Lesson #17 Genetic Information #2

Created by

Rudra Dutta

Cards (53)

Who proposed the chromosomal theory of inheritance?
Walter Sutton
What did Walter Sutton observe during meiosis?
Similar chromosomes pair during meiosis
What is the chromosomal theory of inheritance?
Chromosomes are the carriers of genetic information and the basis for genetic inheritance
What organism did T.H. Morgan use for his genetic studies?
Drosophila melanogaster (fruit fly)
What was the first mutant trait discovered by T.H. Morgan in fruit flies?
White eyes instead of red
What were the phenotypes of the F1 generation when crossing a mutant male fly with a normal red-eyed female?
All F1 generation were red-eyed (dominant)
What was the result of the F2 generation in the cross of the mutant male fly and the normal female?
All white-eyed flies were male
How is sex determined in Drosophila?
The number of X chromosomes determines sex
What are the common sex chromosomes in many species?
X and Y chromosomes
How do female and male gametes differ in Drosophila during meiosis?
Female gametes are X, while male gametes are X or Y
What determines sex in humans?
The presence of the Y chromosome
What is the structure of the Y chromosome in humans?
The Y chromosome is highly condensed
What is the "default" sex for humans?
The default is female
What gene is required for "maleness" in humans?
The SRY gene on the Y chromosome
What type of trait is white eye color in fruit flies?
It is a sex-linked (X-linked) trait
Name two examples of X-linked traits in humans.
Hemophilia and colorblindness
What are epigenetic mechanisms?
Regulators of gene function/expression that do not involve a change in the DNA sequence
What does the term "epigenetic" refer to?
It refers to inheritance that is "over and above" genetic inheritance
What is dosage compensation?
It ensures equal expression of genes from the sex chromosome in females and males
What happens to one of the X chromosomes in female cells?
One X chromosome is inactivated and condensed into a Barr body
What does it mean for females heterozygous for genes on the X chromosome to be genetic mosaics?
Different cells express different alleles depending on which X chromosome is inactivated
How is fur color in female mammals determined?
By a gene present on the X chromosome
What is genomic imprinting?
Imprinted genes are inactivated based on which parental line the gene was inherited from
How is mitochondrial DNA inherited?
Mitochondrial DNA is generally inherited from one parent, usually the mother
What is maternal inheritance?
It refers to the inheritance of traits associated with organelle genomes from the mother
What is sickle cell anemia caused by?
A defect in hemoglobin
What is the effect of sickle cell anemia on oxygen delivery?
It leads to impaired oxygen delivery to tissues
How do homozygotes and heterozygotes for sickle cell anemia differ in terms of symptoms?
Homozygotes exhibit illness, while heterozygotes appear normal under normal O2 conditions
Why is sickle cell anemia particularly prevalent in people of African descent?
It confers resistance to the blood-borne parasite that causes malaria
What is nondisjunction?
Failure of homologous or sister chromatids to separate properly during meiosis
What does nondisjunction lead to?
Aneuploidy, which is the gain or loss of a chromosome
What is monosomy?
Chromosome loss
What is trisomy?
Chromosome gain
How do aneuploid human embryos typically develop?
Aneuploid human embryos rarely develop
What is Trisomy 21 also known as?
Down syndrome
What factors influence the risk of Trisomy 21?
The mother's age influences the risk
What happens when nondisjunction occurs with sex chromosomes?
It may cause somewhat abnormal features, but many reach maturity and may be fertile
What is Triple X syndrome?
It occurs when the X chromosome fails to segregate
What is Klinefelter syndrome?
It occurs when there is an extra X chromosome in males
What is Turner syndrome?
It occurs when there is a missing X chromosome in females