Transcript Special Topics gene expression

Special Topics
Review of Gene Expression
Outline
I. Definition of gene expression
II. Proteins- the end product of gene expression
A. Polymers of monomers
B. Joined by peptide bond
C. Denaturing of proteins leads to loss of function
i. Ways to denature protiens
D. Genes code for proteins
i. Genome vs. gene
ii. Polymer of monomers (nucleic acid vs. nucleotide)
III. Transcription – DNA to RNA
A. Where does this occur?
IV. Translation –RNA to protein
A. Where does this occur?
VI. Why do we care about gene expression as allied health students?
VII. Terminology to be aware of throughout the semester
1
Gene Expression- the process that makes a
heart a heart, a brain a brain, and you
different from me. The final end result is the
synthesis of a protein.
DNA
RNA
Protein
•Structural molecules
•Enzymes
•Receptors for signals and hormones
•Adhesion molecules
•Recognition markers
The physiology comes from protein functions!
2
Proteins are chains of amino acids linked
by the Peptide Bond
Primary structure
3
Essential 20: central carbon, hydrogen, amine
group and carboxyl group....different R groups
Glycine
Alanine
Serine
Threonine
Valine
Cysteine
Leucine
Isoleucine
Methionine Glutamic acid
4
Aspartic acid
Phenylalanine
Lysine
Tyrosine
Arginine
Asparagine
Glutamine
Histidine
Tryptophan
Proline
5
Denaturing proteins: loss of structure
leads to loss of function
Heat
pH
high salt
What is another way to change a
protein’s conformation?
6
Folding and coiling is
First, understand this: stabilized by bonds
formed between the
“R groups” of amino
acids.
R
R
7
Changing a single amino acid
can change the shape of the
protein
Can result in loss of protein function
8
Genes code for proteins
A gene is a code which
determines the
sequence of amino
acids in a protein
DNA
RNA
So changes in a gene can result in
changes in protein structure (and
the protein’s ability to function)
Protein
9
Genome vs gene?
• Genome: like a cookbook
• Gene: single recipe
• How are recipes written?
– Ingredient list
– Order of adding ingredients
• The gene= the recipe for a
protein.
– Which amino acids to link
together
– Order of linking them together
– Mutation= heritable change
10
April 2003- Human Genome Project was
completed.
What do we know
• Haploid genome is a little
over 3 billion base pairs.
• 20-25,000 proteinencoding genes
• What’s the rest?
– RNA genes (tRNA, rRNA,
RNAi/ RNAa’s, too)
– “junk DNA” (pseudogenes)
– Repeating elements,
transposons, etc.
11
DNA is
•Macromolecule made by
dehydration synthesis
•Double stranded
•Antiparallel
•5’ end to 3’end
• has base-pairing rules:
A-T
C-G
12
Transcription: Making a “working copy” of a
gene. This process occurs in the nucleus of a
cell
DNA
transcription
RNA
Protein
RNA:
• Is a macromolecule
• is single stranded
• It contains the sugar ribose (rather than deoxyribose)
• It lacks T, uses U instead (uracil rather than thymine)
13
Translation:
the ribosome makes a protein using the
code in the mRNA molecule and this occurs in the cytoplasm
14
Summary
Interactive Workshop Activity on Protein Synthesis
http://www.pbs.org/wgbh/aso/tryit/dna/index.html#
15
Why do we care about
gene expression?
• Drug reaction due to expression of “alternate”
forms of genes. (Personalized medicine is coming!
NewScientist 27 Oct 2007)
• Some people are more susceptible to disease
states or infection (HIV/ Alzheimer’s / Diabetes/
obesity)
• Your feelings can alter gene expression!
(September 2007 issue of Genome Biology)
loneliness desensitizes the glucocorticoid receptor
and cuts off immune control and anti-inflammatory
effects of cortisol.
• Massage/hugging/gentle touch increases the
synthesis and release of oxytocin (a protein
hormone). More oxytocin means better social
bonds.
• The smell of coffee upregulates gene expression
of nine different genes
• Just to name a few......
16
Terminology
• Mutation vs. DNA damage
• Pluripotent vs. unipotent stem cells
• Determined vs. Differentiated
17