genetic information (meiosis) Flashcards
what are gametes?
sex cells- sperm or egg
what is a zygote?
diploid cell resulting from the fusion of 2 gametes in fertilisation
what type of cells are diploid?
normal body cells
what is a diploid cell?
cell containing two complete sets of chromosomes
what type of cells are haploid?
gametes
what is a haploid cell?
contains a single set of chromosomes
how are gametes formed?
by meiosis
where does meiosis occur?
in the reproductive organs
what is produced in meiosis?
4 haploid cells (gametes) that are genetically different from eachother
what happens in meiosis 1?
prophase 1:
DNA replication
homologous chromosomes pair
DNA crosses over
metaphase 1:
chromosomes align on the cell equator
anaphase 1:
chromosome pairs separate
telophase 1:
nuclear envelopes reform
what happens in meiosis 2?
prophase 2:
chromosomes move towards the cell equator
metaphase 2:
line up on the equator
microtubules attach
anaphase 2:
chromosomes pull apart at the centromere
telophase 2:
new cell membranes and gametes form
what type of reproduction is mitosis/meiosis?
mitosis= asexual meiosis= sexual
is there variation in mitosis/meiosis?
mitosis= no variation meiosis= variation
when does crossing over occur?
meiosis 1
how does crossing over lead to genetic variation?
each of the daughter cells contains chromatids with different alleles
how does independent segregation lead to genetic variation?
when homologous pairs are separated, it’s random which chromosome from each pair ends up in each daughter cell
daughter cells have different combinations of maternal and paternal chromosomes
what are chromosome mutations caused by?
when errors occur in meiosis, cells produced contain variations in the number of chromosomes/parts of chromosomes
