QUIZ 9/Genetics and Nucleic Acid Replication

Question 0

Transcription

Answer 0

The transcription of RNA from DNA for protein synthesis is the key to protein synthesis.
Transcription is the “writing” of the DNA genetic code into mRNA (nucleic acid to nucleic acid) by the RNA polymerase enzyme.

Question 1

What does DNA do?

Answer 1

stores the genetic code for the manufacture the cell’s, and hence, the organism’s structures which then lead to organismal function, or LIFE.

Question 2

Replication

Answer 2

Both DNA and RNA are replicated in the cell nucleus. Replication means DNA or RNA is manufactured from nucleotides and the code from DNA.

Question 3

PROTEIN SYNTHESIS

Answer 3

All proteins have their sequence of amino acids determined by the code of DNA on the original gene.

Question 4

DNA

Answer 4

a double-strand, helical nucleic acid with a backbone of deoxyribose sugar and phosphate withfour nitrogenous bases: adenine, guanine, cytosine and thymine or AGCT — the “genetic
code.”

Question 5

RNA

Answer 5

a single-strand nucleic acid that develops 3different forms. The backbone is ribose sugar and phosphate with four nitrogenous bases: adenine, guanine, cytosine and uracil.

Question 6

3 common forms of RNA

Answer 6

ribosomal (rRNA),
messenger (mRNA)
transfer (tRNA).
RNA can also form ribozymes.

Question 7

Nitrogenous bases

Answer 7

are purine and pyrimidine structures.

Question 8

Nucleosides

Answer 8

are a nitrogenous base bonded to a ribose or deoxyribose sugar

Question 9

Nucleotides

Answer 9

are nucleosides bonded to one or more phosphate groups. Free-floating nucleotides in the nucleus are incorporated into DNA or RNA when these nucleic acids are replicated.

Question 10

What forms a sugar phosphate backbone?

Answer 10

The nucleotides in a nucleic acid are bonded between phosphate and sugar, forming a chain.

Question 11

Hydrogen bond

Answer 11

The nitrogenous bases can hydrogen bond to form their specific couples, such as in DNA, tRNA, rRNA or a ribozyme.

Question 12

DNA

Answer 12

Adenine 
Guanine 
Cytosine
Thymine 
Adenine with Thymine   
Guanine with Cytosine
Cytosine with Guanine
Thymine with Adenine

Question 13

RNA

Answer 13

Adenine 
Guanine 
Cytosine
Uracil 
Adenine with Uracil 
Guanine with Cytosine
Uracil with Adenine
Guanine with Cytosine

Question 14

Chromatin

Answer 14

DNA packed into a cell’s nucleus. Structural proteins tightly
pack and wind DNA into chromatin; this creates stability, organization and protection for the cell’s storage of the genetic cod

Question 15

replicase enzyme

Answer 15

unzips the DNA and also “reads” the DNA code, and thirdly the replicase transcribes a mRNA strand from the revealed code. The DNA is re-zippered closed, thus conserving the genetic code.

Question 16

DNA Structuring

Answer 16

The DNA double helix wraps around a bundle of
histone proteins
-wraps into a ball-like structure called a nucleosome.
-nucleosomes form next level of structure by condensing into another helical structure called the condensed fiber.
-condensed fiber forms a larger level of structure as it bundles itself into chromatin.

Question 17

euchromatin

Answer 17

Active chromatin that gets transcribed regularly and is less compacted

Question 18

heterochromatin

Answer 18

genetic code that is conserved, almost never accessed for transcription, and is densely compacted in the nucleus.

Question 19

What are histones?

Answer 19

The chief protein components of cromatin

Question 20

What do RNA polymerases do?

Answer 20

-This enzyme is responsible for transcribing DNA
code into RNA, allowing protein codes to get to the
cytoplasm for protein manufacture

-they find the site of code on the DNA that is to be transcribed, unzips the DNA, replicates the DNA using RNA nucleotides, and rezips the DNA. The RNA produced will be processed by splicing enzymes and ribozymes into either mRNA,
tRNA, or rRNA.

Question 21

Polymerase enzymes

Answer 21

use copious amounts of ATP to perform their work

Question 22

Simplified DNA Replication

Answer 22

-First, a topoisomerase enzyme untwists the
secondary helix structure
– A helicase untwists the primary helix structure by
relieving the hydrogen bonding between bases. This separates the 2 strands. Binding proteins attach to the strands to keep them separated.
– DNA primase bonds free-floating nucleotides into the deoxyribose-sugar chain.
– DNA ligase connects together the bits of newly
created nucleotide chain
– DNA polymerase finishes the bonding of nucleotides, and re-zips the strands as 2 daughter strands.

Question 23

Protein synthesis

Answer 23

occurs constantly within cells, and uses significant ATP energy to maintain normal organismal functioning.

Question 24

transcription

Answer 24

Replication copies a protein code from DNA specific for the desired protein, writing the code in mRNA

Question 25

translation.

Answer 25

The mRNA is moved out of the cell nucleus to the

cytoplasm, and is translated into an amino acid chain, a polypeptide, by a ribosome

Question 26

codons

Answer 26

The mRNA transcription information are “read” as 3

nitrogenous bases at a time. Codons are unique for each of the 20 amino acids used to create proteins.

Question 27

anticodon

Answer 27

tRNAs loaded with amino acids, enter the active site in a ribosome, and match their anticodon to the codon on mRNA. The line up of tRNA’s amino acids are bonded into a protein chain, still in the active site of the ribosome.

Question 28

ATP

Answer 28

is constantly consumed to operate the enzyme

cascades in protein synthesis

Question 29

The DNA code transcribes other information besides the actual protein sequence;

Answer 29

there are promotion codes, starter codons and termination codons to tell the ribosome to begin translating mRNA, and telling when the protein code is over.
–>Each codon is 3 bases long, and codes for a single amino acid.

Question 30

The starter codon is especially important

Answer 30

it designates where the 3-base codon chain begins. If that start codon is misread by the ribosome, the entire protein’s amino acid sequence will be mistranslated, creating a dysfunctional polypeptide of no use.

Question 31

What do ribosomes splice?

Answer 31

exons and introns

Question 32

introns

Answer 32

spliced out of the mRNA, creating a mature mRNA that is then sent to ribosomes for translation into protein.
eukaryotic organisms transcribe intron codes into mRNA.

Question 33

exons

Answer 33

codes used to make protein

Question 34

tRNA

Answer 34

carries a 3-base anticodon. This is the opposing code which will complement codons coming from mRNA. The tRNA is specific not only for a codon, but an amino acid as well.

Question 35

aminoacyl tRNA synthetase

Answer 35

recycles tRNA that have given up their amino acid by reloading these emptied tRNAs in the cytoplasm with their specific amino acid.

Question 36

Protein Synthesis — Summary

Answer 36

– mRNA is produced in the nucleus, matured, and
transported into the cytoplasm, objective being to
link with ribosomes
– Ribosomal 30 & 50s subunits are available on RER or float freely
– mRNA is sensed by the 30s and 50s subunits; the
subunits join to form a ribosome protein factory
– The mRNA moves into the A and P active site of the ribosome
– tRNA’s loaded with respective amino acids move in and match their anticodons to the codons on the
mRNA.
– Peptide bonds form between the amino acids from the A site to the P site by enzymatic action
– The mRNA shifts one set of codons in the active
site, allowing the next tRNA/amino acid combination in, and the fusion of amino acids
continues until:
– A termination codon is found in the mRNA, and
translation stops
– The emptied tRNA’s go out and pick up their
respective amino acids, being recycled by
aminoacyl tRNA synthetase
– The polypeptide chain is pushed out into the
cytoplasm where it is folded or modified into a
protein, often in the Golgi complex
– The Golgi and ER are where vitamins and other
cofactors are inserted into protein to create a
holoenzyme for use or a zymogen for storage