Life Cycles, Reproduction and...
Transcript of Life Cycles, Reproduction and...
Life Cycles, Reproduction
and Heredity
Reid Pierce
Fulbright Jr. High
Bentonville, AR
Reproduction
Bottom Line: An organism must
reproduce in order for that species to
continue.
How do they reproduce?
…I’m glad you asked
Reproduction
All living things are made of cells.
Cells divide in order to grow, replace
worn out/dead cells and reproduce
Inside each nucleus are chromosomes
(DNA)
DNA determines an organisms traits
(such as hair color, blood type, etc…),
and controls cell processes
Chromosomes
Organized structures of
DNA
The number of
chromosomes can vary
greatly between species.
Each organism gets half
of its chromosomes from
the male and half from
the female
Male sperm
carry 16
Female egg
cells carries 16
Alligators have 32 chromosomes
• 11 from the pistil (female) and 11 from
the stamen (male)
• 29 chromosomes from the
male and 29 from the
female
Beans have 22
Channel Catfish have 58!
Evening Primrose has 28
Violets have 50
White Campion have 22
King Crab have 208!
Porpoise have 44
But Shrimp have 254!!!
Mosquitoes only have 6!
How can they have the
same number of
chromosomes?!
Different genes located on
the chromosomes
Tiger Lily have 24
Tomatoes have
24
And humans have… 46
Does half yellow and half blue
make green?
Gregor Mendel, 1860:
Traits do not blend. Traits are shuffled.
Cell Division
Two types of cell division:
1. Mitosis - produces new body cells in order to
grow and replace worn out / damaged cells Skin cells, Muscle cells, Heart cells, etc…
Mitosis
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
Cell Division
Two types of cell division:
1. Mitosis - produces new body cells in order to
grow and replace worn out / damaged cells Skin cells, Muscle cells, Heart cells, etc…
2. Meiosis - produces new reproductive cells in
order for the organism to reproduce Sperm Cells, Egg cells
Meiosis
Reproduction
Two types of reproduction:
1. Asexual Reproduction – a type of reproduction
in which a genetically identical organism is
produced from one parent (Ex. body cells dividing
or potato buds forming)
Asexual Reproduction
In Plants
Extremely common in plants Vegetative Reproduction – tulip bulbs dividing
Budding – potatoes, yeast
Runners – strawberries
Potato bud will make a
new Potato plant.
Asexual Reproduction
In Animals
The primary form of reproduction in single cell
organisms (such as bacteria and
paramecium).
Binary Fission
Paramecium dividing
into two paramecium
Asexual Reproduction
In Animals
Other methods: Fragmentation – worms, starfish, etc… (some plants -
lichens)
Parthenogenesis – unfertilized egg develops
Asexual Reproduction
Advantages:
Very rapid population growth (everyone can
reproduce, don’t waste time finding a mate, etc…)
Requires less energy
Only one parent needed to continue or start a
colony of the species (an island)
Disadvantages:
Limits genetic diversity (species doesn’t change)
Reproduction
Two types of reproduction:
1. Asexual Reproduction – a type of reproduction
in which a genetically identical organism is
produced from one parent (Ex. body cells dividing
or potato buds forming)
2. Sexual Reproduction – the joining of a male
sperm cell and a female egg cell creating an
organism genetically different from the
parents
Sexual Reproduction
In Plants
Flowers!
Sperm cell is pollen that is produced by
and located on the anther (the male part of
the flower)
Egg is produced by and located
in the ovary (the female part of the flower)
Sexual Reproduction
In Animals
• Sperm cells: • the male reproductive cell
• has a head and a tail
• carries genetic information from the father
• Egg cells: • the female reproductive cell
• site of fertilization
• carries genetic information from the mother
Sexual Reproduction
Advantages:
Promotes genetic diversity (species can change
and adapt to their environment)
Disadvantages:
Slower population growth
Requires more energy
Male & female are needed to continue or start a
colony of the species
Asexual or Sexual?
Tulip bulbs dividing
Flowers being pollinated
Strawberries producing runners
Sperm cell fertilizing egg cell
How many chromosomes
do humans have? 46
-When the 23
chromosomes from the
female (contained in the egg)
join the 23 chromosomes
from male (contained in the
sperm) it is called a
zygote.
Vertebrate Development
In vertebrates there are 3 stages
of vertebrate development:
1. Zygote
2. Embryo
3. Fetus
Vertebrate Development
1st stage: Zygote – a fertilized egg.
Vertebrate Development
Once the egg has been fertilized (zygote) it has genetic information from the mother and father and it begins to divide to produce a multicellular organism.
Vertebrate Development
The result of the zygote dividing by mitosis is the 2nd stage – an embryo – a fertilized egg that has begun to divide – less than 4 days after fertilization.
Vertebrate Development
At about 9
weeks it enters
the 3rd stage
and is called a
fetus – major
structures have
formed – 9
weeks to birth.
Human fetus at 9 weeks