Lecture 3: Gene Expression: Translation / Protein Synthesis Flashcards
Transcription + Translation =
Gene Expression
Section of DNA (a gene) being transcribed & translated to produce a protein.
gene expression
Genes can be turned on and off (called ___________) by various mechanisms.
Occur at any point during gene expression, but most commonly occurs at the
level of ___________.
gene regulation
transcription
Gene regulation:
Signals from the environment or from other cells activate proteins called
_____________ factors which control the level of transcription.
transcription
What are regulatory elements in transcription process?
Enhancers and suppressors
-Genes are turned on and off in different patterns during development stages
There are the 20 biologically active amino acids in humans. They are
encoded directly by the codons of the universal genetic code are called
__________ or ____________ amino acids.
standard, canonical
There are _____ Essential amino acids (indispensable) amino acid , which
cannot be synthesized de novo ), and have to get them from diet.
9
– histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine,
tryptophan, and valine.
Basic amino acid structure:
a central alpha carbon covalently bonded to…
-a carboxyl group
-an amine group
-a hydrogen
-a variable R group
a sequence of three nucleotides that together form a unit of genetic code in a DNA or RNA molecule, and the genetic information is translated into proteins by living cells.
Codon
Amino acids are the structural units (monomers) that make up
proteins.
There are the 20 biologically active amino acids in
Humans
They are
encoded directly by the codons of the universal genetic code are called
standard or canonical amino acids
There are _________ Essential amino acids (indispensable) amino acid , which
cannot be synthesized de novo ), and have to get them from __________
There are nine Essential amino acids (indispensable) amino acid , which
cannot be synthesized de novo ), and have to get them from diet
nine essential AA
histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine,
tryptophan, and valine
Amino Acids join together to form short polymer chains called _____________
or longer chains called either __________ or __________.
*
peptides
or longer chains called either polypeptides or proteins.
*
Basic Amino Acid Structure
a central alpha carbon covalently linked to:
a central alpha carbon covalently linked to:
- Carboxyl group
- an amine group
- a hydrogen
- a variable R group
The Genetic Code
Codon
– a sequence of three nucleotides that together form a unit of genetic code in a DNA
or RNA molecule, and the genetic information is translated into proteins by living
cells.
The Genetic Code
Nonoverlapping and universal in
plant and animal kingdoms (ex. Mitochondrial code)
The Genetic Code
Degenerate (wobble base codon
– The first two positions of the mRNA codon observe Watson-Crick base pairing rules
(A-U, C-G) The third position exhibits wobble
The genetic code
codon read by
Read by complementary tRNA linked to aa
Initiation codon
AUG (met)
Stop codons
UAA, UGA, UAG
Translation
Information what
high what
- Information decoding
- High energy consuming process
– consumes 90% of cells energy
– 4 ATP / aa
Protein Synthesis Players
- Ribosome / rough ER / rER (rRNA + protein)
- tRNA = anticodon with aa
- mRNA = codon
Protein Synthesis Players
Ribosome has 2 sites which associate with mRNA
– P site (initaition)
– A site (elongation)
Protein Synthesis Steps
Initiation
– 1st aa always methionine (Met) at P site
– Template = mRNA
– mRNA moves down in register (A site) and codon is read by
anticodon of tRNA
Protein Synthesis Steps
Elongation
– new aa brought in to match new codons and peptide bonds formed
Protein Synthesis Steps
Termination
Stop codon (UGA,UAA,UAG)
Massager RNA (mRNA)
Carries instructions from DNA to where
tells the ribosome what
- Carries instructions from DNA to the rest of the ribosome.
- Tells the ribosome what kind of protein to make
Transfer RNA (tRNA)
A go-getter.
Gets the right
parts to make the
right protein
according to
mRNA instructions
Ribosomal RNA (rRNA)
Part of the _____
helps in ______
- Part of the structure of a ribosome
- Helps in protein production
Ribosomal RNA (rRNA)
Ribosomes contain two ______ and 50 or more ________
rRNA sequences are widely used for ________
- Ribosomes contain two major rRNAs and 50 or more
proteins - rRNA sequences are widely used for working out
evolutionary relationships among organisms
Ribosomal RNA (rRNA)
Prokaryotic rRNA
size 70s
large subunits- 50s and 23s
small subunits: 30s
Ribosomal RNA (rRNA)
eukaryotic rRNA size
size: 80s
large subunits- 60s and 28s
small subunit- 40s
End Product of protein synthesis
- The end products of protein synthesis is a primary structure of a
protein. - A sequence of amino acid bonded together by peptide bonds.
Post Translational Modification and Regulation
Recognition of
Signal Peptide