I. REPRODUCTION

Requires cell division

A. The Cell Cycle:

Cell Growth and Division

1. Interphase

a. A period of cell growthb. Cell size increasesc. Metabolic functions are carried outd. Chromosomes (DNA) are replicated in preparation for

cell division

2. Mitosisa. Nuclear division occurs

b. Two daughter cells are formed each containing a complete set of chromosomes

c. After mitosis, the cytoplasm divides separating the two daughter cells

d. The two daughter cells enter Interphase

B. Normal cells

1. Spend most of their time in interphase, growing and carrying out normal cell functions

2. Spend a small amount of time in mitosis

3. Cycle back and forth between interphase and mitosis

C. Purposes of Cellular Reproduction1. Growth

2. Development

3. Repair

4. New organisms (species survival)

II. TWO TYPES OF CELL REPRODUCTION

A. ASEXUAL REPRODUCTION: Basic Facts

1. One “parent”

2. Requires division of the nucleus by mitosis

3. Advantagesa. Rapidb. Efficientc. Does not depend on outside forces to help

4. 4 Types of

Asexual Reproduction

a. Vegetative

– new plant is produced from existing plant organs or parts of

organs

b. Binary Fission

– (prokaryotes) cell divides into 2separate, genetically identical cells

c. Budding

– (yeast) cell or groups of cells pinchoff from the parent and form a new individual

Budding in Hydra

d. Regeneration

– replacement or regrowth of body parts

Regeneration

B. Sexual Reproduction

1. Involving 2 parents

2. Advantage - Greater genetic variation due to genetic recombination

3. Produces offspring that are genetically differentfrom each other and their parents.

4. A species with genetically diverse offspring is more likely to adapt and survive to changes in the environment

5. Occurs through Meiosis

a. Occurs only in the reproductive cells

b. The process separates the DNA so there is only one of eachpair of chromosomes (1/2 of the DNA) in a cell

c. Gametes* 4 gametes are formed

* Each gamete is haploid – has one copy of each chromosome (half the number of chromosomes of every other cell in the body)

*. Haploid: One of each chromosome

a. The process of one male (sperm) gamete and one female (egg) gamete coming together

b. Zygote: Cell formed when two gametes come together

c. Diploid: Has two copies of every chromosome◦ Will undergo mitosis to develop into a mature organism

Diploid (2N): Two of each chromosome

Gametes: Sex cells

Makes 4 unique haploid daughtercells

Puberty

Nucleus of ovary or testes

Sexual reproduction to make unique offspring.

a. Crossing over occurs when pieces of chromosome pairs exchange genetic information

b. Crossing over is important because it creates offspring that are genetically unique.

1a. Diploid Cell

1b. DNA doubles

2. Chromosomes match up

3. Crossing over occurs

4a. Cell divides into two haploid cells

4b. Cell divides again into four haploid cells

Passing traits to offspring

A. The process of meiosis, special cell division, creates haploid (4) sex cells, gametes, so that only half of a parent’s DNA gets passed to the child.

B. Two gametes combine through fertilization, creating offspring with two sets of chromosomes. One set is from Mom, the other set is from dad.

C. Traits (physical features) are inherited as pieces of DNA

1. Gene: piece of DNA that codes for a trait.◦ Example: Gene for hair color

2. Allele: version of a gene

a. Dominant Allele: Masks recessive allele. * Symbol is capitol letter. * Example “R” is the allele for brown hair

b. Recessive Allele: Masked by dominant allele.* Symbol is lower case letter* Example: “r” is the allele for blonde hair

1. Diploid (body) cells have two alleles for each gene

There are three genotypes:

a. Homozogous dominant: Two dominant alleles. Shows dominanttrait

b. Heterozygous: One dominant and one recessive allele. Showsdominant trait

c. Homozogous recessive: Two recessive alleles. Shows recessivetrait

a. Genotype: Gene makeup (alleles)

TT Tt tt

b. Phenotype: Appearance (photo)

Example: Gene for brown hair (B) dominant over the gene for blonde hair (b)

1. Homozygous dominant Genotype:

BB Phenotype:

Brown hair

2. Heterozygous Genotype:

Bb Phenotype:

Brown hair

3. Homozygous recessive Genotype:

bb Phenotype:

Blonde hair

Shows the possible combinations of alleles from both parents as a result of meiosis and then fertilization

What would the daughter cells look like if the parent was Rr?

( R R r r)

What would the daughter cells look like if the parent was Rr?

( R R r r)

1. Determine parent genotypes

2. Arrange parent alleles on outside of the Punnett Square

Example: RR x rr?

1. Determine parent genotypes

2. Arrange parent alleles on outside of the Punnett Square

R R

r

r

Example: RR x rr?

1. Determine parent genotypes

2. Arrange parent alleles on outside of the Punnett Square

3. Use the alleles on the outside to make allele combinations on the inside of the square.

4. Each square represents a possiblecombination of alleles

R R

r

r

Example: RR x rr?

Rr

Rr

Rr

Rr

RR X rr

r

r

R R

r

r

R R

Rr

r

r

R R

Rr Rr

r

r

R R

Rr Rr

Rr

r

r

R R

Rr Rr

Rr Rr

r

r

R R

Rr Rr

Rr Rr

Probability = # Purple/Total

Fraction = = 4/4

Ratio = = 100%

Probability = # White/Total

Fraction = = 0/4

Ratio = = 0%

Rr X Rr

R

rR

r

R

r

RR

R

r

R

r

RR Rr

R

r

R

r

RR Rr

R

Rr

r

R

r

RR Rr

R

Rr rr

r

R

r

RR Rr

R

Rr rr

r

Phenotype Possibilities for purple or white

Probability = # Purple/TotalRatio

=3/4Percentage

=75%

Probability = # White/TotalRatio

=1/4Percentage

=25%

Rr X rr

r

rR

r

r

r

Rr

R

r

r

r

Rr rr

R

r

r

r

Rr rr

R

Rr

r

r

r

Rr Rr

R

rr rr

r

r

r

Rr Rr

R

rr rr

r

Phenotype Possibilities for purple or white

Probability = # Purple/TotalRatio

=1/2 (2/4 )Percentage

=50%

Probability = # White/TotalRatio

=1/2Percentage

=50%