Genetics-Merit connections

How does sexual reproduction increase genetic variation?

Two parents contribute genetic material to offspring, producing new combinations of alleles. Meiosis also creates variation through crossing over and independent assortment.

How does crossing over increase genetic variation?

Homologous chromosomes exchange sections of DNA during meiosis, creating new combinations of alleles in the resulting gametes.

How does independent assortment increase genetic variation?

Homologous chromosome pairs are distributed into gametes in different combinations during meiosis, producing genetically different gametes.

How can a mutation increase genetic variation?

A mutation changes the DNA sequence and may create a new allele. If it occurs in a cell that gives rise to gametes, it can be inherited by offspring and introduce variation into the population.

What is the difference between gametic and somatic mutations?

Gametic mutations can be inherited by offspring, whereas somatic mutations in ordinary body cells are generally not passed to offspring.

How are genotype and phenotype related?

Genotype is the combination of alleles an organism possesses. Different genotypes can produce different phenotypes, although environmental factors can also influence phenotype.

How can genetic variation produce phenotypic variation?

Different combinations of alleles can affect how a characteristic develops or is expressed, producing differences in observable characteristics between individuals.

How can the environment influence phenotype?

Environmental factors such as nutrition, temperature, or habitat conditions can affect how a characteristic develops or is expressed, sometimes producing different phenotypes in individuals with similar genotypes.

How do DNA, genes, alleles, and phenotype relate to one another?

DNA contains genes, and genes can have different versions called alleles. Alleles influence the proteins produced or how they function, which can affect the phenotype.

How can a mutation affect an organism's phenotype?

A mutation changes the DNA sequence and may alter a gene's function or the protein it produces. This can change a characteristic, although some mutations have no noticeable effect.

How can a mutation cause a genetic disorder?

A mutation may alter a gene so that it produces a faulty or non-functional protein. If this disrupts an important biological process, it can cause a disease phenotype.

How do dominant and recessive alleles affect phenotype?

A dominant allele can determine the phenotype in a heterozygote, masking the effect of a recessive allele. A recessive phenotype is typically expressed when two recessive alleles are present in a simple single-gene inheritance model.

How can two unaffected parents produce offspring with a recessive genetic disorder?

If both parents are heterozygous carriers, each can pass on the recessive allele. Offspring who inherit the recessive allele from both parents can express the disorder.

What does a Punnett square show?

The possible allele combinations of offspring from a genetic cross and the probability of each genotype under the assumed inheritance model.

Why can a recessive allele remain in a population even when it causes a harmful disorder?

Heterozygous carriers may not show the disorder but can pass the allele to offspring, allowing it to persist across generations.

How can DNA sequencing help scientists study a population?

By determining and comparing DNA base sequences, scientists can identify genetic differences, estimate genetic diversity, and investigate how closely related individuals are.

How can gene tracking help scientists study inheritance?

Scientists can follow a particular allele through individuals or generations to investigate its inheritance, distribution, and association with characteristics.