Final Biology Flashcards

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

What is the modern classification system?

Binomial nomenclature

 each type of organism is given a unique, 2-word, latin scientific name showing the genus and species of the organism.  Genus is capitalized.

Phylogeny

 the evolutionary history of a species; often classification of organisms is based on their phylogeny

Phylogenetic Tree

- a diagram that illustrates the evolutionary relationship between groups of organisms based on characteristics such as:

- biochemical similarities

- embryological development

- fossil record

Cladogram

 a diagram that illustrates the evolutionary relationship between groups of organisms based on shared derived traits.

Shared derived traits

- traits that organisms have acquired from their ancestors and share with other members of the group

Clade

 a group of species that share certain specific traits that were derived from their ancestors

Dichotomous Key

- a reference tool that uses a series of paired choices to progressively lead to the identification of an unknown organism

 Viruses

- tiny, non-living biological particles; not a cell!

- have genetic material but lack a nucleus/organelles/cell membrane

- much smaller than even bacteria

- disease-causing pathogens

- must invade other cells in order to replicate themselves

Vaccines

- discovered in 1796 (Edward Jenner)

- used to prepare the immune system for a viral attack

Virus Characteristics of Life

• no growth

• no metabolism

• no homeostasis

• mutations

• genetic code is DNA or RNA

• reproduction only within host cells

Cell characteristics of life

• growth

• homeostasis

• metabolism

• mutation

• DNA genetic code

• reproduction independently

Fossils

the preserved remains, or traces of remains, of ancient organisms. Ex. Molds, casts, imprints, and remains

Absolute Dating

process of determining age of remains based on content and decay rate of radioactive isotopes

Relative Dating

process of determining age of remains based on position in rock strata

Law of Superposition

in any undisturbed sequence of rocks deposited in layers, the youngest layer is on top and the oldest on bottom

Index Fossil

widely distributed fossil, of narrow range in time, regarded as characteristic of a given geological formation

Biogeography

geographic distribution of organisms on Earth indicates evolution in conjunction with the movement of tectonic plates over geological time.

Homologous Structures

 structurally similar features in different  organisms suggesting common ancestry.
- structures perform different functions

- may suggest divergent evolution

Analogous Structures

- similar features found in unrelated organisms that have evolved to perform the same function
- structurally dissimilar, no common ancestry

- Analogous structures suggest convergent evolution

Vestigial Structures

- an anatomical feature that no longer seems to have a purpose in the current form of an organism

Comparative Embryology

-  the study of the similarities and differences in the development of embryos of different species.

- similarities in embryos are evidence of common ancestry

Molecular Evidence

- comparing DNA sequences and protein sequencing between species to determine relatedness

Molecular Clock

using the number of changes in sequences of biomolecules (mutations) to deduce the time in prehistory when two or more life forms diverged; mutation rate is relatively constant, therefore history can be inferred

Theories of Mechanisms of Evolution

ideas about how species change over time

Lamarck

- presented one of the first theories of evolution in 1809

- believed that evolutionary changes were caused by organisms actively adapting themselves to environmental conditions

Law of Use and Disuse (Lamarck)

- the more an animal uses a particular structure the more prominent and well-developed the structure will become. The less a structure is used the less prominent and well-developed it will become.

Inheritance of Acquired Characteristics (Lamarck)

 belief that traits an organism has developed could be passed onto offspring

Three Major Points of Darwin’s Theory of Descent with Modification through Natural Selection

1. Species over-reproduce

2. Competition for limited resources occurs

3. Variations exist among individuals making some better able to compete for limited resources than others; those who gain the most resources reproduce more; their offspring skew the gene pool resulting in evolution of the species

Adaptation

favorable genetic variation; makes an organism more likely to survive and reproduce

Fitness

 measure of reproductive success; how many surviving offspring are produced

Speciation

- accumulation of favorable adaptations over time which result in the  formation of a new species

Genetic Equilibrium

- condition in which allele frequencies in a population do not change from one generation the next; rate of occurrence of traits remains constant; no evolution occurring

evolution

Disruption of genetic equilibrium

Directional Selection

- extreme phenotype becomes a favorable adaptation; usually caused by change to environment or migration to new habitats

Stabilizing Selection

- average phenotypes become more favorable and extreme phenotypes become more unfavorable; usually inhibits the rate of evolution because of a narrowed range of variation

Disruptive Selection

- rare form of natural selection; extreme phenotypes become more favorable than average phenotypes.

- creates two separate subpopulations

Hardy-Weinberg Principle

- outlines conditions necessary for genetic equilibrium in a population to be maintained (no evolution)

Allelic Frequency

- term used to describe how often a particular allele occurs in a population

Gene Pool

- all of the possible alleles that exist in a population

Conditions necessary to maintain Genetic Equilibrium

1. No mutations

2. Individuals may neither enter nor leave a population

3. Large Population

4. Individuals mate randomly; no selective breeding

5. No natural selection (equal survivorship)

Gene Flow

movement of genes from one population to another

Genetic Drift

a change in the allelic frequency of a small population brought about by chance; two important causes of genetic drift: Founder’s Effect and Bottleneck Effect

Founder’s Effect

 populations started by a few pioneering individual moving into a new region (reduces genetic variation)

Bottleneck Effect

 a small group of surviving members of a population breeding together (reduces genetic variation)

Hardy Weinberg Mathematical formulas

used to predict both allele frequencies and genotype frequencies in a population; can predict the occurrence of hidden genotypes

Speciation

Disruption of genetic equilibrium may lead to evolution of an existing species but may not result in the formation of new species
- formation of a new species may occur over many generations

- formation of new species requires isolation of subpopulations

Geographic Isolation

new land or water barriers form; examples include change in the course of a river or new highway built across a field

allopatric speciation

species arise in separate settings

Reproductive Isolation

inability of formerly interbreeding organisms to mate and produce fertile offspring 

sympatric speciation

 species arise in the same setting

Prezygotic

species evolve adaptations that prevent mating

Ex. Different breeding times or mating calls

     Closely related species of frogs breed in spring vs fall

Postzygotic

though species interbreed, mating is unsuccessful 

Ex. inability for zygote develop fully or offspring are sterile

      Tigers and lions produce ligers; ligers are sterile  

Definition of Species

•  members of a species share identical traits

• live in the same geographic area

• have the opportunity to mate

• can mate successfully to produce fertile offspring.

Coevolution

- joint change in two or more species in close interaction i.e. predators/prey or plants/pollinators

Convergent Evolution

 unrelated species become more and more alike (evidence = analogous structures) in appearance as they adapt to similar environmental pressures

 Divergent Evolution

- process by which two related species become more dissimilar ( evidence = homologous structures) over time as they adapt to separate environments

Adaptive Radiation

- type of divergent evolution; process by which a single species develops simultaneously into many different species  

Gradualism

proposes evolution is a slow, gradual and continuous change; fossils show slight changes in organisms between rock layers

Punctuated Equilibrium

proposes that species have long periods of genetic equilibrium interrupted by geologically brief periods of rapid evolutionary change

Genetics

study of heredity

Heredity

- process by which traits are passed from 1 generation to the next

Gregor Mendel

- father of modern genetics

• discovered that offspring inherit at least two genes (one from each parent) for each trait; these genes appear on homologous chromosomes.

Gene

specific region of DNA (found within chromosomes) that codes for a particular trait

Allele

Versions of the same gene (ex. cleft or no cleft for chin shape gene)

Genotype

- combination of alleles an individual has for a specific trait; the actual genetic makeup

Homozygous

- same allele on both homologous chromosomes (ex TT or tt)

Heterozygous

- opposing alleles on homologous chromosomes (ex Tt)

Phenotype

- physical expression of a genotype; the way a person looks

Law of Dominance

- when an organism has a pair of contrasting alleles for a trait, the dominant allele is expressed and the recessive allele is hidden.

Law of Segregation

- homologous chromosomes carrying genes for the same traits are separated during gamete formation (meiosis) and recombined/restored through fertilization.

Punnett Square

- diagram used to determine the possible outcomes of a specific genetic cross

Five Types of Genetic Crosses:

I. Simple Dominance

II. Incomplete and Codominance

III. Sex-linked

IV. Multiple alleles

V. Dihybrid

I. Simple Dominance

cross between two individuals that involves a pair of contrasting alleles; one allele is dominant and can hide the presence of the other in a heterozygous genotype.

II. Incomplete/Codominance

 a combination of the two contrasting alleles resulting in an intermediate phenotype. Neither allele is completely dominant over the other.

III. Sex-Linked

genes for certain traits that are linked to the X sex chromosome with no corresponding gene on the Y chromosome.

IV.  Multiple Alleles

 Inheritance of some traits are determined by more than two types of alleles

V. Dihybrid Cross

Cross between two individuals that looks at the inheritance of two different traits/two pairs of alleles at the same time.

Conclusion Statement for Chi square

The probability that the results are due to pure chance and not bias are

between _____ and _____ %; therefore the results are accepted/not accepted

pedigree

a genetic representation of a family tree that diagrams the inheritance of a trait or disease through several generations.

Autosomal Dominant Trait (Inheritance Pattern)

• typically no skipped generations

• equal incidents in female and male

• no carriers

Autosomal Recessive Trait (Inheritance Pattern)

• skipped generations are possible

• equal incidents in male & female

• both male & female carriers

Recessive X-sex Chromosome Linked (Inheritance Pattern)

• primarily affects males

• can skip generations

• only female carriers

What is Mitosis is used for?

a. Growth in multicellular organisms

b. Repair and regeneration of tissues/organs

c. Asexual repro in multicellular organisms (ex: spores, veg propagation)

d. Asexual Reproduction of unicellular organisms

What are the steps of mitosis?

Prophase, Metaphase, Anaphase, Telophase, (Cytokinesis)

Interphase

Nuclear membrane visible; no chromosomes present

Prophase

Nuclear membrane disappears, chromosomes appear

mitotic spindle begins to appear; centrioles on animals appear and migrate towards poles of cell

Metaphase

Chromosomes in single line along equator of cell; mitotic spindle formed

Anaphase

Sister chromatids separate; migrate to poles of cell

Telophase

Sister chromatids (now called individual chromosomes) clustered at poles of cell; nuclear membrane begins to reform, mitotic spindle disappearing

Cytokinesis

Cleavage furrow (animal) or cell plate (plant) visible; chromosomes disappearing or invisible; nuclear membrane reformed

Results of Mitosis

1 diploid (2N) somatic cell -----> 2 diploid (2N) somatic cells

Both cells should be identical except for point mutations

What is meiosis used for?

Used by multi celled organisms for: production of gametes only!

Only occurs in gonadal tissues

Prophase I

the nuclear membrane disappears, chromosomes appear, centrioles appear 

and begin to migrate to the poles; “Tetrads” form and “crossing over” occurs

during synapsis

Synapsis

Homologous chromosomes “find” each other; form tetrads

Crossing over

Form of genetic variation in which non sister chromatids in the same tetard exchange genes

Metaphase I

Homologous pairs line up as partners at equator; mitotic spindle fully formed; maternal/paternal chromo. randomly situated 

Anaphase I

Homologous pairs separate; whole chromosomes migrate to poles

Random distribution of maternal/paternal chromosomes to poles ensures “independent assortment” of genetic information

Telophase I

Chromosomes collected at poles; mitotic spindle disappears

Nuclear membrane reappears