Study Guide – Genetics & Heredity
- Understanding Punnetts Squares:
Ex) Two dogs are bred. One dog has long hair (Hh) and the other dog has short hair (hh). What is the probability the puppy will have long hair?
We will work this together.
- When is Down syndrome most likely to occur?
When chromosomes fail to separate properly during meiosis
- What must occur for a child to be color blind? (Hint: Genotypes of parents)
Each parent must carry the recessive allele for colorblindness
- What are the characteristics of a person who is a carrier?
A carrier is a person who has one recessive and one dominant allele for a trait
- Two parents both have type B blood. What blood type will their child have?
B
- The result of cloning is?
Two organisms that are genetically identical
- Genetic Disorders are caused by?
DNA mutations or changes in chromosomes
- How are pedigrees used by geneticists? Explain what a pedigree is.
A pedigree is a chart that tracks which members of a family have a particular trait. Geneticists use pedigrees trace the inheritance of traits in humans.
- What is the combination of sex chromosomes that result in a male?
XY
Why are sex-linked traits more common in males than females?
Because a recessive allele on the X chromosome will always produce the trait in a male b/c the male does not have another X chromosome to mask the recessive allele
What is a human trait that can be altered by variations in the environment? (Consider the environmental variation to be lack of nutrition.)
height
Why does height in humans have such a wide variety of phenotypes?
Height is a quantitative trait meaning it has at least four genes
Multiple alleles are?
Three or more forms of a gene that code for a single trait
A heterozygous organism is made up of what type of genotype?
The genotype has two different alleles for a trait
A homozygous organism is made up of what type of genotype?
The genotype has two identical alleles for a trait
What is an organism’s genotype?
Is its genetic makeup
What term refers to the physical characteristics that are studied in genetics?
Phenotype
A mutation is?
Any change in a gene or chromosome
When sex cells combine to produce offspring, each sex cell will contribute?
Half of the number of chromosomes in body cells
A purebred chicken that has white feathers is crossed with a purebred chicken with black feathers. Each of their offspring has both black and white feathers. Why does this happen?
Because the alleles for feather color are codominant
What is a Punnett Square? What is it used for?
A Punnett Square is a chart that shows all the possible combinations of alleles that can result from a genetic cross. It is used to show all the possible outcomes of a genetic cross.
Probability is…
A number that describes how likely it is that an event will occur.
When reading a notation that has one capital letter and one lower case letter (Tt) what could be determined by geneticists? If the notation had two capital letters (TT) what could be determined by geneticists?
(Tt) One dominant allele and one recessive allele (tt) two recessive alleles
Scientists call an organism that has two different alleles for a trait a______.
Hybrid
Factors that control traits are called______.
genes
What did Mendel study when he was conducting his gene experiments?
He cross pollinated plats to observe how traits were passed.