Chapter 17
There are three types of RNA and they are:
1. messenger RNA (mRNA) which is produced inside the nucleus and carries genetic messages the DNA to the protein-synthesizing machinery of the cell.

2. ribosomal RNA (rRNA) which is produced in the nucleolus and it functions as enzymes throughout the cell.

3. transfer RNA (tRNA) which is produced in the nucleus its function is to transfer amino acids from the cytoplasmic pool of amino acids to a ribosome.

Transcription is the synthesis of RNA under the direction of DNA. Both nucleic acids use the same language, and the information is simply transcribed, or copied, from one molecule to the other. Just as a DNA strand provides a template for the synthesis of a new complementary strand during DNA replication, it also can serve as a template for assembling a complementary sequence of RNA nucleotides.Translation is the synthesis of a polypeptide, which occurs under the direction of mRNA. During this stage, there is a change in language: The cell must translate the base sequence of an mRNA molecule into the amino acid sequence of a polypeptide.

Sometimes there are changes to the genetic information of a cell and these changes are called mutations. Mutations are responsible for the huge diversity of genes found among organisms because mutations are the ultimate source of new genes.

Point mutations are chemical changes in a single base pair of a gene. Point mutations within a gene can be divided into two general categories: base-pair substitutions and base-pair insertions or deletions.
A base-pair substitution is the replacement of one nucleotide and its partner with another pair of nucleotides. Some substitutions are called silent mutations because, oweing to the redundancy of the genetic code, they have no effect on the encoded protein. Substitutions that change one amino acid to another one are called missense mutation. There are also nonsense mutations, which is a mutation that changes an amino acid codon to one of the three stop codons, resulting in usually a shorter and nonfunctional protein.Insertions or deletions are additions or losses of nucletide pairs in a gene. These muatations have a disastrous effect on the resulting proteins more often than substitutions do. This causes frameshifts, which are mutations occurring when the number of nucleotides inserted or deleted is not a multiple of three, resulting in the improper grouping of the subsequent nucleotides inot codons.Chapter 17 vocabulary

aminoacyl-tRNA synthetase is an enzyme that joins the each amino acid to the appropriate tRNA.

mutation is a change in the nucleotide sequence of an organism's DNA, ultimately creating genetic diversity. They can also occur in the DNA or RNA of a virus.

base-pair substitution is a type of point mutation; the replacement of one nucleotide and its partner in the complementary DNA strand by another pair of nucleotides.

splicesome is a large complex made up of proteins and RNA molecules that splices RNA by interacting whith the ends of an RNA intron, releasing the intron and joining the two adjacent exons.

missense mutation is a base-pair substitution that results in a codon that codes for a different amino acid.

RNA processing is a modification of RNA transcripts, including splicing out of introns, joining together of extrons, and alteration of the 5' and 3' ends.

nonsense mutation is a mutation that changes an amino acid codon to one of the three stop codons, resulting in a shorter and usually nonfunctional protein.

frameshift mutation is a mutation occurring when then number of nucleotides inserted or deleted is not a multiple of three, resulting in the improper grouping of the subsequent nucleotides into codons.

terminator is in a bacteria, a sequence of nucleotides in DNA that marks the end of a gene and signals RNA polymerase to release the newly made RNA molecule and detach from the DNA.

point-mutation is a change in a mutation at a single nucleotide pair.

promoter is a specific nucleotide sequence in DNA that binds RNA polymerase, positioning it to start transcribing RNA at the appropriate place.

wobble is the flexibility in the base pairing rules in which the nucleotide at the 5' end of a tRNA anticodon can form hydrogen bonds with more than one kind of base in the third position (3' end) of a codon.

exon is a sequence within a primary transcript that remains in the RNA after RNA processing; also refers to the region of DNA from which this sequence was transcribed

intron is a noncoding, intervening sequence within a primary transcript that is removed from the transcript during RNA processing; also refers to the region of DNA from which this sequence was transcribed.

P site is one of a ribosome's three binding sites for tRNA during translation. The P site holds the growing polypeptide chain.

A site is one of a ribosome's three binding sites for tRNA during translation. The A site holds the tRNA carrying the next amino acid to be added to the ploypeptide chain.

TATA box is a DNA sequence in eukaryoktic promoters ccrucial in forming the transcription initiation complex.

E site is one of a ribosome's three binding sites for tRNA during translation. The E site is the place where discharged tRNAs leave the ribosome.

translation is the synthesis of a polypeptide using the gentis information encoded in an mRNA molecule. There is a change of "language" from nucleotides to amino acids.

transciption is the synthesis of RNA using a DNA template.

Roots
intro-withing
muta-change

Questions:
1. How many types of RNA are there?
a. 1
b. 2
c. 3
d. 4

2. What are the different types of RNA?
a. mRNA
b. rRNA
c. tRNA
d. all of the above

3. What are the two types of point mutations?
a. base-pair substitutions and base-pair insertions or deletion
b. base-pair substitutions and nonsense mutation
c. nonsense muatation and missense mutation
d. none of the above

4. Which type/types of RNA are produced in the nucleus
I. messenger RNA
II. ribosomal RNA
III. transfer RNA
a. I only
b. I and II only
c. I and III only
d. I, II, and III

5. A frameshift mutation is
a. a mutation that changes an amino acid codon to one of the three stop codons, resulting in a shorter and usually nonfunctional protein.
b. a mutation occurring when then number of nucleotides inserted or deleted is not a multiple of three, resulting in the improper grouping of the subsequent nucleotides into codons.
c. a base-pair substitution that results in a codon that codes for a different amino acid.
d. a change in the nucleotide sequence of an organism's DNA, ultimately creating genetic diversity.

Answers
1. c
2. d
3. a
4. d
5. b