bio chap 19 cell division

chromosomes

rod shaped structures made up of DNA that carry genetic information

homologous chromosome pairs

two chromosomes, one paternal one maternal, contain similar gene sequence

genes

segments of DNA that give your cells instructions for specific traits or body functions

karyotype

organized size order display of an individual’s chromosomes; used to identify abnormalities/genetic disorders

female karyotype

44 autosomes and XX

male karyotype

44 autosomes and XY

cell cycle S phase

DNA synthesis and replication of DNA

mitosis and meiosis

types of cell division

mitosis

produces two identical daughter cells for growth and repair; genetically identical

meiosis

produces four genetically unique daughter cells (gametes) for sexual reproduction; reduces chromosome number to half 

prophase (mitosis)

chromosomes shorten and thicken; duplicated chromosomes are held together at the centromere

metaphase (mitosis)

duplicated chromosomes line up at the center of the cell

anaphase (mitosis)

each chromosome separates from its attached duplicate and moves to the opposite poles of the cell

telophase (mitosis)

chromosomes complete their move to the opposite poles of the cell

cytokinesis

physical process of cell division that divides the cytoplasm of a parental cell into two daughter cells

prophase 1 (meiosis)

chromosomes shorten and thicken; homologous chromosomes align closely~synapse and undergo crossing over (exchanging genes)

end of telophase 1 and cytokinesis (meiosis)

two daughter cells are produces, each with one half the number of chromosomes of the original parent (23)

end of meiosis

four daughter cells are produced each with half the number of chromosomes (haploid; 23; genetically different)

spermatogenesis

production of sperm in the testis

oogenesis

production of eggs (ova) in the ovaries

zygote

fertilization of sperm and egg

down syndrome

extra 21st chromosome

klinefelter syndrome

47 chromosomes; XXY

turner syndrome

45 chromosomes; X0 (44X)

XXX females

poly X; 47 chromosomes; tall stature, small head

jacobs syndrome

XXY

Y only embryo

dies early during development

cri du chat

chromosome 5p deletion syndrome

X-inactivation or lyonization

in females, one of the two X chromosomes is randomly inactivated; ensures that females, like males, have one functional copy of the X chromosome in each body cell