LS 3 Lecture 2
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The entire DNA sequence required to encode a functional polypeptide (protein) or RNA
An old name for gene
A DNA sequence that looks like a gene but is not transribed
- - the DNA sequence that determines transcription (RNA synthesis) initiation
- - always at the 5' end of the transcribed region
Transcription regulatory sequences
Sequences that are not promoters but can also regulate transcription
The sequence that is actually transcribed into RNA
- - The sequence that terminates transcription
- - it always occurs at the 3' end
Poly vs. Monocistronic
- Poly (prokaryotic genes): one promoter directs the synthesis of a mRNA that can encode more than one protein
- Mono (eukaryotic genes): ...only one protein
Introns vs. Exons
Introns are non-coding sequences that are transcribed into RNA, but never translated into a protein. Exons are eventually translated.
Why is ssDNA stable in alkaline solution, but not RNA?
The 2' hydroxyl group makes RNA unstable in alkali because it can attack the phosphodiester bonds of the RNA chain and break it (hydrolysis) into nucleotide monomers
Two common secondary structures of RNA
mRNA function and structure
- "message RNA"
- - template for protein translation
- - usually a linear structure
tRNA function and structure
- "transfer RNA"
- - brings amino acids for the translation reaction
- - has a unique clover-leaf structure
- "ribosomal RNA"
- - RNA molecules found in ribosomes, which are the protein synthesis apparatus
What special modifications does eukaryotic mRNA have?
A cap at the 5' end and a poly(A) tail at the 3' end
Describe the bond that holds together two amino acids
It is a covalent peptide bond
How stable is a peptide bond?
How can you break one?
Stable, but can be broken by acid hydrolysis or proteolysis
Components of an amino acid
- - amino group
- - carboxyl group
- - side chain (R)
Hydrophobic amino acids
Alanine (Ala), Valine (Val), Isoleucine (Ile), Leucine (Leu), Methionine (Met), Phenylalanine (Phe), Tyrosine (Tyr), Tryptophan (Trp)
Hydrophilic amino acids
Lysine (Lys), Arginine (Arg), Histidine (His), Aspartate (Asp), Glutamate (Glu), Serine (Ser), Asparagine (Asn), Threonine (Thr), Glutamine (Gln)
Special amino acids
- Cysteine (Cys)
- Glycine (Gly)
- Proline (Pro)
- Degrades proteins
- adds phosphate to a protein
- removes phosphate
- Synthesize RNA
- DNas and RNase
How can you measure protein function? (three ways)
- Affinity - binding strength
- specificity - binding preference
- velocity - speed of reactions
The region of an antigen recognized by the antibody
Complementarity Determining Region (CDR)
The region of an antibody that binds to an antigen
How do enzymes catalyze chemical reactions?
- - bringing two substrates together at the right orientation
- -changing +/- charges of the substrate
- -inducing tensions in chemical bonds of the substrate molecule
The Central Dogma states that...
The flow of genetic information is always from DNA to RNA
Transcription is catalyzed by...
Transcription is the process by which...
RNA is synthesized
What are the components needed for translation?
DNA replication results in a newly synthesized dsDNA that contains one parental strand and one new strand
DNA replication is catalyzed by...
Three types of point mutations
- - Nonesense (change of amino acid codon to the stop codon)
- - Missense (change from one amino acid to another)
- - Silent (change to a different codon for the same amino acid)
Sickle cell anemia
- person inherits two mutant alleles, resulting in a mutant HbS protein that cause their erythrocytes to change shape, which results in anemia
How are sickle cells different from normal red blood cells?
- - they are sickle-shaped and rigid
- - they only last about 10-20 days instead of 4 months
Describe the HbS mutation
A point mutation in the beta-globin gene causes the glutamate codon GAG to change into the valine codon GUG
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