Chapter 9 Powerpoint Flashcards
show continuous variation
Quantitative traits
Large range of phenotypes
Quantitative traits
Height, weight, and intelligence
Quantitative traits
variation due to both genetic and environmental differences
Quantitative traits
adding all of the values for a trait in the population and dividing by the number of individuals in the population
Mean
a measure of how much variability there is in the population
Variance
Traits influenced by many genes
Polygenic traits
include quantitative traits, with continuous variation
Polygenic traits
Interaction of multiple genes with multiple alleles
Polygenic traits
human eye color is an example of
polygenic traits
continuous variation may result form _______ effects
Environmental
Most traits that show continuous variation are influenced by _____ and the ______.
Genes
Environment
a heterozygote expresses an intermediate, “blended” phenotype
Incomplete dominance
RR
Red Flowers
rr
White flowers
Rr
Pink flowers
shows incomplete dominance
Sickle cell allele
Mutates oxygen carrying hemoglobin molecules in red blood cells
Sickle cell disease
Requires two copies of mutant allele
sickle cell disease
Causes painful sickling attacks and organ damage
sickle cell disease
Heterozygous carriers produce some mutant hemoglobin (sickle cell)
true
In low ______, sickle cell disease symptoms may occur.
oxygen
the heterozygote’s phenotype is a combination of two fully expressed traits
co-dominance
_____ pairs of human chromosomes
23
____ pairs of autosomes (non-sex chromosomes)
22
____ pair of sex chromosomes
1
who has 2 X chromosomes
Women
who has 1 X and 1 Y chromosome
Men
Sperm cells with an X or Y determine the ______ _____ of human offspring.
genetic sex
____ gene on Y chromosome leads to testes development
SRY
more common in either males or females
Sex-linked trait
Some traits due to genes on the sex chromosomes
Sex-linked trait
located on the X chromosome
X-linked
______ only have one copy of X-linked genes.
Males
More likely to be affected by recessive alleles on X chromosome
Males
______ are less likely to express X-linkage
Females
Must carry two defective X chromosomes
females
_______traits-only males have Y chromosomes, so a y-linked mutated gene can only be passed from father to son
Y-linked
Y-linked mutated gene can only be passed from father to son.
True
