Exam 2:
Genetics:
1. What is the difference between genetics and genomics?
Genetics is the study of inherited traits and their variation, examines a particular gene or a
small group of genes, focused picture (family and individual). Genomics is the study of
total genetic composition of an organism or species, it is a broad view
2. What is a gene? What is the most important thing a gene codes for?
Gene is the basic unit of heredity, consists of DNA, codes for specific protein leading to a
particular characteristic or function. Alteration in a protein = disease state
3. What is a wild-type allele? A disease-causing mutation? Polymorphism? Allelic variant
of unknown significance?
Wild-type- normal; disease causing, causes disease (altered or absent gene function);
polymorphism- alteration in normal gene (wild type) but function is normal/no disease;
unknown significance- alterations but unclear significance
4. Why is variability important?
Maintains robust population, too much homogeneity can weaken species because of
inability to adapt to new challenges. Autosomal recessive disorders are examples of no
variability.
5. What is penetrance? Consanguinity? Anticipation? Mosaicism?
Penetrance- proportion of individuals with a mutation that causes a particular disorder
who exhibit symptoms (affected) aka autosomal dominant
Consanguinity- Genetic relatedness, same ancestor aka incest
Anticipation- Tendency in certain genetic disorders for individuals in successive
generations to present at an earlier age or more severe manifestations. Expression of
trinucleotide repeat mutation.
Mosaicism- when single individual/tissue has two or more cell lines with different
genetic or chromosomal constitutions
6. What is deletion? Duplication? Inversion? Translocation? Mutation? What is
harmful what is not harmful?
, Deletion- absence of a segment of DNA (small as a base or big as one or more genes)
harmful; duplication- presence of an extra segment of DNA, redundant copies of genes
(usually harmless); inversion- segment of chromosome has inverted from end to end and
reinserted at same breakage site. If it’s balance, harmless, imbalanced, harmful.
Translocation- whole chromosome or segment becomes attached or interchanged with
another whole chromosome or segment. Balanced harmless, imbalanced harmful.
Mutation- any alteration in a gene from its natural state, can be harmful or harmless
7. What is Mendalian inheritance? What is the probability of passing on a genetic
disorder to an offspring given the type of inheritance? Include autosomal dominant,
autosomal recessive, and sex-linked.
Autosomal dominant- Trait or disorder in which the phenotype is expressed in those
who have inherited only one copy of a particular gene mutation (abnormal)
(heterozygotes), specifically refers to a gene on one of the 22 pairs of autosomes (non-
sex)
• Often seen in multiple generations
• Both parents equally likely to transmit and inherit disorder
• Children of an affected parent are equally like to inherit and transmit,
each offspring has a 50% chance of inheriting mutation
Autosomal recessive- requires the presence of 2 copies of a gene mutation at a
particular locus in order to express observable phenotype (non-sex)
• Seen in a single generation of a family
• Mother and fathers are equally likely to transmit or inherit the disorder
• Each offspring has a 50% chance of being a carrier or non-carrier
(both unaffected) if only one parent carries the mutation
• Each offspring has a 25% chance of inheriting mutation and being affected
when both parents have the autosomal recessive gene, 25% chance of being
a non-carrier, and 50% chance of being a carrier
• Each offspring has a 50% chance of being a carrier and 50% chance of
inheriting mutation and being affected if one parent is affected and the other is a
carrier.
Sex-linked Dominant- Dominant trait or disorder caused by mutation in a gene on the X
chromosome. Phenotype is expressed in heterozygous females and hemizygous males
(only have 1 x), affected males tend to have more severe phenotypes than females. Rare,
most offspring don’t survive.
• Via female: 50% affected (25% male, 25% female) and 50% unaffected
• Via male: 50% affected (all females) 50% unaffected (all males)
Sex-linked recessive- caused by mutation in a gene on the X chromosome. Phenotype is
expressed in homozygous females and hemizygous males (only have 1 x), carrier
females do not usually express the phenotype, only men. Male to male transmission does
not occur, affected males are always are related to each other through females.
8. What is mitochondrial inheritance?
Genetics:
1. What is the difference between genetics and genomics?
Genetics is the study of inherited traits and their variation, examines a particular gene or a
small group of genes, focused picture (family and individual). Genomics is the study of
total genetic composition of an organism or species, it is a broad view
2. What is a gene? What is the most important thing a gene codes for?
Gene is the basic unit of heredity, consists of DNA, codes for specific protein leading to a
particular characteristic or function. Alteration in a protein = disease state
3. What is a wild-type allele? A disease-causing mutation? Polymorphism? Allelic variant
of unknown significance?
Wild-type- normal; disease causing, causes disease (altered or absent gene function);
polymorphism- alteration in normal gene (wild type) but function is normal/no disease;
unknown significance- alterations but unclear significance
4. Why is variability important?
Maintains robust population, too much homogeneity can weaken species because of
inability to adapt to new challenges. Autosomal recessive disorders are examples of no
variability.
5. What is penetrance? Consanguinity? Anticipation? Mosaicism?
Penetrance- proportion of individuals with a mutation that causes a particular disorder
who exhibit symptoms (affected) aka autosomal dominant
Consanguinity- Genetic relatedness, same ancestor aka incest
Anticipation- Tendency in certain genetic disorders for individuals in successive
generations to present at an earlier age or more severe manifestations. Expression of
trinucleotide repeat mutation.
Mosaicism- when single individual/tissue has two or more cell lines with different
genetic or chromosomal constitutions
6. What is deletion? Duplication? Inversion? Translocation? Mutation? What is
harmful what is not harmful?
, Deletion- absence of a segment of DNA (small as a base or big as one or more genes)
harmful; duplication- presence of an extra segment of DNA, redundant copies of genes
(usually harmless); inversion- segment of chromosome has inverted from end to end and
reinserted at same breakage site. If it’s balance, harmless, imbalanced, harmful.
Translocation- whole chromosome or segment becomes attached or interchanged with
another whole chromosome or segment. Balanced harmless, imbalanced harmful.
Mutation- any alteration in a gene from its natural state, can be harmful or harmless
7. What is Mendalian inheritance? What is the probability of passing on a genetic
disorder to an offspring given the type of inheritance? Include autosomal dominant,
autosomal recessive, and sex-linked.
Autosomal dominant- Trait or disorder in which the phenotype is expressed in those
who have inherited only one copy of a particular gene mutation (abnormal)
(heterozygotes), specifically refers to a gene on one of the 22 pairs of autosomes (non-
sex)
• Often seen in multiple generations
• Both parents equally likely to transmit and inherit disorder
• Children of an affected parent are equally like to inherit and transmit,
each offspring has a 50% chance of inheriting mutation
Autosomal recessive- requires the presence of 2 copies of a gene mutation at a
particular locus in order to express observable phenotype (non-sex)
• Seen in a single generation of a family
• Mother and fathers are equally likely to transmit or inherit the disorder
• Each offspring has a 50% chance of being a carrier or non-carrier
(both unaffected) if only one parent carries the mutation
• Each offspring has a 25% chance of inheriting mutation and being affected
when both parents have the autosomal recessive gene, 25% chance of being
a non-carrier, and 50% chance of being a carrier
• Each offspring has a 50% chance of being a carrier and 50% chance of
inheriting mutation and being affected if one parent is affected and the other is a
carrier.
Sex-linked Dominant- Dominant trait or disorder caused by mutation in a gene on the X
chromosome. Phenotype is expressed in heterozygous females and hemizygous males
(only have 1 x), affected males tend to have more severe phenotypes than females. Rare,
most offspring don’t survive.
• Via female: 50% affected (25% male, 25% female) and 50% unaffected
• Via male: 50% affected (all females) 50% unaffected (all males)
Sex-linked recessive- caused by mutation in a gene on the X chromosome. Phenotype is
expressed in homozygous females and hemizygous males (only have 1 x), carrier
females do not usually express the phenotype, only men. Male to male transmission does
not occur, affected males are always are related to each other through females.
8. What is mitochondrial inheritance?
