genome structure and chromosome abnormalities Flashcards

1
Q

how many hydrogen bonds between AT and GC

A

A-T 2

C-G - 3

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2
Q

DNA-RNA

A

transcription

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3
Q

RNA-protein

A

Translation

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4
Q

what are introns

A

non-coding regions

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5
Q

intergenic regions

A

region of genome that do not contain protein-coding sequences - involved in switching on or off

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6
Q

Mitochondrial dna encodes for what

A

mitocondrial function

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7
Q

what happens in 3 parent embryos

A

mother has problem with mitocondria - nucleus removed form maternal egg and placed in donor in an empty egg containing healthy mitochondria

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8
Q

what makes up chromatin

A

DNA
RNA
protein - histones

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9
Q

what protein does DNA wound around to from nucleosomes( organise solenoids)

A

histones

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10
Q

what do solenoids do

A

loop up into structure of chromatin

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11
Q

what are the two types of chromatin

A

Euchromatin

Heterochromatin

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12
Q

open chromatin and prevalent in parts of genome that is regularly used - what type

A

euchromatin

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13
Q

condensed form of chromatin made up of tight loops - abundant - what type

A

heterochromatin

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14
Q

how many chromosomes in gamete - haploid

A

23

1 copy of autosomes and I sex chromosome

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15
Q

what is a somatic cell

A

diploid - 46

2 copies of autosome and 2 sex chromosomes

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16
Q

do changes in germ cells cause heritable defects

17
Q

MMR

A

mismatched repair enzyme

18
Q

when does crossing over occur and what is it

A

homologous chromosomes exchange at chiasma
Prophase 1
genetic variation

19
Q

when does independent assortment occur and what is it

A

during anaphase 1 - centrosomes do not duplicate and divide
only one member of each part migrates
paternal and maternal chromosomes randomly sorted due to this

20
Q

Nullisomic gametes results in what

A

monosomic zygote - only one copy of chromosome

21
Q

disomic gamete results in what

A

triatomic zygote - 3 copies of it

22
Q

trisomy 21

A

downs syndrome

23
Q

FISH - fluroesnece in situ hybridisation is a way of checking what

A

patients chromosomes for inblacne

24
Q

aneuploidy

A

loss or gain of one or more chromosomes

25
gain of one of 2 homologous chromosomes called
trisomy
26
monosomy
loss of a single chromosome
27
Signs of downs syndrome
Newborn period Hypotonia, sleepy, excess nuchal skin Craniofacial Brachycephaly, epicanthic folds, protruding tongue, small ears, upward sloping palpebral fissures Limbs Single palmar crease, small middle phalanx of fifth finger, wide gap between first and second toes Cardiac Atrial and ventricular septal defects, common atrioventricular canal, patent ductus arteriosus Other Anal atresia, duodenal atresia, Hirschsprung disease, short stature, strabismu
28
trisomy 13
Patau syndrome descresed muscle tone small hands and ears and head and mouth slower physical development
29
trisomy 18
Edwards syndrome heart defects small head and jaw overlapping fingers
30
two phenotypic consequences of chromosome deletions - syndromes
Deletions of the terminal portions of chromosome 4 cause the Wolf-Hirschhorn syndrome Deletions of the terminal portions of chromosome 5 cause cri-du-chat syndrome (5p–) serve learning difficulties
31
Degeorge syndrome
Characterized by heart malformations (particularly those involving the cardiac outflow tract) Thymic and parathyroid hypoplasia Cleft palate and typical facial features The molecular defect is a 3-Mb microdeletion on chromosome 22 (22q11.2) ~ have short stature ~25% have schizophrenia-like episodes in adult life