Chapter 10

Cell Reproduction

10.1 Cell Division & Mitosis

A. The Cell Cycle

1. formation- growth & development- death

2. Individual cells have life cycles-cell cycle varies for different types of cells

-may take seconds to hours

-repair, growth, or replacement

B. Mitosis

1. Process in which the nucleus divides to form two identical nuclei

2. Chromosomes are found in the nucleus- they contain your hereditary information

3. Interphase- each chromosome duplicates, then tighten into thicker strands called chromatids

C. Steps of Mitosis

1. Prophase- chromatid pairs are now visible

- spindle fibers are forming

2. Metaphase- chromatid pairs are lined up in the center of the cell

3. Anaphase- chromosomes have separated and pull toward the poles

4. Telophase- cytoplasm separates

- two new cells form

Prophase Metaphase Anaphase

Telophase

D. Results of Mitosis

1. Every cell in your body has 46 chromosomes (23 pairs)

2. Each cell has the same copy of DNA

3. All actors in a play have the same script, but each actor has it’s own lines

4. Each cell has a different job

5. Allows growth and replaces worn out or damaged cells

E. Asexual Reproduction1. A new organism is produced from one

organism

2. Each has the same DNA

3. Examples:-strawberry runners

-bacteria (fission)

-hydra (budding)

-starfish (regeneration)

10.2 Meiosis

A. Sexual Reproduction

fertilizationMale Sex cell = sperm

23 chromo-somes

haploid

Female Sex cell = egg

23 chromo-somes

haploid

1st cell = Zygote23 pairsdiploid

Meiosis = division of sex cells-4 new sex cells are produced (4 eggs or 4 sperm)-Each new sex cell has 23 chromosomes (haploid)

B. MeiosisMeiosis 1 Prophase 1

Metaphase 1Anaphase 1Telophase 1

Produces 2 new cells similar to Mitosis

These 2 new cells undergo division again

Meiosis 2 Prophase 2Metaphase 2Anaphase 2Telophase 2

Produces 4 new cells -4 egg or-4 sperm

Each cell now has 23 chromosomes (haploid)

10.3 DNA

A. General Information

DNA = deoxyribonucleic acid Blueprint of life (instructions) 1st model made in 1953 by James Watson

and Francis Crick Looks like a twisted ladder (“double helix”)

Duplicates during interphase 1 ladder becomes 2 identical ladders

Sides of ladder = sugar and phosphate

Steps of ladder = nitrogen bases

A = Adenine

T = Thymine

G= Guanine

C = Cytosine

Base-Pair Rule

A bonds with T

G bonds with C

B. Parts of the Ladder

New strands

unzips

C. Making Copies

D. RNA1. Ribonucleic Acid

2. DNA remains in the nucleus, but in order for it to get it’s instructions, it must send a message out to the ribosomes in the cytoplasm to make the correct proteins

3 types of RNA

1. Messenger RNA (mRNA)-Carries the code that directs the order in which amino acids bond (train)

2. Ribosomal RNA (rRNA)-protein factories

3. Transfer RNA (tRNA)-brings amino acids to protein factories (match-maker)

RNA is similar to DNA except for three things:

1. RNA has 1 strand instead of 2

2. RNA has Uracil (U) instead of Thymine (T)

3. RNA has ribose sugar instead of deoxyribose sugar

DNA mRNA Protein

transcription translation

(Draw picture from the board)

E. Genes

Genes are sections of DNA on a chromosome

Contain instructions for making specific proteins

Cells use only the genes that direct the making of proteins needed by that particular cell

F. Mutations

1. Any permanent change in the DNA sequence of a chromosome

2. Caused by:a) Outside factors called Mutagens

-X-rays, sunlight, chemicals, drugs

b) Incorrect copying of DNA on the ladders