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Bio Quiz 2 to Exam 2
Bio Quiz 2 to Exam 2
79
Biology
Graduate
10/31/2010

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Term
what is the ratio for incomplete or partial dominance?
Definition
1:2:1
Term
What antibody does A blood have?
Definition
antibody for B
Term
what antibody does AB blood have?
Definition
none
Term
what antibody does O blood have?
Definition
Antibodies for A and B
Term
what is the expected ratio in a dihybrid cross?
Definition
9:3:3:1
Term
what is the distribution of phenotypes for multiple genes?
Definition
a normal distribution/gausian curve
Term
what is heritability?
Definition
a measure of how much a trait is due to the environment, the fraction of variability due to genetic effects.
Term
how can you determine if a gene is sex influenced?
Definition
trait will not distribute evenly among sexes, but it is NOT on the sex chromosome
Term
what does it mean for a gene to be sex influenced?
Definition
it means that a gene can effect members of each sex differently. ex. baldness is dominant in men and recessive in women.
Term
what is a sex limited gene?
Definition
one that ONLY expresses in one sex or another but is not on the sex chromosome
Term
what does epistatis mean? how can we detect it from a phenotypic ratio?
Definition
it means standing upon, so when the expression of one gene affects the expression of another gene.

We can detect it from a skewed 9:3:3:1 ratio
Term
what are some environmental factors that effect genes we've learned about?
Definition
temperature--effects color of siamese cats; drugs: thalidomide, effected limb formation even though drug was intended to combat morning sickness,
Term
in a pedigree what sex is indicated by a circle, what by a square?
Definition
women are circles, men are squares
Term
What risk is increased with a consanguinous marriage?
Definition
the risk that recessive genes will be brought back together
Term
what does autosomal mean?
Definition
that the gene is not sex-linked
Term
what are the visual clues in a pedigree if a trait is autosomal recessive?
Definition
-most affected children have normal parents
-two affected parents will always have affected children
Term
what are genes?
Definition
the nucleic acid sequence
Term
what is the wild type?
Definition
the dominant type
Term
what is a reciprocal cross?
Definition
when a sex linked gene is crossed between a male with the trait and a female without the trait. In the f2 generation all possible combinations will be expressed
Term
how can we tell from a pedigree if a gene is recessive x linked?
Definition
often skips a generation (criss-cross inheritance), and the affected son can have parents with a normal phenotype (means mom is a carrier)
-ratio of inheritance is skewed male
-ex. Duchenne muscular dystrophy
Term
how can we tell from a pedigree if a gene is autosomal dominant?
Definition
-only need one copy of gene to express it (ex. Huntington's)
-affected children usually have an effected parent (unless it's a mutation)
-doesn't skip generations
-kids have a 50% chance of getting the disease
Term
what does atavistic mean?
Definition
ancestral, probably all early humans expressed this gene
Term
what is an example of a Y-linked trait?
Definition
hairy ears
Term
what is a linkage group?
Definition
genes that are located on the same chromosome
Term
do linked genes sort independently?
Definition
no
Term
does crossing over effect results of linked genes?
Definition
yes
Term
what is the ratio of phenotypes in a dihybrid test cross?
Definition
1:1:1:1
Term
changes are always ___ in crossing over?
Definition
reciprocal
Term
what is another term for crossing over?
Definition
genetic recombination
Term
when genes are not linked, what is the ratio of phenotypes? what is percentage of non-parental types?
Definition
1:1:1:1

50%
Term
when genes are linked and close together, what is the ratio of phenotypes? what is percentage of non-parental types?
Definition
1:1

0%
Term
when genes are linked and far apart, what is the ratio of phenotypes? what is percentage of non-parental types?
Definition
9:9:1:1

low percentage ~5 or 10%
Term
the farther apart genes are the _____ a chiasmata is going to be between them
Definition
more likely
Term
how can you identify the cross over gene in a three point test cross?
Definition
it has the smallest number in terms of phenotype. it is the middle gene
Term
what is disjunction?
Definition
the distribution and separation of chromosomes in meiosis I or of sister chromosomes in meiosis II
Term
what is non-disjunction?
Definition
when chromosomes do not sort properly/fail to sort and two end up in one cell
Term
what is primary non disjunction?
Definition
when chromosomes don't sort (i.e. X AND Y go into one cell)
Term
what is secondary non disjunction?
Definition
when sister chromatids don't sort in meiosis II
Term
are big or small genes more likely to experience non-disjunction?
Definition
big
Term
what is aneuploidy
Definition
an abnormal number of chromosomes
Term
what is trisomy?
Definition
having 3 copies of one chromosome
Term
are missing genes or extra copies more likely to be lethal/make gamete non-viable?
Definition
missing genes
Term
downs sydrome occurs from what?
Definition
extra copy of chromosome 21
Term
what are some of the charateristics of down syndrome?
Definition
-high level of blood purines
-elevated risk of cancer
-simian line
-affable!
Term
if an individual had 3 copies of all chromosomes, would it survive?
Definition
probably not
Term
what does "ploidy" mean?
Definition
a full set of haploid chromosomes
Term
what syndrome is XO?
Definition
Turner syndrome: only one x copy, low fertility, extra skin at neck
Term
what syndrome is XXX?
Definition
Triplo X, viable though most individuals are sterile
Term
what is XYY?
Definition
Jacob's syndrome: 40% higher incidence in prison population, speculation that extra Y leads to more aggresive behavior
Term
what is XXY, XXYY or XXXY?
Definition
Kleinfelter's: long lower limbs, small breast development but genetically male, low fertility rate
Term
What is x inactivation?
Definition
when one of the x genes in females is turned off so that they both do not express. Decendents of that cell the same X is turned off. This is what normally happens
Term
in x inactivation what do we call the condensed x chromosome?
Definition
a barr body, looks like a little black spot
Term
what is a visual example of X inactivation?
Definition
calico cats: color depends on what colors are activated where. also skin cells in women
Term
when are sex organs developed?
Definition
approximately 10 weeks in. either Y gene turns testosterone production on or lack thereof leads to female genetalia
Term
what is an example of how the sex-determining gene is also a regulatory gene?
Definition
production of testosterone and estrogen effects other processes. ex. delay in making testosterone--> delay in sex organs "guevodoces"
Term
what is androgen insensitivity?
Definition
when testosterone receptors don't work so an individual is genetically male but phenotypically female
Term
what happens in CAH (Congenital Adrenal Hyperplasia)?
Definition
excess testosterone and reduced cortisol synthesis lead to masculization of extrnal organs in females
Term
what did the Stern experiment show?
Definition
confirmed that crossing over does involve breaking and rejoining a chromosome, and that crossing over leads to non-parental types
Term
what are polytene chromosomes?
Definition
chromosomes in the saliva of flies that are very enlarged, easy to see chromosomal abberations
Term
what are the 4 kinds of chromsomal mutations/aberrations
Definition
1. deletion
2. translocation
3. insertion
4. duplication
Term
what happens in a chromosomal inversion
Definition
two genes are cut out, swapped, and put back in. i.e. abcd becomes acbd
Term
what happens in a chromosomal translocation?
Definition
section on one chromosome and another chromosome swap (i.e. bottom part of chromosome 2 swaps with bottom part of chromosome 5)
Term
what happens in a chromosomal deletion?
Definition
a part of a chromosome is completely lost
Term
what happens in a chromosomal duplication?
Definition
one section of the chromosome is duplicated and re-insterted
Term
what percent of failed fertilizations have a chromosomal defect?
Definition
1/2
Term
in a deletion, can a recessive trait express?
Definition
yes if the concordant gene on the other chromosome was deleted because now there is nothing to mask this gene
Term
what is a paracentric inversion?
Definition
an inversion that does NOT include the centromere
Term
what is a paricentric inversion?
Definition
an inversion that DOES include the centromere
Term
can a paracentric inversion affect gametes?
Definition
yes, leads to inviable chromosomes becuase they can me missing genetic information
Term
what are the two notable kinds of translocations?
Definition
Robertson translocation and philadelphia translocation
Term
what happens in a robertson translocation?
Definition
chromosomes break and rejoin to create a new long chromosome and a smaller fragment. now the full set has 3 copies of the critical area (think Down Syndrome)
Term
what happens in a philadelphia translocation?
Definition
two genes have translocations that puts two genes next to eachother than combined can have a new effect, ex. cancer-causing
Term
do prokaryotes/bacteria exchange genes during replication?
Definition
no
Term
what are the three ways that bacteria exchange genetic information?
Definition
1. conjugation
2. transformation
3. transduction
Term
What occurs in bacterial conjugation?
Definition
an F+ bacteria (plasmid) hooks onto an F- bacteria w/out a plasmid via a pillus. This pillus (sometimes called the sex pillus) creates a bridge, and allows the F+ to replicate the plasmid, which codes for the ability to replicate genes, and inserts it in the F- cell, which becomes an F+ cell
Term
what is bacterial transformation?
Definition
taking in of naked DNA from the environment
Term
what is bacterial transduction?
Definition
a viral infection when a bacterial virus takes over a cell and makes it a viral production factory
Term
what is the PAR region on the Y chromosome?
Definition
are genes in the Y chromosome that are inherited like any other autosomal genes, not like sex-linked genes
Term
what is the function of the PAR region on the x and y chromosomes
Definition
The function of these pseudoautosomal regions is that they allow the X and Y chromosomes to pair and properly segregate during meiosis in males
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