in meiosis, the nucleus divides to form 4 daughter nuclei. meiosis allows for differences in...
TRANSCRIPT
In meiosis, the nucleus divides to form 4 daughter nuclei.
Meiosis allows for differences in inherited characteristics.
Interphase similar to mitosis.chromosomes are replicated chromatidssubsequent phases differ
Prophase I
Members of homologous pair do not have identical DNAOne from each parent
Crossing overoccurs early in Prophase Igenetic recombinationan average of 1-3 “crossovers” per pair
Metaphase I
Pairs are not arranged maternal vs. paternal
independent assortment
Anaphase IIn humans, there are roughly 8 million possible combinations per gamete.When gametes fuse, that’s about 64 trillion combinations.
Meiosis II
CancerNeoplasms (tumors)
benign or malignantMalignancy (cancer)
fast growingnot encapsulatedcan metastasize
Loss of Cell Cycle Control
Growth factors (and their receptors)
Mechanisms (11.18-21)
Oncogenes1. may code for growth factors or their receptors
HER-2, ras called proto-oncogenes when they function normally
Loss of “Brakes”
Tumor suppressor genesp53
Carcinogenschemicalsradiation virusesare mutagens
Viruses and Cancer
Human Papilloma Virus (HPV)
Hepatitis
Herpes
Fig. 06.