B4 : Types Of Mutation Flashcards
(85 cards)
1
Q
What is a gene mutation?
A
A gene mutation is a change in the DNA sequence that can affect gene function.
2
Q
What are the factors causing gene mutations?
A
Factors causing gene mutations include environmental influences, radiation, and chemical exposure.
3
Q
What are point mutations?
A
Point mutations are changes in a single nucleotide in the DNA sequence.
4
Q
What are frame shift mutations?
A
Frame shift mutations occur when nucleotides are inserted or deleted, altering the reading frame of the gene.
5
Q
Can you give an example of a disease caused by point mutations?
A
Sickle cell anemia is an example of a disease caused by a point mutation.
6
Q
What are chromosome mutations?
A
Chromosome mutations involve changes in the structure or number of chromosomes.
7
Q
What is trisomy?
A
Trisomy is a condition where an individual has three copies of a chromosome instead of two.
8
Q
What is monosomy?
A
Monosomy is a condition where an individual has only one copy of a chromosome instead of the normal two.
9
Q
What are genetic diseases resulting from chromosomal deletion mutations?
A
Examples include Cri du Chat syndrome and Williams syndrome.
10
Q
What are sex chromosome mutation diseases?
A
Examples include Turner syndrome and Klinefelter syndrome.
11
Q
A
12
Q
What are gene mutations?
A
Changes in the nucleotides in a gene result in a change in the products of that gene that may be inherited.
13
Q
What factors can cause genetic mutations to occur?
A
Radiation and chemical mutagens.
14
Q
What types of radiation can cause genetic mutations?
A
Ultraviolet light and X-rays.
15
Q
How does ultraviolet light cause mutations?
A
It can cause two adjacent pyrimidines to form a covalent dimer, distorting DNA.
16
Q
What are chemical mutagens?
A
Substances that can cause mutations in DNA.
17
Q
What are base analogues?
A
Chemicals that have a similar structure to nitrogenous bases (A, T, C, G).
18
Q
What is an example of a thymine analogue?
A
5-bromouracil (5Bu).
19
Q
What is an example of an adenine analogue?
A
2-aminopurine.
20
Q
What causes spontaneous mutations?
A
Replication errors during DNA replication.
21
Q
Where can mutations occur?
A
In germ cells and somatic cells.
22
Q
What is a pyrimidine dimer?
A
A covalent bond formed between two adjacent pyrimidines due to UV light exposure.
23
Q
What effect do X-rays have on DNA?
A
They cause breaks and alterations in DNA.
24
Q
What happens when 5-bromouracil is incorporated into DNA?
A
It pairs with adenine instead of thymine, leading to mispairing with guanine during replication.
25
26
What is a chemical modifier that directly changes the bases in DNA?
Hydroxylamine changes G to A and C to T. Nitrous oxide changes G/C to A/T.
27
What are the types of gene mutation?
Silent, Missense, Nonsense, Point mutation, Insertion, Deletion.
28
What is intercalation in DNA?
Intercalators are molecules that slip between adjacent bases, interfering with DNA polymerase and inhibiting transcription.
29
What is a silent mutation?
A silent mutation does not affect the amino acid sequence of the protein despite nucleotide changes.
30
What are examples of intercalators?
Antibiotics such as Actinomycin D and Ethidium bromide.
31
What is a frameshift mutation?
A frameshift mutation occurs due to insertion or deletion of nucleotides, altering the reading frame.
32
What is a non-frameshift mutation?
A non-frameshift mutation involves changes that do not alter the reading frame, such as certain insertions or deletions.
33
What is a missense mutation?
A missense mutation causes one amino acid in the protein to be replaced by a different amino acid.
## Footnote
Example: In sickle cell disease, CTC (glutamate) is changed to CAC (valine) in the 6th codon of the B-globin gene.
34
What are the effects of sickle cell disease?
It causes mutant forms of B-globin chains and HbS, leading to sticky, fragile, and easily hemolysed RBCs, which can block blood flow (vaso-occlusion) to organs.
## Footnote
This results in more bacterial infections and damage to body organs.
35
What is B-thalassemia-minor?
It is characterized by insufficient production of B-globin, resulting from a mutation that changes tryptophan to a stop codon.
36
What is a nonsense mutation?
A nonsense mutation causes premature termination of a polypeptide chain.
37
What is an insertion mutation?
An insertion mutation occurs when one or more nucleotides are added to the DNA sequence.
## Footnote
Non-frameshift example: CAG CCC ACT to CAG TCC CAC.
38
What is a frameshift mutation?
A frameshift mutation occurs when nucleotides are inserted or deleted, altering the reading frame of the gene.
39
What is Huntington's disease?
Huntington's disease is associated with multiple CAG repeat insertions leading to sticky polyglutamine repeats, causing atrophy of brain nucleus cells.
40
What happens if an insertion does not generate a stop codon?
A protein with more amino acids could be produced.
41
What is the new amino acid sequence after a nonsense mutation?
The new amino acid sequence can include serine and tyrosine, with a new RNA sequence of CAG UAG CAG.
## Footnote
Example: Gln Phe Pro Thr becomes Gln stop.
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43
What is deletion in biochemistry?
One or more nucleotides are removed from the DNA.
## Footnote
Whole gene deletion can also occur.
44
What are the types of deletion?
Non-frameshift deletion and frame shift deletion.
## Footnote
Examples include cystic fibrosis and B-thalassemia major.
45
What is an example of a deletion disorder?
Cystic fibrosis.
## Footnote
Deletion of a single nucleotide leads to an incorrect amino acid sequence.
46
What is the result of B-thalassemia major?
Deletion of B-globin gene & no B-globin production.
## Footnote
Initial sequence: A|CCGTAT.
47
What is the consequence of a deletion in a regulator protein?
Phenylalanine absence causes thickening of airway secretions & recurrent life-threatening infections.
48
What is euploidy?
Normal number & structure of chromosomes.
49
What is aneuploidy?
Less/more than normal diploid number.
50
What is monosomy?
Loss of 1 chromosome from a pair.
51
What is trisomy?
Extra 1 chromosome in a pair - 3 chromosomes.
52
What is polyploidy?
More than 2 of all chromosomes. Common in plants but rare in animals.
53
What is triploidy?
3 sets of chromosomes.
54
What is tetraploidy?
4 sets of chromosomes.
55
What is a mutation?
A change in the DNA sequence.
56
What is deletion?
Loss of a piece of DNA.
57
What is duplication?
Production of one or more copies of a DNA piece, or even an entire chromosome.
58
What is inversion?
A DNA segment is inverted & re-joined.
59
What is insertion?
A DNA segment is added to a chromosome.
60
What is translocation?
Breakage of a DNA segment which is then attached to a different chromosome.
61
What is Cri-du-chat?
A genetic disorder caused by a deletion of chromosome 5 at the end of the (p) arm.
## Footnote
Characterized by a cat-like cry, mental disability, delayed development, microcephaly, low birth weight, and weak muscle tone (hypotonia).
62
What are the facial features of Williams Syndrome?
Widely set eyes, low-set ears, a small jaw, and a rounded face.
## Footnote
Caused by a deletion of a part from chromosome 7 at the q arm, characterized by neurodevelopmental disorders and a friendly 'elfin' face with a low nasal bridge.
63
What characterizes Angelman Syndrome?
Mental disability with strong language skills and sociability.
## Footnote
Highly responsive to music, deletion of maternal chromosome 15 at the q arm, characterized by mental and developmental delay, sleep disturbances, seizures, jerky movements (especially hand-flapping), and a generally happy demeanor.
64
What is Prader-willi Syndrome?
A genetic disorder caused by a deletion of paternal chromosome 15 at the q arm.
## Footnote
Characterized by obesity, reduced muscle tone, mental ability issues, and sex glands producing little or no hormones.
65
What is Burkitt's lymphoma?
A type of cancer characterized by the translocation of the Myc gene from chromosome 8 to chromosome 14 (t(8:14)).
## Footnote
The Myc gene encodes for a transcription factor that regulates histone acetyltransferases.
66
What is the genetic cause of Down Syndrome?
Trisomy of chromosome 21.
## Footnote
Characterized by slow development, mental retardation, cardiovascular problems, and stomach illness.
67
What is Edward Syndrome?
Trisomy of chromosome 18 that affects all body systems.
## Footnote
Characterized by mental and developmental retardation, microcephaly, small eyes, deformed limb bones, and congenital heart defects.
68
What is Patau Syndrome?
Trisomy of chromosome 13, characterized by mental retardation, microcephaly, small lower jaw, scalp defects, cleft lip or palate, polydactyly, clenched hands, single palmar crease, skeletal abnormalities, decreased muscle tone, seizures, umbilical and inguinal hernias, low-set ears, and close small-set eyes that may fuse together.
69
What are the characteristics of Trisomy X?
XXX, Female, characterized by learning disabilities, little to no visible differences, and tall stature.
70
What is Klinefelter's syndrome?
A condition in males with XXY, XXYY, or XXXY chromosomes, characterized by normal sexual development, delayed language and skills development, tall stature, mildly impaired IQ, breast development, testicular atrophy, and poor beard growth.
71
What is Jacobs syndrome?
Trisomy (XYY), Male. Characterized by normal male traits and slightly learning difficulties.
72
What is Turner syndrome?
X monosomy, Female. Characterized by early loss of ovarian function, often tall & thin, acne, speech and reading problems, and normal intelligence.
73
What causes Fragile X syndrome?
Increase of CGG repeats in fragile X mental retardation-1 gene (FMR1 gene) on the q arm of X chromosome.
74
What is the normal range of CGG sequence repeats?
Normal CGG sequence repeats range from 6 - 200 repeats.
75
What happens when CGG repeats exceed 200 in Fragile X syndrome?
>200 CGG repeats in FMR1 gene leads to DNA methylation, inhibits transcription, and stops production of protein required for brain growth.
76
What are the characteristics of Fragile X syndrome?
Characterized by mental retardation, short stature, elongated face, large protruding ears, large testicles, flat feet, low muscle tone, hand-flapping, limited eye contact, and some suffering from autism.
77
What traits are inherited through the X-chromosome?
A. Sickle cell anemia
B. Hemophilia
C. Glucose-6-phosphate dehydrogenase deficiency
D. Duchenne muscular dystrophy
E. Fragile X syndrome
78
Why may a point mutation be silent?
A. Non-specific base pairing occurs between DNA and mRNA.
B. Change in base sequence is corrected during transcription.
C. A change in the third base on the codon may produce the same protein.
D. The transcription of mRNA is carried out by a high-fidelity RNA polymerase.
79
What is the molecular cause of trisomy 21?
A. Non-disjunction during meiosis leading to trisomy 21.
80
What is the best diagnosis for a newborn with developmental delay, high-pitched cry, and microcephaly?
A. Cri du Chat syndrome due to a deletion in chromosome 5p.
81
What is the diagnosis for a 16-year-old male with tall stature, gynecomastia, and a 47,XXY karyotype?
Klinefelter syndrome due to the presence of an extra X chromosome.
82
What is a gene mutation?
A gene mutation is a change in the DNA sequence that can affect protein function.
## Footnote
Two factors that can cause gene mutations include environmental factors (like radiation) and errors during DNA replication.
83
What are the types of point mutations?
The types of point mutations include silent, missense, and nonsense mutations.
## Footnote
These mutations alter the protein structure by changing one or more amino acids in the protein sequence.
84
What is a frameshift mutation?
A frameshift mutation occurs when nucleotides are added or deleted from the DNA sequence, altering the reading frame.
## Footnote
This can lead to significant changes in the protein synthesis, often resulting in a nonfunctional protein. An example of a disease caused by a frameshift mutation is cystic fibrosis.
85
What type of mutation is associated with the CFTR gene in cystic fibrosis?
The most likely mutation type is a point mutation, which affects the protein function leading to cystic fibrosis symptoms.
