Processes that determine heredity and contribute to genetic variationMeiosis guarantees that in a sexual life cycle, offspring w
ill inherit one complete set of chromosomes (and their associated genes and traits) from each parent. The transmission of traits from parents to offspring is called heredity.Another important aspect of meiosis and the sexual life cycle is the role these processes play in contributing to genetic variation. Although offspring often resemble their parents, they are genetically different from both of their parents and from one another. The degree of variation may be tremendous.The following processes are associated with meiosis and the sexual life cycle:-DNA replication before meiosis-crossing over-chromosome alignment in metaphase I and separation in anaphase I-chromosome alignment in metaphase II and separation in anaphase II-fertilizationSort each process into the appropriate bin according to whether it contributes to heredity only, genetic variation only, or both. (Note that a bin may be left empty.)
BOTH: all fertilization
, metaphase 1→anaphase & 1 metaphase 2→anaphase 2 crossing over
DNA replication
In organisms that reproduce sexually, the processes of DNA replication, the precise pairing of homologs during crossing over, chromosome alignment and separation in meiosis I and II, and fertilization ensure that traits pass from one generation to the next
Unlike with asexual reproduction, offspring of sexual reproduction are genetically different from each other and from both of their parents. Mechanisms that contribute to genetic variation include:
Errors (mutations) that occur during DNA replication
. The production of recombinant chromosomes due to crossing over
. The independent assortment of homologous chromosomes in meiosis I
The separation of sister chromatids (which are no longer identical due to crossing over) in meiosis II
The random fusion of male and female gametes during fertilization
As a general rule, if you're in the Northern Hemisphere, look towards the southern skies to see the galactic core. This can be southeast (Spring), due south (Summer), or southwest (Fall) depending on the time of year. As mentioned above, Sagittarius is found nearest the galactic core.
