Chapter 14 (2)

Question 1

genetic code

Answer 1

The informational key by the sequence of mRNA nucleotides corresponding to a gene is translated into the sequence of amino acids composing the protein expressed by the gene

Question 2

the ….. specifies which amino acid will be used to build a protein

Answer 2

genetic code

Question 3

codon

Answer 3

The three nucleotides in mRNA that direct the placement of a particular amino acid into a polypeptide chain; Complementary to the corresponding triplet of bases in the DNA molecule from which it is transcribed

Question 4

the genetic code relates codons to their…..

Answer 4

specifically encoded amino acids

Question 5

start codon

Answer 5

initiation signal for translation

Question 6

What is the start codon?

Answer 6

AUG

Question 7

stop (nonsense) codons

Answer 7

termination signals for translation

Question 8

What are the stop codons?

Answer 8

UAA, UAG, UGA

Question 9

sense codons

Answer 9

the 61 codons that encode the 20 amino acids

Question 10

true or false there are more than one way to make an amino acids

Answer 10

true

Question 11

Common Genetic Code….

Answer 11

• nearly universal: the codons are the same in all organisms
  -a common language for evolution
  -allows genetic engineering humans genes can be expressed in E coli

Question 12

a given amino acid may be encoded by more than one codon, BUT

Answer 12

a codon can only code for one amino acid

Question 13

translation

Answer 13

the process by which the information in mRNA (derived from DNA) is used to specify and link a specific sequence of amino acids, produding a polypeptide

Question 14

A ….. is needed to convert the information in mRNA into a polypeptide

Answer 14

translator

Question 15

What is the translator?

Answer 15

transfer RNA - tRNA

Question 16

What catalyzes the formation of a peptide bond between the amino acids

Answer 16

rRNA

Question 17

There is at least … molecule for each of the 20 amino acids

Answer 17

1 specific tRNA

Question 18

What are the three functions of each tRNA?

Answer 18

bind to a particular amino acid
bind to mRNA
interact with ribosomes

Question 19

The ribosomes is what….

Answer 19

molecular workbench

Question 20

Where does translation occur?

Answer 20

the ribosome

Question 21

A-site

Answer 21

the charged tRNA anticodon binds to the mRNA codon; this lines up the correct amino acids to be added to the growing polypeptide chain

Question 22

P-site

Answer 22

the tRNA adds its amino aci to the polypeptide chain

Question 23

E-site

Answer 23

Uncharged tRNA has given up its amino acid, waits to be released back to the cytoplasm to pick up another amino acid; waits to be released back to the cytoplasm to pcik up another amino acid to start the process again

Question 24

what is the fidelity function

Answer 24

When proper binding occurs, hydrogen bonds form between base pairs of the anticodons and the rRNA codon. The small unit rRNA validated - if h bonds haven’t formed between all three base pairs, the tRNA must be incorrect match then rejected

Question 25

What has the fidelity function?

Answer 25

Ribosomes

Question 26

What happens in initiation of translation?

Answer 26

begins with the formation of an initiation complex - the large subunit joins the initiation complex; the charged tRNA is now in the P side - The A site is aligned with the second mRNA condon

Question 27

How does the initiation complex form?

Answer 27

- a small ribosomal subunit binds to the mRNA - methionine-charged tRNA (anticodon UAC) binds to the mRNA start codon (AUG) Methionine is ALWAYS the first amino acid in any protein, but it may be edited out It is assembled by initiation factors

Question 28

What happens in elongation in translation?

Answer 28

The anticodon of an incoming tRNA binds to the codon at the A site When the first tRNA has released its methionine, it moves to the E site, detaches from the MRNA, and moves into the cytoplasm, where it can be charged again

Question 29

What happens elongation continue?

Answer 29

Elongation factors

Question 30

As the chain of amino acids grows, what is this called?

Answer 30

protein synthesis

Question 31

What is termination in translation?

Answer 31

Translation ends when a stop codon enters the A site. A protein releases factor bind to the complex The proteins release factor disconnects the polypeptide from the tRNA in the P site by hydrolyzing the bond between them

Question 32

True or false several ribosomes can work together to translate the same mRNA producing multiple copies of the polypeptide

Answer 32

true

Question 33

What happens to the polypeptide after translation?

Answer 33

A signal sequence is added to the polypeptide, indicating where in the cell (or out of the cell) it belongs.

Question 34

If there is no signal sequences.....

Answer 34

the protein remains where is was synthesized

Question 35

What does the RER do?

Answer 35

is modifies proteins, it is where protiens go to be further modified

Question 36

The Golgi apparatus does what?

Answer 36

It gets the modified proteins and recognizes the signal sequences to see where to send it in the organism

Question 37

what are ways polypeptides can be modified after translation?

Answer 37

proteolysis - polypeptide is cut (signal sequences if the protein is needed in the cell) Glycosylation - addition of sugar to form glycoproteins Phosphorylation - addition of phosphate groups