Lesson 10: Mutations Flashcards
what are mutations
errors in genes and DNA
are mutations only harmful
no they can be neutral, harmful, and even beneficial
what are mutations caused by
chemicals, environmental factors, radiation, etc.
what triggers mutations to start, what is it caused by and WHAT TYPES OF MUTATIONS ARE THERE
it is mainly random
- spontaneous mutations happen in nature by accident
- induced mutations are a result of exposure to a physical or chemical agent
- for instanvce, UV light, etc.
types of mutations- point mutations and chromosome mutations
point mutations: failure by the replicating cell to copy the genetic information accurately
what could point mutations be a result of?
- base-pair substitution
- base-pair insertion
- base-pair deletion
chromosome mutations
involve a mutation involving an entire chromosome or large part of it
example of chromosome mutation and what does it result in
non disjunction is an example of a chromosome mutation that can happen in meiosis- it may result in genetic disorders if it happens in gametogenesis or early in development during mitosis
where does most mutations occur?
in parts of DNA that do NOT code for genes
do mutations that occur in somatic cells affect future generations
no
do mutations that occur in the formation of gametes (sex cells) affect future generations? whats an example
yes
- CFTR cystic fibrosis transmembrane regulatory, which is an allele that causes cystic fibrosis
lactose intolerance, what is it
a trait in which an individual is not able to digest lactose which is the common sugar in milk
what is lactose intolerance caused by
a deficiency of the enzyme lactase which breaks down lactose
what happens if individuals who are lactose intolerant consume lactose
the undigested lactose will be metabolized by the intestinal bacteria which can cause bloating, cramping, and diarrhea
how come 75% of human adults are lactose intolerant?
- adults never consumed milk in human history
- when babies are born, they are lactose tolerant as they need to digest their mother’s milk
- when they grow, they may lose their ability to produce the enzyme to digest dairy products
how are non lactose intolerant adults able to digest lactose
due to genetic mutations that inherited this gene
sickle cell anemia, what is it (base pair… )
a mutation which is caused by a single nitrogenous base substitution- single adenine base is substituted by a thymine
what happens to blood cells when someone has sickle cell anemia
it causes red blood cells to not be healthy and lose its round shape- instead, they turn c-shaped and less effective at moving oxygen around the body through blood
what parasite/disease allows for having sickle cell to be beneficial? hows that?
Malaria
- when the parasite enters a red blood cell of an individual with SCA, it causes the oxygen levels in the cell to drop and it becomes sickle shaped
- because the infected red blood cell is no longer doing its job, its removed and destroyed by the body along with the parasite (which obviously kills it)
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process of base excision repair
where one enzyme snips out the damaged base and the other enzymes come in to trim around the site and replace the nucleotides
how does UV light damage DNA
UV light can cause two nucleotides to stick together, which distorts the DNA’s double helix shape
what kind of repair does UV light damage require? what is the process
nucleotide excision repair, when a team of proteins removes a long strand of 24 or so nucleotides, and replaces them with fresh ones
high radiation such as gamma rays and x rays severs what of the DNA?
one or both strands of the DNA backbone
what repair do we use for double stranded breaks in DNA
homologous recombination or non-homologous end joining
describe and explain homologous recombination
it uses an undamaged section of similar DNA as a template- enzymes interlace the damaged and undamaged strands, get them to exchange sequences of nucleotides, and fill in the missing gaps to end up with two complete double stranded segments
describe and explain non-homologous end joining
a series of proteins trims off a few nucleotides and then fuses the broken ends back together
how is non-homologous end joining inaccurate sometimes?
it can cause genes to get mixed up or moved around a lot
