Term
| the study of the structure and function of chromosomes is better known as? |
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Definition
cytogenics
used for screening and diagnosis of inherited chromosal disorders |
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Term
| a preparation of chromosomes arranged in size order is known as? |
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Definition
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Term
| which is the smallest chromosome? |
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Definition
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Term
| when making a karyotype what is added to blood to stimulate mitosis? |
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Definition
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Term
| when making a karyotype treatment with which substance stops mitosis in metaphase? |
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Definition
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Term
| chromsomes can be stained to show the bandings known as G bands. what is the name of the stain the G bands are name after? |
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Definition
|
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Term
| name the 3 ways to identify a chromsome? |
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Definition
length
banding pattern
placement of centromere |
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Term
| if the centromere was Metacentric where would you find it? |
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Definition
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Term
| if the centromere is sub-metacentric where would it be? |
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Definition
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Term
| if the centromere is Acrocentric where would it be? |
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Definition
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Term
| in relation to the centromere how are chromosomes arranged during karyotyping? |
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Definition
| the centromere at the top |
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Term
| what two changes do karyotyping detect? |
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Definition
change in chromosome number
change in chromosome structure |
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Term
| an extra whole set of chromsomes is known as? |
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Definition
polyploidy
3n - triploid
4n - tetraploid |
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Term
| additional or missing chromsomes is known as? |
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Definition
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Term
|
Definition
| one chromsome missing 2n-1 |
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Term
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Definition
| one extra chromosome 2n +1 |
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Term
| how would trisomy 18 on a female be written? |
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Definition
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Term
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Definition
| extra chromsome on 18.. known as edwards syndrome, clenched hands, mental retardation, heart defects, small heads. affects mainly females |
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Term
| non-disjunction is the cause of aneuploidy but where in meiosis does this occur? |
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Definition
meiosis I non-disjunction of homologous chromosomes
meiosis II non-disjunction of sister chromatids |
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Term
t/f
aneuploidy is very common occuring in 50% of human conceptions |
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Definition
| true - most aneuploids lead to embryonic death or spntaneous abortion. aneuploidies of the sex chromosomes are more common |
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Term
| name the only autosomal aneuploidy that permits survival into adulthoood |
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Definition
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Term
| down's syndrome is also known as? |
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Definition
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Term
| characteristics of trisomy 21 |
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Definition
| shirt stature, sterile, mental retardation, heart defects, suseptibility to leukaemia and alzheimer's disease |
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|
Term
t/f
incidence of trisomy 21 increases with maternal age? |
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Definition
| true - at age 40 around 1:100 chance of trisomy 21 in a baby |
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Term
| amniocentesis is used to screen for chromosomal abnormalities but how long does it take to find the results? |
|
Definition
around 2-3 weeks
faster to use PCR polymerase chain reaction. results in 2-3 days but only tests for 3 main chromsomal defects |
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|
Term
| aswell as karyotyping and amniocentesis name 2 other methods to screen for abnormalities |
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Definition
| blood tests and ultra sound scans to measure the size of the nuchal pad. |
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Term
| what is the name of the only viable human monosomy 2n-1? |
|
Definition
turner's syndrome - 45,XO
1 in 2500 live female births |
|
|
Term
| characteristics of turner's syndrome |
|
Definition
| phenotypically femal, sterile due to immature sex organs, normal intelligence, oestrogen replacement leads to development of secondary characteristics |
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Term
| 47, XXY is known as which syndrome? |
|
Definition
klinefelters syndrome
one of most common genetic abnormalities 1:500-1000 male live births |
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|
Term
| characteristics of klinefelters syndrome |
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Definition
| sterile, essentially male but with female characteristics, testicular atrophy, tall, may have sub normal intelligence but can be treated with testosterone |
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Term
| there are four main structural changes that can happen in chromsomes. what are they> |
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Definition
deletion
duplication
inversion
reciprocal translocation |
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Term
| what is the short arm of a chromsome known as? |
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Definition
|
|
Term
| what is the long arm of a chromosome known as? |
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Definition
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Term
| Cri-du-Chat (cry of the cat) is a chromosomal disorder on which chromsome? |
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Definition
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Term
| prader-willi syndrome/angleman syndrome affect which chromsome? |
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Definition
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|
Term
true/false
cri-du-chat is also known as 5p minus syndrome? |
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Definition
true- occurs from deletion of part of the short arm of chromsome 5
1 in 50,000 live births |
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|
Term
| characteristics of cri-du-chat |
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Definition
| babies have a cat like cry, defects in glottis and larynx, wide face with saddle nose, physical and mental retardation, range of severity depends on extent of deletion |
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|
Term
true/false
Prader-Willi syndrome occurs when there is a deletion in the long arm of chromsome 5 |
|
Definition
false - deletion in long arm of chromsome 15!!
affects 1 in 15,000 live births |
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|
Term
| why does Prada-Willi Syndrome occur only when the affeted chromsome is inherited from the father? |
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Definition
| genomic imprinting - this is a process affecting genes whereby the maternal or paternal gene is silenced |
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|
Term
| characteristics of Prader-Willi Syndrome |
|
Definition
| poor suckling reflex in infants, uncontrolable eating later on in life, obesity, diabetes, poor sexual development in males |
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|
Term
| what is the chromosomal different between Prader-Willi and Angelman's syndrome? |
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Definition
| Angelman's syndrome occurs when the same segment of chromsome 15 is missing from the maternally derived chromsomes - because imprinted genes on the other chromsome are different in each case |
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|
Term
| characteristics of Angelman's syndrome |
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Definition
| happy demeanour, inappropiate outburts of laughter, mental retardation, speech problems, seizures |
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|
Term
| name 2 condtions affected by translocation in chromosomal structure? |
|
Definition
Familial Down's Syndrome
Chronic Myelotic Leukaemia |
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|
Term
| how many percent does Familial Down's Syndrome account for? |
|
Definition
5%
Translocation carrier - t(14:21) one of chromsomes 21's is attached to one of chromosomes 14's |
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|
Term
| in familial down's syndrome what are the chances of the parents having a second child affected? |
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Definition
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|
Term
| what has happened in the chromosomes in CML? |
|
Definition
| there is a reciprocal translocation between chromosome 22-9 |
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|
Term
|
Definition
no it is spontaneous thus not heritable
1 per 50-100,000 of the population |
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|
Term
|
Definition
| Very high white blood cell count |
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|
Term
| what is the 22-9 reciprocally translocated chromsome better known as? |
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Definition
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|
Term
| in CML reciprocal translocation creates the BCR-ABL gene. what type of gene is this? |
|
Definition
| an oncogene that stimulates the over production of white blood cells |
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|
Term
| in which ages is CML most common? |
|
Definition
middle aged/elderly
it accounts for 15-20% of all cases of leukaemia |
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