Chapters 12,13,14

Midterm 2
Created Oct 31, 2009
by emma.feldman
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polygenic diseases
ex: heart disease & cancer; based on many genes working in concert with a given set of...
x-linked disorders
the genes that cause them lie on the x-chromosome; claim more male victims than femaleex: hemophilia,...
recessive disorder
a genetic disorder that will not exist in the presence of a functional allele
autosomal recessive disorder
a recessive dysfunction related to an autosome  (chromosomes other than X & Y)ex:...
a person who does not suffer from a recessive genetic debilitation, but who carries an allele...
dominant disorders
genetic conditions in which a single faulty allele can cause damage, even when a second, functional...
autosomal dominant disorder
dominant genetic disorder caused by a faulty allele that lies on an autosomal chromosomeex:...
a familial history intended to track genetic conditions; can be used to ascertain whether a...
a condition in which one or more entire sets of chromosomes has been added to the genome of...
a condition in which an organism has either more or fewer chromosomes than normally exist in...
a failure of homologous chromosomes or sister chromatids to separate during meiosis; when it...
Down syndrome
the most well-known outcome of aneuploidy in humans; caused by the gain of an additional chromosome...
Turner syndrome
produces people who phenotypically female, but who have only one X chromosome and 45 chromosomes;...
Klinefelter syndrome
XXY men, phenotypically male in most respects, tend to have a number of feminine features:...
It is also possible for aneuploidy to occur in mitosis
as one cell divides, a given chromatid can fail to migrate to its proper "pole" and 1 resulting...
occurs when a chromosome fragment breaks off & then does not rejoin any chromosomeex: cri-du-chat...
PGD (preimplantation genetic diagnosis)
can be used by couples who have no known genetic risk factors but are having a hard time conceiving...
genetic screening that can provide information about conditions; cells are obtained from an...
when a chromosome fragment rejoins the chromosome it came from, with its orientation "flipped"...
a chromosomal abnormality that occurs when two chromosomes that are not homologous exchange...
adding a gene to a chromosome can "free up" an existing gene, such that it can be altered through...
Thomas Hunt Morgan of Columbia
linked a particular trait to a particular chromosome, and found that genes on the same chromosome...
molecular biology
the investigation of life at the level of its individual molecules
James Watson & Francis Crick
presented the structure of DNA in 1953
X-ray diffraction
a purified form of a molecule is bombarded with X rays, the way the rays scatter on impact...
DNA structure
1. phosphate group2. deoxyribose (sugar)3. 4 possible DNA bases: adenine, guanine, thymine,...
the linkage of a phosphate group, a deoxyribose molecule, & one of the four bases; the...
A always pairs with _G always pairs with _
any two bases that can pair together across the helix are said to be ___________
each single strand of DNA serves as a ________ for the synthesis of a new single strand
because new nucleotides can be added to only one end of a DNA strand, the nucleotides are added...
enzymes that unind the double helix, separating its two strands to make the bases on them available...
DNA polymerases
move along each strand of the double helix, joining together nucleotides as they are added,...
a permanent alteration of a DNA base sequence
point mutation
a permanent mistake; a mutation of a single base pair in the genome; a slight change in the...
somatic cells
cells that do not become eggs or sperm; most mutations come about in these cells
germ-line cells
cells that become egg or sperm
germ-line cell mutations
heritable, can be passed on from one generation to the next
substances that can mutate DNAex: cigarette smoke, UV light
UV light
a form of radiation that can link adjacent T's together in a single strand of DNA; sometimes...
when a cell recognizes that damage cannot be repaired and stops dividing
cell suicide
it is the order of _____ _____ that determines which protein is synthesized
amino acids
an organelle, located in the cell's cytoplasm, that is the site of protein synthesis; mRNA...
the process by which the genetic information encoded in DNA is copied onto messenger RNA; a...
the process by which information encoded in messenger RNA is used to assemble a protein at...
structurally very similar to DNA; usually single-stranded; uses adenine, guanine, cytosine,...
RNA polymerase
enzyme that unwinds the DNA sequence and then strings together the chain of RNA nucleotides...
messenger RNA
a type of RNA that encodes and carries to ribosomes information for the synthesis of proteins
how many DNA basis does it take to code for an amino acid?
an mRNA triplet that codes for a single amino acid or a start or stop command in the translation...
genetic code
the inventory of linkages between nucleotide triplets and the amino acids they code for
transfer RNA
a form of RNA that, in protein synthesis, binds with amino acids, transfers them to ribosomes,...
the end of the transfer RNA molecule that can bind with a particular codon on the mRNA transcript
ribosomal RNA
a type of ribosomal RNA that, along with proteins, forms ribosomes
the mRNA codon ___ is the usual "start" codon for a polypeptide chain
termination codons
3 separate codons that don't code for any amino acid but act as stop signals for polypeptide...
the genetic code is redundant
almost all the amino acids are coded for by more than one mRNA codon
with only a few exceptions, the genetic code is universal in all living things
evidence that all life on Earth is derived from a single ancestor
"junk DNA" 
DNA that came mostly from outside our genome (from invading viruses) and has never had any...
promoter sequence
the site on a segment of DNA to which RNA polymerase attaches prior to beginning transcription
enhancer proteins
does not code for anything; serves as a binding site for proteins that help get RNA polymerase...
sequences that are cut out in editing out noncoding sequences; "intervening" sequences; account...
sequences that are retained in editing out noncoding sequences; most are "expressed" as proteins
alternative splicing
another form of genetic regulation; a process in which a single primary transcript can be edited...
when some classes of introns insert themselves into genomes such as ours, a mutation can occur...
enabled organisms such as ourselves to produce more proteins and hence to become more complex;...
not all RNA codes for proteins
transcription an also produce noncoding RNA segments that are regulatory
only about 22 bases long; reduce production of specific proteins, most commonly by interfering...
there is ______ relationship between the number of genes an organism has and the complexity...
complexity is necessary because it enables life

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