77 notecards = 20 pages (4 cards per page)
law of segregation
two alleles for a given character separate during gamete formation, and go to different gametes
law of independent assortment
alleles for different characters sort independently of each other during gamete formation
Gregor Mendel's "hereditary factors" and year introduced
(1860) Genes are segments of DNA located along chromosomes
Cytologists worked out the process of mitosis (year) and meiosis (year)
chromosome theory of inheritance (year)(who)(definition)
Thomas Hunt Morgan
Provided the first solid evidence of a specific gene associating with a specific chromosome.
Morgans choice of experimental organism (spelled correctly) (# of chromosomes) (how often a new generation is bred)
Drosophila Melanogaster; 4; every 2 weeks
the phenotype for most organisms
Morgans experimental conclusions
Which one of Mendel's laws relates to the inheritance of alleles for a single character?
law of segregation
Which one of Mendel's laws relates to the inheritance of alleles for two characters in a dihybrid cross?
law of independent assortment
What is the physical basis for each of Mendel's laws in meiosis?
the law of segregation: separation of homologs in anaphase I
the law of independent assortment: alternative arrangements of different homologous chromosome pairs in metaphase I
When does the anatomical signs of sex begin to emerge in humans?
when the embryo is about 2 months old
78 genes code for about 25 proteins
X-linked genes (human)
X-linked recessive disorders
term used in describing a males X-linked gene due to only one locus (XnY)
Duchenne muscular dystrophy
A compact object of condensed inactive X found on the inside of the nuclear envelope.
When an organism has cells with more than one genotype
genes located near each other on the same chromosome tend to be inherited together
the production of offspring with combinations of traits that differ from those found in either P generation parent.
an offspring whose phenotype matches one of the true-breeding parental phenotypes
an offspring whose phenotype differs from that of the true-breeding parental phenotypes
50% or greater frequency of occurrence of parental types indicates two genes are on the same chromosome.
end portions of two nonsister chromatids trade places; recombination of linked genes
genetic map (who)(what)
Alfred H. Sturtevant; an ordered list of the genetic loci along a particular chromosome
the percentage of recombinant offspring; depends on the distance between genes on a chromosome
the farther apart two genes are, the higher the probability that a crossover will occur between them and therefor the higher the recombination frequency
a genetic map based on recombination frequencies
one of many Drosophila genes affecting eye color
the distances between genes; one map unit is equivalent to a 1% recombination frequency
locate genes with respect to chromosomal features, such as stained bands, that can be seen in the microscope
the members of a pair of homologous chromosomes do not move apart properly during meiosis I or sister chromatids fail to separate during meiosis II
an aberrant gamete that unites with a normal gamete at fertilization
2n-1; missing chromosome in zygote resulting from fertilization of normal gamete with one that has no copy of a particular chromosome
2n+1; extra chromosome in zygote resulting from fertilization of normal gamete with one that has an extra copy of a particular chromosome
Monosomy and trisomy are estimated to occur in between 10 and 25% of human conceptions, and is the main reason for pregnancy loss
more than two complete chromosome sets in all somatic cells
3n; three chromosome sets; may arise by the fertilization of an abnormal diploid egg produced by nondisjunction of all its chromosomes
4n; four chromosome sets; may arise from the failure of a 2n zygote to divide after replicating its chromosomes
examples of polyploid
bananas (triploid, 3n); wheat (hexaploid, 6n); strawberries (octoploid, 8n)
polyploids appear more normal than aneuploids. One extra (or missing) chromosome apparently disrupts genetic balance more than does an entire extra set of chromosomes.
2 ways that lead to changes in chromosome structure
4 types of alterations of chromosome structure
chromosomal fragment is lost
the "deleted" fragment may become attached as an extra segment to a sister chromatid
a chromosomal fragment may also reattach to the original chromosome but in the reverse orientation
most common; nonhomologous chromosomes exchange fragments
less common; a chromosome transfers a fragment but receives none in return
translocations and inversions can alter phenotype because a gene's expression can be influenced by its location among neighboring genes
a set of traits characteristic of the type of aneuploidy
Prenatally and Postnatally Diagnosed Conditions Awareness Act (when)(what)
2008; law stipulates that medical practitioners give accurate, up-to-date information about any prenatal or postnatal diagnosis received by parents and that they connect parents with appropriate support services
aneuploidy of sex chromosomes
disorders caused by structurally altered chromosomes
cri du chat
variation in phenotype depending on whether an allele is inherited from the male or female parent (most imprinted genes are on autosomes)(over 60 imprinted genes have been identified, with hundreds more suspected)
What exactly is a genomic imprint?
not all of a eukaryotic cell's genes are located on nuclear chromosomes, or even in the nucleus; some genes are located in organelles in the cytoplasm
extracellular genes or cytoplasmic genes
genes outside the nucleus
organelle genes are not distributed to offspring according to the same rules that direct the distribution of nuclear chromosomes during meiosis, so they do not display mendelian inheritance (p. 309)
Carl Correns (year)
1909; Discovered that extranuclear genes exist; studied the inheritance of yellow or white patches on leaves of a green plant
parts of body most susceptible to energy deprivation
nervous system, muscles
Leber's hereditary optic neuropathy
mitochondrial mutations inherited from a person's mother