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Ch. 10, Cell Growth and Division Ch. 11, Meiosis (sec. 11-4). Ch. 10: Cell Growth- why do cells divide instead of continue to grow? Cell Division – Cell Cycle and when a cell divides, Mitosis Regulation of the Cell Cycle- how it’s controlled, what happens when it’s out of control Ch. 11:

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ch 10 cell growth and division ch 11 meiosis sec 11 4
Ch. 10, Cell Growth and DivisionCh. 11, Meiosis(sec. 11-4)
  • Ch. 10:
    • Cell Growth- why do cells divide instead of continue to grow?
    • Cell Division – Cell Cycle and when a cell divides, Mitosis
    • Regulation of the Cell Cycle- how it’s controlled, what happens when it’s out of control
  • Ch. 11:
    • Phases of Meiosis
    • Comparing Mitosis and Meiosis
cell growth
Cell Growth

I’m out of control!

Section 10.1 – Cell Growth

Box 3

Understanding the relationship between a cell’s Surface Area and Volume is the key to understanding why cells must divide as they grow.

Too Big!

Just right

TooSmall

  • How do organisms grow? Do their cells get bigger? Or do they make more cells?
      • Answer =Make more cells!!!
  • There is a limit to how big cells can grow!
  • Getting bigger does 2 things:
  • Places more demands on DNA
  • Makes it harder to move molecules across a cell’s membrane

Box 1

Box 2

surface area to volume ratio
Surface Area toVolume Ratio

Surface Area (SA): 1 x 1 x 6 = 6 cm3

(length x width x height x # sides)

Box 4

6 sided cube

1 cm

1 cm

1 cm

Bigger 6 sided cube

Box 5

3 cm

3 cm

Volume increases more rapidly than Surface Area and this causes the ratio of SA to V to decrease.

3 cm

Decreasing the SA to V ratio causes big problems for the cell. More molecules trying to go through the membrane (SA) and there’s less surface area for everything to move through!

Box 6

Bigger is NOT better!

Volume (V): 1 x 1 x 1 = 1 cm3

(length x width x height)

More surface area! Good!

Ratio of SA to V: 6/1 = 6:1

SA: 3 x 3 x 6 = 54 cm3

Less surface area! Bad!

V: 3 x 3 x 3 = 27 cm3

Ratio of SA to V: 54/27 = 2:1

slide4

Instead of growing bigger, let’s make more cells! And to do this, 1 cell will divide into 2 cells.

Box 7

What’s the solution to this traffic problem?

cell division
Cell Division

I’m too fat

daughter

daughter

Mommy?

  • When a cell divides, the 2 cells that result are called “daughter” cells
  • Cell Division = process by which a cell divides into 2 new daughter cells
  • Before cell division, the cell replicates, or makes copies of all of its DNA
      • Solves the 2 problems with cell growth:
      • New daughter cells get one complete set of genetic information- they get their own complete genetic library
      • No more problems with SA to V ratio because daughter cells has an increased ratio of SA to V because their volume overall is reduced (one cell dividing into two makes both cells smaller)

Box 8

Box 9

cell division1
Cell Division

Section 10-2

Genetic information passed from 1 generation to the next is carried by Chromosomes

Chromosomes are made up of DNA- the part that carries the cell’s genetic information

Box 12

Box 13

Mitosis is considered asexual because cells produced by it are genetically identical to the parent cell.

Box 14

  • In Eukaryotes (you!), cell division occurs in 2 main stages:
  • Mitosis = division of the cell’s nucleus
  • Cytokinesis = division of the cytoplasm

Box 11

(Sy-toh-kih-NEE-sis)

chromosomes
Chromosomes

chromatid

  • When a cell isn’t in the process of dividing, chromosomes are not visible because they are spread out within the nucleus.
  • However, when cell division is beginning, the chromosomes condense into compact, visible structures we can see in a microscope.
  • Before cell division occurs, each chromosome is copied, or replicated, and the identical copies are called “sister” chromatids(KROH-muh-tids)

replication

Yo! Sis!

LYLAS!

Centromere

Box 16

Sister chromatid

Sister chromatid

Box 15

the cell cycle
The Cell Cycle

Box 19

  • Cell Cycle consists of 4 phases:
  • Mitosis and Cytokinesis = M phase
  • Growth phase = G1 (“G” = gap)
  • Chromosome replication = S phase
  • Preparation for mitosis = G2

Interphase = “in between” period of growth for a cell

Box 18

Box 17

  • The Cell Cycle is a series of events that cells go through as they grow and divide

1. Cell grows

2. Cell prepares for division

3. Cell divides to form 2 daughter cells (each daughter cell will begin the cell cycle again)

cell cycle phases

Box 21

G1phase = when cells do most of their growing- cells increase in size and make new proteins and organelles

Cell Cycle Phases

Box 24

M phase = when cell division occurs

Box 22

S phase = when chromosomes are replicated and synthesis of DNA molecules occurs

G2phase = when cells make many organelles and molecules needed for cell division

Box 23

Box 20

I

G1phase

I

M

M phase

S phase

I

G2phase

mitosis
Mitosis
  • Interphase then….
  • Mitosis has 4 phases:
  • 1. Prophase
  • 2. Metaphase
  • 3. Anaphase
  • 4. Telophase

I then ..PMAT

Box 25

Interphase is NOT part of Mitosis!!!!! Remember that!

mitosis1
Mitosis

Box 26

Interphase = cell grows and replicates its DNA and centrioles.

Interphase

Centrioles

Nuclear envelope

Chromatin

slide12

Interphase = cell grows and replicates its DNA and centrioles.

Box 27

Prophase= chromatin condenses into chromosomes, centrioles separate, spindle forms, nuclear envelope breaks down

Interphase

Spindle forming

Prophase

Centrioles

Centromere

Nuclear envelope

Chromatin

Chromosomes (paired chromatids)

slide13

Prophase = chromatin condenses into chromosomes, centrioles separate, spindle forms, nuclear envelope breaks down.

Interphase= cell grows and replicates its DNA and centrioles.

Interphase

Spindle forming

Prophase

Centrioles

Centromere

Centriole

Nuclear envelope

Chromatin

Chromosomes (paired chromatids)

Spindle

Centriole

Metaphase

Box 28

Metaphase = chromosomes line up across the center of the cell, each chromosome is connected to a spindlefiber at its centromere

slide14

Prophase = chromatin condenses into chromosomes, centrioles separate, spindle forms, nuclear envelope breaks down.

Interphase = cell grows and replicates its DNA and centrioles.

Interphase

Spindle forming

Prophase

Centrioles

Centromere

Centriole

Nuclear envelope

Chromatin

Chromosomes (paired chromatids)

Spindle

Centriole

Individual chromosomes

Metaphase

Box 29

Anaphase = sister chromatids separate into individual chromosomes andmove apart

Metaphase = chromosomes line up across the center of the cell, each chromosome is connected to a spindle fiber at its centromere

Anaphase

slide15

Prophase = chromatin condenses into chromosomes, centrioles separate, spindle forms, nuclear envelope breaks down.

Box 30

Telophase = chromosomes gather at opposite ends of the cell and lose their distinct shapes- 2 new nuclear envelopes form

Interphase = cell grows and replicates its DNA and centrioles.

Interphase

Spindle forming

Prophase

Centrioles

Centromere

Centriole

Nuclear envelope

Chromatin

Chromosomes (paired chromatids)

Spindle

Centriole

Telophase

Individual chromosomes

Metaphase

Nuclear envelope reforming

Anaphase = sister chromatids separate into individual chromosomes and are moved apart

Anaphase

slide16

Interphase = cell grows and replicates its DNA and centrioles.

Prophase = chromatin condenses into chromosomes, centrioles separate, spindle forms, nuclear envelope breaks down.

Box 31

Cytokinesis = cytoplasm pinches in ½ , each daughter cell has an identical set of chromosomes

Interphase

Spindle forming

Prophase

Centrioles

Centromere

Centriole

Nuclear envelope

Chromatin

Chromosomes (paired chromatids)

Spindle

Cytokinesis

Centriole

Telophase

Individual chromosomes

Metaphase

Nuclear envelope reforming

Anaphase = sister chromatids separate into individual chromosomes and are moved apart

Telophase = chromosomes gather at opposite ends of the cell and lose their distinct shapes- 2 new nuclear envelopes form

Anaphase

slide17

Prophase = chromatin condenses into chromosomes, centrioles separate, spindle forms, nuclear envelope breaks down.

Interphase = cell grows and replicates its DNA and centrioles.

Cytokinesis = cytoplasm pinches in half, each daughter cell has an identical set of duplicate chromosomes

Interphase

Prophase

I…then PMAT

Cytokinesis

Metaphase

Metaphase = chromosomes line up across the center of the cell, and each is connected to a spindle fiber at its centromere

Telophase = chromosomes gather at opposite ends of the cell and lose their distinct shapes- 2 new nuclear envelopes form

Telophase

Anaphase

Anaphase = sister chromatids separate into individual chromosomes and are moved apart

slide18

Product of Mitosis?

2 identical daughter cells

Box 32

Prophase

Interphase

Metaphase

Cytokinesis

Anaphase

Telophase

cell cycle tree map
Cell Cycle Tree Map

Cell Cycleincludes…..

Mitosisis divided into…

Interphaseis divided into…

G1 phase

G2 phase

S phase

Telophase

Prophase

Metaphase

Anaphase

And then………Cytokinesis

slide20

Draw the cell cycle diagram on pg. Label the parts. List the stages of the cell cycle, describe what happens in each stage (G1, G2, S and M)

Title: The Cell Cycle and Mitosis

Your Name:ex. by Fred Cooks

1st : The Cell Cycle & Interphase

Prophase. Draw a cell in prophase using pg. 246 as a reference. List 3 facts describing events in Prophase.

P

2nd : Mitosis - Prophase

M

3rd : Mitosis - Metaphase

Metaphase. Draw a cell in metaphase, and list 3 facts describing events in this phase.

A

4th : Mitosis - Anaphase

T

5th : Mitosis - Telophase

Anaphaseand Telophase. Draw a cell in anaphase and telophase, and list 3 facts describing events in each phase.

6th : Cytokinesis

Include these definitions:

Cytokinesis. Draw a cell in cytokinesis and define what happens to the cell.

Chromosome Centromere

Centriole Spindle

Sister chromatids

regulation of the cell cycle
Regulation of the Cell Cycle

Section 10-3

Box 25

  • For very obvious reasons, the cell cycle is a tightly, highly controlled process.
  • Do you know why?
  • Uncontrolled cell growth is cancer!!!Cancer can be deadly!
  • Not all cells need to divide all the time, or at all.
  • There is a time and place for cell division, and controlling the cell cycle is important because it is part of homeostasis- keeping an organism alive and healthy.

Box 25

Box 33

Box 25

Box 34

controls on cell division
Controls on Cell Division

In the lab, scientists can grow cells by placing them in a petri dish, along with nutrients.

If you remove cells from the center of the dish, cells bordering the open space begin dividing and filling the empty space.

Cells will grow until they form a single layer covering the bottom of the dish, then they stop growing when they come into contact with one another.

These experiments show that controls on cell growth and division can be turned onand off.

Box 35

what happens in your body
What happens in your body?
  • Similar processes happen in your own body.
  • What if you get a cut on your finger? A broken bone?
  • When you’re injured, cells at the edge of the cut or break are stimulated to divide rapidly and produce new cells, starting the process of healing.
  • When the gap is repaired, the controls for cell division turn off again, and everything returns to normal.

Box 27

Box 36

cell cycle regulators
Cell Cycle Regulators
  • Tim Hunt and Mark Kirschner found a protein that, when injected into non-dividing cells, would cause mitotic spindle fibers to form.
  • Levels of this protein rose and fell, depending on the phases of the cell cycle – produced when needed for division, not produced when no cell division is occurring.
  • They called the protein Cyclin (for cycle)
  • Cyclins = regulate the timing of the Cell Cycle in Eukaryote cells (your cells!)

Box 28

Box 37

Box 29

Box 38

hunt and kirschner s experiment
Hunt and Kirschner’s Experiment

A sample of cytoplasm is removed from a cell in mitosis.

Box 30

The reason for this effect is the proteinCyclin, whichtriggers cell divisionin non-dividing cells.

The sample is injected into a second cell in G2 of interphase.

As a result, the second cell enters mitosis.

internal and external regulators
Internal and External Regulators

Box 31

Box 39

  • Internal regulators = regulating proteins that respond to events inside the cell, and control the cell cycle; allow cell cycle to proceed only when certain process have happened inside the cell.
  • Similar to: You can’t eat your dessert until you clean your plate!
  • External regulators = regulating proteins that respond to events outside the cell, and control the cell cycle

Box 32

Box 40

uncontrolled cell growth
Uncontrolled Cell Growth

Box 42

44.77% chance of a man getting cancer

33.08% chance of a woman getting cancer

  • Cancer.
  • Such a scary word, isn’t it?
  • Most common cancers:
  • Men: Prostate cancer (33%)

Lung (13%)

  • Women: Breast (32%)

Lung (13%)

Affects 1 in 6 men

Box 41

Box 33

Affects 1 in 13 men

Affects 1 in 7 women

Affects 1 in 17 women

Box 34

Pretty frightening, yes?

American Cancer Society 2004 Statistics

cancer
Cancer

Box 43

Tumors = masses of uncontrollably dividing cells that damage surrounding tissues

Box 44

  • Cancer cells may Metastasize, or break loose and spread throughout the body.

Untreated Breast Cancer

Tumor on the eye

  • Cancer cells do not respond to the signals that regulate growth of most cells.
  • They divide uncontrollably and form masses of cells called Tumors that can damage the surrounding tissues.

Box 35

Box 36

cancer1
Cancer
  • Cancer is a disease of the Cell Cycle.
  • To find a cure for this horrible disease, we must first deeply and completely understand the Cell Cycle, what regulates it, and how it can go wrong, resulting in cancer.
  • This is a major scientific challenge, but at least we know now where to start searching for a cure- the Cell Cycle.

Box 37

Box 45

stem cells
Stem Cells
  • When you were first conceived, you started out as a SINGLE cell. One cell.
  • That one cell then divided over and over, (Mitosis) producing cells that could and would become all the specialized parts of your body.
  • Fetal Stem Cells= the cells in the earliest stages of fetal (baby) development, they can potentially become any cell type in the body.
  • Adult Stem Cells = usually found in the bone marrow, can be induced (pushed) to become other cell types like muscle, nerve and liver cells

Controversial – Unethical?

Box 38

Box 46

Box 47

Box 39

Has the promise to repair many injuries and replace damaged organs (ex. liver)

meiosis
Meiosis

Section 11-4

46

Box 40

Box 48

  • Humans have 46 chromosomes in every cell of our bodies except the sex cells or gametes (eggs and sperm)- they have 23 chromosomes
  • When a baby is conceived, an egg from mom and a sperm from dad, combine into the first cell of the new baby. 23+23 = 46

Box 49

Box 40

Box 50

46

What would happen if the egg and sperm both had 46 chromosomes?

Baby would have 92 chromosomes!! Disaster!

92

chromosomes

= death, disease

remembering meiosis
Remembering Meiosis

Box 51

  • Mitosis is a process that occurs in almost every cell of your body (body cells), except the sex cells, or gametes.
  • Mitosis = My toe sis, it happens in your toes!
  • Meiosis is a process of cell division that doesn’t happen in your toes, it only happens in your sex cells, gametes
  • Meiosis = My OH! Sis (as in uh-oh!)

Box 40

Box 52

meiosis1
Meiosis

Box 55

Meiosis results in cells with ½ the # of chromosomes, so they can combine in sexual reproduction, which results in an embryo with the normal amount of chromosomes.

  • To solve this problem, the cells in the gametes (eggs and sperm), undergo Meiosis instead of Mitosis, when they divide.
  • Why Meiosis?
  • Most cells in our body are Diploid (“di” = 2)
  • Diploid = have 2 sets of chromosomes, 2n(one from mom, one from dad)
  • Sex cells, or gametes, are Haploid
  • Haploid = have 1 set of chromosomes, 1n

Box 53

Box 41

Box 54

Box 42

chromosome number
Chromosome Number

Box 56

Homologous chromosomes= 2 sets of similar chromosomes, one from mom, one from dad

  • An example.
  • Fruit Flies (Drosophila), have 8 chromosomes total – 4 from dad fruit fly, 4 from mom fruit fly.

Box 43

2n = 8

Diploid number?

Haploid number?

1n = 4

phases of meiosis
Phases of Meiosis

Homologous = same chromosome, it just comes from different parents (mom or dad)

  • How are haploid (1n) gamete cells produced from diploid (2n) cells?
  • By Meiosis (my-OH-sis)
  • Meiosis = process of reduction cell division where the # of chromosomes per cell is cut in ½ by the separation of homologous chromosomes

Box 57

Box 45

Box 58

Box 46

  • Meiosis involves 2 distinct divisions,
  • Meiosis I
  • Meiosis II
  • Results of Meiosis? = cells with a haploid (1n) number of chromosomes

Box 59

meiosis i
Meiosis I

Box 61

Prophase I = Each chromosome pairs up with its matching homologous chromosome forming a tetrad

Interphase I = Cells undergo a round of DNA replication, forming duplicate chromosomes

Tetrads= in prophase I, chromosomes duplicate and form a structure with 4 chromosomes (tetrad)

Box 60

Box 62

4 sister chromatids form a Tetrad

2 sister chromatids

Interphase I

Prophase I

Chromosome duplication

slide37

During prophase I of Meiosis, when the tetrads form, a phenomenon called “Crossing Over” can occur.

Crossing Over = results in the exchange of genetic information between homologous chromosomes

Box 63

You got peanut butter in my chocolate!

You got chocolate in my peanut butter!

Sorry!

Hey hot stuff, wanna dance?

Owww! My arm!

Who me?

I think he likes me!

Help!

meiosis i1
Meiosis I

Anaphase I = Fibers pull the homologous chromosomes towards opposite ends of the cell (“A” for apart)

Prophase I = Each chromosome pairs up with its corresponding homologous chromosome to form a tetrad

Box 64

Metaphase I = Spindle fibers attach to the chromosomes, then they line up in the middle (“M” for middle)

Interphase I = Cells undergo a round of DNA replication, forming duplicate chromosomes

Box 65

Interphase I

Prophase I

Metaphase I

Anaphase I

meiosis i2
Meiosis I

Anaphase I = Fibers pull the homologous chromosomes towards opposite ends of the cell (“A” for apart)

Prophase I = Each chromosome pairs up with its corresponding homologous chromosome to form a tetrad

Metaphase I = Spindle fibers attach to the chromosomes, then they line up in the middle (“M” for middle)

Telophase I and Cytokinesis = Nuclear membranes form, the cell separates into 2 new cells

Interphase I = Cells undergo a round of DNA replication, forming duplicate chromosomes

Box 66

Interphase I

Prophase I

Metaphase I

Anaphase I

Telophase and Cytokinesis

meiosis ii
Meiosis II

Prophase II = of meiosis I results in 2 haploid daughter cells, each with ½ the # of chromosomes as the original cell

Box 67

The 2 new cells now enter a 2nd round of meiotic division

No more chromosome duplication

prophase II

meiosis ii1
Meiosis II

Metaphase II = chromosomes line up in the middle

Box 68

metaphase II

prophase II

Prophase II = of meiosis I results in 2 haploid daughter cells, each with ½ the # of chromosomes as the original cell

meiosis ii2
Meiosis II

Anaphase II = sister chromatids separate and move to opposite ends of the cell

Box 69

Prophase II = of meiosis I results in 2 haploid daughter cells, each with ½ the # of chromosomes as the original cell

Metaphase II = chromosomes line up in the middle

Telophase II and Cytokinesis = of meiosis II results in 4 haploid (1n) daughter cells

Box 70

4

3

metaphase II

anaphase II

telophase II

prophase II

2

1

slide43

Flow Chart for Meiosis

I

P

Interphase I

M

Prophase I

A

Metaphase I

Anaphase I

T

92

Telophase I

&Cytokinesis

92

92

92

Humans = 2n = 46

46

P

Prophase II

A

M

T

Telophase II

&

Cytokinesis

Anaphase II

Metaphase II

46

23

46

46

4 daughter cells

with haploid # (1n)

I then …PMAT…..PMAT

gamete formation
Gamete Formation

For Sexual Reproduction, where egg and sperm unite to make an embryo

Box 72

  • Why do we even have Meiosis?
  • To make gametes (eggs and sperm).
  • Male gametes = sperm
  • Female gametes = eggs

Box 71

Skip Box 59

Why do we need eggs and sperm?

End of Chapter 10 and Chapter 11 Section 11-4

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