Genetics Exam - Mutations & Detection
Methods: Questions and Answers
Genetic mutations: CORRECT ANSWERS -Permanent alterations and DNA
sequence
-produce new forms of alleles
Gain vs. Loss of function Mutations: CORRECT ANSWERS -gain: dominant disorders
since new function will be expressed
-loss: seen in recessive disorders or haploinsufficient heterozygotes
NOTE: recessive disorders in general are NOT well preserved in populations
Spontaneous vs. Induced mutations CORRECT ANSWERS Spontaneous mutations-
occur during DNA replication
Induced mutations-
Mutagens: radiation or chemical
Types of mutagens: CORRECT ANSWERS Radiation: ionizing & non-ionizing. first
reported in 1920s
Chemical: base analogs & intercalating agents.
Non-ionizing vs. ionizing radiation: CORRECT ANSWERS Ionizing: formation of
electrically charged ions/free radicals (I.e. XRay & nuclear fallout!!!!!!). Usually causes
damage via water free radicals (OH), which interact with DNA, proteins, lipids in cell
membranes
Non-ionizing: does NOT form charged ions but CAN move electrons from inner to outer
orbits within an atom , causing atom to become chemically unstable (I.e. UV radiation)
Base analogs vs. Intercalating agents as chemical mutagens: CORRECT ANSWERS
Base analogs: substitute DNA bases with another base
Intercalating agents: will physically insert themselves between existing bases
When was mutagenic action of a chemical first reported? CORRECT ANSWERS
1942 w mustard gas from WW1 & WW2
, How does UV radiation act as a mutagen? CORRECT ANSWERS It causes formation
of covalent bonds between adjacent pyramidine bases
These PYRIMIDINE DIMERS are unable to pair properly with purines during DNA
replication
Results in base pair substitution
**UV radiation is absorbed by the epidermis so it does not reach the germ line cells but
can cause SKIN CANCER!!!!!!
Mutation repair mechanisms: CORRECT ANSWERS -Damage reversal: simplest;
enzymes restore structure without breaking backbone
-Damage removal: involves cutting out and replacing a damaged or innaproproaye
base/nucleotide section
-Damage tolerance: not truly repair!!!! But way of coping with damage so life can go on
Where do mutations most frequently occur? CORRECT ANSWERS Most mutations
are happening in somatic cells:
•cancer-consequence of somatic mutation,
•aging-accumulation of somatic mutations over time
Germ line mutation & common associated disease: CORRECT ANSWERS Germ line
cells are the only mutations genetic consequence to the next generation so that it
stands a chance of being inherited
Cystic fibrosis occurs in sperm or egg and is passed down
4 possible scenarios where mutation may arise: CORRECT ANSWERS 1. Single
germ line cell
2. Somatic cells
3. Some germ line, some somatic
4. ALL cells (germ & somatic)
Mosaicism: CORRECT ANSWERS -existence of two or more genetically different cell
lines in an individual
-Occurs in one cell of the developing embryo
All descendants that have the same mutation, resulting in mosaicism
DNA vs. Chromosomal mutations: CORRECT ANSWERS -single base pair mutations:
not microscopically observable, mutations take place in coding DNA or regulatory
sequences
-alterations in number or structure of chromosomes in a cell: observable microscopically
Methods: Questions and Answers
Genetic mutations: CORRECT ANSWERS -Permanent alterations and DNA
sequence
-produce new forms of alleles
Gain vs. Loss of function Mutations: CORRECT ANSWERS -gain: dominant disorders
since new function will be expressed
-loss: seen in recessive disorders or haploinsufficient heterozygotes
NOTE: recessive disorders in general are NOT well preserved in populations
Spontaneous vs. Induced mutations CORRECT ANSWERS Spontaneous mutations-
occur during DNA replication
Induced mutations-
Mutagens: radiation or chemical
Types of mutagens: CORRECT ANSWERS Radiation: ionizing & non-ionizing. first
reported in 1920s
Chemical: base analogs & intercalating agents.
Non-ionizing vs. ionizing radiation: CORRECT ANSWERS Ionizing: formation of
electrically charged ions/free radicals (I.e. XRay & nuclear fallout!!!!!!). Usually causes
damage via water free radicals (OH), which interact with DNA, proteins, lipids in cell
membranes
Non-ionizing: does NOT form charged ions but CAN move electrons from inner to outer
orbits within an atom , causing atom to become chemically unstable (I.e. UV radiation)
Base analogs vs. Intercalating agents as chemical mutagens: CORRECT ANSWERS
Base analogs: substitute DNA bases with another base
Intercalating agents: will physically insert themselves between existing bases
When was mutagenic action of a chemical first reported? CORRECT ANSWERS
1942 w mustard gas from WW1 & WW2
, How does UV radiation act as a mutagen? CORRECT ANSWERS It causes formation
of covalent bonds between adjacent pyramidine bases
These PYRIMIDINE DIMERS are unable to pair properly with purines during DNA
replication
Results in base pair substitution
**UV radiation is absorbed by the epidermis so it does not reach the germ line cells but
can cause SKIN CANCER!!!!!!
Mutation repair mechanisms: CORRECT ANSWERS -Damage reversal: simplest;
enzymes restore structure without breaking backbone
-Damage removal: involves cutting out and replacing a damaged or innaproproaye
base/nucleotide section
-Damage tolerance: not truly repair!!!! But way of coping with damage so life can go on
Where do mutations most frequently occur? CORRECT ANSWERS Most mutations
are happening in somatic cells:
•cancer-consequence of somatic mutation,
•aging-accumulation of somatic mutations over time
Germ line mutation & common associated disease: CORRECT ANSWERS Germ line
cells are the only mutations genetic consequence to the next generation so that it
stands a chance of being inherited
Cystic fibrosis occurs in sperm or egg and is passed down
4 possible scenarios where mutation may arise: CORRECT ANSWERS 1. Single
germ line cell
2. Somatic cells
3. Some germ line, some somatic
4. ALL cells (germ & somatic)
Mosaicism: CORRECT ANSWERS -existence of two or more genetically different cell
lines in an individual
-Occurs in one cell of the developing embryo
All descendants that have the same mutation, resulting in mosaicism
DNA vs. Chromosomal mutations: CORRECT ANSWERS -single base pair mutations:
not microscopically observable, mutations take place in coding DNA or regulatory
sequences
-alterations in number or structure of chromosomes in a cell: observable microscopically
