GENES

Question 1

EXPLAINS WHAT SONIC HEDGEHOG GENE IS

Answer 1

SHH> MAKES SONIC HEDGEHOG PROTEIN
EMBRYONIC SIGNALING PROTEIN
MANY EMBRYONIC ROLES> LIMBS, BRAIN, EYES.

KEY ROLES> CNS DEVELOPMENT
LIMB DEVELOPMENT

Question 2

WHAT IS THE IMPORTANCE OF THE SHH GENE IN THE CENTRAL NERVOUS SYSTEM?

Answer 2

FORMATION FOREBRAIN
SIGNALING SEPARATES RIGHT AND LEFT BRAIN
ESTABLISHES MIDLINE
MUTATION> HOLOPROSENCEPHALY
SO THIS WILL BE A BABY BORN WITH A WHOLE HOLOPROSENCEPHALY, MEANING THE BABY DOES NOT HAVE LEFT AND RIGHT HALVES OF THE BRAIN

Question 3

WHAT IS THE HOLOPROSENCEPHALY

Answer 3

FAILURE OF CLEAVAGE OF PROSENCEPHALON
LEFT, RIGHT HEMISPHERES FAIL TO SEPARATE
SINGLE LOBED BRAIN> NO LEFT, RIGHT HEMISPHERES
FACIAL ABNORMALITIES> CLEFT LIP / PALATE, CYCLOPIA

Question 4

EXPLAIN THE LIMB DEVELOPMENT

Answer 4

LIMBS DEVELOP ALONG THREE PLANES

-PROXIMAL TO DISTAL > HUMERUS, RADIO, WRIST
-DORSAL - VENTRAL AXIS > DORSAL - ETENSORS MUSCLES AND VENTRAL - FLEXORS MUSCLES
- ANTERIOR - POSTERIOR AXIS >
ANTERIOR> TOWARDS HEAD

Question 5

WHAT IS THE APICAL ECTODERMAL RIDGE

Answer 5

CRITICAL FOR PROXIMAL TO DISTAL DEVELOPMENT.
ECTODERM OVERLYING MESODERM
AREA OF LIMB BUD FORMATION
REMOVAL> LIMB STOP GROWING

INFLUENCES UNDERLYING MESODERMAL GROWTH
MESODERMAL ALSO INFLUENCES ECTODERMAL RIDGE.

KEY TRANSCRIPTION FACTOR> FIBROBLAST GROWTH FACTOR / FGF /

RIDGE REMOVED, REPLACED WIH FGF > NORMAL GROWTH

Question 6

EXPLAIN THE DORSAL - VENTRAL AXIS

Answer 6

INCLUDES FLEXORS AND EXTENSORS MUSCLES.
DEPENDS AND MULTIPLE GENES
-RADIAL FRINGE / DORSAL
-ENGRAILED 1 / VENTRAL
-SER 2 /BORDER/
-Wnt - 7a

Question 7

Wnt-7a

Answer 7

key for the dorsal development.
activates LMX -1 gene in mesoderm
dorsalizes mesoderm
gene deletion > two ventral sides to limb
mouse embryos> sole on both surfaces of paws

Ventral side> engrailed 1 represses Wnt-7a

Question 8

EXPLAIN THE ANTERIOR -POSTERIOR AXIS

Answer 8

DEPENDS ON ZONE OF POLARIZING ACTIVITY
INFLUENCES AER
MAJOR SIGNALING MOLECULE > SHH
- SONIC HEDGEHOG PROTEIN

Question 9

WHAT IS THE HOMEOBOX GENE

Answer 9

ALSO CALLED HOX GENES
CODE FOR TRANSCRIPTION FACTORS
REGULATORS OF AP AXIS DEVELOPMENT
HOMEOTIC GENES>
-HOMEOSIS > TRANSFORMATION OF ONE STRUCTURE INTO ANOTHER
-HOMEOTIC GENES> LEAD TO FORMATION OF BODY SEGMENTS
-MUTATION> ABNORMAL BODY PART FORMATION

ALL HOMEOTIC GENES HAVE THE SIMILAR SEQUENCE / 180 BASES/ CALLED THE HOMEOBOX _ PART OF GENE.