class3

Flashcards focusing on key genetic concepts, inheritance patterns, and related terminology for studying.

What is the difference between genotype and phenotype?

Genotype refers to the genetic constitution of an organism, while phenotype refers to the observable physical characteristics.

Define allele.

An allele is a variant form of a gene at a particular locus on a chromosome.

What genotype is described as homozygous?

A homozygous genotype has two identical alleles for a particular gene.

What is the definition of a heterozygous genotype?

A heterozygous genotype has two different alleles for a particular gene.

What is crossing over in meiosis?

Crossing over is the exchange of genetic material between homologous chromosomes during meiosis, which leads to genetic recombination.

Explain the significance of independent assortment in genetics.

Independent assortment refers to the way different genes independently separate from one another when reproductive cells develop.

What visual tool is used to predict genotype and phenotype ratios?

Punnett squares are used to predict genotype and phenotype ratios of offspring from genetic crosses.

What are recombinant chromatids?

Recombinant chromatids are chromatids that have exchanged segments due to crossing over, resulting in new allele combinations.

Define linked genes.

Linked genes are genes that are located close together on the same chromosome and are usually inherited together.

What is a pedigree used for?

A pedigree is a diagram that depicts the biological relationships between individuals and is used to trace the inheritance patterns of specific traits.

How do X-linked traits differ in inheritance patterns compared to autosomal traits?

X-linked traits primarily affect males because they have only one X chromosome; males require only one copy of the mutant allele to exhibit the trait.

What type of inheritance is observed with alleles on the same chromosome that are far apart?

Alleles on the same chromosome that are far apart can assort independently due to crossing over.

Describe the characteristics of autosomal dominant traits in pedigree analysis.

Affected individuals appear in every generation, and both males and females are equally likely to be affected.

What is the expectation for the offspring of an affected parent with an autosomal dominant trait?

About 50% of the offspring are expected to be affected when one parent is affected.

What distinguishes autosomal recessive traits in a pedigree?

Autosomal recessive traits often skip generations, and unaffected parents can have affected children if they are carriers.

Define sex-linked inheritance.

Sex-linked inheritance refers to genetic traits associated with genes found on the sex chromosomes, often leading to different inheritance patterns in males and females.

Explain why males are disproportionately affected by X-linked recessive traits, such as red-green color blindness.

Males have only one X chromosome, so a single recessive allele on that chromosome will express the trait, whereas females require two recessive alleles.

Describe the typical characteristics of an X-linked recessive pedigree.

Most affected individuals are male, affected males have unaffected sons, and daughters of affected males may be carriers.

What happens during Prophase I of meiosis?

Homologous chromosomes pair up and may undergo crossing over to exchange genetic material.

When can independent assortment occur during meiosis?

Independent assortment can occur during Metaphase I when homologous chromosomes align randomly at the metaphase plate.

What is meant by a non-recombinant chromatid?

A non-recombinant chromatid retains the original combination of alleles and has not undergone crossing over.

How does meiosis contribute to genetic diversity?

Meiosis introduces genetic diversity through independent assortment of chromosomes and crossing over between homologous chromosomes.

What is the role of the gametes at the end of meiosis II?

Each gamete contains one set of chromosomes, and resulting combinations can vary due to crossing over and assortment.

What are some limitations of studying human genetics compared to pea plant genetics?

Limitations include fewer offspring, long generation times, and the inability to set specific matings.

Typical pedigree of autosomal recessive traits shows which unique feature?

It often skips generations due to carriers not expressing the trait.

What is the expected offspring ratio of a heterozygous female and unaffected male for a dominant trait?

50% affected and 50% unaffected offspring.

What key feature distinguishes mitochondrial and chloroplast DNA inheritance patterns?

Mitochondrial and chloroplast DNA follow their own unique inheritance patterns, separate from nuclear chromosomes.

In a typical pedigree of an autosomal dominant trait, how are affected individuals distributed across genders?

Affected individuals are equally likely to be male or female.

What effect does crossing over outside the interval between genes have on allele combinations?

There is no recombination between the alleles of the genes, resulting in non-recombinant gametes.

How does chromosome behavior during Meiosis I differ from Meiosis II?

In Meiosis I, homologous chromosomes separate; in Meiosis II, sister chromatids separate.

What causes genetic linkage?

Genes that are physically close together on the same chromosome tend to be inherited together because crossover events between them are less likely.