Honor's Bio Term 2 (Units 5-8)

spontaneous generation

The now disproved theory that living things can arise from nonliving things

biogenesis

The theory that living organisms come only from other living organisms

hominids

Humans and their close fossil relatives; all species are bipedal and Homo sapiens are the only living species

cyanobacteria

A photosynthetic bacteria that started development of oxygen and ultimately ozone in the atmosphere

vertebates

Organisms with backbones

ozone

A gas that protects the surface of the Earth from ultraviolet light = allowed life to move on land

endosymbiosis

How the mitochondria and chloroplasts of eukaryotic cells likely evolved; may have occurred when a small prokaryote was engulfed by a larger prokaryote.

Redi

Person who demonstrated that maggots do not rise spontaneously from decaying meat and thus attempted to disprove spontaneous generation

Pasteur

Through studies with a curve-necked flask and broth, he proved spontaneous generation was false.

Oparin and Haldane

Believed the early atmosphere contained ammonia, hydrogen gas, water and hydrocarbons that could form organic compounds at high temperatures.

Miller and Urey

Conducted studies to simulate early earth and determine if organic compounds could be created; successfully created amino acids

Spallanzani

Conducted studies to disprove spontaneous generation using broth in flasks. Critics of his study claimed his techniques destroyed a "vital force" and thus were not valid

Cambrian Period

A time during which the earth had an explosion of life in its oceans; most major animals began during this time

arthropod

An invertebrate that has an external skeleton, a segmented body, and jointed appendages; spider, insects and crustaceans

mammal

A warm-blooded vertebrate with hair or fur and females produce milk to feed their young

amphibian

A vertebrate that lives part of its life on land and part of its life in water

reptile

A cold-blooded vertebrate that lives on land, has a body covered in scales, and lays eggs

mass extinction

A large-scale dying out of a large percentage of all living organisms in an area within a short time

primate

A type of mammal characterized by opposable thumbs, four sets of teeth, and binocular vision

evolution

The gradual change in a species over time

natural selection

The process by which individuals that are better adapted to their environment survive and reproduce more successfully than less well adapted individuals do; a theory to explain the mechanism of evolution

artificial selection

The selective breeding of organisms (by humans) for specific desirable characteristics. Can be used to speed up the process of divergent evolution.

Inheritance of acquired characteristics

Lamarck's incorrect idea that individuals could acquire traits during their lifetimes and pass them on to offspring

adaptation

A feature/trait that allows an organism to better survive in its environment

differential reproduction

Organisms with the best adaptations (highest level of fitness) are most likely to survive and reproduce

fossil

The trace or remains of an organisms that lived a long time ago

convergent evolution

Pattern of evolution in which distantly related species evolve similar features

divergent evolution

Pattern of evolution in which species diversify when introduced to new environments; one species evolves into many

mutations

Errors in DNA caused by replication errors or mutagens; a source of genetic diversity.

vestigial structures

Structures without function that can be found in living things; remnants of an organism's evolutionary past

homologous structures

Structures that share a common ancestry

transitional species

Organisms that exhibit intermediate characteristics between two other organisms; smaller change

half-life

The length of time required for half of the radioactive atoms in a sample to decay

carbon dating

A scientific method used to determine the age of an artifact using the amount of Carbon-14 left in an organism

coevolution

The process by which two or more species evolve in response to changes in each other over time

superposition

The principle that in a series of stratified sedimentary rocks, the lowest stratum is the oldest; helps determine fossil age based on relation to the ages of other objects

analogous structures

Structures that have closely related functions but did not derive or come from a common ancestor. Wings of birds, bats and butterflies for example

biogeography

The geographic distribution of species

Hardy-Weinberg Equilibrium

The principle that the shuffling of genes that occurs during sexual reproduction by itself cannot change the overall genetic makeup of a population; only exists very rarely when specific conditions are met

genetic variation

The variety of different types of genes/alleles in a species or population.

genetic drift

A change in the gene pool of a population due to chance

species

A group of organisms that are closely related and can mate to produce fertile offspring

gene pool

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

stabilizing selection

Favors intermediate or average individuals in a phenotypic range

disruptive selection

Favors individuals at both extremes of the phenotypic range

gene flow

Movement of alleles between populations

founder effect

Genetic drift that occurs when a small number of individuals colonize a new area or become isolated from the larger population; the new poulation's gene pool will likely not be representative of the larger population

directional selection

Favors individuals at one end of the phenotypic range and thus shifts population to that side of the range

bottleneck effect

Genetic drift that results from an event (often a natural disaster) that drastically reduces the size of a population

balancing selection

Natural selection that maintains stable frequencies of two or more phenotypes in a population

sickle cell anemia

Hereditary condition that causes red blood cells to become misshapen and break down. Example of balancing selection because one allele is beneficial, but two alleles are harmful.

population

A group of individuals of the same species living in the same place at the same time

Mendelian inheritance

Predictable pattern of genetic inheritance in which the dominant trait is always completely dominant over recessive

Codominance Inheritance

pattern in which alleles are equally dominant and both show up (checkered chicken \= example)

Polygenic

Inheritance pattern in which trait is controlled by more than one gene (skin color, height in humans \= examples)

Multiple alleles

Inheritance pattern in which more than two alleles control the trait (blood type \= example)

Sex-linked traits

Traits carried on the 23rd X chromosome

Incomplete Dominance

Inheritance pattern in which the dominant and recessive trait blend to form an intermediate characteristic in heterozygous individuals (example: Snapdragon color)

Punnett Square

A tool to predict the probability of certain traits in offspring that shows the different ways alleles can combine

Allele

Alternative forms of a gene (example: tall or short height in pea plants)

Recessive trait

A trait that is apparent only when two recessive alleles for the same characteristic are inherited (Mendelian Inheritance)

Dominant trait

The trait observed when at least one dominant allele for a characteristic is inherited (Mendelian Inheritance)

Monohybrid cross

A cross in which only one characteristic or trait is tracked

Gamete

Haploid reproductive cells, egg or sperm

Genetics

The branch of biology that studies heredity

Phenotype

The way an organism looks

Genotype

The gene combination of an organism

Homozygous

Having two identical alleles for a trait (BB or bb)

Heterozygous

Having two different alleles for a trait (Bb)

Dihybrid cross

A cross in which two characteristics or traits are tracked

Heredity

The passing on of characteristics from parents to offspring

Rule of Unit Factors

Organisms have 2 factors for each trait, factors are called genes and can exist in alternative forms called alleles

Law of Independent Assortment

The inheritance of one trait has no effect on the inheritance of another due to the separation of homologous chromosomes and crossing over in prophase/metaphase of meiosis

Law of Segregation

The two alleles for each trait separate when gametes are formed during meiosis and a parent passes on at random only 1 allele per trait to each offspring

Rule of Dominance

One trait dominates or masks the other (Mendelian Inheritance)

Pedigree

Chart showing inheritance of a trait through the generations of a family

Dominant trait pedigree

no generation-skipping of the trait, every shaded child has at least 1 shaded (dom) parent, + if 2 shaded (dominant) have an unshaded child (recessive) since that is only possible in this type of pedigree

Recessive trait pedigree

there is generation-skipping of the trait + if 2 unshaded (dominant) have a shaded (recessive) child since that is only possible in this type of pedigree

Sex-linked trait pedigree

more boys than girls are shaded in this type of pedigree; girls would have to have a dad w/ the trait + either a carrier mom or a mom w/ the trait

centromere

connects + holds together two chromatids

chromosomes

tightly coiled DNA; form of DNA prior and during cell division

sister chromatids

two copies/sides within each duplicated chromosome; they are identical

gamete

a haploid reproductive cell (egg/sperm)

binary fission

how prokaryotic cells divide

diploid

a cell with two of each chromosome or pairs of each chromosome (2n)

haploid

a cell with one set of chromosomes or half the number of chromosomes (1n)

chromatin

loose combination of DNA and proteins that is present during interphase

autosomes

any chromosome that is not a sex chromosome; pairs 1-22 in a humans

sex chromosomes

the 23rd pair of chromosomes in humans; responsible for determining the sex - XX is female and XY is male

S phase

synthesis phase of interphase in which the cell's DNA is copied/replication occurs

cytokinesis

division of the cytoplasm when the cell splits in two, occurs after mitosis

G1 phase

phase of interphase in which cells grow in size

G2 phase

phase of interphase in which cell grows and prepares for cell division

interphase

period of growth in the cell cycle

mitosis

period of division in the cell cycle, division of the nucleus

G0 phase

a state that cells, such as nerve cells, enter when they leave the cell cycle and stop dividing

prophase

1st + longest phase of mitosis - chromatin coils into chromosomes, the nucleus begins to disappear, centrioles move to opposite sides, + the spindle begins to form

metaphase

2nd phase of mitosis - doubled chromosomes become attached to the spindle by the centromeres, which pulls and pushes them to the middle of the cell

anaphase

3rd phase of mitosis - sister chromatids separate as centromeres split apart, ensures that each new daughter cell gets an identical copy

telophase

4th and final phase of mitosis - chromatids reach the poles of the spindle and begin to unwind, the spindle breaks down, and new nuclei begin to form; cytokinesis occurs after this phase