Revision Flashcards
What is fur colour an example of?
Fur colour is an example of an allelic series because it involves multiple alleles of a gene that produce different variations of the same trait. For example, in rabbits, the gene responsible for fur color has multiple alleles, such as the dominant allele for black fur (B), the recessive allele for brown fur (b), and the recessive allele for white fur (c). These alleles exist in a series, where each allele produces a different level of pigmentation. The allelic series allows for a range of fur colours, from black to brown to white, depending on which alleles are present. It’s pretty fascinating how these different alleles can create such a variety of fur colours in animals! Fur colour is also an example of a modifier. For example, in the context of coat colour in cats, there are modifier genes that can affect the intensity or pattern of the fur colour produced by the main colour gene. These modifier genes can result in variations such as tabby patterns or colour point patterns in different cat breeds. So, modifiers play a role in shaping the final appearance of a trait.
What is a modifier?
A modifier refers to a genetic factor that can alter or modify the expression of a gene or trait. It can influence the way a particular gene is expressed, either enhancing or suppressing its effects. Think of it like a “modifier” that adjusts the outcome.
What is gene dosage compensation?
Gene dosage compensation refers to the mechanism by which organisms equalize the expression of genes on sex chromosomes between males and females. In many species, including humans, there is a difference in the number of sex chromosomes between males (XY) and females (XX). This difference in gene dosage can lead to an imbalance in gene expression. To compensate for this, organisms have evolved mechanisms to equalize the expression of genes on the sex chromosomes. In mammals, for example, one of the mechanisms is X chromosome inactivation, where one of the X chromosomes in females is randomly inactivated in each cell. This ensures that both males and females have the same effective dosage of X-linked genes. It’s a pretty fascinating way that organisms maintain balance in gene expression between the sexes!
What is Red Queen coevolution?
It’s like a never-ending race in the world of evolution. The term “Red Queen” comes from Lewis Carroll’s “Through the Looking-Glass,” where the Red Queen tells Alice, “It takes all the running you can do, to keep in the same place.” In the context of biology, Red Queen coevolution refers to the constant evolutionary arms race between two or more species. For example, predator and prey, host and parasite, or even competing species. Each species must keep evolving and adapting just to maintain their relative fitness and survival. It’s a fascinating concept that highlights the dynamic and ever-changing nature of life’s interactions.
What is neofunctionalization?
Neofunctionalization refers to a process in evolutionary biology where a duplicated gene acquires a new function or role over time. When a gene is duplicated through mechanisms like gene duplication or whole-genome duplication, one copy of the gene may retain the original function, while the other copy is free to accumulate mutations and evolve a new function. This process can lead to the evolution of new traits or adaptations in organisms. It’s like the duplicated gene taking on a new job or function, adding to the genetic diversity and potential of a species.
What is a copy number variant?
A copy number variant (CNV) refers to a type of genetic variation where there are differences in the number of copies of a particular segment of DNA in an individual’s genome. These variations can range from small deletions or duplications of DNA segments to larger structural changes. CNVs can have an impact on gene expression and can contribute to genetic diversity and disease susceptibility. It’s like having different numbers of certain genetic segments, which can affect how genes are expressed and function.
What is an allelic series?
An allelic series refers to a group of alleles of a specific gene that exists in a particular order or sequence. These alleles are alternative versions of the same gene and can result in different variations of a trait. In an allelic series, each allele has a slightly different effect on the phenotype, leading to a range of possible expressions for that trait. For example, in the ABO blood group system, the alleles A, B, and O form an allelic series where A and B are co-dominant, while O is recessive. This allows for different blood types, such as A, B, AB, and O. So, an allelic series is like a lineup of alleles, each with its own impact on the trait.
Why is the bombay blood group in humans an example of recessive epistasis?
The Bombay blood group in humans is indeed an example of recessive epistasis. In this case, the presence of a recessive allele at one gene, called the H gene, masks the effects of alleles at another gene, called the ABO gene. The H gene is responsible for the production of a precursor molecule required for the synthesis of A and B antigens on red blood cells. However, individuals with the Bombay blood group have a mutation in the H gene, preventing the production of this precursor molecule. As a result, even if an individual has A or B alleles at the ABO gene, they can not express the A or B antigens on their red blood cells. Instead, they will have blood type O, which is the absence of A and B antigens. This is a great example of recessive epistasis in humans.
Why does recessive epistasis not apply to haploid organisms?
Haploid organisms, like bacteria, fungi, and some plants, have only one set of chromosomes. In these organisms, the concept of recessive epistasis doesn’t really apply because there is no second allele to interact with. Recessive epistasis occurs when the presence of one recessive allele at one gene masks the effects of alleles at another gene. Since haploid organisms only have one allele per gene, there isn’t a second allele to interact with and exhibit recessive epistasis.
What is the antagonistic pleiotropy hypothesis?
The antagonistic pleiotropy hypothesis suggests that certain genes or genetic traits can have both positive and negative effects on an organism’s fitness. In other words, these genes or traits can have beneficial effects early in life but detrimental effects later in life.
According to this hypothesis, natural selection may favour genes that confer advantages during early stages of development or reproduction, even if they have negative consequences later in life. This trade-off occurs because the benefits early in life outweigh the costs later on, leading to the persistence of these genes in a population.
An example of antagonistic pleiotropy is seen in certain genes associated with increased reproductive success in early life but also an increased risk of diseases or aging-related problems later in life.
The antagonistic pleiotropy hypothesis provides a potential explanation for why certain genetic traits associated with aging-related diseases or conditions may persist in populations. It highlights the evolutionary trade-offs that can occur due to the complex interactions between genes, development, and fitness.
What is adaptive introgression?
Adaptive introgression is a fascinating concept in phylogenetic trees. It occurs when genetic material from one species is introduced into the gene pool of another species through hybridization. This genetic exchange can happen when certain advantageous traits from one species are beneficial for the survival and adaptation of the other species. As a result, the species receiving the genetic material may gain new adaptive traits that enhance their fitness and evolutionary success. It’s like a genetic handshake between species, leading to a sharing of advantageous traits. 🌳🤝🧬
What is genetic drift?
Drift in biology refers to genetic drift, which is a random fluctuation in the frequency of certain traits or alleles within a population over time. It occurs due to chance events, such as random mating, genetic mutations, or the migration of individuals. Genetic drift can have significant effects on the genetic makeup of a population, leading to the loss or fixation of certain alleles. It’s like a roll of the genetic dice, shaping the diversity and evolution of species.
What is the least condensed region of chromatin called?
Euchromatin
What is the most condensed region of chromatin called?
Heterochromatin
What is the central dogma of molecular biology?
The central dogma of molecular biology is a fundamental principle that describes the flow of genetic information within a cell. It states that DNA is transcribed into RNA or from RNA back to DNA, and then RNA is translated into proteins. However, genetic information can never be transferred from a protein back to the nucleic acids.
