Pick up a white index card from the stool in

the front of the room as well as ABCD cards

Also grab your notebooks

On your index card

• How do you think you grow and repair yourself after you cut your finger?

(Hint: think about the three parts of cell theory)

Cell Cell ReproductionReproduction

Cell Cycle, Binary Fission, Mitosis & Cell Cycle, Binary Fission, Mitosis & MeiosisMeiosis

The Cell Cycle and How Cells Divide

Functions of Cell Division20 µm100 µm 200 µm

(a)Reproduction. An amoeba, a single-celled

eukaryote, is dividing into two cells. Each new cell will be an individual organism

(b) Growth and development. This micrograph shows a sand dollar embryo shortly after the fertilized egg divided, forming two cells

(c) Tissue renewal. These dividing bone marrow cells (arrow) will give rise to new blood cells (LM).

Cell Division• An integral part of the cell cycle• Results in genetically identical daughter

cells• Cells duplicate their genetic material

– Before they divide, ensuring that each daughter cell receives an exact copy of the genetic material, DNA

Which one of these is NOT a reason for cell division that

we talked about?A. ReproductionB. PhotosynthesisC. Growth and developmentD. Tissue repair

DNA• Genetic information - genome• Packaged into chromosomes

50 µm

Figure 12.3

DNA And Chromosomes

• An average eukaryotic cell has about 1,000 times more DNA then an average prokaryotic cell.

• The DNA in a eukaryotic cell is organized into several linear chromosomes, whose organization is much more complex than the single, circular DNA molecule in a prokaryotic cell

Chromosomes

• All eukaryotic cells store genetic information in chromosomes.– Most eukaryotes have between 10 and

50 chromosomes in their body cells.– Human cells have 46 chromosomes.– 23 nearly-identical pairs

Think about the following…Turn to your should partner and talk about these points.

Press Pause, Think, & Share

1) What are the functions of cell division? (Hint there are three main functions)

2) Which structures in the nucleus stores genetic information?

3) How many chromosomes does a human have in their normal body cells?

What did you discuss?1)What are the functions of cell division? (Hint there

are three main functions)– Reproduction in some organisms (unicellular)– Growth– Repair

2)Which structures in the nucleus stores genetic information?– Chromosomes

3)How many chromosomes does a human have in their normal body cells?– 46 (23 pairs)

• What are the reactants and products for

Time to Write

• On top of the Cell Cycle Diagram write in the function of cell division

• Fill in the number or chromosome as well

Phases of the Cell Cycle• The cell cycle consists of

– Interphase – normal cell activity– The mitotic phase – cell division– Cytokinesis INTERPHASE

Growth

G 1(DNA synthesis)

Growth

G2

Cel

l Div

sion

Phases of the Cell Cycle

• Interphase

– G1 - primary growth

– S - genome replicated

– G2 - secondary growth

• M - mitosis• C - cytokinesis

Interphase

• G1 - Cells undergo majority of growth

• S - Each chromosome replicates (Synthesizes) to produce sister chromatids– Attached at centromere– Contains attachment site (kinetochore)

• G2 - Chromosomes condense - Assemble machinery for division such as centrioles

Which represents the correct sequence of stages

in the cell cycle?

A) G1, G2, S, M B) G1, G2, M, S C) G1, M, G2, S D) G1, S, G2, M E) G1, M, S, G2

Chromosomes are duplicated during ____ of the

cell cycle.

A. G1 phase B. G2 phase C. S phase D. metaphase

MitosisEukaryotic cells divide by mitosisEach new cell receives one copy of every

chromosome that was present in the original cell. Produces 2 new cells that are both genetically

identical to the original cell.

DNA duplication during interphase

Mitosis

Diploid Cell

Cytokinesisoccurs within the nucleus•Cleavage of cell into two halves

•Final Stage of Cell Cycle–within the nucleus

The method by which a cell's cytoplasm divides is

called ____.A.DNA replicationB.interphaseC.mitosisD.cytokinesis

Think about the following…Turn to your shoulder partner and talk about these points.

Press Pause, Think, & Share

1) What are the steps of the cell cycle? (Hint: there are three)

2) Describe the major event that happens in each step.

What did you discuss?1)What are the steps of the cell cycle? (Hint: there

are three)– Interphase– Mitosis– Cytokinesis

2)Describe the major even that happens in each step.– Interphase= DNA replicates during the S phase of

interphase– Mitosis= Nucleus divides– Cytokinesis= cleavage of cell into two halves

• What are the reactants and products for

Time to Write

• Using the graphic note guide fill in the information about the stages of the cell cycle and the major events that happen in each stage.

• When you are finished compare yours to your partners. Made any necessary changes.

Binary FissionBinary Fission• Most cells reproduce Most cells reproduce

through some sort of through some sort of Cell Cell DivisionDivision

• Prokaryotic cells divide Prokaryotic cells divide through a simple form of through a simple form of division called division called Binary Binary FissionFission

• 3 step process3 step process• Single “naked” strand Single “naked” strand

splits and forms a duplicate splits and forms a duplicate of itself.of itself.

• The two copies move to The two copies move to opposite sides of the cellopposite sides of the cell

• Cell “pinches” into two new Cell “pinches” into two new and identical cells called and identical cells called "daughter cells"daughter cells". (Cell wall ". (Cell wall then forms if applicable)then forms if applicable)

You need ABCD cards and your notes packet

• Make sure your notebook’s cell cycle chart is labeled

• Make sure your cell cycle questions from yesterday’s reading have been completed

• BTW: Quiz Tomorrow!

Mitosis• The process by which

eukaryotic cells reproduce themselves, resulting in daughter cells that contain the same amount of genetic material as the parent cell.

• Occur in body cells (somatic cells)

Cell Division Occurs in a series

of stages of phases

Animated Mitosis Cyclehttp://www.cellsalive.com/mitosis.htm

•Prophase

•Metaphase

•Anaphase

•Telophase

Interphase occurs before mitosis begins

• Chromosomes are copied (# doubles)• Chromosomes appear as threadlike coils

(chromatin) at the start, but each chromosome and its copy(sister chromosome) change to sister chromatids at end of this phase

CELL MEMBRANENucleus

Cytoplasm

Why is it necessary for DNA to replicate prior to cell division?

A. So that each daughter cell will have 23 chromosomes

B. So that each daughter cell will have a complete copy of the genetic material

C. So that each daughter cell will have 46 homologous (pairs) of chromosomes

D. So that each daughter cell will have 2 sister chromatids

The term used for DNA in a nucleus BEFORE it becomes condensed in preparation

for mitosis is

A) chromosome. B) chromatin. C) cytokinesis. D) centromere.

InterphaseInterphase

Animal Cell

Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Prophase 1st step in Mitosis

• Nuclear envelope disappears• Centrioles appear and begin to move to

opposite end of the cell. • Spindle fibers form between the poles.

CentriolesSister chromatids

Spindle fibers

Why do chromosomes have a X-shape?

A. Because they are made of two sister chromatins

B. Because they are made of sister centromeres

C. Because they are made of two sister chromosomes

D. Because they are made of two sister chromatids

Prophase

Animal Cell

Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Spindle fibers

Centrioles

Metaphase 2nd step in Mitosis

• Chromatids (or pairs of chromosomes) attach to the spindle fibers.

• Line up in the middle of the cell

Centrioles

Spindle fibers

Metaphase

Animal Cell

Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Turn to your partner and answer:

• Partner with the longest hair:– What are the first two stages of

mitosis

• Partner with the shortest hair:– What happens during these two stages

Anaphase 3rd step in Mitosis

• Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell.

Centrioles

Spindle fibers

Anaphase

Animal Cell

Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Telophase 4th step in Mitosis

• Two new nuclei form. • Chromosomes appear as chromatin

(threads rather than rods).• Mitosis ends.

NucleiNuclei

Chromatin

Telophase

Animal Cell

Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Cytokinesisoccurs after mitosis

• Cell membrane moves inward to create

two daughter cells – each with its own nucleus with identical chromosomes.

45

Cell Cycle

Think about the following…Turn to your should partner and talk about these points.

Press Pause, Think, & Share

1) What are the phases of mitosis (hint: there are 4)

2) Describe the major even that happens in each phase.

What did you discuss?1)What are the phases of mitosis? (Hint: there are four)

– Prophase– Metaphase– Anaphase– Telophase

2)Describe the major even that happens in each step.– Prophase= spindle fibers form, nuclear envelope disappears– Metaphase= chromatide line up at center of cell– Anaphase= chromatide are pulled to opposite ends of the cell– Telophase= nuclei appear, mitosis ends

• What are the reactants and products for

Time to Write

• Use the guided notes to fill in the information that was just discussed.

• Once you are finished share your paper with a partner.

• Make any necessary changes.

You need ABCD cards!

• You need your notes out

MeiosisMeiosis

• Similar in many ways to mitosisSimilar in many ways to mitosis• Several differencesSeveral differences• Involves 2 cell divisionsInvolves 2 cell divisions• Results in 4 cells with 1/2 the normal Results in 4 cells with 1/2 the normal

genetic information genetic information

VocabularyVocabulary• Diploid (2N)Diploid (2N) - Normal - Normal

amount of genetic materialamount of genetic material• Haploid (N)Haploid (N) - 1/2 the - 1/2 the

genetic material.genetic material.• Meiosis results in the Meiosis results in the

formation of haploid cells.formation of haploid cells.• In Humans, these are the In Humans, these are the

OvaOva (egg) and (egg) and spermsperm..• Ova are produced in the Ova are produced in the

ovariesovaries in females in females• Process is called Process is called

ooogenesisogenesis• Sperm are produced in the Sperm are produced in the

testestestes of males. of males.• Process is called Process is called

spermatogenesisspermatogenesis

Meiosis Phases

• Meiosis occurs in 2 phases; Meiosis I, & Meiosis II.

• Meiosis I.– Prior to division,

amount of DNA doubles

Crossing OverCrossing Over

• During metaphase During metaphase 1 homologous 1 homologous chromosomes line-chromosomes line-up along the up along the metaphase platemetaphase plate

• Areas of Areas of homologous homologous chromosomes chromosomes connect at areas connect at areas called called chiasmatachiasmata

Crossing over contd.Crossing over contd.

• Crossing OverCrossing Over of of genes occurs now genes occurs now – Segments of Segments of

homologous homologous chromosomes break chromosomes break and reform at similar and reform at similar locations.locations.

– Results in new genetic Results in new genetic combinations of combinations of offspring.offspring.

– This is the main This is the main advantage of sexual advantage of sexual reproductionreproduction

What process does this show?

A. protein synthesisB. replication of DNAC. chromosomal segment exchangeD. mitosis

Chromosome reductionChromosome reduction

• During anaphase During anaphase 1, each 1, each homologous homologous chromosome is chromosome is pulled to pulled to opposite sides of opposite sides of the cell. Unlike the cell. Unlike mitosis, mitosis, THE THE CENTROMERES CENTROMERES DO NOT DO NOT BREAKBREAK..

Think-pair-share

• Discuss with your table partner:– What does meiosis produce?– What is crossing over?– How is this an advantage?

Meiosis I continuedMeiosis I continued

• Nuclei may or Nuclei may or may not may not reform reform following following division.division.

• Cytokenesis Cytokenesis may or may may or may not occur not occur

Meiosis II• DNA does not double• Chromosomes

randomly line-up along metaphase plate like regular mitosis.

• During anaphase 2, CENTROMERES BREAK and each chromosome is pulled to opposite sides of the cell.

• Nuclei reform and cytokenesis usually occurs (although it is often unequal).

Overview of MeiosisOverview of Meiosis

Comparison of Mitosis & Comparison of Mitosis & MeiosisMeiosis

Meiosis produces ____ in gametes.

A.enzymesB. identical daughter cellsC.forty-six chromosomesD.genetic variation

Try the fluency builder again

• Don’t forget to keep score• AND DON’T LOSE THE PIECES!!!!