03 Processes Involving the Genetic Material

Question 1

is the process where DNA duplicates itself.

Answer 1

Replication

Question 2

is the process where DNA is converted into mRNA.

and is sequentially divided into 3 parts:

Answer 2

Transcription

i. Initiation
ii. Elongation
iii. Termination

Question 3

is the process where the genetic information in the mRNA is used to make proteins

and is sequentially divided into 3 parts:

Answer 3

Translation

i. Initiation
ii. Elongation
iii. Termination

Question 4

_____ are enzymes that catalyze the synthesis of DNA or RNA polymers whose sequence is complementary to the original template, as defined by Watson–Crick base pairing.

Answer 4

Polymerases

Question 5

RNA polymerases

● _____ utilize one RNA polymerase for all transcription of types of RNA.
● ____ utilize three slightly different RNA polymerases: RNA polymerase I, RNA polymerase II, and RNA polymerase III.
- (RNA Polymerases I, which transcribes ____; II, which transcribes ____; and III, which transcribes ____).

Answer 5

Prokaryotes
Eukaryotes

rRNA
mRNA
tRNA

Question 6

____is responsible for the process of DNA replication by making the new strand of DNA by adding DNA bases in one direction from the 5’ prime end to the 3’ prime end.

Answer 6

DNA polymerase

Question 7

In eukaryotes, a major function of DNA polymerases is to accurately replicate the _____ that constitute the human genome to replicate the genome and thus to allow transmission of genetic information from one generation to the next, or simply making the new strand of DNA by adding DNA bases in one direction from the 5’ prime end to the 3’prime end.

Answer 7

six billion nucleotides

Question 8

In prokaryotes, three main types of polymerases are known: _________. It is now known that ____ is the enzyme required for DNA synthesis or responsible for replication; DNA pol I and DNA pol II are primarily required for repair.

Answer 8

DNA pol I, DNA pol II, and DNA pol III

DNA pol III

Question 9

The general process of transcription can be applied to both prokaryotic cells and eukaryotic cells. The basic biochemistry for each is the same; however, the specific mechanisms and regulation of transcription differ between prokaryotes and eukaryotes

Question 10

While specific aspects of transcription differ between prokaryotes and eukaryotes, the basic chemistry behind the process is the same. Both utilize ____ to catalyze the synthesis of RNA, and while regulation may differ, the ultimate product of transcription in prokaryotes and eukaryotes is ____.

Answer 10

RNA polymerase

RNA

Question 11

Stages of Transcription
1. Initiation
• RNA polymerase binds to a sequence of DNA called the ____, found near the beginning of a gene.
• Each gene (or group of co-transcribed genes, in bacteria) has its own promoter.
• Once bound, RNA polymerase ____ the DNA strands, providing the single-stranded template needed for transcription.

Answer 11

promoter

separates

Question 12

Stages of Transcription

2. Elongation
   • One strand of DNA, the _____, acts as a template for RNA polymerase.
   • As it “reads” this template one base at a time, the polymerase builds and RNA molecule out of complementary nucleotides, making a chain that grows from 5’ to 3’.
   • RNA transcript carries the same information as the non-template (coding) strand of DNA, but it contains the base uracil (U) instead of thymine (T).

Answer 12

template strand

Question 13

Stages of Transcription
3. Termination
• Sequences called terminators signal that the RNA transcript is complete.
• Once they are transcribed, they cause the transcript to be released from the RNA polymerase
• Example mechanism is the ____. ___ is an unpaired loop of messenger RNA (mRNA) that is created when an mRNA strand folds and forms base pairs with another section of the same strand.

Answer 13

hairpin

Question 14

Process of making complementary DNA, cDNA, from single stranded RNA and • Allows scientists to work backward.

Answer 14

Reverse Transcription

Question 15

RNA processing

Both prokaryotes and eukaryotes process their ribosomal and transfer RNAs. The major difference in RNA processing between them is in the processing of _____ In prokaryotes, RNA transcripts are ready to act as messenger RNAs and get translated into proteins right away. In eukaryotes, RNA transcripts (called pre-mRNA) undergoes extensive processing before it is ready to be translated.

Answer 15

messenger RNAs (mRNAs).

Question 16

Process of post-transcriptional modifications

Answer 16

• Capping at the 5’ end
• Addition of a polyA tail at the 3’ end; and
• Splicing for intron removal

Question 17

Capping
• While the pre-mRNA is still being synthesized, a ____ is added to the 5′ end of the growing transcript by a 5′-to-5′ phosphate linkage.
• First, at the 5’ end of the mRNA, one phosphate is removed.
• Next, guanyl transferase attaches a guanosine monophosphate (GMP) molecule to the end of the mRNA.
• Then the newly transferred guanine is methylated by a guanine-7-methyltransferase.

Answer 17

7-methylguanosine cap

Question 18

The cap protects the 5’ end of the mRNA from degradation by nucleases and also helps to position the mRNA correctly on the ribosomes during protein synthesis.

Question 19

polyA tail addition

Polyadenylation of the 3’ end of eukaryotic mRNAs begins with an _____ of the mRNA, usually between a conserved ____ sequence and a downstream U- orGU-rich region. CA nucleotide near the AAUAAA sequence marks the cleavage point for precursor mRNA. Then, a tail of approximately ______ is added by poly(A) polymerase, thus the name “polyA tail”. The tail makes the transcript more stable and helps it get exported from the nucleus to the cytosol.

Answer 19

initial cleavage
AAUAAA
200 adenine nucleotides

Question 20

RNA splicing

Eukaryotic genes are composed of _____, which correspond to protein-coding sequences and intervening sequences called ____, which may be involved in gene regulation, but are removed from the pre-mRNA during processing. Intron sequences in mRNA do not encode functional proteins, thus they are spliced out. The process of mRNA splicing is carried out by the ____, a dynamic complex of RNA and protein subunits that removes introns from precursor mRNA.

Answer 20

exons
introns
spliceosome

Question 21

_______ recognize sequences at the 5′ end of the intron because introns always start with the nucleotides ___ and they recognize sequences at the 3′ end of the intron because they always end with the nucleotides ____

Answer 21

Spliceosomes
GU
AG

Question 22

The spliceosome cleaves the pre-mRNA’s sugar phosphate backbone at the G that starts the intron and then covalently attaches that G to an internal A nucleotide within the intron. Then the spliceosome connects the 3′ end of the first exon to the 5′ end of the following exon, cleaving the 3′ end of the intron in the process. This results in the splicing together of the two exons and the release of the intron in a lariat form.

Question 23

Major Components of translational machinery:

_____ = came from transcription; provides the information that must be interpreted by the translation machinery and is the template for translation

Answer 23

mRNA

Question 24

Major Components of translational machinery:

_____ = binds to mRNA; composed of both RNA and protein. It coordinates the correct recognition of the mRNA by each tRNA and catalyzes peptide-bond formation between the growing polypeptide chain and the amino acid attached to the selected tRNA.

Answer 24

Ribosomes

Question 25

Major Components of translational machinery:

_____ = every tRNA is gonna come with 1 amino acid (20 different types of tRNA); provide the physical interface between the amino acids being added to the growing polypeptide chain and the codons in the mRNA.

Answer 25

tRNA

Question 26

Major Components of translational machinery:

________= couple amino acids to specific tRNAs that recognize the appropriate codon

Answer 26

aminoacyl-tRNA synthetases

Question 27

____ is the process in which cells make proteins. It occurs in two stages: transcription and translation. Transcription is the transfer of genetic instructions in DNA to mRNA in the nucleus. It includes three steps: initiation, elongation, and termination.

Answer 27

Protein synthesis

Question 28

Amino Acid Activation
• The attachment of an amino acid to its respective acceptor T RNA is catalyzed by ______. One molecule of amino acid synthase corresponds to one molecule of amino acid. The amino acid elation process of tRNA has two phases.
• Firstly, the active site of amino acid tRNA synthetase binds the amino acid and the ATP molecule. Then ____(adenosine monophosphate aamp) complex is formed and a specific tRNA molecule is recruited.
• In the second phase, the tRNA is bound to the amino acid and AMP is released. Finally, the enzyme releases the activated amino acid or charged tRNA is produced.

Answer 28

aminoacyl tRNA synthetas

Amino acid-AMP

Question 29

Initiation:

The initiation of protein synthesis is the process that results in bringing together an ____ with a messenger RNA (mRNA) and initiator methionyl-transfer RNA ____

Answer 29

80S ribosome

Met-tRNAi

Question 30

The ______ is a ribosomal binding site in bacterial and archaeal messenger RNA, generally located around 8 bases upstream of the start codon AUG. The RNA sequence helps recruit the ribosome to the messenger RNA to initiate protein synthesis by aligning the ribosome with the start codon.

Answer 30

Shine–Dalgarno sequence

Question 31

_____ is the phase of the protein-synthesis pathway that is responsible for the growth of nascent polypeptide chains.

Answer 31

Elongation

Question 32

Living organisms use ______ to form long chains of amino acids, known as proteins.

Answer 32

peptide bonds

Question 33

Termination:
Protein synthesis terminates once a stop codon has been encountered. The new polypeptide chain is released with the help of termination sequences and the larger and smaller ribosomal subunits break apart from each other.

Question 34

Protein synthesis occurs during a process called _______

Answer 34

‘translation’.

Question 35

_______ of proteins, being one of the later stages in protein biosynthesis, refers to the reversible or irreversible chemical changes proteins may undergo after translation.

Answer 35

Post Translational modification (PTM)

Question 36

Post-translational modification can occur at any step in the “life cycle” of a protein. For example, many proteins are modified shortly after translation is completed to mediate proper protein folding or stability or to direct the nascent protein to distinct cellular compartments (e.g., nucleus, membrane).

Question 37

Most common post-translational modifications:

-_______=Reversible protein phosphorylation, principally on serine, threonine or tyrosine residues, is one of the most important and well-studied post-translational modifications

Answer 37

Phosphorylation

Question 38

Most common post-translational modifications:

______ - is acknowledged as one of the major post-translational modifications, with significant effects on protein folding, conformation, distribution, stability and activity.

Answer 38

Glycosylation

Question 39

Most common post-translational modifications:

______ - The transfer of one-carbon methyl groups to nitrogen or oxygen (N- and O-methylation, respectively) to amino acid side chains increases the hydrophobicity of the protein and can neutralize a negative amino acid charge when bound to carboxylic acids.

Answer 39

Methylation

Question 40

Most common post-translational modifications:

___ - is a method to target proteins to membranes in organelles (endoplasmic reticulum [ER], Golgi apparatus,mitochondria), vesicles (endosomes, lysosomes) and the plasma membrane.

Answer 40

Lipidation

Question 41

Most common post-translational modifications:

______ - Peptide bonds are indefinitely stable under physiological conditions, and therefore cells require some mechanism to break these bonds. Proteases comprise a family of enzymes that cleave the peptide bonds of proteins and are critical in antigen processing, apoptosis, surface protein shedding and cell signaling.

Answer 41

Proteolysis

Question 42

Most common post-translational modifications:

_______- N-acetylation, or the transfer of an acetyl group to nitrogen, occurs in almost all eukaryotic proteins through both irreversible and reversible mechanisms.

Answer 42

Acetylation

Question 43

______ is the term used for the way that the four bases of DNA– the A, C, G, and Ts; and A, C, G, U bases of RNA– are strung together in a way that the cellular machinery, the _____, can read them and turn them into a protein. In the genetic code, each three nucleotides in a row count as a triplet and code for a single amino acid.

Answer 43

Genetic code

ribosome

Question 44

The four bases make up the ____ of the genetic code. The letters are combined in groups of three to form code “words,” called ____. Each codon stands for (encodes) one amino acid, unless it codes for a start or stop signal.

Answer 44

“letters”

codons

Question 45

______ is known to inhibit protein synthesis in eukaryotic cells by catalytically transferring the adenosine diphosphate ribose (ADPR) moiety from NAD to EF-2, thereby inactivating EF-2 and inhibiting chain elongation during protein synthesis.

Answer 45

Diphtheria toxin