Meiosis Flashcards
diploid
cell contains 23 pairs of chromosomes- 46 in total
haploid
cell contains 23 single chromosomes (half the genetic information needed)
zygote
the cell made when a sperm cell fertilises an egg cell in sexual reproduction
mitosis
cell division to produce genetically identical cells
describe the make up of chromosomes in a sperm cell
1 chromosomes from each pair in the male
describe the make up of chromosomes in the egg cell
1 chromosome from each pair in the female
what type of cells are made in mitosis?
body cells
what type of cells are made in meiosis?
sex cells
where does mitosis take place in a human?
everywhere in the body
where does meiosis take place in a human?
reproductive organs (testies and ovaries)
are the daughter cells genetically identical or genetically different in mitosis?
identical
are the daughter cells genetically identical or genetically different in meiosis?
different
how many divisions take place in mitosis?
1
how many divisions take place in meiosis?
2
how many daughter cells are produced in mitosis?
2
how many daughter cells are produced in meiosis?
4
give two similarities between mitosis and meiosis?
-DNA replicates before process starts
-stages are PMAT for both
give two differences between mitosis and meiosis
-number of cells
-mitosis is diploid and meiosis haploid
how does sexual reproduction lead to variation?
-mutation can occur
-it is random when gametes fuse
-meiosis creates variation
-
meiosis
cell division to produce gametes(sex cells)
how does meiosis create variation?
-random as to which sides of the cell chromosome/chromatid is facing
-crossing over between chromatids can occur (alleles are swapped between them)
what are the phases of meiosis I?
-prophase I
-metaphase I
-anaphase I
-telophase I
describe meiosis I
division I- diploid to haploid (DNA already replicated in S phase of cell cycle)
describe prophase I
-nucleus envelope breaks down
-chromosomes condense
describe metaphase I
-chromosomes line up in pairs on the equator of the cell
-spindle fibres attach to centromere
describe anaphase I
chromosomes are pulled to opposite sides
describe telophase I
-nucleus reforms
-cytoplasm starts to split
-23 chromosomes in each cell (they are now haploid)
cytonkinesis
splitting of cytoplasm
what are the phases of meiosis II?
-prophase II
-metaphase II
-anaphase II
-telophase II
describe meiosis II
division 2- splits copies of the chromosomes
describe prophase II
-nuclear envelope breaks down
-chromosomes condense
describe metaphase II
chromosomes line up on the equator
describe anaphase II
chromatids are pulled to opposite sides of the cell
describe telophase II
nuclear envelope reforms
