Introduction to Genetics, Evolution, and Speciation Concepts, Reproduction Types: Mitosis, Sexual Reproduction, and Human Reproductive Systems Pt.2

What is pleiotropy?

When a single genotype affects multiple phenotypes.

What is epistasis?

When one gene affects the expression of another gene.

What are sex chromosomes?

Chromosomes that determine the sex of an organism (X and Y in humans).

What is the SRY gene?

The gene on the Y chromosome that triggers male anatomical development.

What is natural selection?

The process where organisms better adapted to their environment tend to survive and produce more offspring.

What is fitness in the context of natural selection?

The ability of an organism to produce offspring.

What is a gene pool?

The total collection of genes in a population at any one time.

Know how Meiosis l and Meiosis ll differ

Meiosis one involves splitting pairs of homologous chromosomes and meiosis 2 involves splitting the actual chromosomes into chromatids.

What is the heritable molecule that contains genes?

DNA.

What is the term for the observable traits of an organism?

Phenotype.

What is the term for the genetic makeup of an organism?

Genotype.

How many copies of each gene do humans have?

Humans are diploid, having 2 copies of every gene.

What are homologous chromosomes?

Chromosomes that carry the same genes but may have different alleles.

What are sister chromatids?

Duplicates of a chromosome that appear after DNA replication.

What is a locus?

A specific location on a chromosome where a gene is found.

What is the difference between homozygous and heterozygous?

Homozygous means having the same allele on both chromosomes; heterozygous means having different alleles.

What is codominance?

A genetic scenario where both alleles are expressed equally in the phenotype.

What is incomplete dominance?

A genetic scenario where the phenotype is a blend of the two alleles.

What is the significance of crossing over during meiosis?

It increases genetic diversity by exchanging genetic material between homologous chromosomes.

What is the role of environmental pressure in evolution?

It influences which traits are favorable for survival and reproduction.

What is the difference between mitosis and meiosis?

Mitosis creates diploid somatic cells, while meiosis creates haploid gametes.

What does polygenic mean

It means that traits are controlled by multiple genes.

What is the historical significance of blood types in genetics?

Blood types were crucial for safe blood transfusions and understanding genetic inheritance.

What is the importance of variation in a population for evolution?

Variation is necessary for natural selection to occur.

What does independent assortment do

during Metaphase I of meiosis, where homologous chromosome pairs line up randomly, meaning maternal and paternal chromosomes mix in the resulting gametes.

What is the impact of environmental factors on genetic traits?

Environmental factors can influence the expression and development of genetic traits.

What is sexual dimorphism?

When the sexes of a species differ dramatically in their appearance.

What is intrasexual selection?

a mechanism of sexual selection where members of the same sex (usually males) compete directly for access to mates, leading to the evolution of traits like large size, strength, or weapons (antlers, horns). Winners gain higher mating success, while losers are often excluded from reproducing.

What does intersexual selection refer to?

Selection that occurs between the sexes, also known as mate choice. Where individuals of one sex choose mates of the opposite sex based on specific, desirable traits like bright plumage.

What is genetic drift?

The shift of allele frequency which can be at random without a fitness advantage.

What is the bottleneck effect?

A significant reduction in population size due to a catastrophic event, leading to a loss of genetic diversity.

What is the founder effect?

When a small group of individuals becomes isolated, leading to a shift in allele frequency that may not represent the original population.

What are the requirements for fossil formation?

Hard parts (bones, teeth, shells), rapid burial, high pressure, and low oxygen environments.

What is radiometric dating?

A method of dating fossils by comparing the ratios of radioactive isotopes, such as Carbon-14.

What is divergent evolution?

Structures develop differences over time due to environmental pressures. Structures that come from a common ancestor, but have changes over time.

What are homologous structures?

Homologous structures are physical features in different species that share a common evolutionary ancestor, even if they serve different functions. (vertebrae of humans, cats, and whales.)

What are vestigial structures?

Structures that no longer serve a purpose but provide clues about ancestors, such as the pelvis and femur in whales.

What is convergent evolution?

When organisms evolve similar characteristics due to shared environmental pressures, not shared ancestry.

What distinguishes analogous structures from homologous structures?

Analogous structures have different origins but serve similar functions, while homologous structures have a common origin but different functions. Analogous structures come from convergent evolution and homologous structures come from divergent evolution.

What is phylogenetics?

The study of placing organisms on a tree based on their ancestors.

What is a monophyletic group?

A group that shares one common ancestor and all its descendants.

What is a paraphyletic group?

A group that shares a common ancestor but does not include all of its descendants.

What is a polyphyletic group?

A group that includes organisms with different ancestors.

What does Hardy-Weinberg equilibrium state?

In a population that is not changing, allele frequencies remain constant.

What are the conditions for a population to be at Hardy-Weinberg equilibrium?

No new mutations, random mating, large population size, no immigration/emigration, and no differences in survival or reproductive success.

What is the biological species concept?

Defines species based on the ability of individuals to produce viable, fertile offspring. If they can, they are members of the same species

What are prezygotic mechanisms of reproduction?

Mechanisms that prevent fertilization from occurring, such as habitat isolation and temporal isolation.

What are postzygotic mechanisms of reproduction?

Mechanisms that occur after fertilization, such as reduced hybrid viability and reduced hybrid fertility.

What is allopatric speciation?

Speciation that occurs when populations are geographically separated.

What is sympatric speciation?

Speciation that occurs in populations that live together, often driven by factors like sexual selection or habitat differentiation.

What is the punctuated equilibrium model?

A model of evolution that suggests species change rapidly during short periods of time, followed by long periods of stability.

What is the gradual model of speciation?

A model that suggests species diverge from each other steadily and slowly over time.

What is a characteristic of asexual reproduction?

An organism makes an exact copy of itself.

Which organisms commonly reproduce asexually?

Single-celled organisms like bacteria and yeast.

What is the main disadvantage of asexual reproduction?

It sacrifices genetic diversity.

What are gametes?

Cells produced in sexual reproduction that contain half of the genetic information.

What is formed when two gametes fuse?

A zygote with a complete genome.

What does isogamy mean?

Gametes are equal in size.

What does anisogamy mean?

One large gamete and one small gamete.

What is a hermaphroditic organism?

An organism that produces both male and female gametes simultaneously or sequentially.

What does gonochoric or dioecious mean?

Organisms, like humans, that have distinct male and female individuals.

What does it mean to be hemizygous

a diploid organism that has only one copy of a specific gene or chromosome instead of the usual pair (Happens in male XY)

What are the conditions needed for natural selection to occur

Variation of trait within a population, time, and a mechanism. The variation must be heritable and the variation must result in a difference of fitness.

What is the half life of carbon-14

5730 years

What is a transitional species

A species that is midway between an ancestor and amodern animal

What is habitat isolation

Two species are never in the same place preventind reproduction.

What is temporal isolation

Two species do not mate at the same time of day/year preventing reproduction.

What is behavioral isolation?

When two species have different courtship rituals preventing reproduction.

What is mechanical isolation?

Where mating is attempted, but morphological differences prevent successful fertilization

What is gametic isolation?

Where mating can happen, but gametes cannot meet or fuse properly.

What are post-zygotic mechanisms

mechanisms after fertilization

What is reduced hybrid viability

The genes impair the survival of the hybrid where it does not make it to reproduction or the fetus dies.

what is reduced hybrid fertility

when the hybrid survives, but they are sterile

Hybrid breakdown?

When the first gen of hybrids is vigorous and can reproduce, but the second generation is feeble or sterile.

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