Genetics 133 Exam 2 with
100% correct answers 2025
Melanocortin 1 Receptor (MC1R) - answer A control point for the pigment
melanin for hair
What causes red hair? - answer Mutation on MC1R receptor.
Normal MSH levels but can't activate melanocytes.
What happens when MC1R is stimulated? - answer Produces eumelanin
(brown)
What happens when MC1R is mutated? - answer Produces pheomelanin
(blonde)
Pleiotropic means? - answer A gene that influences 2 or more seemingly
unrelated traits
What determines eye color? - answer Several genes including HERC2 and
OCA2, mutations in EITHER cause blue eyes
What are the two types of mutation? - answer Spontaneous and induced
What is a spontaneous mutation? - answer Mutation that occurs as a
result of natural biological and/or chemical processes (DNA replication,
recombination, repair, cellular metabolism)
What is semi-conservative? - answer Refers to DNA replication where a
new copy of DNA has one old strand and one new strand
Types of spontaneous mutations? - answer SNP (single nucleotide
change), Indel (insertion/deletion), Copy number variation
, Copy Number Variation - answer sections of the genome are repeated
and the number of repeats in the genome varies between individuals in
the human population
What is an example of CNV? - answer Huntington's disease
What mutation can occur from a spontaneous mutation during cellular
metabolism? - answer Reactive oxygen species can form during oxidative
phosphorylation (unstable molecules can easily react with other molecules
in a cell and can damage RNA, DNA, etc)
What is an induced mutation? - answer A mutation that results from the
influence of extraneous factors; the result of either natural or artificial
agents (radiation, chemicals)
What are examples of induced mutations? - answer Thymine dimers
prevent base pairing, x-rays, radiation
What is a germ? - answer A gamete (sperm or egg)
What is a germline cell? - answer A cell that when fully developed is a
sperm/egg cell. The only kind of cell that can pass on mutations to
offspring
What happens when somatic cells mutate during development? - answer
Cause changes in portions of the body. I.e. white patch of hair
What is a de novo mutation? - answer an alteration in a gene that is
present for the first time in one family member as a result of a mutation in
a germ cell (egg or sperm) of one of the parents or in the fertilized egg
itself
What is a harmful mutation? - answer A mutation that decreases the
chances of an organisms survival and reproduction. Less common that
expected. 1 every 600 hours, 1% lethal.
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