Sources of Genetic Variation in Cells

What is the process that involves the random orientation of homologous pairs of chromosomes at metaphase I?

Independent assortment

What is the term used to describe the production of chromosomes with new combinations of maternal and paternal alleles?

Recombinant chromosomes

What type of chromosomal mutation involves a segment or the entire DNA molecule?

Chromosomal mutation

Which process involves the insertion of 'jumping genes' into an existing gene?

Transposition Signup and view all the answers

In which type of organisms is polyploidy more common?

Plants Signup and view all the answers

How many possible chromosome combinations can be formed through random fertilization?

8.4 million (2^23) Signup and view all the answers

What is the definition of a species based on reproductive criteria?

a set of organisms that interbreed among themselves but not with other species Signup and view all the answers

What is the definition of a species based on phenotypic criteria?

a set of organisms that are sufficiently similar to one another and sufficiently different from members of other species Signup and view all the answers

What is allopatric speciation and when does it occur?

It occurs when gene flow is interrupted due to geographical separation of populations. Signup and view all the answers

What are the barriers to sympatric speciation?

Polyploidy, habitat differentiation, and sexual selection Signup and view all the answers

What is an autopolyploid?

An individual with more than two chromosome sets derived from a single species Signup and view all the answers

How do small and isolated populations contribute to the formation of new species?

They are more likely to become a new species but are also often likely to perish. Signup and view all the answers

Explain how the introduction of drug 3TC led to an increased frequency of 3TC-resistant HIV strains in the population.

The drug 3TC replaced Cytosine in normal DNA, making reverse transcriptase enzyme more discriminating and leading to the emergence of 3TC-resistant HIV strains. Signup and view all the answers

Describe the adaptive advantage of the pea comb mutation in chickens in cold environments.

The pea comb mutation, being small-sized, dissipates less heat and offers less area for injury, making it advantageous for cock-fighting in cold environments. Signup and view all the answers

Explain how a single gene mutation resulted in the pea comb in chickens.

The mutation involved a massive amplification of a duplicated sequence in intron 1 of the gene for SOX5 transcription factor, leading to the development of the pea comb. Signup and view all the answers

How do characteristic traits pass from parents to offspring according to Mendel's laws?

Characteristic traits pass on due to heritable variations with alternative forms of genes (alleles), following Mendel's laws of segregation and independent assortment. Signup and view all the answers

Explain the concept of genes having two alleles, one from each parent.

Each gene has two alleles, one inherited from each parent, which can have distinct states and may differ in nucleotide sequence at the same locus. Signup and view all the answers

How can a difference in nucleotide sequence in one place of a gene lead to phenotypic changes?

A difference in nucleotide sequence in one place of a gene can alter the protein structure produced, affecting the gene's function and potentially resulting in observable phenotypic changes. Signup and view all the answers

What is the difference between dominant and recessive alleles in terms of phenotypic expression?

Dominant alleles are phenotypically expressed for homozygous or heterozygous conditions, while recessive alleles are only expressed phenotypically for homozygous condition. Signup and view all the answers

Give an example of multiple alleles in humans and explain how they exhibit three or more discrete states.

Human blood type A, B, AB, and O are examples of multiple alleles. The varied combinations of two alleles result in the expression of three or more discrete states. Signup and view all the answers

What is pleiotropy in genetics and provide an example of a genetic disorder that exhibits pleiotropy?

Pleiotropy is when a single gene has multiple phenotypic effects. An example is sickle cell anemia, which shows multiple symptoms associated with the disease. Signup and view all the answers

Explain the concept of epistasis in genetics with a brief example.

Epistasis occurs when a gene at one locus alters the phenotypic expression of a gene at a second locus. An example is the gene E controlling the expression of dark pigment in certain organisms. Signup and view all the answers

What is meant by polygenic inheritance and provide an example of a trait in humans that exhibits polygenic inheritance?

Polygenic inheritance refers to differences in appearance or function shown in small, incremental ways, involving multiple genes. An example is human skin color, which is controlled by multiple genes. Signup and view all the answers

Describe the process of cell division that leads to the formation of gametes in terms of chromosome number.

Sex cells undergo two consecutive cell divisions that reduce the chromosome number from diploid to haploid, resulting in the formation of gametes. Signup and view all the answers

Explain the Founder Effect and provide an example.

The Founder Effect occurs when few individuals from a large population migrate to an isolated area, leading to a small genetic composition of the colonists compared to the original population. An example is when a few birds from a mainland population colonize a remote island. Signup and view all the answers

What is the main outcome of Natural Selection?

The main outcome of Natural Selection is the differential success in reproduction, leading to the selection of alleles that are passed on to the next generation in proportions disproportionate to their frequencies in the present generation. Signup and view all the answers

How does Gene Flow affect genetic diversity between populations?

Gene Flow tends to reduce genetic differences between populations as it involves the exchange of alleles through migration, which can lead to the fusion of populations into a single one. Signup and view all the answers

What is a Mutation and how does it contribute to genetic variation?

A Mutation is a change in the sequence of nucleotides in an organism's DNA. It is the source of new alleles and can give rise to structural, functional, or behavioral alterations that impact an individual's chances of survival and reproduction. Signup and view all the answers

Differentiate between Lethal and Neutral mutations.

Lethal mutations result in a drastic change in phenotype that leads to the death of the organism, while Neutral mutations are changes in the base sequence that have no effect on survival or reproduction. Signup and view all the answers

Explain how Natural Selection leads to the adaptation of populations to their environment.

Natural Selection results in differential reproductive success based on genetic variations, allowing individuals with advantageous traits to survive and pass on their alleles to the next generation, thus adapting the population to its environment. Signup and view all the answers