Lectures 3 + 4

Question 1

Fragile X syndrome

Answer 1

X-linxed dominant

reduces penetrance (80% boys 30% boys)

from expansion of CGG triplet repeat

methylation of FMRI => deficiency of protein

Normal, Premutation, mutation

Full blown mutation is inherited from carrier female

Question 2

EagI

Answer 2

Methylation sensitive enzyme = wont cut if methylation is present

mutation occurs after 200 repeats

Question 3

Sickle Cell disease

Answer 3

Structural changes in the globin chain

2 types: HbS: GAG –> GTG

HbC: GAG–> AAG

Homo= has disease

Carriers= immune to malaria

Question 4

Mnl I site

Answer 4

This site gets destroyed during thiese mutations and this the restriction enzymes can destinguish between A and S/C but not between S and C

Question 5

Thalassemia

Answer 5

Deficiency of one of the chains leading to inclusion body formation by excess amounts of the other chain

Question 6

Beta thalassemia

Answer 6

usually due to single base pair substitution

results in excess alpha with no beta to pair with so forms alpha homotetramer (heinz body)

these cause destruction of RBC

Question 7

Alpha thalassemia

Answer 7

Beta globin cluster

due to deletions from mismatched crossovers

can loose either one or both alpha genes

Question 8

Hb constant spring

Answer 8

mutation UAA –> CAA

this causes a stop to the production of alpha chain

tetramer of beta that will not release Oxygen

Question 9

Cystic Fibrosis

Answer 9

Autosonal recessive

Defective CFRT gene (normally produces Cl channels)

Delta508 is a common mutation

Question 10

Embryology

Developmental Biology

Answer 10

study of development between fertilization and birth

study of embryonic and other developmental processes

Question 11

embryogenesis

Answer 11

when the organ primordia is established

Question 12

Carnigie stages

Postovulatory stages

Answer 12

based on external features = arbitrary

Days since last ovulation

Question 13

cleavage

Answer 13

increases the number of cells but not the overall size

Question 14

compaction

Answer 14

after third division cells maximize their contact with eachotehr

segregat inner cells from outer cells

outer cells form tight junctions for stability

Question 15

Blastocysts

Answer 15

When the inner cell mass is positionned on one side of the trophoblast cell

Question 16

Cavitation

Answer 16

trophoblast cells excrete fluid into morula to create blastocoel (fluid filled cavity)

Question 17

pluripotent

Answer 17

can differentiate into any cell type in the body

Question 18

totipotent

Answer 18

can differentiate into any cell type including extraemryonic tissue

Question 19

L-selectin

Answer 19

on the trophoblast and interacts with receptor on uterus wall causing rolling and tethering interactions

Question 20

ectopic pregnancy

Answer 20

implantation somewhere other than uterus

Question 21

cytotrophoblast

Answer 21

inner layer of mononucleate cells

releases proteolytic enzymes to remodel the uterine blood vessels

Question 22

syncyotrophoblast

Answer 22

outer multinucleate cells that lack distinct bounderies

dijest uterine wall and connect the blood vessels

Question 23

bilaminar germ disc

Answer 23

ICM differentiates into hypoblast and epiblast

Question 24

primative streak and primative node

Answer 24

primative node is organizer tissue which expresses genes that induce formation of embryo

Question 25

invagination

Answer 25

movement of epiblast cells through primitive streakand slps beneath it to give rise to the endoderm and mesodern

cells remaining in epiblast form ectoderm

Question 26

anterior visceral endoderm (AVE)

Answer 26

Signals anterior-posterior axis

by expressing genes that direct the head formation

Question 27

Steps of neurulation

Answer 27

1. Formation and folding or the neural plate
2. elevation of the neural crest
3. convergence of the neural folds
4. clolsure of the neural tube when the neural folds are brought in contact with eachother

then neural crest cells migrate away

Question 28

Spina bifida

Answer 28

failure of closure in the posterior portion of the neural tube

Question 29

Anenchephaly

Answer 29

Failure of neural tube to close in the anterior portion

Forbrain remains in contact with amniotic fluid and degenerates

Question 30

eithelial-to-mesenchymal transition

Answer 30

Neural crest cells change from epithelial to loosely organized connective tissue of any origin