microbiology-ch 9

messenger RNA (mRna) is:

a transcribed version of a structural gene or genes in DNA

nucleotide

basic unit of DNA structure (composed of phosphate, deoxyribose sugar, and nitrogen base)

Introns are removed and exons are spliced together

before translation.

Early in the process of DNA replication, the enzyme ______ separates the two strands

helicase

Synthesis of mRNA is

in the 5' to 3' direction with new nucleotides being added to the 3' end of the mRNA molecule

what are the five stages of translation?

initiation, elongation, termination, and protein folding and processing

Eukaryotic mRNA contains non-coding regions called _____

introns

genetics

is the science that studies the inheritance of biological characteristics by life forms

back-mutation

occurs when a gene that has undergonePage 285 mutation reverses (mutates back) to its original base composition

A(n) ______ is a cluster of genes that perform related functions found in _____

operon; prokaryotes

The specific point on the DNA molecule where replication begins is the

origin of replication

the expression of the genotype creates traits referred to as the _

phenotype

the genome of prokaryotic or eukaryotic cell includes DNA found in which sites?

plasmids, chromosomes, mitochondria, chloroplast

Latter mutations, which involve addition, deletion, or substitution of single bases, are called

point mutations

an enzyme that is named for its ability to build strands of DNA is DNA _

polymerase

the enzymes responsible for building the DNA strand, proofreading newly produced DNA strands, and removing the RNA primer are DNA _ 1 and 3.

polymerase

alterations to a protein made after translation, such as removal of f-met, addition of cofactors and joining with other proteins for quaternary structure, are referred to as __ modifications.

posttranslational

What usually terminates the process of translation

presence of a stop codon on mRNA

the specific order of amino acids bound to each other by peptide bonds represent __ structure of a protein.

primary

Translation of mRNA into protein begins before transcription is complete in ___

prokaryotes only

the initiation of transcription occurs when RNA polymerase recognizes and binds to a region of DNA called the __ region.

promoter

Transcription begins when RNA polymerase binds to the ___

promoter on DNA

__ are functional biochemicals in cells formed from one or more long chains of amino acids.

proteins

the prokaryotic ribose is composed of __ and protein.

rRNA

which type of RNA comprises ribosomal subunits?

rRNA

the termination of transcription involves __

separation of RNA from the DNA template

what strand is transcribed?

template strand

frameshift

the reading frame of mRNA will shift to the left or right, depending on the type of change

Two different mechanisms for copying the DNA strands are used because

the strands are oriented in opposite directions

The process of synthesizing RNA from a DNA template is _____

transcription

__ is the process of decoding DNA into messenger RNA

transcription

before a bacterial cell can undergo binary fission, the _ must be duplicated.

DNA

genetics examines:

-the transmission of biological properties (traits) from parent to offspring, -the expression and variation of those traits, -the structure and function of the genetic material, and -how this material changes or evolves

the key points that connect DNA and protein function:

1. DNA is a blueprint that indicates which kinds of proteins to make and how to make them. This blueprint exists in the order of triplets along the DNA strands. 2. The order of triplets directs a protein's primary structure—the order and type of amino acids in the chain—which determines its characteristic shape and function.Page 271 3. Proteins contribute significantly to the phenotype by functioning as enzymes and structural molecules

Please choose all of the statements that are true regarding transcription and translation in prokaryotes

1. Prokaryotic mRNAs often contain information from several genes in a seriesT 2. Transcription and translation can occur at the same time in prokaryotes 3. Translation occurs in the cytoplasm of prokaryotes

which DOES NOT occur during translation elongation?

1. formyl methionine is delivered to the ribosome 2. enzymatic breaking of bond between tRNA and polypeptide chain

How does RNA differ from DNA in bacteria and eukaryotes?

1. in RNA, uracil replaces thymine 2. RNA is single-stranded

Please match the types of RNA with the statements that most accurately describe them to test your understanding of the different types of RNA and their basic functions in genetic expression. 1. transcribed version of a structural gene or genes in DNA __ 2. contains the anticodon and an amino acid binding site __ 3. forms a complex cellular structure that contributes to the process of translation __

1. messenger RNA 2. transfer RNA 3. ribosomal RNA

Please match the types of mutations with the statements that most accurately describe them, to test your understanding of their causes. 1. random change in the DNA arising from errors in replication that occur without a known cause 2. result from exposure to known mutagens, which are primarily physical or chemical agents that damage DNA 3. changing of single base in the DNA code that may result in the placement of a different amino acid 4. addition or deletion of bases that changes the reading of mRNA codons

1. spontaneous mutation 2. induced mutation 3. substitution mutation 4. frameshift mutation

three categories of genes:

1. structural genes that code for proteins 2. genes that code for RNA 3. regulatory genes that control gene expression

DNA polymerase _ is the enzyme responsible for building the DNA strand

3

the enzyme involved in replicating a new DNA strand is DNA polymerase __, and DNA polymerase __ is involved in removing the RNA primer, closing gaps, and repairing mismatched bases.

3 and 1

nucleotides can only be added to the _ end of a growing chain

3'

a strand of mRNA is constructed in the __ to __ direction.

5' and 3'

If the codon GGU is positioned in the A site of the ribosome, which of the following will occur

A tRNA with the anticodon CCA will deliver its amino acid to the site

the central dogma hypothesis of genetics states that __ encodes __ which encodes proteins.

DNA and RNA

The initial transfer RNA occupies the _____ site on the ribosome

P site

the large enzyme complex involved in synthesizing RNA from DNA template is which of the following?

RNA polymerase

the main enzyme responsible for transcription is

RNA polymerase

What happens when a hairpin loop forms in mRNA

The RNA polymerase and the mRNA dissociate from the DNA

A phenotypic change that is due to an alteration in the genotype is called

a mutation

in DNA, a purine combines with

a pyrimidine

If an organism lost the ability to make primase, what would it be unable to do?

add a short sequence of complementary RNA to the existing DNA strand

silent mutation

alters a base but does not change the amino acid and thus has no effect

nucleotide is to nucleic acid as __ __ is to protein.

amino acids

transfer RNAs (tRNA)

are complementary copies of specific regions of DNA; however, they differ from mRNA

what is the function of tRNA?

brings amino acids to the ribosome

which component of DNA determines the 3' and 5' ends of the strand?

carbons in the deoxyribose sugar

nonsense mutation:

changes a normal codon into a stop codon that does not code for an amino acid and stops the production of the protein wherever it occurs

_____ are groups of three bases in mRNA that specify one amino acid in the amino acid chain

codons

which pentose sugar is found in DNA?

deoxyribose

Please select all of the characteristics of DNA to test your understanding of its chemical structure

deoxyribose sugar, phosphate, group, and nitrogenous bases

what is true regarding DNA replication?

each new DNA helix contains one parent strand and one newly synthesized strand

Eukaryotic mRNA usually specifies multiple proteins

false

Which of the following are directly needed in order for translation to occur?

mRNA, tRNA, rRNA, amino acids

__ RNA contains the codons for the polypeptide

messenger

During semiconservative _________ the DNA is duplicated prior to binary fission.

replication

DNA polymerase

requires a template for the synthesis of DNA

the pentose sugar found in RNA is __

ribose

what kind of gene encodes a protein?

structural

genome

sum total of genetic material (DNA) carried within a cell

during which process is mRNA converted into protein?

translation

In prokaryotes, the mRNA transcript encounters ribosomal parts immediately as it leaves the DNA

true