACHED TO CELL MEMBRANE

DNA in EUKARYOTES (Plants & Animals) DNA is ROD-SHAPED CHROMOSOMES MANY PAIRS FOUND IN NUCLEUS

Chromosome structure ___________________ 2 identical arms __________________ constricted area holds chromatids together __________________ PAIR 2 of each chromosome (one from mom; one from dad) CHROMATIDS CENTROMERE HOMOLOGOUS

HOMOLOGOUS CHROMOSOMES SAME SIZE SAME SHAPE CARRY GENES for the SAME TRAITS BUT ______________! (Don’t have to have the SAME CHOICES) NOT IDENTICAL

CFU Work alone on a separate sheet of paper. 1.Why do cells need to divide? 2.How is the DNA different in Prokaryotes vs. Eukaryotes? 3.How are Chromatids related to each other? 4.How are Homologous Chromosomes related to each other?

Vocabulary When a cell divides, its offspring are called Daughter Cells. Why? Because that’s what they decided long ago. No you can’t call them Son cells, it just doesn’t sound right.

CELL DIVISION in PROKARYOTES Bacteria reproduce using __________________________________ 1.It’s fast 2.Simple 3.Produces Identical Offspring/No sex required! BINARY FISSION

______________ = series of events that cells go through as they grow and develop or more simply, A cell’s lifetime cells alive cell cycle CELL CYCLE What about Eukaryotes; You know, things with a nucleus?

CELL CYCLE INTERPHASE – non-dividing phase- Includes: G 1 - Grow bigger Cell is “doing its job” DNA is spread out as chromatin S - Synthesis (copy DNA) G 2 - Grow bigger, copy organelles & molecules needed for cell division

CELL DIVISION MITOSIS – Nuclear division in 4 stages 1. Prophase 2. Metaphase 3. Anaphase 4. Telophase Cytokinesis – Final step, Cytoplasm divides You end up with 2 identical copies- very important!!!!

M phase G 2 phase S phase G 1 phase Figure 10–4 The Cell Cycle Section 10-2

Cell Cycle Check for Understanding 1.What are the stages of the cell cycle? 2. Define mitosis: 3. In what phase does a cell spend most of its life? 4. In what phase does the DNA get copied?

INTERPHASE (G 1 - S - G 2 ) In between divisions Cells are in this phase most of the time Can see nucleus DNA spread out as chromatin Can’t see chromosomes DNA gets copied (S) Cell gets ready to divide

PROPHASE 1st dividing phase P= Preparing 4. Spindle fibers form & attach to chromosomes 3. Nucleus disappears= DNA EXPOSED! 1. DNA scrunches into chromosomes 2. Centrioles appear Pearson Education Inc publishing as Pearson Prentice Hall

METAPHASE Chromosomes line up in ___________ middle Images from: Pearson Eduction Ince; Publishing as Pearson Prentice Hall

ANAPHASE Centromeres split Centrioles pull chromatids_______ Apart Images from: Pearson Eduction Ince; Publishing as Pearson Prentice Hall

TELOPHASE (reverse prophase steps) See ______ nuclei Nucleus returns but now there are two! Chromosomes spread back out as chromatin and get back to work now that They are safe again. two Images from: Pearson Eduction Ince; Publishing as Pearson Prentice Hall

CYTOKINESIS Cytoplasm splits into 2 cells ANIMAL CELLS pinch cytoplasm in two with a ______________________ CLEAVAGE FURROW

CYTOKINESIS Cytoplasm splits into 2 cells PLANT CELLS can’t pinch because they have a sturdy ____________ Plant cells separate cytoplasm by growing a _______________ down the middle. CELL PLATE CELL WALL

Mitosis Check for Understanding 1.List the four stages of Mitosis in order 2.In what stage are copies (sister chromatids) pulled Apart from each other? 3.What is the name of the phase where the cell splits into two? 4.When mitosis is complete are the daughter cells identical to the parent cell?

Videos Animal Cell Mitosis Animal Cell Cytokinesis

includes is divided into Concept Map Section 10-2 Cell Cycle

includes is divided into Concept Map Section 10-2 Cell Cycle M phase (Mitosis) Interphase G 1 phaseS phaseProphaseG 2 phaseMetaphaseTelophaseAnaphase

Interest Grabber Answers 1.How do you think the body repairs an injury, such as a cut on a finger? The cut is repaired by the production of new cells through cell division. 2.How long do you think this repair process continues? Cell division continues until the cut is repaired. 3.What do you think causes the cells to stop the repair process? Students will likely say that when the cut is filled in, there is no room for more cells to grow. Knowing When to Stop Suppose you had a paper cut on your finger. Although the cut may have bled and stung a little, after a few days, it will have disappeared, and your finger would be as good as new.

REGULATING the CELL CYCLE

Control of Cell Division Section 10-3 Cells grow until they touch other cells If center cells are removed, cells near the space will start to grow again. SHOWS: Cell division genes can be turned on and off

CELL DIVISION GENES EXAMPLE: Cell division genes can be ________ in case of injury. Cells near injury are stimulated to divide to heal and replace damaged/missing cells and shut off when the repair has been made. turned on

CELL DIVISION GENES Some cells divide frequently (some human skin cells divide once/hour) Some cells divide occasionally (liver cells divide about once/year) Some cells don’t divide once they form (nerve cells)

Molecules on the surface of neighboring cells act as signals to slow down or stop the cell’s cycle. These signals prevent excessive growth and keep tissues from disrupting each other. EXTERNAL REGULATORS Pearson Education Inc; Publishing as Pearson Prentice Hall

Cancer cells have lost control of their cell division genes CHO (Chinese Hamster Ovary) cells in culture SEM Image by: Riedell

Cancer cells don’t stop when they touch nearby cells... they just keep growing! That’s what makes a tumor. NO CONTACT INHIBITION See a video

Cancer cells Don’t stop dividing Like a “car with no brakes” Can spread to new places (METASTASIS) ______________ are substances that can damage DNA and cause cancer Ex: Cigarette smoke (OR CHEW), Radiation, chemicals in environment, even viruses, Carcinogens

Cancer cells Cancer is complicated and can have many causes, but all cancers have one thing in common...… They have lost control over their _____________. Many cancers cells have a damaged or defective gene called _____, so they can’t respond to normal cell signals to control their growth. CELL CYCLE p53

Check For Understanding 1.What is contact inhibition? 2.What causes a healthy cell to replicate? 3. What is a Carcinogen? Give one example.

ANTI-SMOKING commercial

MEIOSIS 11-4 Making gametes…

1. How many chromosomes would a sperm or an egg contain if either one resulted from the process of mitosis? 2. If a sperm containing 46 chromosomes fused with an egg containing 46 chromosomes, how many chromosomes would the resulting fertilized egg contain? Do you think this would create any problems in the developing embryo? 3. In order to produce a fertilized egg with the appropriate number of chromosomes (46), how many chromosomes should each sperm and egg have ? Interest Grabber 46 chromosomes = 92; a developing embryo would not survive if it contained 92 chromosomes. Sperm and egg should each have 23 chromosomes.

Planaria animation: Family Remember from Chapter 1: CHARACTERISTICS OF LIVING THINGS ALL LIVING THINGS __________ REPRODUCE

ASEXUAL REPRODUCTION Bacteria reproduce using __________________________________ Budding & regeneration are used by plants and animals to reproduce asexually (mitosis) Planaria animation: BINARY FISSION

Single Celled Eukaryotes: EX: Yeast and Algae Yeast and Algae are single celled or unicellular, but are still Eukaryotes They reproduce from Mitosis only How do their offspring (Daughter cells) compare to the parent cells? Two Unicellular Eukaryotes Bacteria or Prokaryote

BINARY FISSION & MITOSIS Two types of Asexual Reproduction Produces cells that are __________ copies of parent cell identical

ADVANTAGES OF ASEXUAL REPRODUCTION Can make offspring faster Don’t need a partner

DISVANTAGES OF ASEXUAL REPRODUCTION ALL ALIKE Species CAN’T change and adapt One disease can wipe out whole population

SEXUAL REPRODUCTION Combines genetic material from 2 parents (sperm & egg) so offspring are genetically __________ from parents DIFFERENT Family image from:

ADVANTAGES OF SEXUAL REPRODUCTION Allows for variation in population Individuals can be different Provides foundation for EVOLUTION Allow species adapt to changes in their environment

EGG + SPERM  If egg and sperm had same number of chromosomes as other body cells... baby would have too many chromosomes! Image by Riedell

MEIOSIS is the way… to make cells with ½ the number of chromosomes for sexual reproduction

Video 1 Click the image to play the video segment 11A. Video 1 Meiosis Overview

DIPLOID & HAPLOID Most cells have 2 copies of each chromosome = ______________ (one from mom; one from dad) All BODY (___________) cells are diploid DIPLOID2n HOMOLOGOUS CHROMOSOMES = SOMATIC

DIPLOID & HAPLOID Some cells have only one copy of each chromosome = _____________ All sperm and egg cells are haploid HAPLOID1n

MITOSIS Makes ___ cells genetically _________ to parent cell & to each other Makes ___ cells Makes __________ Used by organisms to: increase size of organism, repair injuries, replace worn out cells 2 identical 2n SOMATIC (body)

MEIOSIS Makes ____ cells genetically different from parent cell & from each other Makes _____ cells Makes ______________ Used for ____________ 4 1n Gametes (sperm & eggs) sexual reproduction

WHAT MAKES MEIOSIS DIFFERENT ? 1.SYNAPSIS & CROSSING OVER 2.SEGREGATION & INDEPENDENT ASSORTMENT 3. CELL DIVIDES TWICE, BUT… ONLY COPIES DNA ONCE

WHAT MAKES MEIOSIS DIFFERENT ? 1.Homologous chromosomes pair up during ________________ = ______________ SYNAPSIS Images modified from: PROPHASE I

WHAT MAKES MEIOSIS DIFFERENT? 1. Exchange of DNA between homologous pairs = _____________ during PROPHASE I CROSSING OVER Allows shuffling of genetic material

Video 5 Click the image to play the video segment. 11E Video 5 Crossing Over SEE CROSSING OVER ANIMATION

HOMOLOGOUS CHROMOSOMES Image modified by Riedell SAME SIZE SAME SHAPE CARRY GENES for the SAME TRAITS BUT ______________! (Don’t have to have the SAME CHOICES) NOT IDENTICAL

CROSSING OVER Image modified by Riedell Allows for_________________ in different combinations After crossing over, chromatid arms are________________ anymore rearranging of DNA NOT IDENTICAL

WHAT MAKES MEIOSIS DIFFERENT ? 2. Separation during ANAPHASE I INDEPENDENT ASSORTMENT Separates gene choices and allows shuffling of genetic material SEGREGATION &

Video 4 Click the image to play the video segment 11D. Video 4 Segregation of Chromosomes

SEGREGATION (Anaphase I)

SEGREGATION & CROSSING OVER together make even more combinations See an animation

INDEPENDENT ASSORTMENT

INDEPENDENT ASSORTMENT at ANAPHASE I Lots of different combinations are possible! This is why you don’t look exactly like your brothers and sisters even though you share the same parents!

WHAT MAKES MEIOSIS DIFFERENT ? Crossing over Segregation Independent assortment are ALL ways MEIOSIS results in =______________________________ So daughter cells are ______________ from parents and from each other different GENETIC RECOMBINATION

WHAT MAKES MEIOSIS DIFFERENT ? 3. CELL DIVIDES TWICE, BUT … ONLY COPIES ITS DNA ONCE G1G1 G2G2 S   PM  A T C G1G1    MITOSIS: MEIOSIS:    SG2G2 PM ATC PM A TC ( I ) ( II )

Video 2 Click the image to play the video segment 11B. & C Video 2 Animal Cell Meiosis, Part 1 & Part 2

Check for Understanding 1.What is an advantage of Asexual Reproduction? 2.What makes sexual reproduction different from asexual reproduction? 3.Give one advantage of sexual reproduction? 4.Name two ways that Meiosis is different from Mitosis? 5.Are the daughter cells in Meiosis identical to the original cell?

Ways Meiosis is different? Homologous pairs match up & trade DNA SEGREGATION & INDEPENDENT ASSORTMENT Shuffling genes (Dividing TWICE but copying DNA once) produces 1n cells

Mitosis Vs Meiosis MitosisMeiosis Process that divides the nucleus into 2 new nuclei in BODY cells (hair, skin, etc.) Process that divides SEX cells only (sperm or egg) Produces TWO new daughter cells are EXACT copy of the original body cell Produces FOUR new daughter cells that will be sperm or egg Daughter cells have SAME number of chromosomes (called DIPLOID) Daughter cells have HALF the original number of chromosomes (called HAPLOID) PMAT oncePMAT twice`