{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

BIPN 144 Discussions

BIPN 144 Discussions - BIPN 144 Discussion 1 Two important...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
BIPN 144 Discussion 4/12/2010 1) Two important molecules a. Transcription factors – can activate (turn genes on) and repress (turn genes off) b. Morphogens – to be a morphogen i. Molecule must be distributed in a graded fashion ii. Different concentrations elicit different cellular responses. Example is dorsal. High levels of dorsal mesoderm turns on snail and twist (mesoderm) Sna blocks neuronal genes Twist activates neuronal genes o These are transcription factors (TF’s) Moderate levels activates neuronal genes u have Sog, Rho, Brk, AS-C (neural ectoderm) Brk turns off epidermal genes (done by blocking dpp) AS-C activates neural genes (is indep of dorsal, theoretically can be expressed anywhere but dpp blocks this and snail blocks this via repression but u don’t need to know this) Sog blocks the activity of dpp Rho activates the expression of epidermal genes on the ventral side Absence of dorsal we get epidermal genes u have dpp (epidermal ectoderm) Dpp promotes activation of epidermal genes and blocks neural genes (mention both on exam) (what happens on the lateral side? There are ventral epidermal cells involved as well as neural genes) Know how to draw and label this embryo. Coding region for snail (see notes for pictures). Binding sites are dorsal…are low affinity sites because need a lot of dorsal for snail to be expressed, therefore low affinity – wont bind to R for very long but has constant bindings of the high levels of dorsal. Coding region for rho – has snail and dorsal binding sites. Dorsal binding site is high affinity here and therefore needs low amt of dorsal to be activated. Can ask a Q on like binding sites for snail and rho being high/low affinity and how rho has repressor receptors for it. So if snail is present (a repressor) then rho wont be activated in the ventral side. Dorsal comes from the maternal factor in the mom. For a gene to be activated: Activator must be present All the repressors must be absent *What is the diff/similarity in dorsal/ventral patterning between fruit flies and frogs? Similarity is dorsal/ventral patterning has a morphogen (just diff TF’s). Difference is an extrinsic factor such as sperm entry in the frog, but the fly doesn’t have this.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
See picture of frog embryo w animal pole and vegetal pole. Vegetal pole has latent dorsalizing factors – so when sperm enters the egg cell u get cortical rotation where the dorsalizing factor moves up and activates something called activated dorsalizing factor – lead to high levels of beta catenin in the dorsal side to lower levels towards the ventral side. There’s a TF called Veg-t on the vegetal pole – it activates expression of mesoderm inducing factors. It also suppresses the response to these diffusible factors in the endoderm. The endoderm being after the mesoderm (on the vegetal pole), so technically veg-t makes the mesoderm Sperm entry defines the ventral side. Causes cortical rotation, causes latent dorsalizing factors to move to the opp pole from where sperm
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

Page1 / 8

BIPN 144 Discussions - BIPN 144 Discussion 1 Two important...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon bookmark
Ask a homework question - tutors are online