Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MED 109- BIOLOGY II > 7. SEX CHROMOSOME LINKED DISORDERS > Flashcards

7. SEX CHROMOSOME LINKED DISORDERS Flashcards

1
Q
  1. What causes Sex Chromosome Linked Disorders?
A
  • they are caused by mutations on the alleles
  • these alleles are found on the sex chromosomes
    (the X and the Y chromosomes)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q
  1. What can be said about the genes on the Y Chromosome?
A
  • the Y chromosome has very few genes
  • this means that there are very few Y-Linked disorders
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q
  1. What are most Sex Chromosome Linked Disorders a
    result of?
A
  • mutations on the genes on the X chromosome
  • these are known as X linked disorders
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q
  1. What are the 2 types of X-linked disorders?
A
  1. X-Linked Dominant
  2. X-Linked Recessive
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q
  1. Which kind of X-linked disorder is more common?
A
  • X-linked recessive disorders are much more common
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q
  1. In which gender are X-linked recessive disorders much more common?
A
  • these kinds of disorders are much more common in
    men than in women
  • this is due to the absence of the allele on the Y
    chromosome
  • this is because the X and the Y chromosome are non-
    homologous
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q
  1. What are X-linked Recessive Disorders?
A
  • this is a disorder on the X chromosome
  • the recessive, mutant allele is present on the one X
    chromosome

IN MALES:
- there is an absence of the normal allele on the Y
chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q
  1. What happens to the offspring if the mother is a carrier of an X-linked recessive disorder?
A
  • 50% of her sons will be affected
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q
  1. Are females often affected by X-linked recessive disorders?
A
  • no
  • they are rarely affected
  • this is because women have another X chromosome
  • this X chromosome has the normal allele on it
  • this dominant, normal allele will ensure that the
    disorder does not appear in the phenotype
  • women will be carriers of the recessive disorder
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q
  1. What are 3 examples of X-Linked Recessive Disorders?
A
  1. Haemophilia
  2. Colour Blindness
  3. Duchenne Muscular Dystrophy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q
  1. Fill in descriptions for the following labels related to X-Linked Recessive Disorders.
A
  1. Normal Woman
    (Healthy Female)
  2. Affected Woman
    (Woman with the disease)
  3. Normal Male
  4. Male with the disease

NB:
- there can be no male carriers of this kind of disease
- a women with a XA Xa genotype is a carrier of the
disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q
  1. What are 4 characteristics of X-Linked Dominant Disorders?
A
  1. They are less common than X-linked recessive
    disorders
  2. They are extremely rare
  3. They are usually fatal
  4. The males are not more affected than the females
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q
  1. Where is the mutant allele found in X-Linked Dominant Disorders?
A
  • the mutant allele is dominant
  • it is written with a capital letter
  • it is found on the X-chromosome
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q
  1. What are 2 examples of X-Linked Dominant Disorders?
A
  1. Vitamin D Resistant Rickets
    (Hypophosphataemic Rickets)
  2. Alport Syndrome
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q
  1. Provide descriptions for the following labels related to X-Linked Dominant Disorders.
A
  1. Affected Females
  2. Normal Female
  3. Affected Male
  4. Normal Male
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q
  1. What happens in an affected father breeds with an unaffected mother?
A
  • the chromosomes with the mutant genes from the
    affected father will be inherited by all his daughters
  • all the daughters will be affected
  • none of his sons will be affected
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q
  1. What happens when an affected mother breeds with an unaffected father?
A
  • she has a fair chance of passing her chromosomes
    with the mutated gene to all her children
    REGARDLESS of their gender
  • 50% of her children will be affected
18
Q
  1. What two components do many disease have?
A
  1. A genetic component
  2. An environmental component

EG:
- diseases such as cancer and heart diseases

19
Q
  1. What can Genetic Counsellors provide clients with?
A
  • they can provide information to prospective parents
  • these parents are often concerned about a family
    history for a specific disease
20
Q
  1. What do Genetic Counsellors use pedigrees for?
A
  • pedigrees help to reveal family histories
  • genetic counsellors use these to help couples
    determine the odds that their children will have genetic
    disorders
21
Q
  1. What 2 teachings is Genetic Counselling based on?
A
  1. Mendelian Genetics
  2. Probability Rules
22
Q
  1. What is the purpose of Genetic Tests?
A
  • they identify carriers of various diseases
  • they help to define the odds that the offspring will have
    the disorder
23
Q
  1. What is B-thalassaemia?
A
  • Beta Thalassaemia is a blood disorder
  • it reduces the production of haemoglobin
  • Hemoglobin is an iron-containing protein in red blood
    cells
  • it carries oxygen to cells throughout the body

IN PEOPLE WITH B-THALASSAEMIA:
- low levels of haemoglobin reduce oxygen levels in the
body

24
Q
  1. What percentage of the Cypriot people are affected by B-thalassaemia?
A
  • 16% of the Cypriot Population
  • they are heterozygous carriers of the B-Thalassaemia
    trait (allele)
25
Q
  1. What was introduced in Cyprus in the 1970s?
A
  • a Screening Policy
  • this helped to reduce the incidence of B-thalassaemia

NB:
- Iran and other countries have similar screening
policies

26
Q
  1. What are the 4 options that the Cypriot Government has available to decrease the percentage of B-thalassaemia?
A
  1. Premarital Screening
    (this is because 1 out of 8 members of the Cypriot
    Population are carriers)
  2. Prenatal Screening
  3. Abortion
    (provided by the government)
  4. In Vitro Fertilisation with a healthy embryo
27
Q
  1. Have the screening policies had success in lowering the B-thalassaemia percentage amongst the Cypriot population?
A
  • yes
  • the number of children born with this hereditary
    disease has decreased from 1 in 158 births
    TO almost zero
28
Q
  1. What is Prenatal Screening?
A
  • this is the testing for diseases or conditions in a foetus
    or embryo
  • this is done before the child is born
  • it assists in detecting birth defects
29
Q
  1. List 2 examples of Birth Defects that Prenatal Screening can detect?
A
  1. CHROMOSOMAL ABNORMALITIES
    • EG: Down Syndrome
    • this is done through karyotyping
    • this is when we examine the structure and the total
      number of chromosomes of a child’s genetics
  2. GENETIC DISORDERS
    • this is done through genetic testing
30
Q
  1. What are 4 examples of Genetic Disorders?
A
  1. Sickle Cell Anaemia
  2. Thalassaemia
  3. Cystic Fibrosis
  4. Muscular Dystrophy
31
Q
  1. List 3 examples of Prenatal (Foetal) testing?
A
  1. Amniocentesis
  2. Chronic Villus Sampling (CVS)
  3. Non-Invasive Prenatal Diagnosis (NIPD)
32
Q
  1. What is an Amniocentesis?
A
  • this is when amniotic fluid is removed and tested
  • it does pose the danger of causing an abortion
33
Q
  1. What is Chronic Villus Sampling (CVS)?
A
  • this is when a sample of the placenta is removed and
    tested
34
Q
  1. What is Non-Invasive Prenatal Diagnosis (NIPD)?
A
  • this is a new genetic test
  • it is when a sample of the mother’s blood is removed
    and tested
  • this blood contains some foetal cells
35
Q
  1. What are all 3 of the Prenatal Screenings (Foetal
    Tests) followed by?
A
  • karyotyping of the foetal cells
  • genetic testing of the foetal cells
  • this can reveal possible abnormalities
36
Q
  1. List 2 techniques that allow foetal health to be
    assessed visually in utero?
A
  1. Ultrasounds
  2. Foetoscopy
37
Q
  1. What is one example of a disorder that can be detected by a Newborn Screening Program?
A
  • Phenyketonuria
  • this disorder can be detected at birth
  • a series of simple tests are routinely performed in
    hospitals
38
Q
  1. What is Phenyketonuria?
A
  • this is an Autosomal Recessive Disorder
  • it affects 1 in every 10 000-15 000 births
  • it is when there is an inability to metabolise a specific
    amino acid
  • this amino acid is Phenylalanine
39
Q
  1. Where does the Phenylalanine Amino Acid accumulate?
A
  • it accumulates in the blood
  • it accumulates in the urine
40
Q
  1. What is a harmful effect of Phenyketonuria?
A
  • mental retardation
41
Q
  1. How can Phenyketonuria be treated?
A
  • it can be treated with a low diet of Phenylalanine
  • this only works if the disorder is detected early

MED 109- BIOLOGY II (90 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions