genetic diversity Flashcards
what is a mutation
a random change in the DNA that alters the sequence of bases.
what 3 things is DNA code
it is degenerate so more than one codon can codon for the same amino acid. it is universal so the same codon triple always code for the same amino acid. it is non overlapping so each base is only part of one codon.
what is meiosis
is nuclear cell division that results in 4 daughter cells what have half the DNA of the original organism.
what type of cells does meiosis produce
haploid cells
stages of meiosis
prophase 1, metaphase1, anaphase 1, telophase 1, cytokinesis, prophase 2, metaphase2, anaphase 2, telophase 2, cytokinesis.
what happens in prophase 1
the DNA condenses. 2 chromatids joined at centromere. they are arranged in homologous pairs. crossing over may occur. nuclear envelop breaks down.
what happens in metaphase 1
they line up along the equator of the cell. spindle fibres attach. independent assortment. means the proportion of paternal and maternal chromosomes that end up on each side is due to chance.
what happens in anaphase 1
the spindle fibres pull them to opposite ends of the cell. centromeres do not divide
what happens in telophase 1
chromosomes arrive at opposite poles. spindle fibres break down. nuclear envelope form around the 2 groups of chromosomes.
what is cytokinesis
division of the cytoplasm. cleavage furrow. 2 haploid cells.
what is prophase 2
nuclear envelope breaks down and chromosomes condense.
what is metaphase 2
spindle fibres attach and they line up along the equator of the cell.
what is anaphase 2
chromatids pull to opposite poles. 4 groups of chromosomes.
what is telophase 2
nuclear envelope forma around each group of chromosomes.
what is cytokinesis
cytoplasm divides creating 4 haploid cells