Genetic Variation
Questions:
IN ____
The Law of Segregation
•Mendel’s _______________________________
•The 2 alleles of each gene pair separate into
different _______________________________
(egg or sperm) during meiosis.
The Law of Independent Assortment
•Mendel’s _______________________________
•Genes that are inherited _________________Do NOT influence the inheritance of others
•Alleles segregate independently during meiosis
•Some _______________________________ go to one gamete and some to another
INCOMPLETE DOMINANCE
Genes are neither dominant nor recessive= _________________________!!!
Genotype is heterozygous (_________________________--Hh)
Phenotype is between two parents
Dominant gene _____________________________________________the recessive
Ex: white flower x red flower = pink flowers
CODOMINANCE
•
•
•
•
•
•Offspring shows phenotype of _________________________ parent
•Both alleles are _________________________!!!
•Ex: black chicken x white chicken = checkered chicken
MULTIPLE ALLELES
•_______________ OR _____________ alleles control a trait
•You still will only have two of these alleles.
•Ex: height, hair color, eye color and blood type
–There are 3 different alleles for blood:
–IA (_________________________) = IA IA or IA i
– B
I
(_________________________) = IB IB or IB I
–I IB (_________________________) = IA IB
–IO (_________________________) = ii
Sex-Linked Alleles
A
•Controlled by genes located on
_________________________ (XX or XY)
•Usually carried on _________________________
•Since females are XX, they are usually _________________________ of the trait
•Since males are XY, they have a higher tendency for inheritance of trait
•If trait is X-linked, MALES:
–pass it to: _________________________
–none to: _________________________
•If trait is X-linked, MOTHERS:
–have _________________________chance of passing it to all of their children
•Ex: colorblindness, hemophilia, male pattern baldness
Mutations
•Any mistake or ______________________ in the DNA
sequence (doesn’t always mean bad)
Point mutation:
•Change in one nitrogen base in DNA
•Ex: albinism
Questions:
CHROMOSOMAL MUTATIONS
•Changes in chromosome structure
1) INVERSION:
•the order of genes on a chromosome is inverted
2) TRANSLOCATION:
• the movement of a chromosome fragment
to a nonhomologus chromosome
3) DELETION
•Loss of a few bases
•Loss of large regions of a chromosome
4) DUPLICATION
•Duplication of a few bases
•Duplication of large regions of a chromosome
Crossing Over
•Occurs when chromosomes
__________________________.
•2 chromosomes overlap.
•Some genes cross over and switch places
NONDISJUNCTION
•chromosome pair ___________________________________ properly
during meiosis
Monosomy:
•gamete has _____________________ chromosome than it should
•______________ chromosomes is the result
•Ex: Turner syndrome--Missing a sex chromosome
Trisomy:
•Gamete has _____________________ chromosome than it should
•Result is ______ chromosomes
•Ex: Down’s Syndrome--Extra #21 chromosome
Logan Warren Ultrasound
Summary:
Methods of Detection
Chorion villi sampling:
• Take sample of the chorion
(________________________________________)
• Chemical tests and ___________________________
performed
Ultrasound:
•_____________________________ are used to generate an image of the unborn child.
•Used to detect abnormalities of limbs, organs, etc.
Amniocentesis:
• __________________________surrounding the fetus is drawn out by needle
• ___________________________________ are collected and grown in a lab.
• Chromosomes can be then Karyotyped