Mandelian Genetics Flashcards
___(scientist)___ bred pea plants and studied the patterns of inheritance.
Gregor Mendel
Each chromosome contains DNA segments that code for the basic units of heredity and are transmitted from one generation to the next. These DNA segments are called ______.
genes
Each gene has its own location on a chromosome called a gene _______.
locus
What is the difference between a genotype and phenotype?
A genotype is the genes making you up
A phenotype is the physical and physiological traits of an organism. (the observable traits)
What is the Law of Segregation?
when gametes (egg or sperm) are made, the two traits carried by each parent separate.
Define Mendel’s Second Law: Law of Independent Assortment
Genes located on different chromosomes assort independently of each other.
In other words, during the forming of gametes the alleles for height segregate independently from the alleles for a trait such as color. The genes for height and color are on different chromosomes and will assort independently.
The closer the genes are located on a chromosome, the more likely they will be linked. Genes on the same chromosome are said to be linked genes.
What is the difference between incomplete dominance and codominance?
Incomplete dominance will show a “blended” phenotype (red + white = pink)
Codominance: If a person has AB blood type, one parent gave A and the other parent gave B.
The A and B alleles are said to be codominant
An ______ gene is a gene that covers up the expression of another gene in the phenotype.
epistatic
eg. In Labrador Retrievers, we see many different colored dogs.
What does pleiotropy refer to?
a SINGLE gene that can affect an organism in various ways.
eg. in sickle cell anemia, a single mutation occurs, and gives rise to a defective hemoglobin molecule
Describe polygenic inheritance:
In polygenic inheritance we see TWO or MORE genes contributing to a single trait. Hair color, skin color, and height result from the interactions of several genes.
Describe the term Multiple alleles:
When a gene has more than two given alleles
eg. blood type ABO
What antigens and antibodies are present in the following?
Blood type: A
Blood type: B
Blood type: AB
Blood type: O
Blood type: A (A antigen and B antibody)
Blood type: B (B antigen and A antibody)
Blood type: AB (A and B antigens and NO antibodies)
Blood type: O (NO ANTIGENS but A and B antibodies)
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Females (mammals) have 1 chromosome that is inactivated in embryonic development by methylation… called a _______.
Barr body
Males are hemizygous… meaning they contain ____.
XY
What is the difference between alleles in a female who is colorblind and a female who is just a carrier?
Colorblind female: Xc, Xc
Female carrier: Xc, X
(A colorblind female will have the allele on both X chromosomes)
What is the difference between autosomal recessive and autosomal dominant?
Autosomal recessive skips generations!!!
Autosomal dominant: If one gene is affected (X Xc), you have the disease. (does NOT skip generations)
Males give sex-linked genes to their _______.
Females give sex-linked genes to both sons and daughters.
A male gets a sex-linked disease from his ______.
Males give sex-linked genes to their daughters. not their sons
Females give sex-linked genes to both sons and daughters.
A male gets a sex-linked disease from his mother.
The probability of a ______ is proportional to the distance separating the genes!!
crossover
An offspring containing the wrong number of chromosomes as seen in Down syndrome is referred to as ____________.
Aneuploidy
Discuss each of the following:
- Down syndrome
- Turner syndrome
- Kleinfelter syndrome
Down syndrome: Trisomy 21
Turner syndrome: female that is just 1 X (not XX)
Kleinfelter syndrome: a male with XXY
Give examples of polyploidy:
polyploidy is very common in plants. We see a 3N or 4N cell
Many weeds, and dandelions are polyploidy
Endosperm of plant seeds: 3N
Human liver cell are occasionally 3N, 4N, etc.!!!!
A deleted chromosome fragment is joined to a nonhomologous chromosome. This is referred to as ______.
Translocation
The key word here is nonhomologous
How many gametes can be made given the following genotype: Xx Yy Zz WW BB
2^n
n = number of heterozygotes
2^3 = 8
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