genetics and inheritance Flashcards
(37 cards)
What is the basic structure of a gene?
A gene is a segment of DNA that encodes information for protein synthesis, determining a specific trait or function.
What are alleles, and how do they influence traits?
Alleles are different versions of a gene that determine specific traits. The combination of alleles inherited from both parents results in the phenotype (observable characteristics).
What is the difference between homozygous and heterozygous genotypes?
Homozygous: Both alleles are the same (e.g., AA or aa).
Heterozygous: Two different alleles (e.g., Aa).
What is the difference between dominant and recessive alleles?
Dominant allele: Expressed even when only one copy is present (e.g., A).
Recessive allele: Expressed only when both copies are recessive (e.g., aa).
What is a phenotype?
A phenotype is the observable characteristics or traits of an organism, such as eye color or height, influenced by both genotype and environmental factors.
What is a genotype?
A genotype is the genetic constitution of an individual, representing the combination of alleles inherited from both parents.
What is a karyotype, and how is it used in genetics?
A karyotype is the number, size, and shape of chromosomes in an organism. It is used to detect chromosomal abnormalities, such as Down syndrome (trisomy 21).
What is the difference between autosomes and sex chromosomes?
Autosomes: 22 pairs of non-sex chromosomes.
Sex chromosomes: The 23rd pair, determining biological sex (XX = female, XY = male).
What is Mendelian inheritance?
Mendelian inheritance refers to the inheritance patterns of traits controlled by a single gene, following dominant and recessive patterns as described by Gregor Mendel.
What are the patterns of inheritance for autosomal dominant and autosomal recessive traits?
Autosomal dominant inheritance: Only one copy of the dominant allele is needed for the trait to be expressed.
Autosomal recessive inheritance: Two copies of the recessive allele (one from each parent) are needed for the trait to be expressed.
What is an autosomal dominant trait? Provide an example.
An autosomal dominant trait is expressed when only one dominant allele is present.
Example: Marfan syndrome or dominant optic atrophy.
What is an autosomal recessive trait? Provide an example.
An autosomal recessive trait requires two copies of the recessive allele (one from each parent) to be expressed.
Example: Cystic fibrosis or albinism.
How are X-linked traits inherited?
X-linked traits are inherited through the X chromosome. Males (XY) are more affected than females (XX) because males have only one X chromosome.
What is the inheritance pattern for X-linked dominant traits?
X-linked dominant traits require only one copy of the dominant allele on the X chromosome for the trait to be expressed in both males and females.
What is the inheritance pattern for X-linked recessive traits?
X-linked recessive traits require two copies of the recessive allele (one from each parent) in females, while males need only one copy to express the trait (since they have one X chromosome).
What is the role of meiosis in genetic inheritance?
Meiosis is the process of cell division that produces gametes (sperm and egg cells). It reduces the chromosome number by half and ensures genetic diversity through crossing-over and independent assortment.
How is gender determined genetically?
Gender is determined by the X and Y sex chromosomes.
XX = Female
XY = Male
What are dominant optic atrophy and its inheritance pattern?
Dominant optic atrophy is a condition that causes progressive vision loss due to degeneration of the optic nerve. It follows autosomal dominant inheritance.
What is Stargardt’s disease, and how is it inherited?
Stargardt’s disease is a genetic retinal disorder causing progressive vision loss. It is inherited in an autosomal recessive manner.
What is the role of the locus in genetic inheritance?
A locus is the specific location of a gene on a chromosome. Different versions (alleles) of the gene may be present at this locus, determining the trait expressed.
How does codominance affect inheritance patterns?
In codominance, both alleles contribute equally to the phenotype. Neither allele is dominant or recessive.
Example: Blood type AB (both A and B alleles are expressed equally).
What is the inheritance pattern for mitchondrial diseases?
Mitochondrial diseases are inherited through the mother’s mitochondria. Since mitochondria are passed only through the egg cell, all offspring of an affected mother will inherit the condition.
What is color blindness, and how is it inherited?
Color blindness is an X-linked recessive condition that affects the ability to distinguish certain colors, particularly red and green. It is more common in males because they have only one X chromosome.
What is retinitis pigmentosa, and what is its inheritance pattern?
Retinitis pigmentosa is a progressive retinal degeneration that affects vision. It can be inherited in autosomal dominant, autosomal recessive, or X-linked patterns.
