Day 39 Gene Expression

Intro to Gene Expression

The pathway to you...

Nucleotides - Codons - Genes - Chromosomes - DNA

DNA - RNA - mRNA - Ribosome - tRNA - Amino Acids- Protein

The protein pathway...

Ribosome - Rough Endoplasmic Reticulum - Golgi Apparatus - Vesicle - Exocytosis

Enzymes to know

-DNA Helicase

-DNA Polymerase

-DNA Primase

-RNA Primer

-DNA Ligase

-Repair Enzyme

-Binding Protein

Terms to know

- 5' (5 prime) and 3' (3 prime)

-Parent Strand

-Daughter Strand

-Semiconservative Replication

-Complimentary Base Pairs

-Leading Strand

-Lagging Strand

-Replication Fork

-Replication Bubble

Now I want you to take some time to draw your own replication bubble

Assignment:

Write a one to two page paper describing how DNA is replicated

-First paragraph is an intro and background

-Second paragraph describes the process

-Third paragraph explains mutations and relates this info to what you previously learned about cancer

-Fourth paragraph compares your new info to any previous misconceptions you might have had

-Fifth paragraph will be your conclusion

In Eukaryotic cells the Promoter begins with what is known as a TATA Box. It is called a TATA Box because it begins with Thymine, Adenine, Thymine, Adenine, and then continues with Adenines.

-Proteins known as Transcription factors bind to the TATA Box and then the RNA polymerase binds to the transcription factors. The RNA polymerase then begins transcribing the DNA into an RNA molecule.

Turning the RNA into mRNA

Before RNA can leave the nucleus it needs to be modified into mRNA.

-mRNA processing involves

-Adding a modified Guanine cap and a poly-A tail. The tail of mRNA is made up of 50-250 Adenine nucleotides.

-Right after the Cap (5' UTR) and before the tail (3' UTR) is a region known as UTR (Untranslated regions). The ribosome will bind to the 5' UTR and the start codon comes right after the UTR. The stop codon is right before the 3' UTR.

-Next the Introns need to be removed and the Exons spliced together

-Intron is short for intervening sequence

-Exon is short for expressed sequence (sometimes it is easier to think of introns as staying "in" the nucleus and Exons ans "exiting" the nucleus.

-The Introns are cut and the Exons spliced together by ribozymes called spliceosomes

-A ribozyme is RNA that acts like an enzyme

Translation

Codon Wheel

Prokaryotic cells can go through gene expression much faster because they do not have a nucleus. Transcription and translation can happen at the same time. While the RNA strand is being made the ribosomes can translate it at the same time.

This is one reason that bacteria can do things so fast