Lab 6 Flashcards
autosomes
the remaining non-sex chromosomes in the nucleus
karyotype
a photograph of the chromosomes of an actively dividing cell, showing the number, shape and size of the chromosomes
Only having 1 x-chromosome and phenotypes
Turners syndrome
-short arms and neck
-cant reproduce and mensurate
-kidney problems
-swelling of hands + feet
Having 3 chromosome 21’s and phenotypes
down syndrome
-developmental delay
-small ears
-flattened face
Having 2 X-chromosomes and 1 Y-chromosome and phenotypes
Klinefelter’s syndrome
thick hair
small testes
large breasts
Genes located on the X-chromosome
sex-linked genes
Who is more likely to have a sex-linked disease and why
males because they only have one X-chromosomes
What are heterozygous sex linked traits called
carriers
protan deficiency
caused by reduced numbers or a complete absence of red photoreceptors in the eye, which means they can’t see red or its very dark for them
deutan deficiency
caused by reduced numbered or a complete absence of green photoreceptors meaning they can’t see green or it’s very dark to them
who do sex-linked recessive traits effect more
males
who does sex-linked dominant traits effect more
females
Parents of affected individuals of autosomal recessive traits
parents are unaffected
parents for affected individuals of autosomal dominant traits
have at least one affected parent
Huntington’s disease
disease that causes degeneration of brain cells resulting in deterioration of physical and mental abilities
Is this autosomal or sex-linked
Dominant or recessive
Autosomal
Dominant
polygenic traits and examples
phenotypic traits that involve contributions from the alleles of many genes at multiple locations an don sperate chromosomes
height
skin colour
the crossover frequency between two linked genes is proportional to
the distance between them
if genes are close together what is the probability of crossing over and how many recombinant genes would result
low probability of crossover
low number of recombinant genes
how to calculate percent recombination
total # of recombinants
——————————- x100
total # of offspring
which parents gamete determine the sex of offspring in humans
male (y-chromosome)
individuals that have only one X-chromosome have a condition called ______ syndrome. Are they phenotypically male or female?
Turners
female
In traits in Mendelian fashion, are dominant phenotypes always the most common in a population
no
Example of a sex-linked trait
hemophilia
