Week 12: Sex & DNA Structure Flashcards
Which mode of reproduction contributes more of an individual’s genes to the next generation?
A. Cloning
B. Sex (reproduction via 2 gametes)
A. Cloning
what is Binary Fission
Binary fission is a method of asexual reproduction commonly found in unicellular organisms, such as bacteria and some protists.
In binary fission, a single parent cell divides into two daughter cells, each of which is genetically identical to the parent cell
what is budding (asexual reproduction)
Budding is a form of asexual reproduction commonly observed in certain organisms, where a new individual develops from an outgrowth or bud on the parent organism.
This process results in the formation of a genetically identical offspring, or clone, of the parent.
Occurs in yeast and some animals (like the hydra below).
what is Fragmentation (asexual reproduction)
Fragmentation is a method of asexual reproduction where an organism breaks into fragments, and each fragment has the potential to develop into a new, genetically identical individual.
Occurs in many plants, as well as some animals (like coral, sponges, and starfish).
what is Parthenogenesis (asexual reproduction)
Parthenogenesis is a form of asexual reproduction in which offspring develop from unfertilized eggs
In this process, females can produce offspring without the involvement of males or fertilization
Occurs in invertebrates, as well as in some fish, amphibians, and reptiles.
what is Sexual Reproduction (brief explanation)
Each parent contributes a gamete
a gamete is a sex cell that has half of the normal DNA of a regular body cell
In males, the gametes are sperm
in females, the gametes are eggs
When these two gamete combine during fertilization, the result is a zygote, which then continues to develop into an embryo.
which is the original form of reproduction:
a) sexual reproduction
b) asexual reproduction
b) asexual reproduction
which form of reproduction produces a population at a faster rate
Asexual populations grow at double the rate of sexual populations
what are the cons of sexual reproduction
- In a sexual population, half the individuals cannot technically reproduce – the males!
- All offspring inherit only 50% of each parent’s DNA.
what organism is commonly found as a self- fertilizing hermaphrodite (both male and female).
Caenorhabditis elegans
can Caenorhabditis elegans (nematode(roundworm)) have both sexual and asexual reproduction
yes
sexual reproduction occurs through “outcross”
what does “Outcrossing “in the context of Caenorhabditis elegans (a nematode (roundworm)) mean
Outcrossing in the context of Caenorhabditis elegans, a nematode (roundworm), refers to the mating of individuals from different genetic backgrounds or strains.
Why Have Sex?
genetic diversity
Genetic diversity leads to phenotypic diversity, or a range of traits
The world is unpredictable, and diversity is a form of insurance – a range of phenotypes provides opportunities for at least some individuals to succeed under new regimes of natural selection.
Natural selection – and other events – can reduce genetic diversity, and sexual reproduction increases genetic diversity again more quickly than asexual reproduction.
Sex May Have Evolved Primarily Because of Pathogens. why?
Pathogens: diseases – parasitic viruses, bacteria, fungi that infect other cells or organisms to take advantage of them.
Threatened with infection by more than a dozen species of trematode worms, sexually reproducing P. antipodarum snails are the most successful in generating resistant offspring.
Asexual clones may start to rise in frequency, but the parasites quickly evolve to infect these increasingly common genotypes, thereby driving them down in frequency once again.
The “Arms Race” or Red Queen Hypothesis
The “Red Queen Hypothesis” is an evolutionary concept that describes the continuous adaptation and coevolution of organisms in response to each other’s adaptations, emphasizing the idea of an ongoing “arms race” between species.
