Comprehensive Genetics and Inheritance: Key Concepts and Applications

What is inheritance (heredity)?

Transmission of traits from one generation to the next.

What does genetics study?

Heredity and hereditary variation, inherited similarities and differences, and the origin, maintenance, and loss of genetic variation.

What do conservation geneticists focus on?

They focus on where genetic diversity comes from, how it's maintained, and how it's lost over time.

Why is genetic diversity important for populations and species?

It allows them to adapt to changing environments.

What is Huntington's Disease (HD)?

A genetic disorder that affects a person's ability to move, reason, and talk, significantly reducing life expectancy.

How many copies of the allele for Huntington's Disease are needed for it to be fatal?

Only one copy is needed for it to be fatal.

Where is the HD gene located?

At the tip of chromosome 4.

What genetic characteristic is associated with Huntington's Disease?

It has too many CAG repeats (more than 35).

What is an example of evolution discussed in the notes?

The speciation of kiwi species.

What morphological difference was noted between North and South Island Kiwi?

North Island Kiwi have a more bristly appearance.

How many species of Brown Kiwi were revealed through genetic work?

Three species.

What ecological dynamic was observed on Pleasant Island?

An increase in wolf population decreased the deer population, leading to wolves feeding on sea otters.

What technique was developed to detect prey items in wolf scat?

Metabarcoding.

What happens to wolf-deer density in the absence of sea otters?

Wolf-deer density is coupled; no deer means no wolves.

What happens to wolf-deer density in the presence of sea otters?

Wolf-deer density is decoupled; wolves remain even if there are no deer.

What is notable about albatross mating systems?

Albatrosses are long-lived, form long-term pair bonds, and require bi-parental care for chick-rearing.

What is unique about the reproductive rates of albatrosses?

They have the lowest reproductive rates among birds and the longest time for pair bond formation.

What is the misconception about albatross pair bonds?

Despite being seen as monogamous, Wandering Albatross have high rates of extra-pair paternity.

What is the conservation status of the New Zealand kakī (black stilt)?

It is one of the world's rarest birds, with only about 170 individuals remaining despite conservation efforts.

What factors threaten the recovery of the kakī?

Introduced mammalian predators, habitat loss, and degradation.

What is the risk associated with hybridization in kakī?

The risk associated with hybridization between kakī and the self-introduced poaka (pied stilt) is less clear.

What is hybridisation and its associated risk?

Hybridisation poses a threat, but the extinction risk is relatively low.

When did Poaka self-introduce from Australia?

Approximately 150-200 years ago.

How does the course text define genes?

Genes are discrete units of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA, in some viruses).

What do most genes program cells to synthesize?

Most genes program cells to synthesize proteins.

What is the function of the YELLOW UPPER (YUP) gene?

YUP does not synthesize a protein; instead, it produces phased small interfering RNAs (phasiRNAs) that regulate pigment deposition.

What are alleles?

Alleles are variants of genes that parents pass to their offspring as hereditary units.

What is the difference between genes and alleles in inheritance?

We inherit alleles for the genes underlying phenotype X, not the genes themselves.

Where is the majority of DNA found in eukaryotes?

In chromosomes located in the nucleus.

What is a locus in genetics?

A locus (plural, loci) is the location of a gene on a chromosome.

What are homologous chromosomes?

Homologous chromosomes carry the same genes but are not identical in base sequence.

What is the human karyotype?

The human karyotype is 2n = 46, consisting of 23 pairs of homologous chromosomes.

What is an autosome?

Autosomes are chromosomes that are not sex chromosomes; humans have 22 pairs of autosomes.

What is a karyotype?

A karyotype is a display of the chromosome pairs of a cell arranged by size and shape.

What is the main difference between asexual and sexual reproduction?

Asexual reproduction involves a single parent passing copies of all its genes to offspring, while sexual reproduction involves two parents each passing half of their genes, resulting in genetically unique offspring.

What is the sequence of the human life cycle in terms of ploidy?

The human life cycle goes from Diploid to Haploid to Diploid.

What is transcription in genetics?

Transcription is the synthesis of RNA complementary to a template strand of DNA.

What is translation in genetics?

Translation is the synthesis of a polypeptide whose amino acid sequence is specified by the nucleotide sequence in messenger RNA (mRNA).

What are codons?

Codons are sequences of three nucleotides in mRNA that are translated into amino acids or serve as stop signals.

What occurs during Prophase I of meiosis?

Chromosomes condense, form tetrads, undergo synapsis, and non-sister chromatids cross over.

What happens during Metaphase I of meiosis?

Tetrads arrange on the metaphase I plate.

What occurs during Anaphase I of meiosis?

Homologous chromosomes move to opposite poles.

What is the outcome of Telophase I and Cytokinesis in meiosis?

Two haploid daughter cells are formed, with sister chromatids remaining attached.

What is the significance of node I/J in the context of kakī and Poaka?

Node I/J birds have mostly kakī DNA but some are not genetically kakī; they have black feathers with a few white tufts.

What does the genetic assignment probability indicate for the Green Yellow/Yellow Black specimen?

It has a 99% genetic assignment probability to kakī, having inherited more kakī DNA than poaka DNA from its mother.

What is the significance of independent assortment during meiosis?

It leads to 223 possibilities of how chromosomes can line up, resulting in 70 trillion possible combinations when combined with random fertilization.

What is crossing over in meiosis?

A process where homologous chromosomes pair up and exchange segments, creating new combinations of genes.

What occurs during early prophase I of meiosis?

Duplicated chromosomes condense and homologous chromosomes pair in a process called synapsis.

What happens during the middle of prophase I?

Crossing over occurs, resulting in sister chromatids that are no longer identical.

What is the role of the chiasma during meiosis?

It is the site where homologous chromosomes are held together after crossing over.

Why is crossing over important?

It creates more possible genetic variations than can be counted, allowing for greater diversity.

What is random fertilization?

The process by which a random egg combines with a random sperm, contributing to genetic diversity.

How do offspring acquire genes from their parents?

By inheriting chromosomes, which carry the genes.

What is the difference between meiosis and mitosis in terms of chromosome sets?

Meiosis reduces the number of chromosome sets from diploid to haploid, producing four genetically different daughter cells, while mitosis produces two genetically identical cells.

What are sex chromosomes in humans?

The X and Y chromosomes, where females have XX and males have XY, with most genes on the X not having counterparts on the Y.

What is the outcome of meiosis compared to mitosis?

Meiosis produces four daughter cells with half the number of chromosomes, while mitosis produces two identical daughter cells.

What unique events occur during meiosis I?

Synapsis and crossing over, alignment of homologous pairs at the metaphase plate, and separation of homologues.

What happens to sister chromatids during anaphase I of meiosis?

The duplicated chromosomes of each homologous pair move towards opposite poles, but sister chromatids remain attached.

What is the role of cohesins in meiosis?

Cohesins hold sister chromatids together after DNA duplication during interphase.

What is the difference between autosomes and sex chromosomes?

Autosomes are non-sex chromosomes, while sex chromosomes (X and Y) determine an individual's sex.

How does meiosis contribute to genetic diversity?

Through independent assortment and crossing over, meiosis produces genetically unique gametes.

What is the significance of the number 10^100 in the context of random fertilization?

It illustrates the vast number of possible genetic combinations resulting from random fertilization.

What is synapsis?

The pairing of homologous chromosomes during prophase I of meiosis.

What occurs during metaphase I of meiosis?

Homologous pairs are aligned at the metaphase plate, unlike individual chromosomes in mitosis.

What is the result of crossing over on sister chromatids?

It results in new combinations of genes, making sister chromatids no longer identical.

What is the outcome of meiosis II?

It separates sister chromatids, resulting in four haploid cells.

How do single-celled eukaryotic organisms reproduce?

They can reproduce asexually by mitotic cell division, copying and allocating DNA equally to daughter cells.

What is the difference in genetic outcomes between meiosis and mitosis?

Meiosis produces genetically diverse cells, while mitosis produces genetically identical cells.

What is synapsis in meiosis?

The pairing and physical connection of one duplicated chromosome to its homolog during prophase 1 of meiosis.

What is the primary difference in DNA replication between mitosis and meiosis?

In mitosis, DNA replication occurs during interphase before mitosis begins. In meiosis, it occurs during interphase before meiosis 1 but not before meiosis 2.

How many divisions occur in mitosis and meiosis?

Mitosis involves one division, while meiosis involves two divisions.

What occurs during prophase 1 of meiosis that does not occur in mitosis?

Synapsis of homologous chromosomes occurs during prophase 1 along with crossing over between non-sister chromatids.

What is the outcome in terms of daughter cells for mitosis versus meiosis?

Mitosis produces two genetically identical daughter cells, while meiosis produces four genetically different haploid daughter cells.

What role does mitosis play in multicellular organisms?

Mitosis enables the growth, repair, and asexual reproduction of multicellular animals, fungi, or plants.

What is the role of meiosis in sexual reproduction?

Meiosis produces gametes in animals or spores in fungi and plants, reducing the number of chromosomes by half and introducing genetic variability.

What is the original source of genetic diversity?

Mutations are the original source of genetic diversity, creating different versions of genes known as alleles.

How does sexual reproduction contribute to genetic variation?

Reshuffling of alleles during sexual reproduction produces variation, resulting in unique combinations of traits in each member of a sexually reproducing population.

What is the significance of natural selection in relation to genetic variation?

Natural selection favors individuals best suited to the environment, leading to the accumulation of advantageous genetic variations.

What unique reproductive strategy do Bdelloid Rotifers use to increase genetic diversity?

Bdelloid Rotifers can incorporate foreign DNA from other species during periods of suspended animation, increasing their genetic diversity.

Can crossing over occur during prophase 2 of meiosis?

No, crossing over cannot occur during prophase 2 because homologous chromosomes are in different cells after meiosis 1.

What advancements in microscopy contributed to the understanding of meiosis?

Light microscopes allowed scientists to observe chromosomes replicating and dividing during meiosis in the mid-1800s.

What was the predominant model of inheritance before the particulate model?

The blending mode of inheritance was the predominant model, which was later found to be unsatisfactory.

What is the particulate mode of inheritance?

The particulate mode of inheritance is a model that explains inherited similarities and differences based on discrete units (genes) rather than blending.

What was a limitation of the early models of inheritance?

There was no compelling, quantitative evidence to differentiate between the blending and particulate models of inheritance.

What is the genetic composition of daughter cells produced by meiosis?

The daughter cells produced by meiosis are haploid (n) and genetically different from the parent cell and from each other.

What is the role of crossing over in meiosis?

Crossing over introduces genetic variability by exchanging genetic material between non-sister chromatids.

What is the significance of chiasmata during meiosis?

Chiasmata hold homologous chromosome pairs together during prophase 1 due to sister chromatid cohesion.

What happens to homologous chromosomes at the end of meiosis 1?

At the end of meiosis 1, the two members of a homologous pair end up in different cells.

How does meiosis contribute to evolution?

Meiosis generates genetic diversity through recombination and independent assortment, which contributes to the evolutionary process.

What is the relationship between meiosis and gamete formation?

Meiosis is responsible for the formation of gametes, which are essential for sexual reproduction.

How does meiosis differ in haploid and diploid cells?

Meiosis only occurs in diploid cells, while mitosis can occur in both diploid and haploid cells.

What is the blending mode of inheritance?

Genetic material contributed by parents mixes in offspring.

Who was Gregor Mendel?

An Austrian monk (1822-1884) known for his work on inheritance using pea plants.

What innovative approach did Mendel use in his experiments?

He used a quantitative experimental approach to study inheritance.

Why did Mendel switch from studying bees to pea plants?

Bees stung the monks too often, while pea plants allowed him to control mating.

How did Mendel demonstrate the particulate mode of inheritance?

He used pollen from white-flowered plants to fertilize purple-flowered plants, showing that white flowers could reappear.

What did Mendel conclude about the heritable factors for flower color?

Purple-flower factor is dominant, and white-flower factor is recessive.

What is the expected ratio of dominant to recessive traits Mendel observed?

Approximately a 3:1 ratio of dominant to recessive traits.

What is Mendel's model regarding alleles?

Alternative versions of genes (alleles) account for variations in heritable characters.

What is the law of segregation?

Two alleles for a character separate during gamete formation and end up in different gametes.