Sexual reproduction Flashcards
Two processes involved in sexual reproduction
meiosis
fertilisation
What happens in a haplontic life cycle
the mature organism is haploid and the zygote is the only diploid stage
What happens in alternation of generation life cycle
organisms passes through haploid and diploid stages that are both multicellular
What happens in a diplontic life cycle
the organism is diploid and the gametes are the only haploid stage
SRY
Sex determining Region Y
What induces male development
gene on the Y chromosome that encodes for a transcription factor
What drives male development
induces expression of the Sox9 transcription factor
Disadvantages of sexual reproduction
- need to maintain molecular machinery of SR
- need mating partner
- decreased reproduction capacity
Benefits of sexual reproduction
- high genetic variability
- brings together advantageous alleles
- paired chromosomes allow deleterious mutations to be masked
Benefits of sexual reproduction
- high genetic variability
- brings together advantageous alleles
- paired chromosomes allow deleterious mutations to be masked
What does crossing over lead to
recombinant chromatids containing mix of DNA from both homologues
What does crossing over increase
genetic variation of the gametes
What is crossing over
during first phase of meiosis
- when homologous chromosomes are aligned, chromosomes frequently exchange parts of their DNA
Consequences of cross-over
- incomplete linkage of genes
( alleles on chromo not always inherited together)
What does incomplete linkage of genes on the same chromosome leads to
results in offspring with recombinant phenotype
