Warm Up1. Do all living things grow and develop?2. Which type of cells have a nucleus?3. What information does the nucleus

store?4. Do you think cells grow like we do?

Explain why or why not.

AgendaObjective: SWBAT: Explain what happens during the cell cycle and how the nucleus divides during mitosis AND determine the number of chromosomes a cell has following cellular division.Go over quizzesMitosis cardsMitosis Hand jive

Phase cardsTry to put the cards in order

What are the diagrams on the cards?

How did you decide what order to put them in?

What do you think is happening at the end of this process?

Unit 4

Mitosis and Meiosis…

How things grow and develop!

1. How do we grow?a) The process starts with our cells

Our cells can only grow so big. Then they have to divide to produce more cells.

Example: When a fetus is developing and growing, it’s cells are dividing

What happens when a cell gets too big?

If your mom got pregnant with sextuplets (meaning 6 babies at once!),the house would get REALLY crowded. Anyone would have a hard time taking care of all those kids!

2. What happens when a cell gets too big? a. When a cell is small, the information

stored in that DNA is able to meet all of the cell’s needs.

b. When a cell increases in size, the DNA has a harder time performing all of its functions.

3. What are Chromosomes?a. Chromosomes are made up of DNAb. Every organism has a certain

number of chromosomesExample: Humans have 46

c. Most the time, you cannot see chromosomes because they are spread out in the nucleus

Chromosomes are only visible during cell division

3. What are chromosomes?d. Before a cell divides, it has to copy

it’s genetic information.e. DNA is a type of nucleic acid that

carries proteins and all the cell’s genetic information

DNA controls what a cell doesIn Eukaryotic cells, DNA is stored in the nucleus

f. DNA is bundled up into structures called chromosomes

4. What is the structure of a chromosome?

a. When they become visible, you can see that each chromosome is made up of two identical parts, called chromatids

b. Each “sister” chromatid is connected in the center by a centromere

Draw & Label the Chromosome

5. How does a cell divide?a. Cell Cycle: series of events that a cell

goes through as it grows and dividesb. Interphase is what happens in a cell before it

divides. “Inter” means between, so interphase means between phasesStep 1: The cell increases in size and makes

new proteins and organellesStep 2: DNA is synthesized (copied)Step 3: The cell finishes everything it needs to

do before it divides

5. How does a cell divide?

c. One of the most important events is the “M” phase

d. During the M phase, two things occur:Mitosis: the division of a cell’s nucleus

AND

Cytokinesis: the division of a cell“Cyto” = cell

“kinesis”= movement

The Cell Cycle

What is this?

Watch a couple movies

Mitosis 1

BrainPop Mitosis

Exit Ticket1. What is a chromosome made of?

2. What must a cell do before it divides?

3. __________ is when the nucleus of a cell divides.

4. Why do cells divide? Explain in complete sentences.

Warm Up1. How do we grow?

2. What happens to the DNA when a cell gets too big?

3. DNA is a type of ________________?

4. How many cells are produced after cytokinesis?

AgendaObjectives: SWBAT: Identify the types of cells that undergo mitosis as well as the type of cells that undergo meiosis AND identify why approximately half of an individual’s DNA sequence comes from each parent.

Review Mitosis and learn about Meiosis

Mitosis Hand Jive

Go over quizzes

Exit Ticket

Review of Cell Division

Before a cell becomes too large, it divides to form two “daughter” cells.

What must a cell do before it can divide?Copy its DNA!

What divides in the process of mitosis?The Nucleus

1. Mitosis

a. Mitosis is the division of a cell’s nucleus

b. It’s a part of the M-phase of the Cell Cycle- The Cell Cycle: is the entire life span of a cell

from creation to division- Before a cell can divide, it goes through the

period of growth called Interphase. DNA is also copied

Mitosis Hand Jive

Review of Chromosomes: a. Each chromosome is a

single, long structure that only becomes the “x” shape after DNA replication.

b. A human has 23 pairs (46 total) chromosomes- After DNA is copied, we have 46 pairs (92 total!) chromosomes!!!!

6. Put these pictures in order

During Interphase the cell prepares for mitosis and DNA is replicated

Parent cell

centrioles

spindle fibers

centrosome

nucleus withDNA

1. Prophase

a. Prophase is the first phase of mitosis.

b. During Prophase the chromosomes bundle up and become visible.

c. The centrioles split up and take positions on opposite sides of the nucleus.

d. The nuclear envelope that surrounds the nucleus breaks down

Prophase

2. Metaphase

a. Metaphase is the second stage of mitosis

b. During metaphase, chromosomes line up in the middle of the nucleus

c. The centrioles are on opposite sides of the nucleus and the spindle fibers attach to each chromosome

Metaphase

3. Anaphase

a. Anaphase is the third phase of Mitosis.

b. During Anaphase the chromosome pairs separate and move toward the opposite poles or sides of the cell.

Anaphase

4. Telophasea. Telophase is the fourth and final phase of

mitosis.

b. During Telophase the chromosomes begin to loosen and form bundles of material that are hard to see.

c. The cell membrane starts to pinch down and divide into two cells in Telophase.

d. The nuclear envelope also reappears and

begins to form around the two new nuclei.

Telophase

5. Cytokinesis

a. Cytokinesis happens AFTER mitosis

b. This is when the cell’s cytoplasm divides to create two identical cells

c. After this process, each new cell will begin Interphase and the Cell Cycle will start all over again

Cytokinesis

Review

• If a cell has 12 chromosomes, how many will it have after mitosis?

• How many daughter cells are produced after mitosis?

• What types of cells go through mitosis?

Sexual vs. Asexual Reproduction

Do all organisms reproduce in the same way?

No

What type of organisms reproduce sexually?

Animals and Plants

What type of organisms reproduce asexually?

Bacteria

All Living Things Reproduce *This is one of the 7 characteristics of living things*

a. Most plants and animals reproduce by sexual reproduction.

b. In sexual reproduction, cells from two different parents combine to form the first cell of the new organism.

What is Asexual Reproduction? a. Other organisms reproduce asexually,

where a single parent produces offspring that are identical to the parent.

b. What is Mitosis, asexual or sexual production?

- Asexual. It’s one parent cell producing two identical cells from itself.

What organisms reproduce asexually?

c. Most prokaryotes, like bacteria, reproduce asexually.

d. Asexual reproduction is the primary form of reproduction for single-celled organisms such as bacteria.

Asexual Reproduction

What are diploid cells?a. Asexually Reproducing organisms have

diploid cells.

b. A diploid cell is a cell that has two copies of each chromosome. Diploid means two sets (2n) of chromosomes.

Exit Ticket1. What happens in cytokinesis?2. DNA is arranged in _______________. 3. If a cell has 4 chromosomes and goes

through mitosis, how many chromosomes would it’s daughter cell have?

4. In asexual reproduction, offspring get their genetic information from ______________.

Warm Up1. If a daughter cell has 23 pairs of

chromosomes, how many pairs does the original cell have? What living thing has 23 pairs of chromosomes?

2. A ________ cell has two full sets of chromosomes.

3. What happens in asexual reproduction?

AgendaObjectives: SWBAT: Explain that meiosis is necessary for sexual reproduction AND Determine the number of chromosomes a cell has following the process of meiosis.

Notes on Meiosis

Video and Questions

Exit Ticket

Mitosis hand-jive review!

What are Haploid Cells?a. Sex cells (eggs and sperm) contain only

one copy of chromosomes. b. Haploid means one set of chromosomes.

A haploid cell is a cell that only has one set (1n) of genes.

c. Eggs have an X chromosome and sperm cells can have either an X or a Y chromosome.

Haploid vs. Diploid cells

What happens before Sexual Reproduction?

b. Cellular division happens two times to produce sex cells. DNA is copied one time, but the total number of chromosomes is divided two times.

What happens before Sexual Reproduction?

a.Offspring inherit half of their genetic information from each parent

b.That means sex cells will only contain half of the parents’ DNA

What is Meiosis?a. Meiosis is the type of cellular division that

results in 4 daughter cells with half the number of chromosomes.

• Only occurs in organisms that can reproduce sexually.

• Produces haploid cells

What happens to the # of chromosomes?

a. In Meiosis, the nucleus divides four times leaving each nuclei with half the number of chromosomes.

b. Example:• Parent cell- 2n• Replication- 4n or 2 pairs• Mitosis- 2n• Meiosis- n

DEMO!

I need 4 volunteers

Meiosis and Sexual Reproductiona. Meiosis occurs to make gametes (sex

cells) which combine to create an offspring.

b. Sexual reproduction is what makes living things different from one another. The fertilized cell is different from both the mother's egg and father's sperm because it has two different sets of DNA.

What is Genetic Variability?

a. Genetic Variability means that the genes are different from each other.

b. Meiosis produces genetic variability among organisms.

Do these 3 boys look identical to their mom?

What are the Advantages of Meiosis?a. Sexual reproduction increases the

amount of variation within a species.

b. This variation improves the chance that a species will adapt to its environment and be able to survive.

Example

The number of owls increase in a park and the amount of mice decreases rapidly. However, the quickest mice are able to escape the owls. In time, more fast mice are born, allowing them to survive. They adapted to the change and survived because they were genetically different.

What are the Disadvantages of Mitosis?a. Organisms that reproduce asexually

cannot develop much variety, because they are just "copying" the parent.

b. Since they are all exactly the same, the organisms will probably not survive a disaster.

White Board Review

How many chromosomes do we have total?

How many chromosomes did we get from each parent?

Meiosis produces how many daughter cells?

4

Which type of cellular division allows for genetic variability, mitosis OR meiosis

Meiosis

A dog has 78 chromosomes in each of its cells. One of its cells goes through mitosis. How many chromosomes will the new, daughter cell have?

78!!!

Remember, a cell that has gone through mitosis will have the same number of chromosomes!

Write out the correct order of the pictures

3, 2, 5, 1, 4

What type of cells has two sets of chromosomes (2n) ?

Diploid

Sex cells are a type of ___________ cell because they have half the number of chromosomes

haploid

This is a picture of which process?

LAST Question

What occurs AFTER mitosis in the Cell Cycle?

Cytokinesis!

Exit Ticket

Exit Ticket1. Diploid cells have twice as many

chromosomes as ______________ cells2. Mitosis occurs in Asexual or Sexual

reproduction?3. If a living thing has 20 chromosomes and it’s

cell goes through meiosis, how many chromosomes will be in one of the new cells?

4. What is an advantage of meiosis?

Warm-Up1. How many cells are produced by

Mitosis?2. How many cells are produced by

Meiosis?3. Mitosis is a form of _______________

reproduction4. Meiosis is a form of ______________

reproduction

AgendaObjectives: SWBAT: describe “crossing over” and explain how it leads to further genetic variability AND evaluate the role of meiosis in maintaining genetic variability.

Notes

Video Clips

What does Meiosis look like?

MEIOSIS I

MEIOSIS II

Possible gametes Possible gametes

How do we get genetic variation?

independent assortment of chromosomes in meiosis.Chromosomes pair up randomly, and then split into two new cells

That means two traits can be inherited independently from one another

Example: a cat's color and tail length

How do we get genetic variation? random fertilization of gametes (sex cells)

Any sperm can fertilize any egg

There are trillions of different combinations of chromosomes

How do we get genetic variation?

When chromosomes cross-over in meiosis

What is crossing-over?Crossing over occurs when genes from one chromosome are exchanged with genes from another chromosome

results in new combinations of genes

Also called recombination

What does Crossing-over look like?Crossing over is important because it allows for variation in the genes we inherit from our parents. Crossing over

Video Clips

http://www.goldiesroom.org/video_archive.htm

http://www.brainpop.com/science/cellularlifeandgenetics/genetics/

Compare Mitosis and Meiosis

Diagrams