week 3 - blood types and genes Flashcards
biological male
individuals having the capacity/biological equipment to make small, mobile gametes: sperm
biological female
individuals having the capacity/biological equipment to make large immobile gametes: eggs
male heterogamety
when a male organism produces two different types of sex gametes
female heterogamety
female produces two different sex chromosomes and male has two copies of the same chromosomes
are all sex linked traits in the x chromosome?
yes
what is a pedigree?
a chart that diagrams the inheritance of a trait or health condition through generations of a family
-shows up in the phenotype
-also helps us determine the alleles that individuals will carry and the likelihood that the offspring of two individuals will exhibit a particular trait
how many sex chromosomes do we have?
one copy each of their sex chromosomes
-two copies of every chromosome in every cell (autosomal)
heredity
the passing of characteristics from parents to offspring through their genes
single gene traits
traits that are determined by the instructions a person carries on one gene
-ex. fur length or coat color in cats because some traits are determined by the instruction that an organism carries on one gene
true breeding
when parents always produce offspring with the same variant of the trait as the parents
segregation
you have two copies of each gene but each sperm or egg you produce has just one copy
key to understanding dominant and recessive traits
a dominant trait masks the effect of a recessive trait when an individual carries both the dominant and the recessive versions of the instructions for the trait
broken down law of segregation
- one of two alleles for a gene is passed to a gamete. at fertilization, offspring receive one allele from each parent that codes for one gene
- rather than passing on the trait itself, each parent puts into every sperm or egg it makes a single set of instructions for building the trait (called a gene)
- offspring receive two copies of the instructions for any trait
- trait observed in an individual depends on the two copies of the gene it inherits from its parents
- same two alleles inherited = homozygous genotype
- different two alleles inherited = heterozygous genotype
- dominant and recessive alleles are defined by their action when they are in the heterozygous state
phenotype
outward appearance and behavior of an individual
(ex. pigmentation, eye color)
genotype
an organisms genetic composition (in reference to a particular trait)
-also used as a way of referring to all of the genes an individual carries
sex linked traits
traits that are controlled by genes on the sex chromosomes
-recessive sex linked traits appear more frequently in males, and dominant sex linked traits appear more frequently in females
how do you exhibit dominant traits?
all affected individuals must have at least one parent who exhibits the trait
how can a recessive trait be exhibited?
may exhibit a recessive trait even if neither parent shows the trait
-individuals parents must be heterozygous for that trait
-unaffected parents can also have offspring with the disorder as a recessive trait
genome
an organisms entire set of DNA
-
when trait is autosomal dominant
- trait cannot skip generations
- shaded individuals are heterozygous dominant or homozygous dominant
-unshaded individuals are homozygous recessive
when trait is autosomal recessive
-shaded individuals are homozygous recessive
- unshaded individuals must be heterozygous
- can skip generations
when trait is x linked dominant
affected daughters come from affected fathers
when trait it x linked recessive
- if the female has it, that means that all of her sons will have it
- affected daughters come from affected fathers
- can skip generations
- males only need one copy to show the trait
example of a pedigree
