Chapter 14

Question 1

In bacteria what two processes occur at the same time and why?

Answer 1

Transcription and translation due to no compartmentalization

Question 2

Primary transcript

Answer 2

Pre-mRNA

An initial RNA transcript from any gene; also called pre-mRNA when transcribed from a protein-coding gene.

Question 3

Codons are written in which direction

Answer 3

5’-3’

Question 4

Triplet code

Answer 4

The genetic instructions for a polypeptide chain are written in the DNA as a series of non overlapping, three nucleotide codes

Question 5

UAA, UAG, UGA

Answer 5

Stop codon

Question 6

AUG

Answer 6

Start signal and methionine

Question 7

Promoter

Answer 7

DNA sequence where RNA polymerase attaches and initiates transcription

Question 8

Terminator

Answer 8

In bacteria, the sequence that signals end of transcription.

Question 9

Bacteria have one type of RNA polymerase that synthesizes mRNA and other types of rna how many do eukaryotes have?

Answer 9

3- RNA polymerase, pre-mRNA, RNA polymerase 3 (synthesis)

Question 10

Start point

Answer 10

In transcription, the nucleotide position on the promoter where RNA polymerase begins synthesis of RNA

Question 11

Transcription factors

Answer 11

A regulatory protein that binds to DNA and affects transcription of specific genes.

Question 12

Transcription initiation complex

Answer 12

The completed assembly of transcription factors and RNA polymerase bound to a promoter.

Question 13

Initiation

Answer 13

After RNA polymerase binds to the promoter, the DNA strand unwinds and the polymerase initiates RNA synthesis at the start point on the template strand.

Question 14

Elongation

Answer 14

The polymerase moves downstream, unwinding the DNA and elongating the RNA transcript in 5’-3’

Question 15

Termination

Answer 15

RNA transcript is released, and the polymerase detached from the DNA.

Question 16

Tata box

Answer 16

A DNA sequence in eukaryotic promoters crucial in forming the transcription initiation complex.

Question 17

Termination in eukaryotes

Answer 17

RNA polymerase 3 transcribes a sequence on the DNA called the polyadenylation signal sequence, which specifies a polyadenylation signal (AAUAAA) in the pre-mRNA. Then 10-30 nucleotides downstream 5ese proteins cut the RNA transcript free from polymerase.

Question 18

RNA processing

Answer 18

Modifications to pre-mRNA

• splicing out of introns
• joining Exons
• alteration of 5’-3’ ends (5’ end receives 5’ cap, 3’ end receives poly-A tail. These facilitate export of mRNA out from nucleus, protect from degradation by enzymes, help ribosomes attach to 5’ end.)

Question 19

RNA splicing

Answer 19

after synthesis of eukaryotic pre-mRNA, the removal of portion (introns) that will not be included in the mrna.

Question 20

Intron

Answer 20

A non-coding sequence within pre-mRNA that is removed.

Question 21

Spliceosome

Answer 21

Large complex of proteins and small DNA’s that remove introns

Question 22

Ribozymes

Answer 22

An rna molecule that function as an enzyme such as an intron that catalyzes its own removal during RNA splicing.

Question 23

Transfer rna

Answer 23

An rna molecule that functions as a translation between nucleic acid and protein languages by picking up specific amino acids and carrying it to the ribosome, where the rna recognizes the appropriate codon in the mRNA,

Question 24

Anti codon

Answer 24

Particular nucleotide triplet that base-pairs to a specific mRNA codon (3’-5’)

Question 25

Aminoacyl tRNA synthetases

Answer 25

An enzyme that joins each amino acid to the appropriate tRNA . (20 different)

-uses hydrolysis of ATP

Question 26

Three binding sites of ribosomes and function

Answer 26

P-site= holds the tRNA carrying the growing polypeptide chain
A-site=Holds the tRNA carrying the next amino acid to be attached to the chain.
E-site= Where discharges tRNAs leave the ribosome

Question 27

Initiation of translation

Answer 27

1. Small subunit binds to the mRNA, initiator tRNA with anticodon UAC base pairs with the start codon AUG.
2. Arrival of large subunit. Initiation factors bring all components in p site together.

Question 28

Elongation of translation

Answer 28

Amino acids are added one by one to previous acid at the c terminus

Question 29

Termination of translation

Answer 29

Elongation continues until stop codon in mRNA reaches A-site. Release factor (protein) beings to the stop codon causing addition of H2O molecule instead of amino acid. Creates hydrolysis and breaks bond between polypeptide and the tRNA in p site.

Question 30

Post translation modifications

Answer 30

• addition of sugars, lipids, phosphate group….
• removal of 1+ amino acids
• chain may be cleaved into pieces
• 2 chains may attach (quaternary structure)

Question 31

Signal peptide

Answer 31

A sequence of 20 amino acids at or near the leading amino acid end of a polypeptide that targets it to the ER or other organelle.

Question 32

Signal-recognition particle

Answer 32

A protein RNA complex that recognized a signal peptide as it emerges from a ribosome and helps direct the ribosome to the ER by binding to a receptor protein on the ER.

Question 33

DNA Polymerase 1 function

Answer 33

Removes rna primer and adds DNA

Question 34

Point mutation

Answer 34

Changes In a Single nucleotide pair of a gene

Question 35

Nucleotide- pair substitution

Answer 35

Replacement of 1 nucleotide and its partner with another pair of nucleotides. (Some have no effect)

Question 36

Silent mutation

Answer 36

Substitution with no observable effect on the phenotype

Question 37

Missense mutations

Answer 37

Substitutions that change one amino acid to another

Question 38

Non-sense mutation

Answer 38

Point mutation that changes a codon for a stop codon

Question 39

Frameshift mutation

Answer 39

The number of nucleotides inserted or deleted is not a multiple of 3. Effects all further nucleotides.

Question 40

Mutagens

Answer 40

Physical or chemical agents that cause mutations of DNA

X-rays, UV light

Question 41

Nucleic acid hybridization

Answer 41

Fluorescent probes base pair to a sequence

Ex: telomeres

Question 42

DNA amplification with PCR

Answer 42

Take target DNA, denature it, cool and add primers, polymerase, and end up with two copies of DNA. Can produce billions of copies of a gene in few hours.

Question 43

CRISPR-CAS 9 system

Answer 43

Bacterial based system
Cas 9 is a nucleus which cuts double stranded DNA 
uses a guide rna to go to a place
Cleaves DNA and adds “good” DNA
Or cleaves bad DNA from a gene.

Question 44

UTR

Answer 44

Untranslated region- not removed, but non coding, these recognize ribosomes

Question 45

In translation what entero source is used

Answer 45

GTP

Question 46

Poly ribosomes

Answer 46

In both euk and prok. Multiple ribosomes translate single mRNA at once