Biology I - Exam 4

Gregor Mendel

founder of modern science of genetics; studied how genes work

Mendel’s Hypothesis

information was in the form of distinct unit factors of info about heritable traits; tested using common garden pea plants

Genes

a unit of heredity; an organized unit of base sequences in a DNA strand that ultimately result in formation of a functional product

Genome

complete genetic material of an organism/species

Alleles

a variant form of a gene; each diploid carries one gene for a given character

Dominant Allele

allele whose trait is displayed

Recessive Allele

allele is masked by presence of dominant; not expressed

Genotype

genetic composition of an individual

Homozygous

both alleles are identical

Heterozygous

one allele is different from the other

Phenotype

characteristics of an organism that are result of expression

Locus

physical location of a gene

Uppercase Letters

designate the dominant alleles

Lowercase Letters

designate the recessive allele

Mendel’s First Experiment

cross-fertilizing two contrasting, true-breeding pea varieties

Single Factor Cross (Monohybrid)

a cross that follows only two variations of a single character

F1 Generation (White vs Purple)

all flowers were purple (tall)

F2 Generation

resulted in a purple to white ratio of 3:1

Mendel’s Law of Segregation

the two alleles of a gene separate from each other during the process that gives rise to gametes, so every gamete only receives one allele

Punnett Square

a way to predict the outcome of a simple genetic cross between individuals of known genotypes

Two Factor Cross (Dihybrid)

inheritance of two different characters

Mendel’s Second Experiment

studied the inheritance of seed color and shape

F1 Generation (Dihybrid Cross)

all plants were round (Rr) and yellow (Yy)

F2 Generation (Dihybrid Cross)

four different phenotypes in a ratio of 9:3:3:1; 9 yellow round, 3 green round, 3 yellow wrinkled, & 1 green wrinkled

Mendel’s Law of Independent Assortment

the alleles of different genes assort independently of each other during the process that gives rise to gametes

Male Chromosome

XY chromosome pair

Female Chromosome

XX chromosome pair

Variations in Inheritance Patterns

pleiotropy, incomplete dominance, multiple alleles & codominance, and the environment

Pleiotropy

refers to possible multiple effects that a gene may have on an individual phenotype

Incomplete Dominance

results when dominant allele of heterozygous genotype is not fully dominant over the recessive

Multiple Alleles and Codominance

a gene that has more than two alleles; depend upon combo of the two alleles you inherit will determine phenotype

Codominance Example

ABO blood types - A and B are dominant over O, but codominant to each other

Polygenic

multiple genes contribute to outcome and increase number of phenotypes

Phenotypes and the Environment

sometimes the surrounding environment determines whether or not a trait is expressed

Levels of Biology - Cellular Level

atoms → molecules → organelles → cells

Levels of Biology - Organismal Level

tissues → organs→ organisms

Levels of Biology - Population Level

population → community → ecosystem → biosphere

Evolution

results from a heritable change in one or more characteristics of a population from one generation to the next

Microevolution

evolution resulting from a succession of relatively small genetic variations or mutations within a population; can create new subspecies

Macroevolution

evolution that results in the formation of a new species or groups of related species over a long period of time

Charles Darwin

hypothesized that existing species come from pre-existing species based on observations

Galapagos islands

where Darwin observed birds to form his theory

Darwin’s Findings

finches have different sized beaks and shapes and were probably modified from the original mainland species

Genetic Variation

the diversity of DNA sequences among individuals within a population or species

Natural Selection

individuals with heritable traits that better suit the environment tend to flourish and reproduce; survival of the fittest

Selective Breeding

programs and procedures designed to modify traits in domesticated species

Biogeography

the study of geographic distribution of extince and living species

Convergent Evolution

two different species from different lineages show similar characteristics because they occupy similar environments

Fossils

the preserved remains of life; give info on evolutionary changes

Radiometric Dating

used to estimate the age of fossils

Homology

a similarity between organisms that occurs due to descent from a common ancestor

Anatomical Homologies

comparison of body structure between different organisms

Developmental Homologies

comparison of the process and structures involved in development of different organisms

Molecular Homologies

comparison of molecular level aspects (DNA, RNA, etc) of different organisms

Molecular Evolution

the process of evolution at the level of genes

Population Genetics

the study of genes and genotypes in a population

Population

groups of interacting individuals of the same species that occupy the same environment

Gene Pool

all of the alleles for every gene in a given population

Mechanisms that Effect Microevolution

natural selection, sexual selection, genetic drift, and migration

Sexual Selection

a form of natural selection that results in individuals with certain traits being more likely yo reproduce than others

Genetic Drift

genetic fluctuation in allele frequencies due to random chance from one generation to the next

Two Forms of Genetic Drift

bottleneck and founder

Bottleneck Effect

sudden change in the environment that drastically reduces population size (natural disasters)

Founder Effect

when a small group becomes separated from a larger population

Migration

movement if individuals in or out of a population

Species

group of related organisms that share a distinctive set of attributes in nature

Speciation

process of generating a new species

Common Identification of Species

morphological traits, reproductive isolation, molecular features, ecological factors, and evolutionary relationships

Morphological Traits

the physical characteristics of a populations members

Reproductive Isolation

prevents one species from successfully interbreeding with another species

Molecular Features

used to compare similarities and differences among different populations (DNA, gene order, etc.)

Evolutionary Relationships

utilizing such evidence like fossils and DNA samples to compare among different populations`

Spontaneous Generation

the idea that nonliving material could give rise to living organisms

Louis Pasteur

disproved the idea of spontaneous generation

Biogenesis

life from life

Big Bang

a dense mass of matter exploded resulting in the formation of atoms

Extraterrestrial

organic molecules came from other planets

Creationism

humans, life, the Earth, and/or Universe as a whole were created by a supreme being or by another deities intervention

Formation of Cells - Stage 1

nucleotides and amino acids were produced prior to the existence of cells; formed spontaneously in atmosphere

Formation of Cells - Stage 2

simple organic molecules, such as nucleotides and amino acids, became polymerized to form DNA/RNA and proteins, respectively

Formation of Cells - Stage 3

polymers became enclosed in membranes; protobionts

Formation of Cells - Stage 4

polymers enclosed in membranes acquired cellular properties; RNA first macromolecule found in protobionts

Geological Timeline (Condensed)

• Earth forms 4.55 bya

• prokaryotes 3.8-3.5 bya

• single celled eukaryotes 1.8 bya

• multicellular eukaryotes 1.5 bya

• dinosaurs and mammals 225 mya

• flowering plants 135 mya

• anatomically modern humans 300,000 ya

Environmental Changes

influence the type of organisms that have existed during different periods of time

Extinction

complete loss of a species or groups of species

Ecology

study of interactions among organisms with each other and their surrounding environment

Biotic Interactions

all of the interactions among the organisms such as humans, plants, animals, and insects

Abiotic Interactions

all of the interactions among organisms and their nonliving environment such as light, water, temperature, etc.

Organismal Ecology

individual organisms behavior, physiology, morphology, etc. in response to interactions with abiotic environment

Physiological Ecology

how organisms are physiologically adapted to their environment

Behavioral Ecology

how behavior of organisms contribute to their survival and reproductive success

Population Ecology

factors which affect population composition, size, and density

Community Ecology

interactions between populations of different species in a given area

Ecosystem Ecology

responses and changes in the community as a result of interactions between biotic and abiotic factors

Temperature

most important factor because of its effect on biological processes

Wind

amplifies effects of temperature by increasing heat and water loss

Water

essential for life and all organisms depend on it for survival

Light

provides energy necessary to drive photosynthesis and thus the primary source of energy in nearly all ecosystems

Periodic Disturbances

fires, hurricanes, typhoons, and volcanic eruptions can devastate biological communities

Density

the number of organisms in a given unit area or volume