Genetic Martin lecture 2

what are totipotent cells?

cells which can become any cell type including extra embryonic membranes

what are pluripotenti cells?

cells which can become any cell of the three germ layers

what are the three germ layers

endoderm, mesoderm and ectoderm

what are multipotent cells?

cells which can become any cell type of a specific lineage

what are housekeeping genes?

subset of genes expressed in practically all cells

housekeeping genes code for RNA and proteins that are required to build common cellular structures such as …

cytoskeleton, plasma membrane and microtubule organising center

3 things housekeeping genes code for

1. common cellular structures

2. organelles

3. basic functions

3 examples of structural proteins encoded for by housekeeping genes

actin, tubulin and lamin A and B

4 types of patterns of gene expression

1. transcriptional

2. post transcriptiona

3. translational

4. post translational

the subunits of a pro RNAP

1 alpha, 1 beta, 1 beta’ and 1 omega

the sigma factor recognises common sequences in the promoter and helps position the RNAP in the right place

copy cus this is important

the sigma factor recognises common sequences in the promoter and helps position the RNAP in the right place

consensus of the TATA / Pribnow box at -10bp in pro cells

TATAAT

consensus of the -35bp box in pro cells

TTGACAT

the sigma factor positions the RNAP in the right place and … the DNA strands

separates

chain termination sequences cause the growing RNA molcules to form what shapes

hairpins

the hairpins forming on the growing RNA molecule cause it to … the DNA template

fall off

what type of sequences regulate mRNA termination without an external signal?

intrinsic termination signals

the protein … binds to … … sequences and then also binds to RNAP causing it to fall off the DNA template

rho, termination signal

in prokaryotic cells where do transcriptional repressors sit?

close to the promoter

name of a group of related genes that are cotranscribed under the control of the same promoter and repressor

operon

which repressor is the lac operon regulated by?

lac repressor protein

what enzymes do lacZ, lacA and lacY code for respectively?

beta galactosidase, permease and thiogalactoside transacetylase

which gene of the lac operon encodes the lac repressor?

lacI

does the lac repressor bind to the operator in the presence of lactose?

no

does the lac repressor bind to the operator in the absence of lactose?

yes

what molecule binds to the lac repressor displacing it from the promoter?

lactose

which two guys discovered how the lac operon is organised and regulated?

Jacob and Monod