exam 4 part 2 Flashcards
anagenesis
evolution within a lineage over time
cladogenesis
splitting of one lineage into two
what is used to evaluate evolutionary divergence
DNA sequences
paralogs
homologous sequences found in the same species and arrive through gene duplication
orthologs
homologous sequences found in different species
highest mutation rates are observed where?
regions of the genome that have the least effect on function
- the more substitutions the less it effects
outgroup
an OTU that is known to have diverged earlier than all the others
terminal node
the last node in the branch that doesn’t have any child nodes
internal nodes
any node that has atleast 1 child node
cancer is — but rarely —
genetic, heritable
G1/S checkpoint
monitors for proper cell size and undamaged DNA
G2/M checkpoint
holds up cycle until replication and DNA repair are complete
M checkpoint
proper spindle formation and attachment
tumor
distinct mass of abnormal cells that do not have normal controls on cell division
benign
abnormal cells remain localized and do not invade surrounding tissue
malignant
cancer cells invade surrounding tissue
metastic
cancer cells spread and establish secondary tumors in other sites in the body
genetic causes of cancer
- mutations in somatic cells
- single defective gene
- polygenic (more that one defective gene)
- chromosome aberration
- viruses
environmental influences on cancer can …
cause mutations and alter gene expression
most cancers are …
sporadic and influenced by the environment
cancers develop …
over time
mutations leading to cancer usually result from
errors in replication
tumor suppressor gene function
prevent bad cells from dividing
proto-oncogenes
allow good cells to divide
- must be activated to be regulated properly
to lose cell cycle regulation what must happen
must disrupt both copies of the gene
- recessive action
knudson two hit hypothesis
both copies have to be defective in same cell to allow tumor to develop
tumor suppressor genes
- RB
- p53
- BRCA1
RB suppressor gene
Knudson two hit hypothesis
- normal protein responsible for regulating G1/S checkpoint
BRCA1/2 suppressor gene
causes breast cancer
- normally used to repair double strand breaks
p53 suppressor gene
functions at G1 checkpoint
- if p53 isnt working right, cell division occurs even through DNA is damaged
difference in proto-oncogenes and tumor suppressor genes
proto-oncogene only need mutation in 1 copy (dominant) while tumor suppressor needs both (recessive)
oncogenes
normal function: transcription factor
abnormal function causes reciprocal translocation leading to cancer
retroviruses can cause cancer by
- causing mutations and rearrangement of proto-oncogenes
- insert a strong promoter near proto-oncogenes
telomere length affect on cancer
telomeres usually shorten as a cell ages, but in cancer cells there is more telomerase expression causing “immortality”
angiogenesis
growth of new blood vessels
