Protein Synthesis and Protein Functions

Question 1

What is the process of creating custom treatment based on the genetic basis of condition?

Answer 1

precision medicine

Question 2

What is translation?

Answer 2

the process of making a peptide chain using mRNA that is read 5’-3’
-codons are 3 nucleotides in a row that are read by the anticodons on tRNA

Question 3

which RNA contains all anticodons?

Answer 3

tRNA

Question 4

Where is translation completed?

Answer 4

in the ribosomes

Question 5

What is the structure of ribosomes?

Answer 5

2 subunits (40s and 60s)
-33 proteins in the 40s subunit
-46 proteins in the 60s subunit
-there are 4 rRNAs that make up the ribosomes: 18S, 28S, 5.8S, and 5S rRNA

Question 6

What is the most abundant RNA in the cell?

Answer 6

rRNA

Question 7

How is 18S, 28S, and 5.8S rRNA made?

Answer 7

transcribed by RNA polymerase I
-further processed in the nucleolus

Question 8

How is 5S rRNA made?

Answer 8

transcribed by RNA polymerase III outside the nucleolus

Question 9

What transcribes mRNA?

Answer 9

RNA polymerase II

Question 10

What are the functions of rRNA in the ribosomes?

Answer 10

1. structural- framework that hold ribosomal proteins together
2. facilitate chemical reactions involved in peptide elongation
3. binding sites for tRNA
4. conformational changes- allow ribosome to move along the mRNA
5. subunit coordination- aid proper alignment of 40S and 60S subunit

Question 11

What do RNA modifications allow?

Answer 11

1. Ribosome assembly
2. ribosome stability
3. tRNA recognition
4. codon-anticodon interactions
5. peptide bond formation

Question 12

What are some possible modifications of rRNA?

Answer 12

-methylation of 2-OH position on the nucleotide ribose sugar
-isomerization of uridine nucleotides to pseudouridine
-acetylation

Question 13

What guides rRNA modification?

Answer 13

snoRNA

Question 14

Where does a majority of ribosome assembly occur?

Answer 14

in the nucleolus

Question 15

What are the two types of ribosomes?

Answer 15

membrane bound and free

Question 16

What are membrane bound ribosomes?

Answer 16

the most abundant type
-located on the surface of ER

Question 17

What are free ribosomes?

Answer 17

move anywhere in the cytosol
-make proteins in the cytoplasm

Question 18

Where do proteins made in membrane bound proteins go?

Answer 18

exported out of the cell or to the plasma membrane

Question 19

What allows for mRNAs to be translated? (as opposed to other RNAs)

Answer 19

the have a poly A tail that allows them to exit the nucleus
-allows for formation of mRNA activation complex

Question 20

What are the two components of the translation initiation complex?

Answer 20

1. mRNA activation complex
2. pre-initiation complex
   -40s subunit
   -multiple initiation factors
   initiator methionine tRNA

Question 21

What is an anti-codon?

Answer 21

three nucleotides that associate with the codon on mRNA through base pairing

Question 22

What allows for a decrease in the number of tRNAs required?

Answer 22

redundancy in the genetic code
-inosines in the first position allow for binding of any nucleotide in the third position of codon

Question 23

What are the roles of charged tRNAs?

Answer 23

-use anticodons to read codons
-become charged when amino acids bind

Question 24

What are the steps of translation?

Answer 24

-initation
-elongation
-terminatioin

Question 25

Process of translation:

Answer 25

-first methionine codon in P site -next aminoacyl-tRNA binds in the A site -methionine released form tRNA -peptide bond formed between it and the amino acid on the tRNA in the A site -ribosomes moves 5' to 3' along the mRNA discharging the empty tRNA and shift peptide into the P site -process is repeated over until a stop codon -termination of polypeptide chain involves hydrolysis of the ester bond, releasing the protein

Question 26

What is the primary structure of a protein?

Answer 26

the amino acid sequence in a chain

Question 27

What is the secondary structure of a protein?

Answer 27

stretches of polypeptides that form alpha helices and beta sheets -held in shape by hydrogen bonds

Question 28

What is the tertiary structure of a protein?

Answer 28

refers to the 3D structure of the protein -formed due to interactions between R groups

Question 29

What is the quaternary structure of a protein?

Answer 29

designation for proteins that are made of more than one polypeptide chain -complete structure of all polypeptides

Question 30

What are motifs of proteins?

Answer 30

shared sequences of amino acids that can be used to identify potential members of a protein family

Question 31

What are domains of proteins?

Answer 31

structural entities that function independently within a protein and can be built from a specific motif or set of motifs

Question 32

What are examples of protein sequence motifs?

Answer 32

-proteolytic enzyme cleavage sites -phosphorylation sites -binding motifs -transmembrane spanning sequences -protein secretion leader sequences -transcription factor DNA recognition sequences

Question 33

How do mutations affect protein function?

Answer 33

removing or changing amino acids that define a motif or domain can have an affect on secondary, tertiary, and even quaternary structure -this will affect the way that proteins can function

Question 34

What does amelogenin do?

Answer 34

stabilize the amorphous Ca-P phase -control apatite crystal morphology and organization, control of enamel thickness -ability to self assemble into nanospheres and guide HAP crystal formation/growth

Question 35

What does ameloblastin do?

Answer 35

cell adhesion protein, controls cell differentiation, maintains rod integrity

Question 36

What does enamelin do?

Answer 36

cooperates with amelogenin to control mineral nucleation and elongated growth

Question 37

What does Kallikrin 4 do?

Answer 37

digests enamel proteins during maturation stage facilitating their removal and hardening the final layer of enamel

Question 38

What does Mmp-20 do?

Answer 38

cleaves amelogenin, ameloblastin, and enamelin at the secretory stage to produce stable intermediates with defined functions

Question 39

As apatite crystals grow, what happens to amelogenin?

Answer 39

it is removed

Question 40

What is the amelogenin dependent on?

Answer 40

hydrophilic C terminal

Question 41

What is the structure of amelogenin?

Answer 41

double-ring barrel (six dimers) and assemble into structured nanospheres

Question 42

Mutations in amelogenin cause...

Answer 42

amelogenesis imperfecta