Transcript Asexual vs. Sexual Reproduction

Asexual vs. Sexual Reproduction
Please copy this chart in your notebook – use the WHOLE page.
Name
1. Binary Fission
2. Bacterial
Conjugation
3. Fragmentation
4. Budding
5. Pollination
6. Sexual
Reproduction
Type
(asexual
What
or
happens
sexual)
?
Organisms
that use
this type
+
Positives
Negatives
Asexual vs. Sexual
Reproduction
Reproduction & Development
Selective Forces
-- all of evolution is based on reproduction
-- to persist through evolutionary time,
animals must put copies of their genes into
the next generation
-- for sexual reproduction, fertilized egg
must develop into surviving offspring
Asexual reproduction
The primary form of reproduction for singlecelled organisms such as archaea, bacteria,
and protists.
Some plants and fungi may reproduce
asexually as well.
Reproduction
Asexual reproduction
-- only one parent
-- no reproductive organs
-- no gametes (sex cells) produced
-- no fertilization or zygote formation
-- offspring are genetically identical to
parents (clones)
Asexual Reproduction
Advantages
-
pass on 100% of genome to each offspring
all individuals can produce offspring directly
can occur rapidly
saves energy and resources (no gonads or
gametes, no finding mates, no courtship, no
STDs)
Asexual Reproduction
Disadvantages
-- no genetic variation in offspring
(except for random mutations)
-- limited ability to respond to changing
environment
Sexual Reproduction
Results in increasing genetic diversity of the
offspring.
Characterized by two processes:
meiosis, halving of the number of chromosomes
fertilization, combination of two gametes and the
restoration of the original number of chromosomes
During meiosis, chromosomes usually cross over =
genetic recombination.
Primary method of reproduction for the vast
majority of visible organisms, including almost all
animals and plants.
Sexual Reproduction
-- usually involves two parents
-- organisms have reproductive organs
-- haploid gametes produced by meiosis;
fertilization  diploid zygote
-- offspring are genetically unique
Sexual Reproduction
Advantages
-- increased genetic variability in offspring
-- ability to respond to changing environment
Sexual Reproduction
Disadvantages
-- pass only 50% of genome to each offspring
-- energy expended for gonads and gametes
-- is complicated; occurs more slowly
-- requires finding mates, courtship
-- STDs
Binary Fission
Asexual
Cell splits and
replicated DNA
goes with each
part
Prokaryotes,
Bacteria
+ Fast and easy
- Everybody has
the same DNA
Bacterial Conjugation
Asexual “Sex”
A bacteria shoots
out a tube and
sends a piece of its
DNA to another
bacteria
Bacteria
+ Mixes DNA
- “Parent” loses a
little piece of DNA
Fragmentation/ regeneration
Asexual
Body of parent
breaks and
produces
offspring
Fungi, moss, sea
stars, planarian
+ Easy
- Parent broken,
same DNA
Fragmentation/ regeneration
Moss
Budding
Asexual
Offspring grows out
of parent
Yeast, hydras
+ Fast, somewhat
easy
- Same DNA
Pollination
Sexual
Pollen is delivered to
female part of plant
Flowering plants
+ Plants don’t have to
move, mixes DNA
- Need external source
for pollination to take
place; wind, bee, bat,
butterfly etc.
Pollination
Sexual Reproduction
Sexual
DNA from 2 individuals
merge to form one
Animals, Plants
+ Diverse DNA
- Takes a long time, 2
individuals needed