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Human Bio > Unit 2 KA4 - ante and postnatal screening > Flashcards

Unit 2 KA4 - ante and postnatal screening Flashcards

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Biology 101 flashcards
1
Q

techniques an be carried out to monitor the health of the …….., ………… and …………

A

mother, developing fetus, and baby

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2
Q

what is the meaning and purpose of antenatal screeening?

A

screening before birth to identify the risk of a disorder so further tests and a prenatal diagnosis can be offered

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3
Q

give examples of antenatal screening

A

ultrasound imaging, blood and urine tests and diagnostic tests

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4
Q

what is ultrasound imaging?

A

when an ultrasound scanner is held against pregnant women’s abdomen and picks up high frequency sounds that have bounced off the fetus
these are converted to an ultrasound image on a computer screen

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5
Q

what are the 2 types of ultrasound screening and when are they carried out?

A

dating scan - 8-14 weeks

anomaly scan - 18-20 weeks

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6
Q

why is the dating scan carried out?

A

to determine the stage of pregnancy and due date

used alongside tests for marker chemicals

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7
Q

why is the anomaly scan carried out?

A

detects presence of serious physical abnormalities in the fetus e.g. spina bifida

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8
Q

when and why are blood and urine tests carried out?

A

throughout pregnancy to monitor concentration of marker chemicals

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9
Q

atypical chemical concentrations indicate a ……., so ………… ………… must take place

A

problem, diagnostic testing

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10
Q

what leads to a false-positive result in a blood/urine test?

A

measuring a chemical at the wrong time since marker chemicals vary at different stages of pregnancy

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11
Q

what is diagnostic testing?

A

definitive test that produces results used to establish if the fetus is suffering a specific condition/disorder

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12
Q

in which cases is diagnostic testing offered to a pregnant woman?

A
  • screening tests have shown a potential problem
  • family history of genetic disorders
  • she belongs to a high-risk group (e.g women over the age of 35)
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13
Q

give examples of diagnostic testing?

A

amniocentesis and chorionic villus sampling (CVS)

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14
Q

what is a karyotype and where are they produced from?

A

shows an individual’s chromosomes arranged as homologous pairs
produced from fetal cells which have been cultured

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15
Q

what are karyotypes used for?

A

to diagnose a range of conditions

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16
Q

where are fetal cells obtained from?

A

amniocentesis and CVS

17
Q

when is amnio and CVS carried out?

A

amnio - 14-16 weeks

CVS - 8 weeks

18
Q

describe the process of amniocentesis

A

amniotic fluid containing fetal cells are withdrawn

they are cultured, stained, and examined under a microscope to create the karyotype

19
Q

give an advantage and disadvantage of amniocentesis

A

advantage - chromosome abnormalities can be detected

disadvantage - risk of miscarriage

20
Q

describe the process of CVS

A

a tiny sample of placental cells are taken using a fine tube inserted into the mother’s reproductive tract
the cells are cultured and used for karyotyping

21
Q

give an advantage and disadvantage of CVS

A

advantage - can be carried out at 8 weeks whereas amnio is 14-16 weeks
disadvantage - higher risk of miscarriage than amnio

22
Q

a family tree looking at ………………. is constructed by a ……………
analysis to spot …….. and ……… chances of parents producing offspring with …………..

A

genetic conditions/disorders, genetic counsellor, patterns, predict, genetic disease

23
Q

once …….. of family members are known, the …….. can be worked out

A

phenotypes, genotypes

24
Q

X and Y chromosomes are called………. and all other chromosomes are called……..

A

sex chromosomes, autosomes

25
Q

give an example of autosomal recessive inheritance

A

cystic fibrosis

26
Q

what patterns can be spotted by a geneticist in autosomal recessive inheritance?

A
  • the trait is expressed rarely
  • the trait may skip generations
  • the trait is expressed in some of the offspring of a consanguineous marriage
  • males and females are affected in approx. equal numbers
27
Q

what are the genotypes of sufferers and non-sufferers in autosomal recessive inheritance?

A

sufferers - homozygous recessive (ff)

non-sufferes - homozygous dominant (FF) or heterozygous (Ff)

28
Q

give an example of autosomal dominant inheritance

A

huntington’s disease

29
Q

what patterns can be spotted by a geneticist in autosomal dominant inheritance?

A
  • the trait is expressed in every generation
  • each sufferer of the trait has an affected parent
  • males and females are affected in approx. equal numbers
30
Q

what are the genotypes of sufferers and non-sufferers in autosomal dominant inheritance?

A

non-sufferers - homozygous recessive (hh)

sufferers - homozygous dominant (HH) or heterozygous (Hh)

31
Q

give an example of autosomal incomplete inheritance

A

sickle cell disease

32
Q

what patterns can be spotted by a geneticist in autosomal incomplete inheritance?

A
  • the fully expressed form occurs rarely
  • partly expressed form occurs more frequently
  • each sufferer of the fully expressed form has 2 parents who suffer from the partly expressed form
  • males and females are affected in approx. equal numbers
33
Q

what are the genotypes of sufferers (partly expressed and fully expressed) and non-sufferers in autosomal incomplete inheritance?

A

sufferers (fully expressed) - homozygous for the other incompletely dominant alleles (SS)
sufferers (partly expressed) - heterozygous for the two alleles (HS)
non-sufferers - homozygous for one incompletely dominant allele (HH)

34
Q

give an example of sex-linked recessive traits

A

hemophilia

35
Q

what patterns can be spotted by a geneticist in sex-linked recessive traits?

A
  • more males than females are affected
  • none of the sons of an affected male show the trait
  • some grandsons of an affected male show the trait
36
Q

what are the genotypes of sufferers and non-sufferers for sex-linked recessive traits?

A

sufferers are homozygous recessive

non-sufferers are homozygous dominant

37
Q

why and why is postnatal screening carried out?

A

after birth when the baby is a few days old to test for metabolic disorders

38
Q

what is phenylketonuria (PKU) caused by?

A

a subsitution mutation which distrupts the metabolic pathway that converts phenylalanine into tyrosine a the enzymes that catalyses this conversion is non functioning

39
Q

how are newborn babies screened for PKU and what steps are taken if they are a sufferer?

A

by having their blood tested for the presence of excess phenylalanine
PKU sufferers are put on a restricted diet to limit amount of phenylalanine

Human Bio (25 decks)

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