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PBHS AP BIO Ch.13-16
Vocab daily work
Term | Definition |
---|---|
heredity | transmission of traits from one generation to the next |
genetics | the study of heredity |
genes | unit of hereditary information consisting of a specific nucleotide sequence in DNA |
gametes | vehicles that transmit genes from one generation to the next. |
asexual reproduction | when a single individual is the sole parent and passes copies of all its genes to the offspring. |
clone | a group of genetically identical individuals |
sexual reproduction | when two parents have offspring that have unique combinations of genes inherited from both of them |
somatic cell | any cell other than those involved in gamete formation. |
karyotype | a display of chromosome pairs on a cell arranged by size and shape |
homologous chromosomes | two chromosomes composing a pair that have the same length |
sex chromosomes | the X and Y chromosomes |
autosomes | the set of chromosomes that are not sex chromosomes |
diploid cell | any cell with two chromosome sets |
fertilization | the union of gametes |
zygote | the resulting fertilized egg after fertilization |
meiosis | a modified type of cell division that forms gametes |
alternation of generations | a type of life cycle that includes both diploid and haploid stages that are multicellular |
gametophyte | a multicellular haploid stage that generates when a haploid spore doesn't fuse with another cell but divides mitotically |
sporophyte | the multicellular diploid stage in alternation of generations |
chiasma | an X shaped region that connects two homologs |
independent assortment | the first meiotic division that results in each pair sorting its maternal and paternal homologs in two daughter cells independently of every other pair. |
crossing over | genetic rearrangement between non sister chromatids |
recombinant chromosomes | individual chromosomes that carry genes derived from two different parents |
true-breeding | plants that produce offspring of the same variety when they self pollinate |
P generation | the parental generation of true breeding plants |
F1 generation | the hybrid offspring of the P generation |
F2 generation | the offspring of the F1 generation |
hybridization | the mating of two true breeding varieties |
law of segregation | states that the two alleles for heritable character separate during gamete formation and end up in different gametes |
alleles | alternative version of a gene |
punnett square | a handy diagram device to predict allele composition of offspring from across between individuals of known genetic makeup |
homozygous | organism that has a pair of identical alleles for a character |
heterozygous | an organisms that has two different alleles for a gene |
phenotype | organisms apperance or observable trates |
genotype | genetic makeup |
monohybrids | heterozygous for one character |
dihybrids | individuals heterozygous for two characters |
law of independent assortment | each pair of alleles segregates independently of each other pairs of alleles during gamete formation |
complete dominance | when the phenotypes of the heterozygote and the domininant homozygote are indistinguishable |
incomplete dominance | neither allele is completely dominant and the F1 hybrids have a phenotype somewhere between those of the two parental varieties |
codominance | when the two alleles both affect the phenotype in separate, distinguishable ways |
epistasis | a gene at one locus alters the phenotypic expression of a gene at a second locus |
tay-sachs disease | an inherited disorder in humans when the observed dominant relationship of alleles depends on the level in which we examine phenotypes. |
polygenic inheritance | an additive effect of two or more genes on a single phenotypic character |
pedigree | a family tree that describes the traights of parents and children across a generation |
cystic fibrosis | the most common lethal genetic disease in the U.S. |
huntington's disease | a degenerative disease of the nervous system caused by lethal dominant allele that has no obvious phenotypic effect until the individual is about 35 to 45 |
sickle-cell disease | the most common inherited disorder among people of african decent |
amniocentesis | a technique that determine whether the developing fetus has tay-sachs disease |
choronic villus sampling | an alternative technique that is an alternative to amniocentesis |
chromosome theory of inheritance | the theory that genes have specific loci along chromosomes and it is the chromosomes that undergo segregation and independent assortment |
wild type | phenotype for a character most commonly observed in natural populations |
sex-linked gene | a gene located on either sex chromosome |
duchenne muscular dystrophy | progressive weakining of the muscles and loss of coordination |
hemophillia | sex linked recessive disorder defined by the absence of one or more of the proteins require for blood clottin |
barr body | it lies along the inside of the nuclear envolope |
linked genes | genes located on the same chromosome that tend to be inherited together in genetic crosses |
genetic recombination | the production of offspring with combinations of traits that differ from those found in either parent |
parental types | the offspring expected to inherit a phenotype that matched one of the parental phenotypes |
linkage maps | a genetic map based on recombination frequincies |
cytogenic maps | maps which locate genes with respect to chromosomal features that can be seen in a microscope |
nondisjunction | mishap where members in a pair of homologous chromosomes do not move apart properly during meiosis 1 |
polyploidy | chromosomal alteration when organisms have two complete chromosomes sets in all somatic cells |
monosomic | a cell that only has one copy of the chromosome instead of the normal two |
deletion | what occurs when a chromosomal fragment is lost |
duplication | when a deleted fragment becomes attached as an extra segment to a sister chromatid |
inversion | when a chromosomal fragment reattaches to the original chromosome but in the reverse orientation |
translocation | a result of chromosomal breakage when a fragment joins a nonhomologous chromosome |
down syndrome | the result of an extra chromosome 21 that results in heart defects, short stature, and mental retardation |
genomic imprinting | variation in phenotype depending on whether an allele is inherited from the male or female parent |
transformation | a change in genotype and phenotype due to the assimilation of external DNA by the cell |
bacteriophages | viruses that infect bacteria |
double helix | the form of native DNA |
semiconservative model | when a double helix replicates, each of the daughter cells will have one old strand derived from the parent molecule |
replication fork | Y shaped region where the parental strands of DNA are being unwound |
helicases | an enzyme that untwists the double helix of DNA at replication forks |
topoisomerases | helps relieve strain by breaking, swiveling, and rejoining DNA strands |
DNA polymerases | enzymes that catalyze the synthesis of new DNA by adding nucleotides to a preexisting chain |
leading strand | the new complementary DNA strand synthesized continuously along template strand toward the replication fork |
lagging strand | a discontinuously synthesized DNA strand that elongates by means of okazaki fragments |
okazaki fragments | short fragments of DNA synthesized away from the replication fork on a template strand during DNA replication, many of which are joined to make up the lagging strand of newly synthesized DNA |
DNA ligase | enzyme that joins sugar-phosphate backbones of all the okazaki fragments into a continuous strand |
mismatch pair | when enzymes remove and replace incorrectly paired nucleotides that result from replication errors |
nuclease | an enzyme that helps a segment of the strand containing DNA damage to be cut out |
nucleotide excision repair | DNA repair system when enzymes involved in filling the gap are a DNA polymerase and legase |
telomeres | special nucleotide sequences that do not contain genes |
telomerase | enzyme that catalyzes the lengthening of telomeres in eukaryotic germ cells, thus restoring their original langth |
chromatin | complex of DNA and protein that fits into the nucleus through a system of DNA packing |
heterochromatin | type of interphase where centromeres and telomeres of chromosomes exist in a highly condensed state |
euchromatin | a less compacted, more dispersed form of heterochromatin |
dispersive model | when the parent helix is broken into fragments, dispersed and copied then assembled into two new helices |