Transcript Sexual reproduction

Asexual Reproduction:
 Creation of genetically
identical offspring from
one parent
Binary Fission:
 A single celled
organism splits into 2
equal parts
 Occurs in prokaryotes
only (bacteria, yeast, &
some algae)
parent cell
DNA
duplicates
cell begins
to divide
daughter
cells
Mitosis: (Eukaryotes)
 Budding: small
Hydra
projections grow on
surface of parent and
forms new organism.
bud
Yeast
Mitosis cont: (Eukaryotes)
 Vegetative
Propagation:
stem of parent grows
into a new organism
Fragmentation : parent
splits into pieces that can
each grown into a new
organism
Advantages to species:
(to reproduce asexually)
 Doesn’t rely on outside forces( ex: pollen relies on
water and wind)
 Rapid
 More efficient (successful)
Disadvantages to species:
(to reproduce asexually)
 All organisms respond same way to environment b/c
they are just alike
 Organisms may lack the ability to adapt in order to
survive changing conditions
(Ex: I Am Legend)
ASEXUAL REPRODUCTION
SEXUAL REPRODUCTION
Requires one parent
Requires 2 parents
Mostly in prokaryotes
Mostly in eukaryotes
Offspring are identical to parent
Offspring are different than parent
C. Sexual Reproduction
1. Sexual reproduction is the fusion of 2 gametes that
results in offspring that are a genetic mixture of both
parents.
2. Fertilization is the fusion of egg and sperm.
l
A. Types of Cells in Your Body:
1.
2.
3.
4.
Somatic cells: body cells (make up body tissues and
organs)
Germ cells: cells in your reproductive organs that
make gametes (in ovaries and testes)
Gametes: sex cells (female: eggs or ova///males:
sperm)
Gametes have DNA that is passed to offspring
Egg
Cell
Somatic cell: (muscle)
Sperm cells
B. Chromosomes
1.
2.
3.
4.
5.
6.
Every species has a certain number of chromosomes per cell
(the number is not related to complexity).
Your body cells have 23 pairs of chromosomes.
Chromosome pairs 1-22 are autosomes.
Pair #23 is sex chromosomes, X and Y, that determine
gender in mammals.
Homologous chromosomes are 2 chromosomes, 1 from
Mom and 1 from Dad, that have the same length and
appearance.
Scientists have arranged the 23 homologous pairs from
largest to smallest.
D. Diploid and Haploid Cells
1. Diploid cells are your body cells.



2 copies of each chromosome (1 from Mom and 1 from Dad)
2n
Human Diploid # is 46.
2. Haploid cells are the gametes (egg and sperm)
 1 copy of every chromosome
 1n
 Haploid number for humans is 23.
 Gametes have 22 autosomes and 1 sex
chromosome.
E. Meiosis
Meiosis is the formation of gametes.
Meiosis reduces chromosome number and creates genetic
diversity.
3. It divides diploid cells into haploid cells.
4. Gametogenesis is the production of gametes.
5. Spermatogenesis is the formation of sperm.
1.
2.



Sperm is much smaller than eggs.
4 are produced each division.
Produced from puberty until death
6. Oogenesis is the formation of eggs. (ova)

1 egg and 3 polar bodies are produced during each division.

All eggs are present at birth.
F. MEIOSIS vs MITOSIS
MEIOSIS
1.
2.
3.
4.
5.
Meiosis is the formation
of gametes.
Form of sexual
reproduction.
Produces 4 haploid cells
(23 chromosomes).
Produces genetically
unique cells
Occurs only at certain times
of an organism’s life cycle
MITOSIS
1.
2.
3.
4.
5.
1. Mitosis is the
formation of body cells.
Form of asexual
reproduction.
Produces 2 diploid cells (46
chromosomes)
Produces genetically
identical cells
Takes place throughout life
Mendel
&
Heredity
A. Basics of Genetics
1. GENETICS: the study of heredity
2. HEREDITY: passing of traits from parents to
offspring.
3. Traits: inherited characteristics
4. Gregor Mendel:



Father of Genetics
He worked with pea plants to see how traits were passed
from one generation to the next.
Mendels Conclusions:

Traits inherited as discrete units.

Law of Segregation: Organisms inherit 2 copies of each
gene, but donate only one copy to each gamete.
Mendel controlled the
fertilization of his pea plants
by removing the male parts,
or stamens.
He then fertilized the female
part, or pistil, with pollen from
a different pea plant.
B. Traits, Genes, & Alleles
A gene is a specific region of DNA that codes for a
particular protein.
2. The same gene can have many different versions.
3. Alleles are different forms of a gene.
1.



Ex-yellow or green , round or wrinkled
Your cells have 2 sets of alleles for each trait (1 from each
parent)
Alleles are represented by letters. (AA, Aa, aa)
4. Types of alleles:
 Homozygous (pure): alleles are the same (AA or aa)
 Heterozygous (hybrid): alleles are different (Aa)
4. Types of Alleles:
*Homozygous:
 Alleles are the same
(AA or aa)
**Alleles are different.
(Aa)
5. Genes influence the development of
traits.
 A genome is all of an
organism’s genetic material.
 A genotype is the genetic
makeup of an organism.
(Represented by AA, Aa,
or aa)
 A phenotype is the physical
appearance of an organism.
(wrinkled or smooth)
 A dominant allele is the
allele that is always expressed
if present.
 Always represented by a
capital letter.
 A recessive allele is the allele
that’s only expressed when 2
copies are present.
 Always represented by a
lowercase letter.
 Both homozygous dominant
(AA) and heterozygous (Aa)
genotypes yield a dominant
phenotype