ch 9 case study Flashcards
How many copies of each chromosome are in a diploid cell
two copies
The exception to this are males who have one X and one Y chromosome
How many total chromosomes does a human cell have
46
How many homologous pairs of chromosomes
23 pairs
How many copies of each chromosome are in a gamete
one copy
A monohybrid cross
the hybrid of two individuals with homozygous genotypes which result in the opposite phenotype for a certain genetic trait.
individual’s phenotype
the combination of their observable characteristics or traits
or
the physical appearance or characteristic of an organism
An individual’s genotype
the combination of alleles that they possess for a specific gene.
or
is a set of genes in DNA responsible for unique traits or characteristics
X-linked inheritance :
that the gene causing the trait or the disorder is located on the X chromosome
. Females have two X chromosomes; males have one X and one Y.
Genes on the X chromosome can be recessive or dominant.
Their expression in females and males is not the same
How do the inheritance patterns differ
for genes on sex chromosomes (chromosomes X and Y) compared to genes located on autosomes, non-sex chromosomes (chromosomes numbers 1-22). This is due to the fact that, in general, females carry two X chromosomes (XX), while males carry one X and one Y chromosome (XY)
What are the sex chromosomes
the chromosomes that are responsible for sex determination. These chromosomes are the 23rd pair of chromosomes in human beings. These are called the X-chromosome and Y-chromosome, both are not the same as other chromosome pairs
What combination of the chromosomes determines if an individual is male? Female?
the egg receives another X chromosome from the sperm, the resulting individual is XX, forms ovaries, and is female; if the egg receives a Y chromosome from the sperm, the individual is XY, forms testes, and is male
the principle of codominance
two versions (alleles) of the same gene are expressed separately to yield different traits in an individua
How does it differ from incomplete dominance? What do the heterozygotes look like?
In complete dominance, there is no difference in phenotype between AA and Aa individuals. In incomplete dominance, the phenotype in a heterozygous individual is visibly less intense than that in an individual homozygous for the dominant allele, so that AA and Aa genotypes produce different phenotypes.
the principle of incomplete dominance
in which the distinct gene products from the two codominant alleles in a heterozygote blend to form a phenotype intermediate between those of the two homozygotes
What is the relationship between the alleles? What trait do you see in the heterozygote?intermediate phenotypes
the phenotype would be a mixture of both the parent’s genes
in genetics, there are three main dominance patterns: complete dominance (only one dominant allele appears in the phenotype), co-dominance (both alleles are visible in the phenotype), and incomplete dominance (a mix of alleles creates a new phenotype
