Take out 4 sheets of paper from your notes section of your binders and head your papers.

Assignment title should be:

Cell ReproductionChapter 10

Level green book

Goals• Section 1: To learn how different organisms can grow, repair

damaged cells, and reproduce because of cell division and mitosis.

• Section 2: To learn that sexual reproduction and meiosis ensure the preservation of species and diversity of life.

• Section 3: To learn that DNA contains the instructions for all life.

BELL WORKGo to page 275 for directions

5 minutes to complete foldable study organizer

Directions for next slide!• Before you read the chapter, respond to the statements below in

your notebook.– Write an A if you agree with the statement– Write a D if you disagree with the statement

• After you read the chapter, look back to this page to see if you’ve changed your mind about any of the statements.– If any of your answers changed, explain why.– Change any false statements into true statements.– Use your revised statements as a study guide.

Before you read

A or D

Statement After you read

A or D

1. All cells cycles last the same amount of time.

2. Interphase lasts longer than other phases of a cell’s cycle.

3. Asexual reproduction requires two people.

4. Cell division and mitosis is the same in all organisms.

5. Meiosis always happens before fertilization.

6. A zygote is the cell formed when an egg and sperm join.

7. Diploid cells have pairs of similar chromosomes.

8. The exact structure of DNA is unknown.

9. A gene is a section of DNA on a chromosome.

10. Mistakes in copying DNA result in mutations.

11. Budding and regeneration can occur in most organisms.

Get a copy of this chart from Ms. Etienne

Section 1: Cell Division and Mitosis• The Cell Cycle– A life cycle begins with the organism’s formation, is

followed by growth and development, and finally ends in death.

– Length of Cycle• Cell cycle is a series of events that takes place from one cell

division to the next. • The time it takes to complete a cell cycle is not the same in all

cells.

– Interphase• Most of the life of any eukaryotic cell is spent in a

period of growth and development known as interphase.• During interphase, an actively dividing cell, such as a

skin cell, copies its hereditary material and prepares for cell division

• Before a cell divides, a copy of the hereditary material must be made so that each of the two new cells will get a complete copy.

• Each cell needs a complete set of hereditary material to carry out life functions

• After interphase, cell division begins. The nucleus divides, and then the cytoplasm separates to form two new cells.

• Mitosis and Cell Division – The process where the nucleus divides to form two identical nuclei mitosis.– Each new nucleus is identical to the original nucleus,– The steps of mitosis in order are named prophase, metaphase, anaphase,

and telophase.– Steps of Mitosis

• When any nucleus divides, the chromosomes play the important part.• Chromosome is a structure in the nucleus that contains hereditary material.• During interphase (not part of mitosis- occurs before)

– each chromosome duplicates– When the nucleus is ready to divide, each duplicated chromosome coils tightly into

two thickened, identical strands called chromatids.

• During prophase– The pairs of chromatids are fully visible when viewed under microscope.– The nucleolus and the nuclear membrane disintegrate.– Two small structures called centrioles move to opposite ends of the cell– Between the centrioles, threadlike spindle fibers begin to stretch across the cell.

• In metaphase– The pairs of chromatids line up

across the center of the cell– The centromere of each pair

usually become attached to two spindle fibers-one from each side of the cell.

• In anaphase– Each centromere divides and the

spindle fibers shorten– Each pair of chromatids separate– Chromatids move to opposite ends

of the cells – Chromatids are now called

chromosomes

• In Telophase– Spindle fibers start

to disappear– Chromosomes start

to uncoil– TWO nuclei form

• Mitosis Ends Here!!!

• After mitosis has ended, the cell still needs to split into two.– The process by which the

cytoplasm separates to form two new cells is known as CYTOKINESIS

Contrasting Mitosis

Plant cells• Appearance of the cell plate

indicates that the cytoplasm is being divided (see figure 4 on page 278).

• Do not have centrioles (see page 278).

Animal cells• The cytoplasm divides as

the cell membrane pinches in the middle of the cell

Results of Mitosis and Cell Division

Mitosis• Mitosis is the division of a

nucleus• Mitosis produces two new

nuclei that are identical to each other

• The original cell no longer exists after mitosis

Cell Division• Cell division allows for

growth and replaces worn out or damaged cells– You are larger and have more

cells than a baby because of cell division

• Cell division is used by some organisms to produce new organisms

Asexual reproductionThere are two types of reproduction: sexual and asexual.• In asexual reproduction, a new organism (sometimes

more than one) is produced from only one organism– This new organism will have the same hereditary

material as the parent organism– Types of asexual reproduction:

• Cellular Asexual Reproduction: mitosis, cell division and fission are all examples of cellular asexual reproduction

• Mitosis is when the nucleus divides into two nuclei.• Cell division is when one cell divides into new cells.

– Fission is a type of asexual reproduction used by bacteria. During fission, the unicellular bacterium (which does not have a nucleus), copies its genetic material and then divides into two identical organisms. • Keep in mind, bacteria are prokaryotes and can undergo

FISSION and not MITOSIS. • Eukaryotes can undergo MITOSIS and not FISSION

• Other types of asexual reproduction:– Budding: made possible because of mitosis and cell division. In

budding, a bud grows on the adult, when it becomes large enough, it breaks away to live on its own.

– Regeneration: process that uses mitosis and cell division to regrow body parts. If organisms that can undergo regeneration break into pieces, a new organism can grow from each piece. Example of organisms that can use regeneration: sponges, planaria and sea stars

Section 2: Sexual Reproduction and Meiosis

• Sexual reproduction– Sexual reproduction- two sex cells, sometimes called an

egg and a sperm, come together.– Sperm- sex cell formed in a male reproductive organs– Eggs- sex cell formed in the female reproductive organs.– Fertilization- the joining of an egg and a sperm.– Zygote- cell that forms during fertilization.

– Diploid Cells• Typical human body cell has 46 chromosomes and is

considered a diploid cell.– Each chromosomes has a similar pair which makes 23

pairs of chromosomes.

• Diploid is when cells have PAIRS of similar chromosomes.– Example 23 PAIRS of chromosomes in a typical body

cell- – 23 pairs of chromosomes = 46 chromosomes

– Haploid Cells• A Sex cell does not have pairs of chromosomes so it is

considered a haploid cell.• Haploid means “single form”• Human sex cells have 23 chromosomes (which is half of

the amount of chromosomes in body cells not in pairs)

Meiosis and Sex cells

• Meiosis- process that produces haploid sex cells.• During meiosis two divisions happen (meiosis I, and

meiosis II)

• Meiosis I– Before meiosis, each chromosome duplicates. – The events in prophase I are similar to those of prophase in mitosis

» Unlike mitosis, in meiosis, each duplicated cells comes near its similar duplicated mate.

– In metaphase I, the pairs of duplicated chromosomes line up in the center of the cell.

– Then centromere of each chromatid pair becomes attached to one spindle fiber so the chromatids do not separate in anaphase I.» The two pairs of chromatids of each similar pair move away

from each other to opposite ends of the cell– In telophase I, the cytoplasm divides, and two new cells are formed

• Meiosis IIThe two cells formed in meiosis I, begin meiosis II– In Prophase II, the duplicated chromosomes and

spindle fibers reappear in each new cell.– In metaphase II, the duplicated chromosomes move to

the centromere now attaches to two spindle fibers instead of one.

– Then the chromatids separate and move to opposite ends of the cell, and each cells become an individual chromosome in anaphase II.

– In telophase II, the spindle fibers disappear and a nuclear membrane forms around each set of chromosomes.

– When meiosis is finished, the cytoplasm divides.

• Summary of meiosis– In meiosis I, two

cells are formed– In meiosis II, both

of these cells form two cells.

– From a human cell with 46 paired chromosomes, meiosis produces four sex cells each with 23 unpaired chromosomes.

• Mistakes of meiosis– Meiosis occurs many times in

reproductive organs– Mistakes can produce sex cells

with too many or too few chromosomes

– Sometimes zygotes are produced from these sex cells• If the zygote lives, every cell

in the organism that grows from that zygote usually have the wrong number of chromosomes

• Organisms that have the wrong number of chromosomes may not grow normally.

Section 3: DNA

• What is DNA?– Code used by cell that is

stored in hereditary material

– This chemical code is called DNA (Deoxyribo Nucleic Acid)• DNA contains information

for organism growth and function

– During cell division DNA code is copied and passed on to the new cells• This passing on of DNA

ensures that new cells have the same coded information as the old cells

– Every cell formed in your body contains DNA

DNA

Discovering DNA

• Scientists have known since mid-1800’s that nuclei contain nucleic acids

• By 1950, chemists learned what nucleic of DNA was made of but structure of DNA was still unknown

• Click on this link http://www.brainpop.com/science/cellularlifeandgenetics/dna/

DNA’s structure

• In 1952- Rosalind Franklin discovered that DNA consisted of 2 chains of molecules in a spiral form– Used X-ray technique to

determine this

• In 1953- James Watson and Francis Crick made a model of DNA molecule

History…

DNA ModelD = Sugar (deoxyribose)P = Phosphate

Nitrogen bases:A = AdenineT = ThymineC = CytosineG = Guanine

Amount of Cytosine in cells always equals amount of guanine in cells. Dame goes for amounts of thymine and adenine.

Copying DNA- Before mitosis or

meiosis, amount of DNA in the nucleus is doubled

- The Watson and Crick model illustrates how this takes place

- Two sides of DNA unwind and separate

- Each side becomes a patter on which new side forms

- See images…

Genes

Making proteins• Genes are found in the

nucleus BUT proteins are made in the cytoplasm

• The codes to make proteins are carried from the nucleus to the ribosomes by RNA (remember: ribosomes make proteins)

Ribonucleic Acid (RNA)• Made in the nucleus on a

pattern of DNA– DNA looks like a ladder but RNA

is a ladder with its rungs cut in half

– Like DNA, RNA has the nitrogen bases Guanine, Adenine, Cytosine but RNA has the nitrogen base Uracil instead of thymine

– The sugar phosphate in RNA contains the sugar Ribose and NOT Deoxyribose as in DNA

A gene is a section of DNA on a chromosome…

RNA continued…Three main kinds of RNA:1. Messenger RNA (mRNA)

i. Protein production begins when mRNA moves into the cytoplasm

2. Ribosomal RNA (rRNA)i. Ribosomes are made of rRNA

3. Transfer RNA (tRNA)i. tRNA in the cytoplasm bring

amino acids to these ribososmes

See page 293 of the Green Book for more details

• Above you have RNA on the left, DNA on the right

Controlling Genes• Just because most cells in

organisms have the same chromosomes and the same genes does not mean they make the same proteins

• Multicellular organisms use thousands of genes that they contain to make proteins

• Cells use only the genes that direct the making of proteins that it needs• Muscle proteins made in muscle

cells and not in nerve cells

• Cells can also turn genes on and off• See how on page 294

Mutations

• Mistakes can occur when DNA is being copied and DNA ends up not being copied properly– These mistakes are called mutations

• When are mutations likely to occur?• What are the results of mutation?– Please read pages 294 and 295 to answer the

following questions• Look at figure 19 on page 295

Reviewing• Please read pages 276 through 295 again and

complete chapter review on pages 300, 301 as practice.

• Fill out the “After you read” portion of the chart on slide 5 of the power point or page 276B of the Green Book

• Sign onto Brainpop.com, watch videos: DNA, RNA and Genetic Mutations– Username: palmbeach– Password: palmbeach