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53 Cards in this Set

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centromere
primary constriction
karyotype
is an assemblage of metaphase chromosomes of an individual arranged in pairs according to the order of descending length and position of the centromere.
metacentric chromosome
is one that has a centrally located centromere and chromosome arms with approximately equal length.
submetacentric chromosomes
have centromeres located close to the center of the chromosome, but he chromosome arms are distinctly unequal in length.
acrocentric chromosomes
have centromeres located much nearer one end than the other, resulting in chromosome arms that are decidedly unequal in length.
telocentric
no human chromosomes have centromeres on the end(telocentric), thus having only one arm.
secondary constrictions
human chromosomes that usually represent the site of ribosomal RNA genes.
satellites
short, distal, chromosomal portions.
region
an area of a chromosome between two major landmarks such as centromere, conspicuous band, or chromosome end.
bands
within each region are numbered starting with the band closest to the centromere and proceeding toward the end of each chromosome arm.
syndrome
a complex of symptoms that may include aneuploidies with morphological, physiological, and psychological deviations form normal.
DNA molecules have areas that
are not genes, called junk DNA.

Junk DNA is thought to play important roles in cellular metabolism and inherited diseases.
RFLP Analysis
is one of the original processes used to create a DNA profile.

Restriction Fragment Length Polymorphism.
Restriction Enzymes
enzymes that cut the DNA molecule at specific sites
Gel Electrophoresis
A process that separates fragments of DNA.
Gel
is a thin sheet of gelatin supported by a glass plate with electrodes atached at both ends.

One end of the gel has a positive charge and the other end has a negative charge.

DNA fragments are attracted to the positive end of the gel plate.

Smaller, lighter fragments migrate more easily through the gel and therefore travel farther in a given time period than larger, heavier fragments.
Molecular probes
small pieces of DNA that use the base-pairing rule to locate and bind only to the fragments that will be used to form the DNA profile.
X-ray film
photographs the sheet of DNA bands.

the only bands visible on the developed film are those that have been labeled with molecular probes.
DNA Restriction Analysis
is a method that uses bacterial enzymes known as restriction endonucleases or restriction enzymes to reveal exact nucleotide sequences.
Restriction Map
can be produced with the information obtained through the use of restriction enzymes that cut DNA molecules, such as circular viral DNAs, into specific fragments.
bacteriophage
a virusthus infects bacteria.Particular forms such as lambda are used as vectors for cloning DNA.
bp(base pair)
a pair of complementary nitrogeneous bases in a DNA molecule; also the unit of measurement for DNA sequences.
cathode
the negative electrode from which electrons are emitted; opposite of the anode.
endonuclease
a class of enzymes that degrades DNA and/or RNA molecules that cleave bonds linking adjacent nucleotides
evolution
is a change in the genetic composition of a population.
evolution results
from a change in the frequency of the alleles in the gene pool produced by one or more of the following factors:

mutation, gene flow, natural selection, genetic drift, or nonrandom mating.
mutation
the naturally occurring mutations of genes and chromosomes produce variation in the gene pool.
gene flow
the frequency of alleles in the gene pool may change due to the immigration of emigration of organisms.
natural selection
the impact of the environment on the survival and reproduction of genotypes within the population is a major force in changing the frequency of alleles.

Selection is always on the phenotypes, but the genetic effect is on the genotypes.
genetic drift
the frequency of alleles in the gene pool may change by pure chance.

It is a significant evolutionary mechanism in small populations only.
nonrandom mating
If there is a mating preference for a certain combination of alleles, the frequency of alleles in a population will change.
Castle-Hardy-Weinberg (CHW) law or Equilibrium
states that in the absence of forces that change gene frequencies, the frequencies of the alleles in a population will remain constant from generation to generation.
CHW equation
p2 + 2pq + q2 = 1

p2 = the frequency of TT individuals(homozygous dominants)

2pq= the frequency of Tt individuals(heterozygotes)

q2 = the frequency of tt individuals (homozygous recessives)
systematics
the classification of organisms and groups of organisms.
species
are groups of actually or potentially interbreeding natural populations, which are reproductively isolated form other such groups.
Chromosomes are arranged by:
size,
location of centromere
Chromosomal Alterations
Errors during meiosis lead to abnormalities
deletion
Chromosomes
Lose a piece
translocation
Chromosomes Recombine with a non-homologous chromosome
Errors during recombination (Meiosis I)
can result in some chromosomal abnormalities.
Chromosomal aberrations fall into three general categories:
Translocation/Chromosomal Breaks
Deletion
Fragile site
Polyploidy
presence of additional sets of chromosomes
Common in plants Lethal in most animals
Aneuploidy
presence of extra chromosome or an absence of one
Trisomy
“three bodies” – having one extra chromosome
Monosomy
missing a chromosome
Meiotic nondisjunction causes
the gain or loss of single chromosomes
Aneuploid Condition:

Trisomy 21
Down Syndrome
Aneuploid Condition:

Trisomy 18
Edwards Syndrome
Aneuploid Condition:

Trisomy 13
Patau Syndrome
Chromosome Breaks
Spontaneous breaks due to errors in DNA replication & errors in crossing-over
Environmental factors: UV light, Radiation, Viruses, Chemicals
Cri du Chat: Caused by partial deletion of Chromosome 5
Infant’s cry sound like a cat. Speech problems after infancy.  abnormal glottis & larynx
Sex Chromosome Aneuploidy
is more common than Autosome Aneuploidy
Turner Syndrome
Female (45 total chromosomes, 1 sex chromosome (X))
Only monosomy that is Not lethal
Abnormalities: don’t develop normal at time of puberty, underdeveloped breasts, rudimentary ovaries
Infertile: do Not ovulate or menstruate
Treatment: Hormone supplements can help these women lead normal lives.
Fragile Sites
Fragile X Syndrome: normally CGG is repeated 50 times; in fragile X, up to 1000 times
Makes a very thin physical region of the chromosome.
Results in range of mental retardation and behavioral problems
Occurs in both sexes; most females with fragile X are heterozygous