Term
|
Definition
◦ Detected from an inheritance pattern that
is different, depending on sex
◦ Affected gene is physically located on the
X or Y chromosome
◦ Female must get their father’s only X
◦ Male cannot get their father’s only X
◦ Affected females are very rare, because
both X chromosomes must be affected,
so frequency is the square of the
frequency in males |
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Term
| What is the typical x-linked recessive pedigree? |
|
Definition
• Usually only seen in males (No affected females because of relative rarity)
The odds change significantly when you have interbreeding |
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Term
| What is the chromosomal basis of inheritance? |
|
Definition
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Term
|
Definition
If assortment is based on separation of distinct
chromosomes during meiosis, genes that are on the
same chromosome should pass together |
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Term
| Describe the gene linkage experiment |
|
Definition
tested on flies for body color and wing type are on the same
chromosome
There is some degree of linkage between them, but
not complete linkage |
|
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Term
| Why is linkage only partial? |
|
Definition
Genetic recombination due
to crossing over |
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Term
| What is Frequency of recombination( Rf) |
|
Definition
◦ Differs based on linear distance between genes
◦ Allows ordered mapping of genes along chromosome |
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Term
|
Definition
A chromosome number that is not an exact multiple
based on the ‘ploidy’ |
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Term
| What are some examples of aneuploidy? |
|
Definition
Down syndrome
Turner’s syndrome
Kleinfelter’s syndrome
Triple X |
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Term
| When does aneuploidy occur? |
|
Definition
◦ Nondisjunction during Meiosis
◦ Can happen in
Meiosis I or
Meiosis II |
|
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Term
| What can errors in crossing over or DNA repair occur with? |
|
Definition
Can create chromosomal abnormalities
Partial trisomy/monosomy |
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Term
|
Definition
| removal of a chromosomal segment |
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Term
|
Definition
| reverses a segment within a chromosome |
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Term
|
Definition
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Term
|
Definition
| moves a segment from one chromosome to a non-homologous chromosome |
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Term
| What does innocuous inversions create? |
|
Definition
chromosomal incompatibility
Major driving force in speciation |
|
|
Term
| What is polyploidy and its causes? |
|
Definition
◦ Complete extra set(s) of chromosomes
Triploidy – 3n
Tetraploidy – 4n
◦ Causes:
Error during meiosis or cytokinesis
Interspecies cross
Triploids can’t undergo meiosis –
triploid lizards arising from interspecies
crosses are parthenogenic,
all females, reproducing by mitosis
alone
Polyploids are frequently larger
but can be sterile (which is perfect for commercial fruits – big, & seedless) |
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|
Term
| describe maternal imprinting |
|
Definition
Some genes are specifically methylated in the egg or sperm
This methylation is replicated during developmental mitosis
The change inactivates (or
activates) the maternal
(or paternal) allele
The individual is effectively
haploid for that gene
Some genes behave differently
if it come from father vs mother |
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