evolution Flashcards
define gene
It’s a segment of DNA that contains instructions for building specific proteins or RNA molecules. Genes are passed from parents to offspring.
define allels
An allele is a variant form of a gene.
Each gene has at least two alleles.
You inherit one allele from each parent.
These alleles can be the same or different.
define genetic variation
Genetic variation refers to the differences in DNA sequences among individuals of the same species. It’s the reason why we all look different and have unique traits.
It’s a result of a sexual reproduction.
how does a new allele form?
Mutations are the primary source of new alleles.
define mutations
A mutation is a permanent alteration in the DNA sequence of a gene. It can involve changes in single nucleotides (point mutations) or larger segments of DNA (chromosomal mutations). that can occur randomly during DNA replication or due to exposure to certain environmental factors (like radiation or chemicals
define phenotypic variation
Phenotypic variation refers to the observable differences among individuals within a population in terms of their physical appearance, behavior, and other characteristics. These traits are collectively known as the phenotype.
define fitness
an organism’s ability to survive and reproduce in a particular environment. It’s a measure of reproductive success, not physical strength or athleticism.
define natural selection
“survival of the fittest”
Natural selection is the process by which organisms better adapted to their environment tend to survive and produce more offspring. This leads to the gradual evolution of populations over time.
Favorable traits are passed on to offspring - increase the frequency of advantageous alleles and reduce the frequency of disadvantageous alleles.
define evolution
Evolution is a fundamental principle in biology that represents the change in the heritable characteristics of biological populations over successive generations. This means that species change over time, and these changes are passed on to their offspring.
what are the seven properties and processes that are associated with life?
- Order: Living organisms exhibit complex organization at various levels, from atoms to molecules, cells, tissues, organs, and organisms.
- Regulation: Organisms maintain internal conditions within a stable range, a process known as homeostasis.
3.Growth and Development: Organisms increase in size and complexity over their lifespan, following specific patterns (that genes control).
- Energy Processing: Organisms acquire and use energy to perform various activities. they emit energy in the form of heat.
- Response to Stimuli: Organisms can detect and respond to stimuli in their environment.
- Reproduction: The ability to produce offspring, either sexually or asexually.
- Evolution and Adaptation: organisms adapt to their environments, ensuring survival and reproduction.
explain the endosymbiotic theory
The endosymbiotic theory suggests that some of the organelles present in eukaryotic cells, specifically mitochondria and chloroplasts, were once free-living prokaryotic organisms.
are the host cells in endosymbiosis prokaryotic or eukaryotic?
The host cell in endosymbiosis is a eukaryotic cell.
define endosymbionts
Endosymbionts are organisms that live within the body or cells of another organism.
define algae
Algae are a diverse group of photosynthetic organisms that primarily live in water. They range from microscopic single-celled organisms to large, multicellular seaweeds.
what’s the primary endosymbiosis
Primary endosymbiosis is the evolutionary process where a eukaryotic cell engulfed a prokaryotic cell, which eventually became an organelle. This event is believed to be the origin of mitochondria and then chloroplasts.
Mitochondria are thought to have originated from an engulfed aerobic bacterium.
Chloroplasts are believed to have evolved from a photosynthetic cyanobacterium.
what’s the secondary endosymbiosis
Secondary endosymbiosis is a more complex process than primary endosymbiosis. It occurs when a eukaryotic cell engulfs another eukaryotic cell that has already undergone primary endosymbiosis. it’s endosymbiosis happening twice.
what is the difference between living and non-living?
The primary distinction between living and non-living things lies in their ability to exhibit the characteristics of life.
define species
A species is the basic unit of biological classification. It is a group of organisms that can interbreed and produce fertile offspring.
define ecosystem
An ecosystem is a community of living organisms (plants, animals, and microbes) interacting with each other and their non-living environment (weather, earth, sun, soil, climate, atmosphere).
define biodiversity
Biodiversity refers to the variety of life in an ecosystem.
define population
A population is a group of individuals of the same species living in a specific area and function as a community.
define taxonomy
Taxonomy is the science of naming, describing, and classifying organisms.
what are the 3 domains of life?
Archaea: These are single-celled prokaryotic organisms that often live in extreme environments, such as hot springs, salt lakes, and deep-sea vents. They were once classified as bacteria but have distinct genetic and biochemical characteristics.
Bacteria: Another group of single-celled prokaryotic organisms, bacteria are incredibly diverse and found in almost every habitat on Earth.
Eukarya: This domain includes all organisms with eukaryotic cells, which have a nucleus and membrane-bound organelles. This domain encompasses animals, plants, fungi, and protists.
define kingdoms
a kingdom is a taxonomic rank below domain. It’s a broad category used to classify organisms based on shared characteristics.
Animalia: Multicellular organisms that consume other organisms for energy.
Plantae: Multicellular organisms that produce their own food through photosynthesis.
Fungi: Decomposers that obtain nutrients by absorbing organic matter.
Protista: A diverse group of mostly single-celled eukaryotic organisms.
Monera: This kingdom has been largely abandoned as it included both bacteria and archaea, which are now classified in separate domains.
describe the taxonomic hierarchy
Domain: The highest rank, encompassing the broadest groups of organisms.
Kingdom: The next level of classification below domain.
Phylum (or Division in botany): A group of related classes.
Class: A group of related orders.
Order: A group of related families.
Family: A group of related genera.
Genus: A group of closely related species.
Species: The basic unit of classification, representing a group of organisms that can interbreed and produce fertile offspring.
how does genetic variation processed?
- Crossing Over: Occurs during meiosis, when homologous chromosomes exchange genetic material. Creates new combinations of alleles on chromosomes
- Independent Assortment: Random distribution of chromosomes into gametes during meiosis. Leads to different combinations of chromosomes in offspring.
- Random Fertilization: Any sperm can fertilize any egg, creating various combinations of alleles in the zygote. Increases genetic diversity in the population.
- Mutation: Changes in the DNA sequence that create new alleles. The ultimate source of new genetic variation. have to be germinal mutation.
define last universal common ancestor
Last Universal Common Ancestor (LUCA) is the hypothetical organism from which all life on Earth is believed to have descended. It’s considered the most recent organism from which all organisms currently living on Earth descend.
define a mutation
A mutation is a change in the DNA sequence of an organism. This change can occur spontaneously during DNA replication or be induced by external factors such as radiation or certain chemicals.
how do environmental conditions affect genetic variations?
While environmental conditions don’t directly cause genetic variations (mutations are the primary source), they can significantly influence the expression of genetic traits and indirectly impact genetic variation over time.
do all mutation affect the phenotype?
no!
While mutations are the ultimate source of genetic variation, many mutations have no noticeable impact on the organism’s appearance or function. like Silent mutations, Mutations in non-coding regions, Redundancy in genetic code
define somatic variations
Somatic variations are genetic alterations that occur in the DNA of somatic cells (body cells) after conception. Unlike germline mutations (which occur in sperm or egg cells and can be passed on to offspring), somatic variations are not inherited.
define germinal variations
Germinal variations are genetic changes that occur in the germ cells (sperm or egg cells) of an organism. These variations are heritable, meaning they can be passed on to offspring.
define mutagens
A mutagen is a physical or chemical agent that changes genetic material, usually DNA, in an organism and thus increases the frequency of mutations above the natural background level.
what are the 2 kinds of germinal variation?
Continuous Variations:
Gradual changes in a characteristic within a population.
No distinct categories or gaps between individuals.
Influenced by multiple genes and environmental factors.
Examples: height, weight, skin color, intelligence.
Discontinuous Variations:
Distinct categories with no intermediate forms.
Controlled by a single gene or a few genes.
Examples: blood group, eye color, gender, presence or absence of a disease.
define Discontinuous Variations
qualitative inheritance.
Limited variation within clearly defined groups.
Distinct categories with no intermediate forms or overlap.
Controlled by a single gene or a few genes.
Examples: blood group, eye color, gender, presence or absence of a disease.
define continuous Variations
quantitative inheritance.
Gradual changes in a characteristic within a population.
No distinct categories or gaps between individuals.
Influenced by multiple genes and environmental factors.
Examples: height, weight, skin color, intelligence.
what critical elements does Darwinism include?
Overproduction of progeny: Organisms produce more offspring than can survive.
The occurrence of variation: Individuals within a population exhibit differences in their traits.
Struggle for existence: Competition for limited resources occurs among individuals.
Survival of the fittest: Individuals with advantageous traits are more likely to survive and reproduce.
Natural selection: The process by which advantageous traits become more common in a population over time.
what are the types of natural selection?
- Stabilizing Selection
Favors the intermediate phenotype
Reduces variation in a population.
Example: Human birth weight - very low or very high birth weights are less likely to survive. - Directional Selection
Favors one extreme phenotype over the other.
Shifts the population’s average trait value in one direction.
Example: The evolution of long necks in giraffes to reach tall trees. - Disruptive Selection
Favors both extreme phenotypes, while selecting against the intermediate.
Can lead to speciation (formation of new species).
Example: Darwin’s finches with different beak sizes adapted to different food sources.
what are the 2 ways that bacteria can acquire drug resistance?
spontaneous chromosomal mutation - Bacteria can develop random genetic mutations during replication. Some of these mutations may confer resistance to antibiotics. Over time, if these resistant bacteria survive and reproduce, they can become the dominant strain.
uptake of R plsamid -Bacteria can share genetic material, including resistance genes, with other bacteria through processes like conjugation, transformation, and transduction. This allows for rapid spread of resistance within and between bacterial species.
define chromosomal resistance
Chromosomal resistance is a type of antibiotic resistance that arises from spontaneous, random mutations in a bacterium’s chromosomal DNA. These mutations can alter the structure or function of target sites for antibiotics, or they can lead to increased expression of efflux pumps that expel antibiotics from the bacterial cell.
define plasmid resistance
Plasmid resistance occurs when antibiotic resistance genes are carried on small, extrachromosomal DNA molecules called plasmids. These plasmids can replicate independently of the bacterial chromosome and be transferred between bacteria through a process called conjugation.
define lactamase
Lactamase is a type of enzyme produced by bacteria that has the ability to inactivate beta-lactam antibiotics.
why is it important to finish the full course of antibiotics?
Antibiotics work to kill bacteria or prevent their growth. Stopping the medication early might leave some bacteria alive, allowing them to multiply and cause the infection to return.
When antibiotics are not taken as prescribed, the strongest bacteria can survive and develop resistance. This makes the infection harder to treat, and can lead to the spread of antibiotic-resistant strains.
define genetic drift
Genetic drift is a RANDOM process in which allele frequencies within a population change over time due to chance. It’s essentially a sampling error in selecting the alleles for the next generation from the gene pool of the current generation. Smaller populations are more susceptible to random fluctuations.
define gene pool
Gene pool refers to the total collection of genes and their different alleles within a population. It’s essentially the genetic makeup of an entire group of interbreeding organisms.
A larger and more diverse gene pool generally increases a population’s ability to adapt to changing environmental conditions.
define chance event
A chance event is an occurrence that happens without a definite cause or pattern. It’s unpredictable and often unexpected. There’s no way to determine when or how it will happen beforehand.
what’s the founder effect?
The founder effect occurs when a small group of individuals breaks off from a larger population to establish a new colony. This small founding group often does not represent the genetic diversity of the original population.
define bottleneck effect
The bottleneck effect occurs when a population’s size is drastically reduced due to a catastrophic event, such as a natural disaster, disease outbreak, or human-induced event. This sudden reduction in population size significantly decreases genetic diversity.
define gene flow
Gene flow is the transfer of genetic material from one population to another. This occurs when individuals migrate and breed with members of another population, introducing new alleles into the gene pool.
what is the hardy-weinberg principle?
The Hardy-Weinberg principle is a mathematical model in population genetics that describes the conditions under which allele and genotype frequencies in a population will remain constant from generation to generation.
Key conditions for Hardy-Weinberg equilibrium:
No mutation: No new alleles are introduced into the population.
-No migration: There is no movement of individuals into or out of the population.
-Random mating: Individuals mate randomly with each other, without regard to genotype.
-Large population size: The population is large enough to prevent random fluctuations in allele frequencies (genetic drift).
-No natural selection: All genotypes have equal chances of survival and reproduction.
-Mandelian Population
define Mandelian Population
A Mendelian population is an idealized concept in population genetics. It represents a hypothetical group of individuals where Mendelian inheritance patterns can be clearly observed and predicted.
2 alleles of a single gene
3 genotypes- receive homozygote, dominant homozygote, hetrozygote.
what are the Hardy Weinberg’s equilibrium formulas?
P+Q=1
AA - PP=P^2
aa - QQ=Q^2
Aa - 2P*Q
define artificial selection
Artificial selection is the process by which humans selectively breed organisms to produce offspring with desired traits. This is achieved by choosing which individuals will reproduce based on specific characteristics.
define gene loci
A gene locus (plural: loci) is the specific, fixed position on a chromosome where a particular gene or genetic marker is located.
define speciation
Speciation is the evolutionary process by which new species arise from an existing species. It occurs when a population becomes isolated from the rest of the species and undergoes genetic changes that eventually prevent them from interbreeding.
This isolation can happen due to various factors like geographic barriers (allopatric speciation), different ecological niches (sympatric speciation), or reproductive isolation.
what are the types of reproductive isolation mechanisms in species?
Prezygotic Isolations - prevent fertilization from occurring
-Geographic isolation: Physical barriers like mountains, rivers, or oceans separate populations.
-Ecological isolation: Species occupy different habitats or niches within the same geographic area.
-Temporal isolation: Species reproduce at different times (different seasons, days, or even times of day).
-Behavioral isolation: Differences in courtship rituals or mating behaviors prevent mating.
-Mechanical isolation: Incompatible reproductive structures prevent mating.
-Gametic isolation: Sperm and egg cells cannot fuse to form a zygote.
-cellular isolation: differnce in chromosome numbers.
Postzygotic Isolations - prevent the hybrid offspring from developing or reproducing.
-Hybrid inviability: Hybrid embryos do not develop properly or die before reaching maturity or even birth.
-Hybrid sterility: Hybrid offspring are born but are unable to reproduce.
define geographical isolation
Geographical isolation is a type of reproductive isolation where physical barriers prevent populations of a species from breeding with each other. These barriers can be natural features like mountains, rivers, oceans, or even deserts.
Over time, these geographically separated populations can evolve independently, leading to the development of distinct genetic and physical characteristics. This process can eventually result in the formation of new species.
define allopatric speciation
Allopatric speciation is a type of speciation that occurs when a population of a species is divided by a geographic barrier.
define sympatric speciation
Sympatric speciation is a type of speciation that occurs when two groups of the same species live in the same geographic area but evolve into separate species without physical barriers separating them. This is in contrast to allopatric speciation, which involves geographic isolation.
results from reproductive isolation.
