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Higher Human Biology (Revised 2021) > Unit 2: Physiology & Health - Key Area 4: Antenatal and Postnatal Screening > Flashcards

Unit 2: Physiology & Health - Key Area 4: Antenatal and Postnatal Screening Flashcards

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1
Q

Why is antenatal care carried out?

A

To monitor the health of a pregnant woman and her developing foetus and baby.

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2
Q

What 3 things checked in a mother during pregnancy?

A

Blood pressure, blood type, blood and urine.

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3
Q

What can antenatal screening identify?

A

The risk of a disorder so that further (diagnostic) tests can be carried out if necessary, and a parental diagnosis can be given.

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4
Q

What are screening tests used for?

A

To detect signs and symptoms associated with a condition or disorder. This allows a degree of risk to be assessed but does not definitely confirm if the disorder is present.

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5
Q

What do screening tests require for more definite answers?

A

Diagnostic testing.

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6
Q

What is diagnostic testing?

A

Definite tests which establish, without doubt, wether a person is suffering from a specific condition or disorder.

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7
Q

What are the 3 types of antenatal screening?

A

Ultrasound, diagnostic testing, blood and urine tests.

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8
Q

What are the two types of ultrasound scans?

A

A dating scan and an anomaly scan.

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9
Q

How many ultrasound scans is a pregnant woman given during pregnancy.

A

A minimum of 2.

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10
Q

At what time of pregnancy is a dating scan carried out and what does this determine?

A

8-14 weeks. Determines the stage of pregnancy and due date which can be used with tests as marker chemicals which vary normally during pregnancy.

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11
Q

At what time of pregnancy are anomaly scans carried out and what for?

A

18-20 weeks. Detects serious physical problems/abnormalities in the foetus which allows parents to prepare/manage specialised birth/intrauterine therapy.

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12
Q

Why are routine blood and urine tests carried out throughout pregnancy?

A

Routine blood and urine tests are carried out throughout pregnancy to monitor the concentrations of marker chemicals which could indicate conditions like alpha fetoprotein e.g.

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13
Q

If a chemical in the blood is measured at he wrong time it could lead to a false positive. The atypical chemical concentration can lead to what further type of testing?

A

Diagnostic testing.

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14
Q

When are diagnostic tests carried out?

A

These tests are carried out if routine screening has indicated a risk of a condition, or for individuals already in high risk categories (e.g. woman over the age of 35), or if there is a family history of a harmful genetic disorder.

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15
Q

What are the 2 main procedures used in diagnostic testing?

A

Amniocentesis and chorionic villus sampling (CVS).

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16
Q

What is the process of amniocentesis?

A

Carried out at 14-18 weeks in the pregnancy where amniotic fluid is withdrawn which contains fetal cells. These are then examined under a microscope to obtain a karyotype for diagnosis.

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17
Q

What is the process of CVS?

A

Carried out between 9-14 weeks where a sample of placenta cells are taken from the fetal tissue. These cells are then cultured and used for karyotyping.

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18
Q

What are 3 differences between CVS and amniocentesis?

A

Amniocentesis: carried out at 14-18 weeks, tests fatal cells and uses needle and syringe through abdominal wall guided with ultrasound to extract.

CVS: carried out at 9-14 weeks, tests placenta cells and uses a needle through the stomach or a tubes, suction and force[s in the cervix.

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19
Q

What are risks of amniocentesis?

A

Miscarriage, infection, injury from the needle, inadequate results, rhesus disease and club foot.

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20
Q

What are the risks of CVS?

A

Miscarriage, infection, inadequate results and rhesus sensation.

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21
Q

Why are cells from CVS and amniocentesis cultured?

A

To obtain sufficient cells to produce a karyotype to diagnose a range of conditions.

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22
Q

What are one of the first parts of postnatal screening?

A

After the birth, the baby is give a blood test. The blood test involves taking a small blood sample by pricking the heel (heel prick test). The blood sample is tested for several rare conditions including phenylketonuria (PKU).

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23
Q

What is phenylketonuria?

A

Phenylketonuria is an autosomal recessive disorder, involving a substitution mutation to the gene coding for the enzyme which converts the amino acid phenylalanine to the amino acid tyrosine. Without the enzyme, phenylalanine accumulates in the blood and severely restricts the development of the brain.

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24
Q

Can phenylketonuria be treated?

A

If treatment is started soon after birth, it can result in normal brain development. This can be achieved through a strict diet where food high in phenylalanine are largely or completely eliminated from the diet.

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25
Q

Why can people with PKU still produce melanin?

A

They can consume tyrosine in their diet which complete the pathway to produce melanin.

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26
Q

What is the definition of haploid?

A

Only 23 chromosomes in a human cell (sex cells)

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27
Q

What is the definition of diploid?

A

46 chromosomes (2 sets) in a human cell (stomatic cell).

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28
Q

What is the definition of Alleles?

A

Different forms of the same gene.

29
Q

What is the definition of Dominant?

A

Dominant allele expressed in the phenotype over the recessive (Hh).

30
Q

What is the definition of recessive?

A

Only expressed if both are present like (hh) not appearing with dominant.

31
Q

What is the definition of Homozygous?

A

The alleles are matching pairs (HH)(hh).

32
Q

What is the definition of Heterozygous?

A

The alleles are different/mixed (Hh).

33
Q

What is the definition of carrier?

A

You have the genotype for a certain disease but it is not displayed/expressed (Hh) or you do not suffer from it. Always heterozygous.

34
Q

What is the definition of genotype?

A

The genetic make up/alleles that you are actually have/are present.

35
Q

What is the definition of phenotype?

A

The observable characteristic/trait. What you can physically see.

36
Q

What is the definition of gene?

A

Part of your DNA/section of chromosome that codes for a protein.

37
Q

In humans what are the sex chromosomes?

A

The X and Y chromosomes.

38
Q

What are all the other chromosomes except from the sex chromosomes in the genotype called?

A

Autosomes.

39
Q

What can be used to analyse a particular characteristic from members of a family?

A

A pedigree chart.

40
Q

What professional would construct a pedigree chart and what would be the possible reasons for doing so?

A

A genetic counsellor would construct a pedigree chart when information and advice is required by a couple how are worried about passing on a genetic condition in their family to their children.

41
Q

What pattern do autosomal recessive show?

A
  • They are expressed relatively rarely.
  • May skip generations.
  • Males and females are affected equally.
42
Q

What genotypes will suffer in an autosomal recessive inheritance trait?

A

Sufferers will be recessive (cc). Non sufferers will be either homozygous dominant (CC) or heterozygous (Cc)

43
Q

What pattern do autosomal dominant show?

A
  • The trait appears in every generation.
  • Each sufferer of the trait has an affected parent.
  • When a branch of the family doesn’t express the trait, the trait fails to reappear in future generations of the branch.
  • Males and females are effected equally.
44
Q

What genotypes will suffer in a dominant recessive inheritance trait?

A
  • All non-sufferers are homozygous recessive.

- All sufferers are either homozygous dominant (CC) or heterozygous (Cc).

45
Q

What are disorders linked to autosomal recessive inheritance?

A

Cystic fibrosis.

46
Q

What are disorders linked to autosomal dominant inheritance?

A

Huntingtons

47
Q

What pattern do autosomal incomplete dominance show?

A
  • The fully expressed form of the disorder occurs relative rarely.
  • The partially expressed form occurs much more frequently.
  • Each sufferer of the fully expressed form has 2 parents who suffer from the partially expressed form.
  • Males and females are affected equally.
48
Q

What genotypes will suffer in an autosomal incomplete dominance inheritance trait?

A
  • All non-sufferers are homozygous for one homozygous dominant allele (HH).
  • All sufferers of the fully expressed form of the disorder are homozygous for the other incompletely dominant allele (SS)
  • All sufferers of the partially expressed form of the disorder are heterozygous for the two alleles (HS).
49
Q

If an individual has the sex chromosome XX, are they male or female?

A

Female.

50
Q

If an individual has the sex chromosome XY, are they male or female?

A

Male.

51
Q

What has more genes absent than the other, the X or the Y chromosome?

A

X has many genes absent which are present in the Y chromosome.

52
Q

What is a disorder linked to autosomal incomplete dominance inheritance?

A

Sickle cell.

53
Q

What are the sex linked genes and where are they found?

A

The sex linked genes are the genes that are present in the X chromosome but absent in the Y chromosome and are there fore only found on the X chromosome.

54
Q

What does the fact the Y chromosome has no matching genes to offer dominance to the X chromosome.

A

The X chromosome will carry an allele but the Y will carry no allele for sex-linked genes.

55
Q

What does the Y chromosome never carry?

A

An allele.

56
Q

What pattern do sex-linked inheritance show?

A
  • Many more males are affected than females
  • None of the sons of an affected male show the trait.
  • Some of the grandsons of an affected male do show the trait.
57
Q

What genotypes will suffer in a sex-linked inheritance trait?

A
  • All sufferers of the trait are recessive (Xh Y).

- Non-sufferers of the trait are ‘homozygous’ dominant (XH Y or XH XH) or carrier females are heterozygous (XH Xh).

58
Q

What is a disorder linked to sex-linked inheritance?

A

Haemophilia or colour blindness.

59
Q

What is the difference between antenatal and postnatal?

A

Antenatal is before pregnancy and postnatal is after pregnancy.

60
Q

Why do pregnant women have their blood taken regularly?

A

To check the blood type of baby and woman so that Rhesus negative disease does not occur.

61
Q

What diagnostic test carries the highest risk of miscarriage - amniocentesis or CVS?

A

CVS

62
Q

What does a karyotype show?

A

The full chromosomal complement of an individual.

63
Q

How is PKU diagnosed in a new born baby?

A

Postnatal screening of a heel prick test.

64
Q

Where are sex linked genes found?

A

On the 23rd chromosome.

65
Q

What type of inheritance may skip generations and affects females and males equally?

A

Autosomal recessive inheritance.

66
Q

What pattern of inheritance is shown if someone can suffer a partially expressed form of a disorder?

A

Incomplete dominance inheritance.

67
Q

In sex-linked inheritance why is the disorder seen far more often in males than in females?

A

Y chromosome is negligible and X chromosome is dominant.

68
Q

What is an advantage of using CVS rather than amniocentesis?

A

CVS can be carried out earlier in pregnancy than amniocentesis.

Higher Human Biology (Revised 2021) (21 decks)

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