Chapter 9 Genetics
Honors Biology
Mr. Pomatto
Intro…
 Inheritance patterns can be _____________________________.
 Behavior can be partially explained by _______________ __________________________.
 9.1
 The science of genetics has ancient roots.
 9.2
 Mendel qualified to do his experiment because he was university trained in
_____________________________________ _________________________.
 If a plant is “cross-fertilized” - it is mated to another __________ .
 9.3
 The Principle of Segregation states - pairs of genes ________________________ during gamete formation.
 Monohybrid crosses only follow 1 particular ____________________.
 Mendel eventually discovered that alternate forms of genes existed and they are called _____________.
 Mendel also discovered that some genes masked others – they were said to be ____________________.
 Genes that were masked were said to be __________________________.
 If both alleles are identical the organism is _______________________ for that trait.
 If one of each allele is present the organism is __________________________ for that trait.
 ______________________ ____________________ can be used to keep track of gametes and potential
offspring.
 9.4
 Mendel knew nothing about __________________________.
 9.5
 The Principle of Independent Assortment states – Each pair of alleles segregates
_________________________ during gamete formation.
 9.6
 A testcross involves crossing a unknown genotype expressing the dominant phenotype with the
______________________ phenotype.
 9.7
 The Rule of Multiplication states - The probability of ______ events together is the product of the
probabilities of the 2 events occurring ___________.
 If 2 coins are flipped at once, what is the probability of getting 2 heads? ½ x ½ = ¼ (product of each
separate probality) ½ chance for heads on the 1st coin and a ½ chance for heads on the 2nd coin)
 The Rule of Addition states – If there is more than one way an outcome can occur, these probabilities must
be ________________ .
 If two coins are flipped at once, what is the probability of flipping a heads/tails or tails/heads?
½x½=¼
 9.8
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and ½ x ½ = ¼ then…. ¼ + ¼ = 2/4 = 1/2
Genetic traits in humans can be tracked through a family _____________________.
A family in Martha’s Vineyard displayed congenital ______________________.
What relation is Elizabeth Eddy to Joshua Lambert? _________________________________________.
In the 2nd generation in fig. 9.8 - Who is older, Abigail or Jonathan? _____________________________
If both parents are not deaf, how is it possible that some of their children are?
 A disease that requires 2 alleles to be expressed is… autosomal ___________________________.
 If a pattern of inheritance is tied to gender, the disorder is __________ ________________.
 9.9
 Over _______________ genetic traits are attributed to a single gene locus.
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The most common lethal genetic disease in the US is ________________ ______________________.
Does inbreeding always result in mutations?

Why do you think laws were created to prevent inbreeding?
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Can disorders be dominant? _____ Are dominant disorders always lethal?
Achondroplasia is a type of ______________________________. What happens if an individual is
homozygous for the allele? ___________________.
If Huntingtons disease is lethal – why doesn’t the condition vanish from populations it afflicts?


If a dominant or recessive trait gives an organism some kind of advantage in their environment – it will most
likely spread _____________________ (quickly or slowly) through a population.
 9.10
 Fetal testing technique that involves taking a sample of amniotic fluid. ______________________________
 Fetal testing technique that involves removing tissue from fetal side of the placenta at 8-10 weeks…
_______________________________.
 Noninvasive view of the inside of the womb. _________________________________
 Fetoscopy uses a needle-thin viewing ___________________ to provide a more direct view of a fetus.
 Analysis of a mother’s blood can detect abnormal levels of certain _______________________.
 9.11
 Briefly describe the following and give an example

Incomplete dominance
 Ex.

Multiple alleles
 Ex.

Pleitropy
 Ex.

Polygenic inheritance

Ex.
 9.12 INCOMPLETE DOMINANCE
 Incomplete dominance shows a _____________________ of phenotypes.
 Cholesterol in blood at high levels can lead to atherosclerosis and vein/artery clogging plaques.
 Hypercholesterolemia is a disease that deals with ______________________________ levels in the blood.
 The fewer ______ receptors present in your blood, the ___________________ your blood cholesterol level.
 Hypercholesterolemia is caused by _________________________ dominance.
 People that are hh for hypercholesterolemia have very high cholesterol levels in their blood.
 Note: Lifestyle also can cause hypercholesterolemia!
 9.13 CODOMINANCE AND ABO BLOOD ALLELES
 Many genes have more than 2 alleles in a population
 Humans can have only 2 of the ____ possible alleles as their genotype for blood type.
 ABO blood groups show _____ possible genotypes and _____ possible phenotypes.
 Type O blood is known as the ___________________________ _______________.
 Type O blood cannot receive no other type of blood.
 Type AB blood is known as the __________________________ ______________________.
 Type AB blood is an example of _______________________________.
 Blood types can be used to disprove or suggest parentage in paternity suits, however, DNA tests are needed
to PROVE parentage!
 9.14 PLEIOTROPY
 A single gene may affect many phenotypic characterisitics. This common situation is known as
___________________________.
 The blood disease called ____________________ _________ _______________ is an example.
 Even though only a single gene is affected, many negative side effects are seen in those who are afflicted.
 List 3 major effects from fig. 9.14 (in blue)
 1.
 2.
 3.
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Sickle Cell anemia is another example of codominance (Heterozygous carriers show some symptoms)
The sickle cell mutations offers some resistance to ____________________________.
 9.15 GENETIC TESTING
 Genetic testing can detect disease-causing ________________.
 There are _____ major categories of genetic testing.
 1.
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2.
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3.
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4.
Ethical, moral, and medical issues are being raised by the increase in genetic testing.
Do you think insurance companies will treat individuals that test positive for serious genetic diseases
differently? Is that fair?
 9.16 POLYGENIC INHERITANCE
 When more than one gene influences a characteristic it is called ____________________ inheritance.
 ____________ _________________ is an example of this.
 9.17 Chromosomal basis of inheritance
 Mendel’s seven garden pea characteristics all sorted independently of each other because the genes
governing each characteristic are all on ___________________________ chromosomes.
 9.18 Genes on the same chromosome tend to be inherited together.
 _____________________ _______________ are located close together on the same chromosome.
 These genes do not follow the rule of independent ___________________________.
 9.19 Crossing over produces new combinations of alleles
 Early examples of recombination were demonstrated in what type of organism? ______________ ______
 9.20 Geneticists use crossover data to map genes
 Fruit flies were great specimens for research because… (list 3)
 1.
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
2.
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3.
Sturtevant assumed that the rate of recombination is proportional to the _____________________ between
2 genes on a chromosome and this information can be used to create a __________________ _________.
 9.21 Chromosomes and Sex-linked genes
 Chromosomes determine ________ in many species.
 In humans ______ (male) and ______ (female)
 Other species display other patterns of sex chromosomes.
 In some reptiles, the ______________________________ at which eggs are incubated determines sex of
offspring.
 9.22 Sex-linked genes exhibit a unique pattern of inheritance.
 All genes found on ______ chromosomes are said to be sex-linked.
 Inheritance of sex-linked genes follows peculiar patterns.
 In humans, since most sex-linked genes are on the X chromosome, mostly ___________ are affected
 9.23 Connection: Sex-linked disorders affect mostly males
 List 3 examples of sex-linked disorders
 1.
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2.
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3
Explain why males will always express disorders found on their X chromosome even if the disorder is
recessive.