MBG 2040 Molecular and Cellular
Biology midterm review 2024 new
exam University of Guelph
Why do we study genetics? Provide an example for each. - ---genetics plays a critical role in
understanding disease (i.e. in understanding cancer)
-genetics improves agricultural practices (we can manipulate crops so they are more resistant
to pests and drought)
-genetics used biotechnology industry for drug design, development, and production
(transcription factors are targets of drugs, so understanding genes helps us to make drugs that
are effective)
What is a gene? - --the fundamental unit of heredity- it is a genetic factor (region of DNA) that
helps determine a characteristic
What do genes come in? - --Multiple forms called alleles
What does genotype confer? (grant or bestow) - --phenotype
What is genetic information carried in? - --DNA
,Where are genes located? - --on chromosomes
How is genetic information transferred? - --from DNA, to RNA, to protein
What is an allele? - --One of two or more alternative forms of a gene
What is a locus? - --a specific place on a chromosome occupied by an allele
define genotype - --set of alleles possessed by an individual organism
define heterozygote - --an individual organism possessing two different alleles at a locus
define homozygote - --an individual organism possessing two of the same alleles at a locus
define phenotype/trait - --the appearance or manifestation of a character
Who discovered the basic principles of heredity? - --Gregor Mendel
What happens in a typical monohybrid cross? - ---Each parental homozygote produces one type
of gamete.
-the F1 heterozygotes produce two kinds of F1 gametes in equal proportions
-self-fertilization of the F1 heterozygotes yields tall and dwarf (in this example) offspring in a 3:1
ratio
,What happened in Mendel's dihybrid cross? - ---purpose of the pea experiment was to see if
the two seed traits are inherited independently
-crossed plants that produced yellow, round seeds with plants that produced green, wrinkled
seeds
-F1 seeds were all yellow and round- therefore these are the dominant traits
-self-fertilized F1 generation to yield F2 seeds that represented all possible combinations of the
colour and texture traits
-two classes resembled parental strain
-the other two showed new combinations of traits
-9:3:3:1 ratio- therefore each trait was controlled by a different gene segregating two alleles,
and the two genes were inherited independently
Describe example of a dihybrid cross - ---Each parental homozygote produces one kind of
gamete
-the F1 heterozygotes produce four kinds of gametes in equal proportions
-self-fertilization of the F1 heterozygotes yields four phenotypes in a 9:3:3:1 ratio
What are the pedigree symbols? - ---blank square: unaffected male
-coloured square: affected male
-blank circle: unaffected female
-coloured circle: affected female
-blank diamond: person who's sex is unknown
-square to circle with one line: mating
-square to circle with two lines: consanguineous marriage (inbreeding)
-vertical line from circle and square leading to shape: offspring (and generation line)
-line connecting siblings: sibship line
, -identical twins are two shapes from one line from parents
What is a pedigree assumption for rare and autosomal recessive traits? - ---individuals who
mate/marry into the pedigree are not carriers but are homozygous for the 'normal' allele
(unless there is evidence to the contrary)
What does a recessive mutation often involve? - --the loss of gene function
What happens when an allele is null or amorphic? Example? - ---a nonfunctional protein is
produced
-OR no protein is produced
-Tyrosinase gene
What happens when an allele is hypomorphic? Example? - ---a poorly functioning protein is
produced
-Or reduced amounts of a normally functioning protein is produced
-SCD
What is an example of an autosomal dominant trait? - ---Huntington disease
What do dominant mutations often involve? - ---gain/change of gene function
What does a dominant hypermorphic allele involve? - ---negative phenotypic consequences due
to the over-production of the normal protein OR
-negative phenotypic consequences due to the production of a protein with increased activity
levels
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