[3.7] Genetics, Populations, Evolution & Ecosystem Flashcards
1
Q
What is meant by the term genotype?
A
- Genetic constitution of an organism.
2
Q
What is meant by the term phenotype?
A
- The expression of the genetic constitution (genotype) of an organism and its interaction with the environment.
3
Q
What are alleles and how do they arise?
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- Variations of a particular gene (same locus) -> arise by mutation (changes in DNA base sequence).
4
Q
How many alleles of a gene can be found in diploid organisms?
A
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2 as diploid organisms have 2 sets of chromosomes (chromosomes are found in homologous pairs).
- But there may be many (more than 2) alelles of a single gene in a population.
5
Q
Describe the different types of alleles.
A
DOMINANY ALLELE
- Always expressed (shown in the phenotype).
RECESSIVE ALLELE
- Only expressed when 2 copies present (homozygous recessive) / NOT expressed when dominant allele present (heterozygous).
CODOMINANT ALLELES
- Both alleles expressed / contribute to phenotype (if inherited together).
6
Q
What is meant by the terms homozygous and heterozygous?
A
HOMOZYGOUS
- Alleles at a specific locus (on each homologous chromosome) are the same.
HETEROZYGOUS
- Alleles at a specific locus (on each homologous chromosome) are different.
7
Q
What do monohybrid and dihybrid crosses show?
A
MONOHYBRID CROSS
- Inheritance of one phenotypic characteristic coded for by a single gene.
DIHYBRID CROSS
- Inheritance of two phenotypic characteristics coded for by two different genes.
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