Chapter 14 Translation and Proteins Flashcards
Translation is the _______________ of amino acids into ____________ chains
polymerization
polypeptide
Translation requires…
- amino acids
- messenger RNA
- ribosomes
- transfer RNA
What are the 4 stages of translation?
- tRNA charging
- Initiation
- Elongation
- Termination
in tRNA charging, __________ bind
amino acids
in initiation, components are assembled at the ________
ribosome
in elongation, __________ are joined
amino acids
in termination, ________________ halts
protein synthesis
What are ribosomes?
ribosomal proteins and ribosomal RNAs (rRNA)
They are subunits
rRNA’s perform _________ functions
catalytic
proteins promote _______
binding
the tRNA structure is a __ structure, like a __________
2D
cloverleaf
the tRNA structure is __-__ nucleotides long
75-90
what are tRNA’s?
triplet codons in mRNA to the correct amino acid
Posttranscriptionally modified bases are unique and ________ hydrogen bonding efficiency.
name 3
enhance
- inosinic acid
- ribothymidylic acid
- pseudouridine
tRNA structure consists of an _________
anticodon
in a tRNA structure, the amino acid is bound to the ___ sequence at the __ end
CCC
3’
pG at __ end
5’
What is the first step in charging tRNA?
tRNA is chemically linked to their amino acids
What is it called when tRNA is chemically linked to amino acids?
Charging
aminoacylation
Aminoacyl tRNA synthetase charges/ activates tRNA’s with the appropriate _____ _____
amino acids
How many tRNA molecules and how many synthetases?
31 tRNA
20 synthetases/ enzymes
CHARGING tRNA
1. Amino acid is _________- aminoacyladenylic acid
activated
CHARGING tRNA
2. Covalent linkage between __ _________ group and amino acid
5’ phosphate
CHARGING tRNA
3. Amino acid is transferred to the appropriate ____
tRNA
CHARGING tRNA
4. Bonded covalently to the adenine residue at the __ end
3’
Charged tRNA is ________ involved in protein syntheses
directly
only recognizes ___ amino acid
one
What are the 6 things initiation requires?
- mRNA
- the small and large ribosomal subunits
- GTP
- charged initiator tRNA
- Mg2+
- 3 initiation factors
TRANSLATION: INITIATION (STEP 2)
- Small subunit binds to _________ _______ and to ____
- fmet- tRNA binds to the small subunit; sets _______ _____
- Large ribosomal unit binds to complex and a molecule of ___ is hydrolyzed (providing energy); __ released
- initiation factors; mRNA
- reading frame
- GTP; IF
STEP 2
IF3 binds to ___ subunit; prevents binding to ___
30s; 50s
STEP 2
IF2 binds to ____- tRNA to 30s- mRNA complex; hydrolyzes ___
fmet; GTP
STEP 2
IF1 binds to ___ subunit; prevents ____ from binding to A site
30s; tRNA
STEP 3 TRANSLATION/ ELONGATION
What enzyme catalyzes peptide bond formation?
peptidyl transferase
catalytic activity 23s rRNA large subunit
STEP 3
AA on the tRNA at the _ site and the growing peptide chain bound to the tRNA in the _ site
A; P
STEP 3
Unchanged tRNA moves to the _ site
E (exit)
STEP 3
tRNA bound to the peptide chain moves to the _ site
P
STEP 3
- charged tRNA binds to _ site
- _______ bond
- _____________ ( movement 5’ to 3’ direction)
- A
- peptide
- translocation
STEP 4 TRANSLOCATION/ TERMINATION
Termination is signaled by a ____ _____ in the A site
stop codon
Why?
GTP- dependent release factors cleave the polypeptide chain from the trRNA.
released from complex
STEP 4
RF1- specific for ___ and ___
UAA and UAG
STEP 4
RF2- Specific for ___ and ___
UGA and UAA
STEP 4
RF3- stimulates ___ and ___
RF1 and RF2
_____________ are mRNAs with several ribosomes translating at once
polyribosomes
As mRNA passes through ribosome, its free to associate with another small _______
subunit
TRANSLATION IN EUKARYOTES
In eukaryotes:
ribosomes are larger than in bacteria (T/F)
True
TRANSLATION IN EUKARYOTES
In eukaryotes:
transcription and translation are spatially and temporally separated (T/F)
True
TRANSLATION IN EUKARYOTES
RNA Processing:
5’ end of mRNA capped with 7- methylguanosine residue at maturation, which is essential for translation (T/F)
True
TRANSLATION IN EUKARYOTES
RNA Processing:
Poly- A tail added at 3’ end of mRNA (T/F)
True
TRANSLATION IN EUKARYOTES
Ribosomes scan for the initiator tRNA that is in the proper context, as identified by the _____ sequence (A/GNNAUGG)
Kozak
TRANSLATION IN EUKARYOTES
Ribosomes are not free- floating, associated with ___________ reticulum.
Endoplasmic
The initial insight that proteins are important in heredity was provided by the study of _______ errors of metabolism
inborn
Hundreds of medical conditions caused by errors in _________ due to mutant genes
metabolism
Alkaptoruria and phenylketonuria result from mutations that lead to _________ blocks
metabolic
ALKAPTORNURIA
Autosomal _________
recessive
ALKAPTORNURIA
individual cannot metabolize alkapton 2,5- dihydroxyphenylacetic acid (or homogentistic acid) (T/F)
True
ALKAPTORNURIA
Accumulates in cells and excreted in urine (T/F)
True
ALKAPTORNURIA
Darkening of ears and nose (cartilaginous areas), joint deposition leads to arthritic condition (T/F)
True
ALKAPTORNURIA
Garrod: identified disorder in 1902 (T/F)
True
ALKAPTORNURIA
Ahead of time… no one failed to see relationship between _____ and _______
genes/ enzymes
PHENYLKETONURIA (PKU)
Phenylalanine hydroxylase is inactive in affected individuals (T/F)
True
PHENYLKETORURIA (PKU)
Phenylalinine is not converted to tyrosine (T/F)
True
PHENYLKETORURIA (PKU)
Phenylalinine enters cerebrospinal fluid with elevated levels; this results in mental retardation (T/F)
True
PHENYLKETORURIA (PKU)
Low ___________ diet
phenylalanine
PKU
1/ 1000 births (T/F)
True
ONE GENE ONE ENYZME HYPOTHESIS
genes are responsible for _______
enzymes
ONE GENE ONE ENZYME HYPOTHESIS
Beadle and Tatum
-nutritional mutations in the bread mold _________
-led to the loss of an enzymatic activity
-catalyzes an essential reaction
neurospora
GENES AND ENZYMES: ANALYSIS OF BIOCHEMICAL PATHWAYS
Neurospora: metabolic pathway investigated
-synthesis of amino acid ________
argenine
GENES AND ENZYMES: ANALYSIS OF BIOCHEMICAL PATHWAYS:’
_ mutant strains studied
7
GENES AND ENZYMES: ANALYSIS OF BIOCHEMICAL PATHWAYS:
Mutations prevented conversion of citrulline to arginine (T/F)
True
STUDIES OF HUMAN HEMOGLOBIN
not all proteins are enzymes (T/F)
true
STUDIES OF HUMAN HEMOGLOBIN
Some proteins have more then ___ subunit
one
STUDIES OF HUMAN HEMOGLOBIN
one gene: one enzyme hypothesis was modified to one gene: one protein and then to one gene: one ___________ chain
polypeptide
SICKLE CELL ANEMIA
recessive _______ disease
genetic
SICKLE CELL ANEMIA
Homozygous for the ___ hemoglobin allele
Hb^s
SICKLE CELL ANEMIA
Low oxygen conditions: red blood cells become _________ and ______
elongated/ curved
SICKLE CELL ANEMIA
red blood cells aggregate in the venous side; tissues become deprived of ______
oxygen
SICKLE CELL ANEMIA
Affects muscles joint, brain, GI, lungs
Usually anemic
(T/F)
True