BIO test 2 review
DNA Polymerase
:Adds nucleotides to the growing DNA strand at the 3' end of the chain.
Central Dogma of Genetics
:DNA is replicated to produce an identical strand of DNA. DNA can alsobe transcribed to mRNA, and that mRNA can be translated to produce apolypeptide
DNA Ligase
:Enzyme that links together Okazaki fragments of the lagging strand
DNA Helicase
:Enzyme that unwinds the DNA double helix
How are Mutations Perpetuated?
Semiconservative replication provides the mechanism through whichmutations are perpetuated. Because the one strand always serves as atemplate for the new DNA, the mutation is maintained through manyreplication cycles
Stop Codon:
Signals the end of polypeptide synthesis, are UAA, UGA, and UAG.Anticodon:Three bases on tRNA that are complementary to the mRNA codon
tRNA
Single stranded RNA that forms a cross-like shape and functions as an adapter tocarry amino acids to the corresponding codon
mRNA:
Single stranded molecule that carries information to make a protein
__________, the ends of eukaryotic chromosomes, shorten with every cell replication event.
Telomeres
Lagging strand
The 5' to 3' non continous
Explain the Three Sites on the Ribosome:
The A site is farthest to the right and is where the amino acid enters the ribosome.The P site is where the polypeptide chain is located and is the middle site. The E site isfarthest to the left and is where the used tRNA exits
What Happens in Termination of Transcription?
The RNA strand stops growing when a termination sequence is identified on thetemplate DNA.
DNA Fingerprinting:
The analysis of unique DNA fragments produced by an individual
How is the chromosome of a bacterial cell replicated?
The circular DNA molecule is replicated from one origin of replication bidirectionally.
What Happens in Initiation of Transcription?
The desired DNA sequence is identified as a promoter. It is recognized by RNApolymerase and the DNA is unwound
RNA primer
made by DNA primase and tells DNA primase where to start
regulated genes
produces repessor proteins
The ends of eukaryotic chromosomes can be lengthened by:
telomerase
X-ray diffraction studies are used to determine:
the distances between atoms of molecules.
What prevents knot formation in replicating DNA?
topoisomerases
The final product of DNA replication is:
two DNA molecules, each of which contains one new and one old DNA strand.
stop codons
uaa uag uga
wobble hypothesis
you only need 2 codons (C & U ) for Leucine ( Leu)
Structure of RNA
a five-carbon sugar (ribose), a phosphate group, and anitrogenous base. RNA uses uracil to bind to adenine and is single stranded, unlike DNA. The nucleotides of RNA are connected by 5'-3'phosphodiester linkages
X-ray crystallography showed that DNA
a helix
operon
a region or a part of a gene specifically where the repressor protein will be able to bind and release from
The 5′ end of each Okazaki fragment begins with:
a separate RNA primer.
The bacteriophages used in Alfred Hershey's and Martha Chase's experiments showed that:
a. DNA was injected into bacteria.
DNA primase
adds nucleotides to growing chains
constitutive genes
always on or always off
Two chains of DNA must run in __________ direction(s) and must be __________ if they are to bond with each other.
antiparallel; complementary
Which of the following nucleotide sequences represents the complement to the DNA strand 5′− AGATCCG- 3′?
3′ − TCTAGGC- 5′
DNA Gyrase
:Also known as topoisomerase, enzyme that relieves the tension causedby unwinding
Nonsense Mutations
:Change in nucleotide that changes the codon into a stop codon, can lead to thepremature termination of translation
Transformation
:Process by which a plasmid is taken up by a host cell.
Franklin's Contribution to DNA Study
:Rosalind Franklin used x-ray diffraction to determine the 3D structureof DNA
How do Bacteria Regulate Gene Expression?
Bacteria regulate gene expression at the transcriptional level becauseit is the most efficient mechanism.
Which of the following adds new nucleotides to a growing DNA chain?
DNA polymerase
Coupling:
Describes how transcription and translation occur simultaneously in bacteria. OncemRNA is transcribed, it is immediately translated by a ribosome because both events occurin the cytoplasm.
Promoter:
Location where RNA polymerase binds to the operon to transcribe thestructural genes
Leading Strand vs Lagging Strand:
The leading strand is synthesized continuously and is complementaryto the 3' end of the template DNA. The lagging strand is synthesizeddiscontinuously and is complementary to the 5' end of the template strand.
How are the chromosomes of a eukaryote cell replicated?
The linear DNA molecules are replicated from multiple origins of replication bidirectionally.
Bioinformatics:
The mathematical analysis of differences between the genomes ofspecies
What do the Structural Genes of the Trp Operon Produce?
These genes produce the components necessary to produce tryptophan
Explain How Multiple Codons Can Code for the Same Amino Acid:
This can be explained by the wobble hypothesis, which says that the third nucleotidein the anticodon can form bonds with more than one type of third nucleotide in codons. Inother words, the third base in an anticodon can associate with multiple bases in the codonsand still bring the same amino acid
If DNA replication rejoined the 2 parental strands, it would be termed:
conservative.
splicing
cutting introns out putting exons together
Chargaff determined that DNA from any source contains about the same amount of guanine as
cytosine
Describe What Occurs When Tryptophan is Present in the Cell:I
if tryptophan is present in the cell, it acts as a corepressor and binds tothe repressor protein. When the corepressor binds to the repressor protein,the repressor changes shape and is now able to bind to the operator. Thisprevents RNA polymerase from transcribing the structural genes andtryptophan is not produced
A replication fork:
is a Y-shaped structure where both DNA strands are replicated simultaneously.
silent mutation
it does not cause an affect/ major change
single binding proteins
keeps the DNA seperated
Primase is the enzyme responsible for:
making short strands of RNA at the site of replication initiation.
introns
non-coding regions
Helicase
seperates the strands
In replication, once the DNA strands have been separated, reformation of the double helix is prevented by:
single-strand binding proteins.
The information carried by DNA is incorporated in a code specified by the
specific nucleotide sequence of the DNA molecule.
Backbone of polynucleotide chain
sugar and phosphate
What Happens in Termination of Translation?
tRNA reaches one of three stop codons, signaling for the release of the protein andthe disassembly of the ribosome
When cultured normal human cells were infected with a virus that carried the genes that coded for a subunit of telomerase:
the cells underwent more cell divisions than normal.
The main reason scientists thought that proteins, rather than DNA, were the carriers of genetic material in the cell was:
the large number of possible amino acid combinations
When a DNA molecule containing a wrong base at one location in one strand is replicated:
the mutation is copied into one of the two daughter molecules.
Enzymes called __________ form breaks in the DNA molecules to prevent the formation of knots in the DNA helix during replication
topoisomerases
repressible
transcription can be turned off (Trp)
inducible
transcription is turned on ( LAC)
codon
3 sequential nucleotides found on mRNA strand
leading strand
3' to 5' and continous
Initation
1) need ribosome to synthesize protein 2) mRNA because codons 3) tRNA because it has anti codons and amino acids (AUG)
Gene
A DNA sequence with the information to produce a specific RNA orpolypeptide
Operator:
Attachment site for the repressor protein
Why does DNA synthesis only proceed in the 5′ to 3′ direction?
Because DNA polymerases can only add nucleotides to the 3′ end of a polynucleotide strand.
Transcription Factors:
DNA binding proteins that regulate transcription in eukaryoticorganisms
Explain RNA Interference:
RNA interference uses different types of RNA to interact with variousmolecules. Small interfering RNAs regulate expression of genes and helpmitigate viral infections. MicroRNAs bind to mRNA and inhibit the expressionof the mRNA.
Free floating monomer is
Triphosphate
rRNA
Type of RNA that is a structural component of ribosomes
Start codon
AUG which codes for MET ( methyamine)
phostphate end of a DNA OR RNA strand
5' end
RNA
5' prime strucrtures
tRNA
3' end normally free to add nucleotide (loose end)
Describe Types of Post-Transcriptional Modification:A 5' cap made of guanosine triphosphate is added to the 5' end of the mRNA. Thiscap will aid with recognition by the ribosome and play a role in initiation of translation. Apoly-A tail made of adenine- containing nucleotides is added to the 3' end of the mRNA.This modification helps protect the molecule as it moves form the nucleus to the cytoplasmfor translation. Finally, introns are removed by spliceosomes and exons are attachedtogether to produce the final mRNA strand
A 5' cap made of guanosine triphosphate is added to the 5' end of the mRNA. Thiscap will aid with recognition by the ribosome and play a role in initiation of translation. Apoly-A tail made of adenine- containing nucleotides is added to the 3' end of the mRNA.This modification helps protect the molecule as it moves form the nucleus to the cytoplasmfor translation. Finally, introns are removed by spliceosomes and exons are attachedtogether to produce the final mRNA strand
Which of the following best describes semiconservative replication?
A DNA molecule consists of one parental strand and one new strand.
Regulatory Gene:
A gene that codes for a repressor molecule and is constitutivelyexpressed
Constitutive Gene:
A gene that is always expressed/ produced
telomers
A special DNA replication enzyme that can lengthen telomeric DNA by adding repetitive nucleotide sequences to the ends of eukaryotic chromosomes; typically present in cells that divide an unlimited number of times.
What Happens in Elongation of Translation?
Amino acids are added to the growing polypeptide at the C-terminus. The ribosomereads the mRNA from 5' to 3' and the polypeptide is synthesized from the N-terminus tothe C-terminus.
The first experimenters to use Griffith's transformation assay to identify the genetic material were:
Avery, MacLeod, and McCarty.
How is a single strand of DNA able to serve as a template for the synthesis of another strand?
Both the pairing of nucleotides and the breaking of hydrogen bonds
How Are Transcription and DNA Replication Similar?
Both transcription and DNA replication occur in the nucleus. The DNA strandsproduced in replication and the RNA produced in transcription are synthesized in the 5' to 3'direction, meaning that nucleotides are added to the 3' ends
Genomics:
Branch of molecular biology that studies the genome and tracksprotein production and gene regulation
Cancerous cells differ from noncancerous cells in that cancerous cells:
Cancerous cells differ from noncancerous cells in that cancerous cells:
Silent Mutations:
Change in a nucleotide that does not result in a change in the amino acid a codoncodes for.
Missense Mutations
Change in nucleotide that results in placement of a different amino acid in apolypeptide chain.
Chargaff's Contribution to DNA Study:
Chargaff discovered the base paring rules of DNA. Adenine pairs withthymine and guanine pairs with cytosine. Because DNA is double stranded,the number of purines equals the number of pyrimidines. The amount ofadenine equals the amount of thymine, and the amount of guanine equalsthe amount of cytosine
Plasmid:
Circular DNA molecule that is used as a vector
exons
Coding regions in eukaryotic genes
DNA Library:
Collection of all DNA fragments from a genome
Which of the following causes the unwinding of the DNA double helix?
DNA helicase
Which of the following statements about DNA is false?
DNA is only found in eukaryotic cells.
Okazaki fragments are joined together by:
DNA ligase.
Restriction Enzyme:
Enzymes that cut DNA at very specific points to create short DNAfragments
Topoisomerase
Enzymes that relieve twists and kinks in a DNA molecule by breaking and rejoining the strands.
How do Eukaryotes Regulate Gene Expression?
Eukaryotes can regulate transcription of genes and perform post-transcriptional modifications (poly-A tail, 5' cap, splicing). These organismsalso regulate translation and incorporate post- translational modifications,such as phosphorylating molecules.
who used x-ray diffraction to provide images of DNA.
Franklin
Structural Gene:
Genes that code for the proteins needed to complete the operon'sgoal
Describe What Occurs When Lactose is Absent in the Cell:
If lactose is absent, there is no need to produce enzymes that willcatabolize lactose. The repressor protein will bind to the operator andphysically block RNA polymerase from transcribing the genes.
How Does Transcription Differ from DNA Replication?
In DNA replication, the entire DNA strand is copied, but in transcription, only specificparts of the DNA are transcribed. DNA polymerase is used in replication and includes thebase thymine, while RNA polymerase is used in transcription and includes the base uracil
Describe What Occurs When Tryptophan is Absent in the Cell:
In the absence of tryptophan, the repressor cannot bind to theoperator. This allows RNA polymerase to transcribe the structural genes, andtryptophan is made
Contrast Inducible and Repressible Operons:
Inducible operons contain structural genes that are normally not transcribed but can be transcribed under certain conditions. Repressor proteins keep the operon turned off until an inducer binds to them. Inducible operons code for genes that catabolize molecules. Repressible operons contain genes that are normally transcribed but can be stopped. These operons produce enzymes for anabolic reactions and are controlled by theend product of the pathway. If there are high levels of this product, theoperon is turned off, and if there are low levels of the product, the operon isturned on
What Happens in Initiation of Translation?
Initiation complex forms with ribosome, mRNA, initiation tRNA containing methionine,and initiation factors. These components allow for the start of translation
Frameshift Mutations:
Insertion or deletion of a nucleotide that alters the reading frame of the codons.
Which of the following statements concerning nucleotide excision repair is FALSE?
It is a type of mismatch repair.
Why is DNA able to store large amounts of information?
Its nucleotides can be arranged in a large number of possible sequences.
What do the Structural Genes of the Lac Operon Produce?
LacZ, LacY, and LacA code for enzymes that metabolize lactose
Who first confirmed that the replication of DNA was semiconservative?
Meselson and Stahl
Vector:
Molecule that can transport DNA to a specific location
What Happens in Elongation of Transcription?
Nucleotides are added to the growing RNA strand at the 3' end. RNA polymerasecatalyzes the formation of phosphodiester bonds by removing two phosphates in theincoming nucleotide and incorporating the remaining phosphate into the backbone on theRNA
PRC:
Polymerase Chain Reaction, a process to amplify (increase thequantity) of a DNA fragment
Alternative Splicing:
Process where exons and introns are spliced in various patterns toproduce various proteins
Cloning
Produces multiple copies of a gene and occurs when a host cell istransformed and divides
Repressor Gene:
Product of a regulatory gene that can inhibit the production of astructural gene
Outline the Structure of an Operon:
The first sequence of an operon contains the regulatory gene,responsible for producing the repressor protein. The promoter is the nextsequence downstream (to the right) of the regulatory gene. RNA polymerasebinds here, and the adjacent sequence, the operator, is where the repressorprotein binds. The structural genes are located farthest downstream
who determined the structure of the molecule DNA.
Watson and Crick
Describe What Occurs When Lactose is Present in the Cell:
When lactose is present in the cell, it is converted to allolactose (theinducer). Allolactose binds to a site on the repressor protein, causing achange in the protein's shape and preventing it from binding to the operator.This leaves the operon clear and allows RNA polymerase to transcribe thestructural genes. Once produced, they catabolize (break down) lactose
anti condon
a complementary base pair of a codon found on tRNA strand
Structure of DNA:
a five-carbon sugar (deoxyribose), a phosphate group,and a nitrogenous base. DNA uses adenine and guanine (purines), cytosine and thymine (pyrimidines). DNA is anti-parallel, one strand runs 3'-5' and one runs 5'-3'. The nitrogenous base is attached to the 1' carbon of the sugar and the phosphate to the 5' sugar. The 3' sugar of one nucleotideis attached to the 5' phosphate of an adjacent nucleotide. This link is aphosphodiester bond and holds nucleotides together.
PCR
amplify the amount of DNA/ Artificial DNA replication
In the experiments of Griffith, the conversion of nonlethal R-strain bacteria to lethal S-strain bacteria:
b. was an example of the genetic exchange known as transformation.
Hydrogen bonds can form between guanine and __________, and between adenine and __________.
cytosine; thymine
Meselson and Stahl separated DNA from different generations using:
density gradient centrifugation.
exons
expressed sequence of DNA; codes for a protein
structural genes
genes trying to be turned on
DNA gyrase (toporsomerase)
helps relieve tension in coiling
Three Models of DNA Replication:T
hough there are three models of replication, only ONE is correct. Theone correct model is the semiconservative model. Here, the original DNAseparates and each strand serves as a template for the new complementarystrand. Thus, the resulting DNA consists of one old strand and one newstrand. In the conservative model, the old strands remain together and twonew strands form a new helix, resulting in one helix made of both old strandsand one new helix made of the fresh strands. Finally, the dispersive modelinvolves parts of the new and old strands being randomly integrated whenreplicated.
spliceosome
is made up of Small Nuclear Ribonucleoproteins which remove introns
In DNA replication, the lagging strand:
is synthesized as a series of Okazaki fragments.
single strand binding
keeps the helixes from binding together
The DNA strand that is replicated smoothly and continuously is called the:
leading strand.
