Module 6: Monohybrid Inheritance Flashcards
What is a gene?
a sequence of bases on a DNA molecule that codes for a protein which results in a characteristic
What is an allele?
different versions of the same gene that codes for variants of a characteristic
What is a locus?
the specific position of a gene on a chromosome
What is meant by homozygous and heterozygous?
homozygous-when an organism has two identical alleles for a trait
heterozygous-when an organism has two different alleles for a trait
Humans are diploid organisms , meaning what?
they almost always have two copies of each gene , so they have two alleles for every characteristic
Gamete cells are haploid , meaning what?
they contain one allele per gene
Monohybrid inheritance involves …
What does a monohybrid cross track?
transmission of one gene from parents to their offspring
the inheritance pattern of the alleles for a single characteristic , controlled by one gene with two possible alleles
Co-dominance occurs when …
2 points
two different alleles are equally expressed in an organisms phenotype
-both alleles share equal dominance meaning both are visible in the organisms observable features
What does multiple alleles refer to?
Make a however point for this concept
genes that exist in more than two allelic forms
an individual can only ever have two alleles of a specific gene at any one time
What does the existence of multiple alleles increase?
the phenotypic diversity among individuals in a population
What is a common example of multiple alleles?
What is this system controlled by?
the ABO blood group system
the immunoglobulin (I) gene
Make 2 points about the ABO blood group system
the alleles IA and IB are co-dominant , as they are both expressed when inherited together , the IO gene is recessive
the potential blood group phenotypes are determined by the combo of I gene alleles inherited
Female body cells have two of which chromosome?
Therefore … female gametes contain what chromosome?
the X chromsome
How do male body cells differ from female body cells?
What does this feature mean in terms of male gametes?
they have one X and one Y chromosome
their gametes may contain either an X or a Y chromosome
Genes located on the X or Y chromosomes are termed what type of gene?
Which chromosome carries the majority of these genes and why?
sex linked genes
the X chromosome due to its larger size
Explain why recessive alleles on the X chromosome appear in the phenotype more often in males than females
because there is no corresponding allele on the Y chromosome to mask the recessive allele
