Biology 9A Kymissis Finals

Meiosis

Type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes and plant spores.

Somatic Cells

Body Cells

Gametes

Reproductive Cells; cell differs depending on sex

Diploid Cell

Cell with 2 complete sets of chromosomes

Haploid Cell

Cell with 1 complete set of chromosomes

Prophase 1

Phase of meiosis where chromatin condenses to form chromosomes joined to a centrosome, and the meiotic spindle forms

Synapsis

Pairing of homologous chromosomes at the start of meiosis that does not occur in mitosis

Homologous Chromosomes

Material that is separated in anaphase 1 of mitosis

Sister Chromatids

Material that is separated in anaphase 2 of mitosis

Law of Independent Assortment

Mendel’s law of meiosis in which homologous chromosomes are randomly distributed to daughter cells, and different chromosomes segregate independently of each other

n

Letter that represents the number of chromosomes in a single set or haploid cell

2^n

Formula for calculating the amount of distinct genotypes possible given a diploid number

8

How many combinations of genotypes are possible given 2n=6?

Epigenetics

The study of changes in organisms caused by modification of gene expression rather than alteration of the genetic code itself

Gene Therapy

The transplantation of normal genes into cells in place of missing or defective ones in order to correct genetic disorders

CRISPR-Cas9

A tool that edits genes by precisely cutting DNA and then letting natural DNA repair processes to take over

Karyotype

A diagram displaying the number and visual appearance of the chromosomes in the cell nuclei of an organism sorted based on size

Nondisjunction

The failure of homologous chromosomes or sister chromatids to separate properly during cell division

Deletion

A type of mutation that involves the loss of one or more nucleotides from a segment of DNA

Duplication

A type of mutation in which one or more copies of a DNA segment is produced

Inversion

A type of mutation in which a section of DNA breaks away and reattaches to the chromosome in a reversed order

Translocation

A type of mutation in which DNA segments are exchanged with the segments of different strands or with different parts of its own strand

Deletion

Most dangerous chromosomal mutation that results in the removal of genetic information

P

Letter representing the parental generation in a genetic cross

F1

Abbreviation representing Filial 1, or first generation of offspring from a cross-mating of distinctly different parental types

F2

Abbreviation representing Filial 2, or second generation of offspring from a cross-mating of distinctly different parental types

Hybridization

The process of an animal or plant breeding with an individual of another species or variety

Monohybrid

A hybrid that is heterozygous with respect to a specified gene

Dihybrid

A hybrid that is heterozygous for alleles of two different genes

Genotype

The genetic constitution of an individual organism

Phenotype

The set of observable characteristics of an individual organism

Allele

Alternate versions of a gene

Law of Segregation

Mendel’s Law that a sperm or egg carries only one allele for each inherited character because allele pairs seperate from each other during the production of gametes

Homozygous

Pair of matching alleles

Heterozygous

Pair of contrasting alleles

9:3:3:1

Classic Mendelian ratio for a dihybrid cross in which the alleles of two different genes assort independently into gametes

1:2:1

Classic Mendelian ratio for a monohybrid cross in which the alleles of two different genes assort independently into gametes

Sickle Cell Anemia

A severe hereditary genetic disorder in which a mutated form of hemoglobin distorts the red blood cells into a crescent shape at low oxygen levels

Carrier

Someone who has the trait that causes a disease, but is not affected by it

Natural Selection

A process by which organisms that are better adapted to their environment tend to survive and reproduce more offspring

Artificial Selection

Process by which humans use animal breeding and plant breeding to selectively develop particular phenotypic traits

Fossils

Natural artifacts that provide a record of how creatures evolved and shows similar structures in different species, showing that all species are related to each other

Homologous Structures

Similar anatomical structures in fossils that prove different organisms evolved from common ancestors

Vestigial Structures

Anatomical structures in modern organism that have no purpose do to being remnants of a past ancestor

Analogous Structures

Features of different species that serve similar purposes but have different structures, and are not from a common ancestors

Variation

Important feature of a population caused by mutations

Microevolution

Small evolutionary change within a species or small group of organisms over a short period

Gene Pool

The stock of different genes in an interbreeding population

Gene Flow

The introduction of genetic material from one population of a species to another by use of interbreeding

Genetic Drift

Change in frequency of an existing gene variant in the population due to random chance

Population Bottleneck

A sharp reduction in the size of a population due to environmental events

Founder Effect

The reduced genetic diversity which results when a population is descended from a small number of colonizing ancestors

Survival of the Fittest

Process in which organisms that are better adapted to their environment are, “fittest,” meaning best suited to survive and successfully reproduce

Directional Selection

Individuals with traits on one side of the mean in their population survive better or reproduce more than those on the other

Disruptive Selection

Extreme phenotypes within a population have a fitness advantage over intermediate individuals

Stabilizing Selection

Intermediate phenotypes within a population have a fitness advantage over extreme individuals

Sexual Selection

Mode of natural selection in which members of one biological sex choose mates of the other sex to mate with, and compete with members of the same sex

Sexual Dimorphism

Distinct difference in size or appearance between the sexes of an animal in addition to difference between the sexual organs themselves

Intersexual Selection

Process in which both sexes progress into mating by reaching a consensus

Intrasexual Selection

Process in which members of 1 sex compete to mate with one of another sex

Speciation

The formation of new and distinct species in the course of evolution

Species

Groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups

Reproductive Barriers

Factors that stop species from interbreeding

Prezygotic Barriers

Barriers that prevent members of different species from mating to produce a zygote

Postzygotic Barriers

 A mechanism that blocks reproduction after fertilization and zygote formation

Temporal Isolation

Prezygotic Isolation in which species are not active for mating at the same period in time

Mechanical Isolation

Prezygotic Isolation in which species do not have compatible reproductive organs

Spatial Isolation

Prezygotic Isolation in which species live areas unreachable from each other

Gametic Isolation

Prezygotic Isolation in which species cannot fertilize each other’s gametes because the fertilization process does not occur even when gametes come in contact

Behavioral Isolation

Prezygotic Isolation in which species do not have matching mating behaviors

Hybrid Inviability

Postzygotic Isolation in which the hybrid that is created from fertilization is not able to survive past embryonic phase

Allopatric Speciation

Mode of speciation that occurs when biological populations become geographically isolated from each other to an extent that prevents or interferes with gene flow

Sympatric Speciation

Evolution of a new species from a surviving ancestral species while both continue to inhabit the same geographic region

Polyploid

Cell containing more than two homologous sets of chromosomes because of rare mitotic or meiotic catastrophe such as nondisjunction

Adaptive Radiation

Rapid increase in the number of species with a common ancestor, characterized by great ecological and morphological diversity

Gradualism

The hypothesis that evolution proceeds chiefly by the accumulation of gradual changes

Punctuated Equilibrium

The hypothesis that evolutionary development is marked by isolated episodes of rapid speciation between long periods of little or no change

Binomial Naming System

Species naming system that names species according to their genus and species

Ecology

The branch of biology that deals with the relations of organisms to one another and to their physical surroundings

Biosphere Ecosystem Community Population Organism

5 levels of ecology sorted from largest to smallest scale

Biotic Factor

A living organism that shapes its environment

Abiotic Factor

A non-living part of an ecosystem that shapes its environment

Population

Group of the same species living in the same area

Community

A group of different species living in the same area

Ecosystem

Area consisting of all the organisms and the physical environment with which they interact

Biosphere

The regions of the surface, atmosphere, and hydrosphere of the earth occupied by living organisms

Birth

Event that of increases population from inside a population

Death

Event that of decreases population from inside a population

Migration

Movement of members of a population from the rest of the population

Clumped Dispersion

Individuals of a population are clustered in groups

Random Dispersion

Individuals of a population are not residing in any noticeable pattern

Uniform Dispersion

Individuals of a population reside in a uniform matter, equal distances away from each other

Exponential Growth

A population's per capita growth rate stays the same regardless of population size, making the population grow faster and faster as it gets larger

Logistic Growth

A population's per capita growth rate gets smaller and smaller as population size approaches a maximum imposed by limited resources in the environment, known as the carrying capacity

Carrying Compacity

The largest a population can grow because it is limited by biotic and abiotic factors

Limiting Factor

A factor that constrains a population's size and slows or stops it from growing

Density Independent Factors

Limiting factors that are not affected by population size (Ex. natural disaster)

Density Dependent Factors

Limiting factors that have varying impacts according to population size (Ex. disease, competition, predation)

Commensalism

Symbiotic relationship in which 1 organism is benefitted while the other is not affected

Mutualism

Symbiotic relationship in which both organisms benefit