Bio II

Genome

cells complete complement of DNA (all its needed DNA)

Prokaryotes

one double stranded circular DNA molecule

Eukaryotes

multiple double stranded linear DNA molecules (Chromosomes)

Chromosomes

 condensed strand of DNA plus histone proteins

Cell cycle check points

internal control mechanisms at which the cell cycle can be stopped if certain requirements are not met

G1 checkpoint

cell reserves and size, DNA damage

G2

ensure all chromosomes have been replicated, replicated DNA is not damaged

M checkpoint

takes place in early metaphase, determine if chromosomes are properly attached to the mitotic spindle

Gene mutation

changes to the DNA nucleotide sequence of a gene

Proto-oncogene

genes that code for positive cell cycle regulators

Oncogene

genes that cause a cell to become cancerous

Tumor suppressing genes

genes that code for negative regulator proteins

Binary fission

common cell division process of prokaryotes

Septum

new cell wall formed between daughter cells

Meiosis

nuclear division process causes four haploid cells

Life cycles

sequence of events in development of organism and production of sex cells

Diploid dominant

multi cellular diploid stage is the most obvious life stage

Haploid dominant

multi cellular haploid stage is most obvious life stage

Alternation of generations

two stages a diploid and a haploid present

Gametophyte

heart of the life cycle that produces gametes and is haploid

Sporophyle

heart of life cycle that produces spores and is diploid

Germ cells

cell lines that produce gametes

Fertilization

union of two cells from two individual organisms

Somatic cells

non reproductive cells of a multi cellular organism

Meiosis I

first round of nuclear division

Prophase I

exchanges DNA and causes crossover between chromosomes within the cell dividing

Synapsis

tight pairing of homologous chromosomes

Crossing over

exchange of chromosome segments between nonsister homologous chromatids

Chiasmata

point of crossing over

Tetrads

four chromatids of each pair of homologous chromosomes

Recombinant

composed of genetic material from two sources

Prometaphase I

attachment of spindle fiber microtubules to chromosomes

Metaphase I (1)

Homologous chromosomes line up along metaphase plate

Metaphase I (2)

Orientation of homologous chromosomes is random

Anaphase I

Spindle fibers pull chromosomes apart

Telophase I

Separated chromosomes arrive at poles

Cytokinesis (1)

Division of cytoplasm

Cytokinesis (2)

One set of chromosomes in each cell

Cytokinesis (3)

Not considered haploid

Interkinesis

brief interphase between meiosis I and II (lacks an S phase)

Meiosis II

second round of nuclear division, proceeds similarly to mitosis

Interphase

nearly identical to the phases preceding mitosis

Mitosis (1)

two diploid daughter cells

Mitosis (2)

genetically identical to parent, functions: grow & repair

Meiosis (1)

four haploid daughter cells

Meiosis (2)

two nuclear divisions, genetically distinct, functions: sexual reproduction

Diploid

two full sets of chromosomes (2n)

Haploid

one full set of chromosomes (n)

Karyotype

number and appearance of chromosomes

Karyograms

visualization of chromosomes

Translocations

movement of a segment of chromosomes to a different chromosome

Non-disjunction

failure of homologous chromosomes or sister chromatids to separate during meiosis

Euploid

individual with appropriate number of chromosomes

Aneuploid

individual with an error in chromosome number

Trisomy

gain of a chromosome to a homologous pair

Monosomy

loss of a chromosome of a homologous pair

X inactivation

condensation of X chromosomes into Barr bodies during development to compensate for double genetic does in femalesPolyploidy

Polyploidy

having more than two sets of chromosomes

Chromosomes inversion

rotation and reinsertion of part of a chromosome

Model system

system commonly used to study biological phenomena

Continuous variation

numerically measured variation, variation along a continuum

Discontinuous/discrete variation

variation with in a few discrete states

Hybridization

mating two individuals that have different traits

F1

first generation of crosses from parent generation

F2

second offspring generation from self pollination of F1

Trat

variation in a heritable characteristic

Reciprocal cross

paired cross in which the respective traits of the male and female in one cross are swapped in the next

Dominant

traits that are inherited unchanged in hybridization

Recessive

traits that become latent in hybridization

Punnett square

tool to predict all possible outcomes of a fertilization event

Allels

gene variants

Phenotype

observable trait expressed by an organism

Genotype

combination of alleles for a given gene

Homozygous

having two identical alleles for a given gene (BB)

Heterozygous

having two different alleles for a given gene (Bb)

Law of Segregation

paired unit factors must segregate equally into gametes such that offspring having an equal likelihood of inheriting either factor

Test cross

method to determine if an organism with a dominate trait was a heterozygote or homozygote

Law of Independent Assortment

every possible combination of alleles for every gene is equally likely to occur

Incomplete dominance

expression of two contrasting alleles that the individual displays an intermediate phenotype (white flower + red flower = pink flower)

Codominance

complete and simultaneous expression of both alleles for a characteristic

Wild type

the most common phenotype or genotype

X-linking

a gene present of X chromosome but not the Y

Linkage

genes being located physically close on a chromosome and likely inherited as a pair

Epistasis

an antagonistic interaction between genes