Class Notes (839,462)
Canada (511,348)
Biology (6,826)
Lecture 15

Lecture 15.docx

4 Pages
91 Views

Department
Biology
Course Code
Biology 1202B
Professor
Brenda Murphy

This preview shows page 1. Sign up to view the full 4 pages of the document.
Description
1 MiRNA (Chapter 14) Human Development  Human egg when released from the ovary is almost completely metabolically active  Within seconds of the egg & sperm meeting, there is rapid cell division o Mitosis (growth) produce cells of the body  Cells differentiate into specialized cells with different functions through translation and transcription  Every nucleated cell of the body contains the same DNA template and genes o Ie. Liver cells do not contain different DNA than skin cells  Structural and functional differences in cell types result from the presence or absence of the products resulting from expressed (transcribed, or transcribed & translated) genes rather than the actual presence of genes themselves on DNA  It is not enough just to have a gene present in DNA through a very complex system o Genes must be expressed (or not expressed) o In the correct tissue (special) o At the correct time (temporal) Gene Expression (Transcription &/or Translation) is like Music Played by an Orchestra  Gene is present in DNA but it is ―on‖ or ―off – but there is a lot of variability in this o Gene is expressed/not expressed o This may change at different tissues or at different times  Development vs. puberty time vs. 20’s are different – some diseases are age specific due to being turned on/off at different times  Gene is individually fine tuned o May be loud (forte) or quiet (piano) o Staccato (short ½ life) vs. legato (long ½ life)  Gene’s tuning is dynamic & aware of its surrounding  Adjust your volume relative to the volume around you o If done properly you get music (normal development) o If not, you get noise (abnormal/lethal development) Regulation of Gene Expression in Prokaryotes  Simple, single celled organisms with generation times in minutes  Rapid & reversible alterations so they can adapt quickly to changes in their environment o Genes are organized into a functional unit called an operon  I.e. coordinated synthesis of proteins with related functions o Example: Lac operon is an example of transcriptional regulation demonstrating how genes are turned on and off Regulation of Gene Expression in Eukaryotes 2  Multicellular cells  More complicated since nuclear DNA is bound to histones o Thus they need chromatin remodeling to loosen histone DNA interaction  Acetylases add acetyl groups to histones  Acetyl Groups = CH 3O  DNA is wrapped on the outside of the proteins—not easily accessible to transcription factors  Therefore, need to do something to the DNA to allow it to bind to the enzymes o Or, Slide nucleosomes (just a little bit) away from the gene’s promoter region o DNA is wrapped around a core of two molecules of each histones H2A, H2B, H3 and H4  Higher level of compaction when H1 is linked to adjacent nucleosomes - Promoter DNA is not accessible to proteins (RNA polymerase, Transcription Factors) that bind to initiate transcription - Using ATP energy, chromatin remodeling complex binds and slices nucleosomes along DNA - Promoter DNA is accessible and the gene may be active - May be active – need RNA polymerase and transcription factors to turn it on – if they are not present, even though the promoter may be accessible, there are other things that affect if it is turned on or off Regulation of Gene Expression in Eukaryotes  More complicated since nuclear DNA is bound to histones o Thus, need chromatin remodeling to loosen/slide nucleosomes from the promoter  This produces a large number of cells, and produces a large number of different types of cells o Transcriptional Regulation – Which genes are transcribed? Most VIP o Post-Transcriptional Regulation – Types & availability of mRNAs to ribosomes o Translational Regulation – Rate at which proteins are made o Post-Translational Regulation – Availability of the finished protein Central Dogma  DNA ---- (transcription) ---> mRNA --- (translation) -
More Less
Unlock Document

Only page 1 are available for preview. Some parts have been intentionally blurred.

Unlock Document
You're Reading a Preview

Unlock to view full version

Unlock Document

Log In


OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit