Biology unit 5

Genotype

The set of genes an organism has

Phenotype

The set of traits an organism expresses

What are the benefits of sexual reproduction

The offspring are more genetically diverse

Diploid

Having 2 sets of chromosomes (2n)

Haploid

Having a single set of chromosomes (1n)

Homologous chromosomes

Chromosomes similar in size and shape

Karyotype

A visual display of condensed chromosomes

Synapsis

When the homologous chromosomes line up gene for gene.

What is the exception to synapsis

Xy chromosomes which line up at their tips only.

When does synapsis occur

In prophase I, when the centromeres migrate.

Crossing over

Occurs during the synapsis. The maternal and paternal homologs cross at points called chiasma. Genetic material is exchanged between non sister chromatids.

Recombinant chromatids

Chromatids that have exchanged genetic info and now have a new combination of genes.

What separates during Anaphase I?

Homologous chromosome, but not sister chromatids.

What does meiosis I result in?

2 genetically different, haploid daughter cells.

What’s the difference between prometaphase I and II?

In PM I, the spindles attach to the kinetochore on both sides of each chromosome. In PM II, the spindles attach to the kinetochores on opposite sides of the chromosome.

What separates during meiosis II?

Sister chromatids

What does meiosis II end in?

4 genetically different, haploid daughter cells.

What happens when gametes fuse?

They become a diploid zygote.

Oocyte

The larger, haploid cell produced by females.

What happens as male daughter cells develop into sperm?

They lose cytoplasm and become smaller.

How does fertilization contribute to genetic diversity?

It pools together the genes of two unique individuals.