Biology 1001A Lecture Notes - Lecture 7: Cosmic Ray, Prophase, Meiosis
7 May 2018
School
Department
Course
Professor
Lecture 08 - Recombination
- draw out how replication/repair errors give rise to SNPs (we already drew out how tautomeric errors
give rise to SNPs)
- DNA pol. Cannot distinguish between thymine and 5-bromouracil b/c they are analogues, but 5-
bromouracil is very mutagenic (very tautomericallly unstable calls for the wrong base)
- Smallest CNV (in/del mutations) one or a few base pairs are missing (or there are extra bps) in a
certain spot. Video: Striesinger Model. Replication slippage can happen in new strand or template (in
new strand slippage adds in an extra bp, while slippage on the old strand ends up losing a bp in the
template strand) Smallest kind of CNV is slippage which could lead deletion or insertion
deostates ho DNA epliatio is a ehais of diffeee / it a e a utagei poess.
- Most radiation is in the natural environment (but we have evolved mechanisms to counteract the
problems)
- Ionization Radiation creates ROS that damages DNA (When exposed to radiation, the water in our
bodies lose electrons and oxygen wants it back so it rips electrons from important proteins in our
bodies)
- Decay of radioactive iodine and esiu eates ioizig adiatio hih a lead to doule staded
breaks can create rearrangements (during NHEJ, the cramming of chromosome ends, can lead to
deletion leading to loss of genes) cosmic radiation breaks in DNA chromosomes put back together
deletion (CNV), duplication (CNV), inversion, translocation
- Burkitt Lymphoma: translocation deregulates a cancer gene Translocation can move a cancer
gee….
Unequal recombination can generate CNVs - Normal crossing-over happens when homologous
chromosomes (chromosomes with same gene sequence that may differ in alleles) pair up (not
tasloatio just sappig oe esio of hoosoe 3 fo the othe - this does not create CNVs)
Unequal recombination - he hoosoes do’t pai itiatel and properly, this can give rise to
CNVs because it can lead to chromosomes with duplication or deletion of genes. (This is a reason why
some people have more copies of genes or less copies of genes on a certain chromosome)
Hox gene family: Duplication and divergence: Vertebrates have a lot of copies of the Hox genes. (How is
this a result of evolution? mutations that lead to CNVs accumulate over time because they provide a
selective advantage)
Over evolutionary time, mutations have allowed us to become as complex as we are (mutations are a
source of variation)
The sexual part of sexual reproduction has to do with sexual recombination. ou ol eist to ig
ou paet’s geeti ifo. ito lose poiit
Homologous chromosomes - same size, shape, similar staining patterns
In meiosis 1 Chromosome number is reduced from diploid to haploid
find more resources at oneclass.com
find more resources at oneclass.com
