BIO 117 Final Exam Review: BIO 117 Final Exam Review Notes
What is a gene? - ANSWER:A segment of DNA that codes for protein. Today we know that individuals of a
species share certain traits because their chromosomes carry the same genes
Who indirectly discovered the role of alleles in inheritance by carefully breeding pea plants and tracking
traits of their offspring? - ANSWER:Gregor Mendel
What did Gregor Mendel breed? - ANSWER:Pea plants
What is a locus? - ANSWER:The location of a gene on a chromosome
What is an allele? - ANSWER:Form of a gene with slightly different DNA sequences; may encode slightly
different versions of a gene's product (The protein is the same, but slightly different. There are different
versions of genes, so there are different versions of proteins)
What is a genotype? - ANSWER:A genotype is the particular set of alleles that is carried by an individual's
chromosomes
How are body cells and sex cells different genotypically? - ANSWER:Body cells are diploid, so they have
two of every gene. Sex cells are haploid so they have one of every gene
What is a phenotype? - ANSWER:A phenotype is an individual's obervable traits
Different alleles come about from mutations. If we did not have mutations we would not have
_________. - ANSWER:Evolution
Why do you not have alleles for some genes? - ANSWER:Some proteins have such a specific function that
any changes would cause an individual to die (Alleles are different versions of a gene that produce
different versions of proteins)
What is meant by homozygous? - ANSWER:It means you have identical alleles for a gene
What is meant by heterozygous? - ANSWER:It means you have two different alleles of a gene
When we say that an individual is homozygous or heterozygous, we are discussing its _________. -
ANSWER:Genotype (the particular set of alleles it carries)
What does it meant for an allele to be dominant? - ANSWER:Refers to an allele that masks the effect of a
recessive allele paired with it in heterozygous individuals. The allele that gets expressed. Since it is
expressed, you get the trait
What does it meant for an allele to be recessive? - ANSWER:Refers to an allele with an effect that is
masked by a dominant allele
What is codominance? - ANSWER:Effect in which the full and separate phenotypic effects of two alleles
are apparent in heterozygous individuals (BOTH SHOW)
, What is an example of codominance? - ANSWER:ABO Blood type. The A and the B allele are codominant
when paired. If your genotype is AB, then you have both versions of the enzyme and your blood type is
AB.
What is incomplete dominance? - ANSWER:Effect in which one allele is not fully dominant over another,
so the heterozygous phenotype is an intermediate blend between the two homozygous phenotypes
(BLEND)
What is an example of incomplete dominance? - ANSWER:Pink roses are often the result of incomplete
dominance. When red roses, which contain the dominant red allele, are mated with white roses, which is
recessive, the offspring will be heterozygous and will express a pink phenotype
What is pleiotropy? - ANSWER:Effect in which a single gene affects multiple traits
What genetic disorders are caused by mutations in single genes? - ANSWER:Sickle cell anemia, cystic
fibrosis and Marfan syndrome. Marfan syndrome is the result of mutations that affect fibrillin. Long
fibers of this protein impart elasticity to tissues of the heart, skin, blood vessels, tendons and other
parts. Mutations can cause tissues to form with defective fibrillin or none at all
What is epistasis? - ANSWER:Polygenic inheritance in which a trait is influenced by multiple genes
What is an example of epistasis? - ANSWER:Coat color in labs, which depends on pigments called
melanins, is an example of a trait affected by multiple genes. Eye color is another example.
How does nature affect phenotypes? - ANSWER:Environmental cues initiate cell-signaling pathways that
trigger changes in gene expression. Some of these cell signaling pathways methylated or demethylate
particular regions of DNA, so they suppress or enhance gene expression in those regions.
What can DNA methylation be affected by? - ANSWER:DNA methylation patterns can be permanently
and heritable affected by diet, stress, and exercise and also exposure to drugs and toxins such as
tobacco, alcohol, arsenic and asbestos
How does nature affect coat color? - ANSWER:Seasonal changes in temperature and the length of day
affect the production of melanin and other pigments that color the skin and fur of many animals. These
species have different color phases in different seasons. Hormonal signals triggered by the seasonal
changes cause fur to be shed and new fur grows back with different types and amounts of pigment
deposited in it. The resulting change in phenotype provides these animals with seasonally appropriate
camouflage from predators
What is continuous variation? - ANSWER:Some traits occur in a small range of differences called
continuous variation. Continuous variation can be an outcome of epistasis (when multiple genes affect a
single trait). The more genes that influence a trait, the more continuous is it's variation. Traits that arise
from genes with a lot of alleles may also vary continuously.
What is short tandem repeat? - ANSWER:In chromosomal DNA, sequences of a few nucleotides repeated
multiple times in a row. These short tandem repeats can spontaneously expand or contract very quickly
compared with the typical rate of mutation and the resulting changes in the gene's DNA sequence may
be preserved as alleles
What is a gene? - ANSWER:A segment of DNA that codes for protein. Today we know that individuals of a
species share certain traits because their chromosomes carry the same genes
Who indirectly discovered the role of alleles in inheritance by carefully breeding pea plants and tracking
traits of their offspring? - ANSWER:Gregor Mendel
What did Gregor Mendel breed? - ANSWER:Pea plants
What is a locus? - ANSWER:The location of a gene on a chromosome
What is an allele? - ANSWER:Form of a gene with slightly different DNA sequences; may encode slightly
different versions of a gene's product (The protein is the same, but slightly different. There are different
versions of genes, so there are different versions of proteins)
What is a genotype? - ANSWER:A genotype is the particular set of alleles that is carried by an individual's
chromosomes
How are body cells and sex cells different genotypically? - ANSWER:Body cells are diploid, so they have
two of every gene. Sex cells are haploid so they have one of every gene
What is a phenotype? - ANSWER:A phenotype is an individual's obervable traits
Different alleles come about from mutations. If we did not have mutations we would not have
_________. - ANSWER:Evolution
Why do you not have alleles for some genes? - ANSWER:Some proteins have such a specific function that
any changes would cause an individual to die (Alleles are different versions of a gene that produce
different versions of proteins)
What is meant by homozygous? - ANSWER:It means you have identical alleles for a gene
What is meant by heterozygous? - ANSWER:It means you have two different alleles of a gene
When we say that an individual is homozygous or heterozygous, we are discussing its _________. -
ANSWER:Genotype (the particular set of alleles it carries)
What does it meant for an allele to be dominant? - ANSWER:Refers to an allele that masks the effect of a
recessive allele paired with it in heterozygous individuals. The allele that gets expressed. Since it is
expressed, you get the trait
What does it meant for an allele to be recessive? - ANSWER:Refers to an allele with an effect that is
masked by a dominant allele
What is codominance? - ANSWER:Effect in which the full and separate phenotypic effects of two alleles
are apparent in heterozygous individuals (BOTH SHOW)
, What is an example of codominance? - ANSWER:ABO Blood type. The A and the B allele are codominant
when paired. If your genotype is AB, then you have both versions of the enzyme and your blood type is
AB.
What is incomplete dominance? - ANSWER:Effect in which one allele is not fully dominant over another,
so the heterozygous phenotype is an intermediate blend between the two homozygous phenotypes
(BLEND)
What is an example of incomplete dominance? - ANSWER:Pink roses are often the result of incomplete
dominance. When red roses, which contain the dominant red allele, are mated with white roses, which is
recessive, the offspring will be heterozygous and will express a pink phenotype
What is pleiotropy? - ANSWER:Effect in which a single gene affects multiple traits
What genetic disorders are caused by mutations in single genes? - ANSWER:Sickle cell anemia, cystic
fibrosis and Marfan syndrome. Marfan syndrome is the result of mutations that affect fibrillin. Long
fibers of this protein impart elasticity to tissues of the heart, skin, blood vessels, tendons and other
parts. Mutations can cause tissues to form with defective fibrillin or none at all
What is epistasis? - ANSWER:Polygenic inheritance in which a trait is influenced by multiple genes
What is an example of epistasis? - ANSWER:Coat color in labs, which depends on pigments called
melanins, is an example of a trait affected by multiple genes. Eye color is another example.
How does nature affect phenotypes? - ANSWER:Environmental cues initiate cell-signaling pathways that
trigger changes in gene expression. Some of these cell signaling pathways methylated or demethylate
particular regions of DNA, so they suppress or enhance gene expression in those regions.
What can DNA methylation be affected by? - ANSWER:DNA methylation patterns can be permanently
and heritable affected by diet, stress, and exercise and also exposure to drugs and toxins such as
tobacco, alcohol, arsenic and asbestos
How does nature affect coat color? - ANSWER:Seasonal changes in temperature and the length of day
affect the production of melanin and other pigments that color the skin and fur of many animals. These
species have different color phases in different seasons. Hormonal signals triggered by the seasonal
changes cause fur to be shed and new fur grows back with different types and amounts of pigment
deposited in it. The resulting change in phenotype provides these animals with seasonally appropriate
camouflage from predators
What is continuous variation? - ANSWER:Some traits occur in a small range of differences called
continuous variation. Continuous variation can be an outcome of epistasis (when multiple genes affect a
single trait). The more genes that influence a trait, the more continuous is it's variation. Traits that arise
from genes with a lot of alleles may also vary continuously.
What is short tandem repeat? - ANSWER:In chromosomal DNA, sequences of a few nucleotides repeated
multiple times in a row. These short tandem repeats can spontaneously expand or contract very quickly
compared with the typical rate of mutation and the resulting changes in the gene's DNA sequence may
be preserved as alleles
