gene expression defines cells
DESCRIPTION
Gene Expression Defines Cells. http:// www.ornl.gov/hgmis. Recall the Central Dogma. Info. Info Carrier. Functional Product. DNARNAPROTEIN. All Information is in DNA. http:// www.ornl.gov/hgmis. DNA is a Nucleic Acid. Principle information molecules in the cell - PowerPoint PPT PresentationTRANSCRIPT
http://www.ornl.gov/hgmis
Gene Expression Defines Cells
Recall the Central Dogma
DNA RNA PROTEINInfo Info Carrier Functional Product
http://www.ornl.gov/hgmis
All Information is in DNA
Principle information molecules in the cell
Linear polymer of nucleotides (or bases)
Two types Deoxyribonucleic Acid – DNA
Information storage in cells Ribonucleic Acid – RNA
Information carrier in cells
DNA is a Nucleic Acid
Three components Nitrogenous Base (A, C, G, T) Ribose Sugar Phosphate
Nucleotides in DNA
Nucleotide Bases
Nucleotide Detail
For DNA bases are A, C, G, T Sugar is deoxyribose (no OH at 2’ position)
For RNA bases are A, C, G. U Sugar is ribose (OH at 2’ position)
DNA and RNA
Phosphodiester Links Nucleotides
Holds nucleic acid strands together
H-bonding between complementary bases This is an interaction that is easily broken
A pairs with T (DNA), (A-U for RNA)
G pairs with C (both DNA and RNA)
Complementary Base Pairing
Complementary Base Pairing
DNA Structure
DNA Structure Reveals Copying Mechanism
DNA is Transcribed
http://commons.wikimedia.org/wiki/Image:DNA_transcription.gif
Transcription Initiation
http://upload.wikimedia.org/wikipedia/commons/thumb/9/91/Simple_transcription_initiation1.svg/721px-Simple_transcription_initiation1.svg.png
Promoter with Transcription Factors
http://stemcells.nih.gov/StaticResources/info/scireport/images/figurea6.jpg
Transcription and Translation
Proteins
Primary functional molecules of the cell; execute the tasks directed by the genetic material
1. Structural molecules (e.g., hair, fingernails, connective tissue)
2. Transmitting Information between cells (e.g., hormones)
3. Defense against infection (e.g., antibodies)
4. Enzymes (catalyze nearly all biochemical reactions)
Building Blocks are Amino Acids
20 different amino acids in proteins
Chemical properties of side chains determine function
Central carbon atom (Ca)
1. H atom
2. Amino group (NH3+)
3. Carboxyl group (COO-)
4. R group (side chain)
R-group (Side Chain)
R -group determines identity, function
A.A. are categorized by chemical properties of the side chains
1) Polar (uncharged) = hydrophilic
2) Positively charged (basic) = ionic
3) Negatively charged (acidic) = ionic
4) Nonpolar = hydrophobic
Nonpolar Amino Acids
The side chains of these a.a. tend to be located in the interior of proteins, where they are not in contact with water.
Peptide Bond
Links amino acids
Amide linkage between -NH3 and -COO-
Defines amino (N) terminus and carboxy (C) terminus
Protein Structure
Polypeptide (protein) chains fold into globular structure
Defines cracks and crevices that can interact with other molecules
Allows proteins to be enzymes
Enzymes
Enzymes are catalysts
They increase the rate of reactions
This allows rapid synthesis and degradation of products in cells
Building Proteins -Translation
mRNA contains 3 nucleotide codons Each codon specifies an amino
acid
Triplet codons are decoded by tRNA decoding is base pairing between
codon on mRNA and anticodon on tRNA
Each tRNA carries a specific amino acid codon-anticodon pairing delivers
specific aa to the growing polypeptide chain
"protein: synthesis." Online Art. Britannica Student Encyclopædia.
10 Aug. 2008 <http://student.britannica.com/eb/art-1692>.
http://www.ornl.gov/hgmis
Overview of Gene Expression