Lesson 4

cell division

process in which cells reproduce, a parent cell divides into 2 daughter cells

mitosis

division of somatic/body cells

meiosis

division of gametes/sperm and egg/sex cells

chromosomes

an organized package of DNA in the nucleus

chromatid

one of the longitudinal subunit of a replicated chromosome

prophase

nuclear envelop disintegrates, chromosomes condense, and mitotic spindle attach to the chromosomes

metaphase

chromosomes align at the equatorial plate

anaphase

cohesion at the centromere disappear and sister chromatids separate

telophase

chromatids reach the poles, nucleolus reappears

nuclear envelope forms, and cytokinesis follow

mito = somatic/body cells

meio = gametes/sperm and egg/sex cells

occurences in mitosis and meiosis

mito = maintained (2n)

meio = halved, to the haploid number (n)

number of chromosomes after division

mito = 1

meio = 2 (meiosis 1 and 2)

major stages in mitosis and meiosis

mito = no

meio = yes

synapsis and crossing over in mitosis and meiosis

mito = sister chromatids

meio = homologous chromosomes (anaphase 1) and sister chromatids (anaphase 2)

what separates during anaphase in mitosis and meiosis

mito = 2

meio = 4

number of daughter cells in mitosis and meiosis

synapsis

pairing of homologous chromosomes

crossing over

exchange of chromosomal materials between homologous chromosomes

homologous chromosomes

chromosomes with the same genetic

meiosis

number of chromosomes of parent cell: 2n = 4

trisomy and monosomy

changes in chromosome number

2n + 1

chromosomes in trisomy

2n - 1

chromosomes in monosomy

13 / Patau’s syndrome

18 / Edward’s syndrome

21 / Down syndrome

examples of trisomy

Monosomy X (Turner’s syndrome)

example of monosomy