Name: __________________________________________
Date: _____________
Chapter 11/14 Notes- Genetics
Chapter 11: Genetics
 All living things have a set of ___________________________inherited from its parent or parents
 ___________________________ – the study of heredity
 _______________________ – a specific characteristic, such as seed color
 Genes – chemical factors (DNA segments) that control traits. Usually code for proteins
 ___________________ – forms of a gene, like T (tall) or t (short)
Gregor Mendel
 Mendel was a monk in charge of the _________________________________________________
 Mendel had stocks of plants that produced only ____________, only ___________________, only green
seeds, and only yellow seeds
 He studied ___________________________ plants with different characteristics and studied the results
 The offspring (F1) of crosses between parents (P) with different traits are called ____________________
 All of the ______________________________________ had characteristic of only one parent (no blending)
 Each characteristic was controlled by 1 gene with two contrasting forms, called __________________
 Principle of _______________________ states that some alleles are dominant while others are recessive
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He then crossed F1 plants to produce _______________________
◦ Recessive traits ___________________________, roughly
_________had the recessive traits
◦ The two alleles of the F1 plant segregate from each other so
that a gamete only has ____________________ of the gene
◦ Each F1 plant ________________________ has either the
dominant or recessive (tall or short)
 Gregor Mendel concluded:
◦ ______________________________ is controlled by factors
passed from one generation to the next.
◦ Some alleles are dominant and others are recessive.
◦ _________________________________ - the alleles (separate) during the formation of gametes.
◦ Independent assortment - genes for different traits can segregate __________________________
during the formation of gametes.
Punnett Squares
 Punnett Squares – tool used to predict the _______________________________ of offspring with a certain trait
or genotype.
 Monohybrid cross – Punnett square with ____________________________________, 4 squares.
Genetic Terms
 Dominant – occurs in the ________________________________ if one allele is present, T
 ______________________________ – must be homozygous to occur in the phenotype
 _______________________________ – having two identical alleles for a trait, TT or tt
 Heterozygous – having two __________________________________ alleles for a trait, Tt
 Phenotype – ______________________________l characteristic, tall
 _______________________________ – genetic makeup, TT or Tt
Monohybrid Cross
Dihybrid Cross
 Since alleles can segregate
_______________________, the inheritance
of one trait doesn’t affect the inheritance of
another (seed color and seed shape)
 A dihybrid cross involves crossing two
_____________________________traits of the F1 generation (both parents are heterozygous for both traits)
Complex Forms of Inheritance
 Some alleles are neither dominant or recessive, and many traits are controlled by multiple alleles or multiple
genes
 ________________________________ – both alleles are present in the phenotype, the black and white chicken,
blood types
 Incomplete dominance – the alleles ________________________ to produce the phenotype, red + white = pink
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_______________________________________ – more than 2 alleles are possible choices, although only 2 can
be used at a time, ex. ABO blood groups, rabbit coat color
_____________________________________________________ – controlled by 2 or more genes, ex. skin color
Sometimes expression is also affected by the environment; height and flower color of a sunflower are affected
by genes and climate, soil, and water availability
Sex-linked
 Genes that are located on sex chromosomes are said to be
_________________________ genes
◦ Since males only have 1 X chromosome, all X-linked alleles are
_____________________, even if recessive
◦ For females, a _________________________ allele must be with
another recessive to be expressed
◦ _______________________________ and hemophilia are examples
Chapter 14: Heredity
Human Heredity
 A _________________________________ is a picture of chromosomes
arranged in their pairs (46, 23 pairs in humans)
_______________
_________________
 All egg cells carry an X chromosome, half sperm cells carry an X, half a Y
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◦ Leads to half combined becoming either XY, or XX
___________________________________ are non-sex chromosomes, labeled pairs 1-22 chromosomes
________________ chromosomes are the 23rd pair of chromosomes
To study how traits are passed from generation to generation a _____________________________ chart is used
◦ Males are ___________________________
◦ Females are ___________________________
◦ _______________________ circle/squares have the trait
◦ Horizontal lines represent marriage
◦ Vertical lines connect parents to their ____________________________
White forelock (lock of hair just above the forehead) is dominant
Many disorders are caused by an autosomal recessive allele (disease is only apparent in the
_____________________________recessive condition)
Some disorders are expressed with only one allele (dominant), which means the disease is apparent in the
______________________________ condition
Some disorders are caused by a co-dominant alleles
Disorder(s)
Inheritance pattern
Symptoms
Cystic fibrosis
Simple (autosomal) recessive
Mucus in lungs, digestive tract, liver
Sickle cell disease
Sickle shaped red blood cells; joint pain, an
Huntington’s disease
Simple (autosomal) recessive (codominant on
molecular level)
Simple (autosomal) dominant
Colorblindness
Sex-linked recessive
Mental deterioration and uncontrollable
movements; onset -35-50
Difficulty discerning colors
Hemophilia
Sex-linked recessive
Blood doesn’t clot correctly, missing Facto
Down syndrome (Trisomy 21)
Trisomy (3 chromosomes instead of 2)
Mild to severe mental retardation
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___________________________________________ leads to serious digestive problems
◦ Thick, heavy mucus clogs lungs and breathing passages
◦ Since it is recessive, must have 2 alleles to be affected
_________________________________ disease leads to bent/twisted shape of RBCs (can clog in capillaries)
◦ Heterozygous individuals are generally healthy and more resistant to malaria
Down syndrome (____________________________)
◦ Nondisjunction occurs when homologous chromosomes don’t separate during meiosis-leads to
abnormal number of chromosomes
◦ ___________ copies of chromosome 21
◦ Mild to severe mental disability, and higher susceptibility to many diseases
Sex chromosome __________________________
◦ Turner syndrome (X): sterile
◦ Klinefelter’s syndrome (XXY): generally sterile