genome structure and chromosome abnormalities

Question 1

how many hydrogen bonds between AT and GC

Answer 1

A-T 2

C-G - 3

Question 2

DNA-RNA

Answer 2

transcription

Question 3

RNA-protein

Answer 3

Translation

Question 4

what are introns

Answer 4

non-coding regions

Question 5

intergenic regions

Answer 5

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

Question 6

Mitochondrial dna encodes for what

Answer 6

mitocondrial function

Question 7

what happens in 3 parent embryos

Answer 7

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

Question 8

what makes up chromatin

Answer 8

DNA
RNA
protein - histones

Question 9

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

Answer 9

histones

Question 10

what do solenoids do

Answer 10

loop up into structure of chromatin

Question 11

what are the two types of chromatin

Answer 11

Euchromatin

Heterochromatin

Question 12

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

Answer 12

euchromatin

Question 13

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

Answer 13

heterochromatin

Question 14

how many chromosomes in gamete - haploid

Answer 14

23

1 copy of autosomes and I sex chromosome

Question 15

what is a somatic cell

Answer 15

diploid - 46

2 copies of autosome and 2 sex chromosomes

Question 16

do changes in germ cells cause heritable defects

Answer 16

yes

Question 17

MMR

Answer 17

mismatched repair enzyme

Question 18

when does crossing over occur and what is it

Answer 18

homologous chromosomes exchange at chiasma
Prophase 1
genetic variation

Question 19

when does independent assortment occur and what is it

Answer 19

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

Question 20

Nullisomic gametes results in what

Answer 20

monosomic zygote - only one copy of chromosome

Question 21

disomic gamete results in what

Answer 21

triatomic zygote - 3 copies of it

Question 22

trisomy 21

Answer 22

downs syndrome

Question 23

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

Answer 23

patients chromosomes for inblacne

Question 24

aneuploidy

Answer 24

loss or gain of one or more chromosomes

Question 25

gain of one of 2 homologous chromosomes called

Answer 25

trisomy

Question 26

monosomy

Answer 26

loss of a single chromosome

Question 27

Signs of downs syndrome

Answer 27

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

Question 28

trisomy 13

Answer 28

Patau syndrome
descresed muscle tone
small hands and ears and head and mouth
slower physical development

Question 29

trisomy 18

Answer 29

Edwards syndrome
heart defects
small head and jaw
overlapping fingers

Question 30

two phenotypic consequences of chromosome deletions - syndromes

Answer 30

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

Question 31

Degeorge syndrome

Answer 31

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