PCB 3063 EXAM 1

genome

complete set of genetic instructions for any organism; encoded in nucleic acid

transmission genetics

encompasses the basic principles of heredity and how traits are passed from one generation to the next

molecular genetics

concerns the chemical nature of the gene itself: how genetic information is encoded, replicated and expressed

population genetics

explores the genetic composition of groups and individuals of the same species (population) and how that composition changes over time and space

model genetic organism

organisms with characteristics that make them particularly useful for genetic analysis and about which a tremendous amount of genetic information has accumulated

pangenesis

ancient greeks developed; concept suggested that specific pieces of information traveled from various parts of the body to the reproductive organs from which they are passed to the embryo; was proven incorrect

inheritance of acquired characteristics

ancient greeks lead to this; which traits acquired in a person;s lifetime e become incorporated into that person's hereditary information and are passed on to offspring; ex. musical ability ; was proven incorrect

preformationism

miniature organism reside in sex cells; thus all traits are inherited from one parent; which was proven to be incorrect

blending inheritance

proposed that the traits of offspring are a blender, or mixture of parental traits; proved to be incorrect

cell theory

schledian and schwann proposed; all life is composed of cells, cells only arise from preexisting cells and the cell is the fundamental unit of structure ad function in living organisms. ; was proven correct

germ plasm theory

weismann; holds that the cells in the reproductive organs carry a complete set of genetic information that is passed to the egg and sperm ; was proven correct

menedelian inhertiance

traits are inherited according to specific pinrciples proposed by mendel- was proven correct

two types of basic cells

eukaryotic and prokaryotic

gene

fundamental unit of heredity; an inherited factor that helps determine a trait; often defined at the molecular levels as a DNA sequence that is transcribed into an RNA molecule

alleles

genes that come in forms of

genes confer

phenotypes

genetic information is carried in

dna and rna

mutations

changes in genetic information that can be passed from cell to cell or from parent to offspring

genetic information is transferred from

dna to rna in protein

repliecated chromosomes separate through

the process of mitosis and meiosis

genes are located on

chromosomes

prokaryote

unicellular with a relatively simple cell structure- no nucleus

eukaryote

has a compartmentalized cell structure with components bounded by intracellular membranes; can be unicellular or multicellular

eubacteria

true bacteria; type of prokaryotic

archaea

ancient bacteria ; type of prokaryotic

nucleus

covered by nuclear enveloped; contains genetic material

chromatin

the complex of dana and histone proteins is called _____ also stuff of eukaryotic chromosomes

histones

in eukaryotes, dna is closely associated with a special class of protein to form a packed chromosome

mitosis

process by which the nucleus of a eukaryotic cell divides

mitochondria

power house of the cell

meiosis

process in which the chromosome of a eukaryotic cell divide to give rise to haploid reproductive cells; consists of two divisions: meiosis I and meiosis II

gametes

male or female sex cell

homozygous

having 2 identical alleys at a locus

geneic sex determiation

sex determination in which the sexual phenotype is specified by genes at one or more loci but there are no obnoxious differences in the chromosomes of males and females

cohesin

molecule that holds the two sister chromatids of a chromosome together. the breakdown of cohesion at the centromeres enable the chromatids to separate in anapahase of mitosis and anaphase II of meiosis

chiasma

point of attachment between homologous chromosomes at which crossing over takes place

cell cycle

stages through which a cell passes from one cell division to the next

centriole

cytoplasmic organelle consisting of microtubules; present at each pole of the spindle apparatus in animal cells

centromere

constricted region o a chromosome that stains less strongly that the rest of the chromosomes; region where spindle micrutbules attach to a chromosome

checkpoint

a key transition point at which progression to the next stage in the cell cycle is regulated

cytokinesis

process by which the cytoplasm of a cell divides

chromosome

structure consisting of DNA and associated proteins that contains genetic information; the cells of each species have a characteristic number of chromosomes

codominance

type of allelic interaction in which the heterozygote simultaneously expresses traits of both homozygotes

consanguinity

mating between related individuals

conditional mutation

mutation that is expressed only under certain conditions

cytoplasmic inhertiance

inheritance of characteristics encoded by genes located in the cytoplasm; because the cytoplasm is usually contributed entirely by only one parent, most cytoplasmically inherited characteristics are inherited from a single parent

allel

one of two or more alternative forms of a gene

autosomes

chromosomes that are the same in number of morphology in males and females

backcross

cross between an F1 and individual and one of the parental (P) geneotypes

Barr body

inactivated X chromosomes that appears as condensed, darkly staining structure in most cells of female placental mammals

bivalent

a homologous pair of synapsed chromosomes

crossing over

exchange of genetic material between homologous but non sister chromatids

dihybrid cross

cross between 2 individuals that differ in two characteristics- more specifically, a cess between individuals that are homozygous for different alleles at the two loci (AA BB x aa bb); also refers to a cross between 2 individuals that are both heterozygous at two loci (Aa Bb x Aa Bb)

diploid

possing two sets of chromosomes

dominant

reers to an alley or phenotype that is expressed in homozygote (AA) and in heteroyzgytoes (Aa) ; only the dominant allele is expressed in a heterozygote phenotype

dosage compensation

equalization in males and females of the amount of protein produced by X linked genes; in placental mammals, this is accomplished by the random inactivation of one X chromosome in the cells of females

epistasis

type of gene interaction in which a gene at one locus masks or suppresses the effects of a gene at a different locus

heterozygous

having 2 different alleles at a locus

g2/m checkpoint

important checkpoint in the cell cycle near the end of g2 after which the cell undergoes mitosis

g overhange

a guanine rich sequence of nucleotides that protrudes beyond the complimentary c rich strand at the end of a chromosome

g1/s chekcpoint

important check point in the cell cycle after hiccup DNA replicates and the cell is committed to dividing

haploid (1n)

possessing a single set of chromosomes

incomplete dominance

type of dominance in which the phenotype of the heterozygote is intermediate between the phenotypes of the two homozygotes

independent assortment

independent separation of chromosome pairs in anaphase I of meiosis; contributes to genetic variation

hemizygosity

possession of a single allele at a locus; males of organisms with XX-XY sex determination are homozygous for X linked loci because their cells possess a single X chromosome

genomic imprinting

differential expression of a gene that depends on the sex of the parent that transmitted the gene

homogametic sex

the sex(female or male) that produces gametes that are all alike with regard to sex chromomses. for example, in the xx-xy sex determining system the female produces only x- bearing gametes

heterogametic sex

the sex (male or female) that produces two types of games with respect to sex chromosomes; for example, in the xx-xy sex determining system, the male produces both x-bearing and y-bearing gametes

karyotype

the complete set of chromosomes possessed by an organism; usually presented as a picture of metaphase chromosomes lined up in descending order of their size

klinefelter syndrome-- xxy 47

human syndrome in which cells contain one or more y chromosome long with multiple x chromosomes ; persons with this are male in appearance but frequently posses small testes, some breast enlargement, and reduced facial and pubic hair, they are often taller than normal, sterile and most have normal intelligence

nucleus

organelle found in eukaryotic cells that is enclosed by the nuclear enevlope and contains the chromosomes

spindle pole

point from which spindle micotubles raidate

spindle microtubule

microtubule that moves chromosomes in mitosis and meiosis

tetrad

the four products of meiosis; all 4 chromatids of homologous pair of chromosomes

spermatogenesis

sperm production in animals

sister chromatids

2 copies of a chromosome that are held together at the centromere; each chromatid consists of a single DNA molecules

telomere

stable end of a chromosome

test cross

cross between an individual with an unknown genotype and an individual with the homozygous recessive genotype

pedigree

pictorial representation of a family history outline the inheritance of one or more traits or diseases

principle of segregation

mendels 1st law; principle of heredity that states each diploid individual posses two alleys at a locus and that these two alleles separate when gametes are formed, one allele going into each gamete

proband

person with a trait or disease for whom a pedigree is constructed

phenotype

appearance or manifestation of a characteristic

p (parental) generation

first set of parents in a genetic cross

psuedoautosomal region

small region of the x and y chromosome that contain homologous gene sequences

synapsis

close pairing of homologous chromosomes

sex linked characteristics

characteristics determined by a gene or genes on a sex chromsome

s phase

stage of interphase in the cell cycle during which DNA replicates

sex limited chacateristics

charactersitisc encoded by autosomal genes and expressed in only one sex. both males and females carry genes for this characteristics; but the chacteristicsc appear in only one of the sexes

sex influenced characteristic

charactersitic encoded by autosomal genes that is more readily expressed in one sex; for example an autsomal dominant gene may have higher penetrance in males that in females or an austoosmoal gene may be dominant in males but recessive in females

sex chromosomes

chromosomes that differ in # or morphology in males and females

sex determination

specification of sex; which include chrosomsoal, genie and environmental sex determining system

sex determing region Y gene

a gene on the Y chromosome that triggers male development

temperature senstive allele

allele that is expressed only at certain temperatures

turner syndrome

human syndrome in which cells contain a single x chromosome and no y chromosomes (XO) ; persons with this are female in appearance but don't undergo puberty and have poorly developed female secondary sex characteristics; most are sterile but have normal intelligence

plasma membrane

found in both prokaryote and eukaryotic cells; membrane that separates the interior of all cells from the outside environment.

nucleolus

a small dense spherical structure in the nucleus of a cell during interphase.

endosymbiont

any organism that lives to mutual benefit within the body or cells of another organism, example: mitochondria and chromoplast

spindle fibers

form a protein structure that divides the genetic material in a cell. necessary to equally divide the chromosomes in a parental cell into two daughter cells during both types of nuclear division: mitosis and meiosis.

ER

a network of membranous tubules within the cytoplasm of a eukaryotic cell, continuous with the nuclear membrane. It usually has ribosomes attached and is involved in protein and lipid synthesis.

interphase

the resting phase between successive mitotic divisions of a cell, or between the first and second divisions of meiosis.