Genetics Chapter 7 + 8 Test Flashcards
What are the ends of linear chromosomes called? Why are bits of the ends lost with each cycle?
Telomeres, bits are lost bc do not replicate as easy the middle of cells
Lengths of telomeres decrease as we age. The effects of aging within cells is known as _______.
senescence
What is central dogma?
Central dogma describes how information flows in a cell.
The first step of information flow is transcription. What is transcription?
Process of copying gene (DNA) into a short mRNA sequence
What is the main enzyme involved in transcription? This enzyme uses single-stranded DNA to synthesize a complementary strand of ________.
RNA polymerase. Complementary strand of RNA
RNA polymerase reads DNA in the ____ to ____ direction. But, it builds an RNA strand in the _____ to _____ direction, adding each new nucleotide to the _____ end of the strand.
3’ to 5’ . It builds RNA 5’ to 3’, new nucleotides added to the 3’ end
Since only one strand of DNA can be transcribed, choose the one that starts w __ ______ (hint: its a number and 3 letters)
3’ TAC
mRNA is the intermediary between ____ and ________. From ribosomes, it is translated into _________.
DNA, ribosomes, protein
Translation is responsible for building a protein’s _______ structure. It assembles _____ _____ using the nucleotide sequence of _____.
primary, amino acids, mRNA
Every three nucleotides is called a _____. The codon chart is specific to ______.
codon, mRNA
What region does RNA polymerase bind to on DNA?
Promoter region
How do DNA and RNA compare location wise?
DNA: nucleus RNA: nucleus and cytosol
The promoter region is high in the bases adenine and thymine.
Adenine and thymine only have two H bonds.
What does RNA polymerase do?
It unwinds and unzips DNA and transcription begins
The start of the bases on DNA is 3’ TAC. Therefore, the first 3 bases of RNA are __ _____.
5’ AUG
The product of transcription is always ________ RNA. It is ______ length to a gene.
immature, equal
Immature RNA (aka _______) will undergo which two modifications?
- Splicing
- Addition of a cap and tail
What is splicing of pre-mRNA? What are the regions that are removed called? The regions that stay?
Splicing is when regions of the pre-mRNA are cut out. The regions that stay are called exons, those that stay are called introns.
An active __________ forms when the enzymes _______ bind to an intron and loop it out.
splicesome, SnRNPs
When two _______ are spliced together to form mRNA, the cleaved ______ and _______ are released.
exons, introns, snRNPs
mRNA can be spliced in many different ways. This is known as ____________ ________.
alternative splicing
After splicing, a ______ and ______ are added to mRNA
cap and tail
A cap contains 7 ________ nucleotides and is added to the ____ end. It aids in the bonding to a _______ and gives mRNA ________.
guanine, 5, ribosome, direction
A tail is added to the ____ end of mRNA. It consists of approximately _____ adenine nucleotides, known as a Poly A Tail.
3 end, 200
Both the cap and tail extend the life of mRNA is the cytosol. Why?
The pre-mRNA needs to last long enough to be translated by the ribosomes before it is recycled.
The translation of a new mature mRNA into a protein is accomplished by a _________. It is a _____ and protein hybrid, and composed of 2 subunits. What are they known as?
ribosome, RNA
Ribosomes bind to the RNA _________ initiation sequence and build a new _________ in the ___ to ___ direction.
translation, polypeptide, 5’ to 3’
The first amino acid on the polypeptide chain has a free amino group, it is called the ____ terminal. The last amino acid has a free acid group, it is called the ____ terminal.
N terminal, C terminal,
Transfer RNA is the adaptor between the three bases of ______ and its corresponding ______ _____.
codon, amino acid
tRNAs are only 70 to ____ base pairs long and have a signature _______ pattern.
90, cloverleaf
Each tRNA has 3 bases that make up its ______. These bases pair w the three bases of codon on the mRNA sequence during _________ (translation/transcription)
anticodon, translation
Each tRNA has an amino acid attached to its ___ end. The aminoacyl RNA _________ are used to charge the tRNA w the proper ______ acid.
3’, synthetases, amino
The third base of an anticodon is called the ________ position. What does it do?
wobble position, it forms base pairs w several different nucleotides
In eukaryotes, ribosomes bind to the 5’ cap, then move down the mRNA until they reach the first ______ (three letter codon)
AUG
A ribosome has two sites for tRNAs, called ____ and ____. The initial tRNA with attached amino acid enters at the ____ site.
P and A, P is the first
Corresponding to the next codon that makes up mRNA, a new tRNA enters SECOND at the ____ site.
A
What catalyzes the transfer of the amino acid from the A to the P site? What kind of bond is formed?
A ribosome! Polypeptide bond is formed
The tRNA at which site holds the polypeptide chain? New tRNA binds to which site?
P holds the polypeptide chain. New tRNA binds to the A site.
___________ is when a ribosome reaches a _____ codon. No more tRNA binds, instead proteins called ________ _______ bind and the polypeptide chain is completed. What still continues past the stop codon?
Termination, stop, release factors, mRNA
What does rRNA stand for? What does it do?
ribosomal RNA, binds with proteins to form ribosomes
What is an operon?
A cluster or series of related genes
What is the lac operon? What is it responsible for?
Cluster of genes responsible for the metabolism (breakdown) of lactose
Operons have a promoter and an operator region. What is the function of each?
Promoters PROMOTE transcription
Operators BLOCK transcription
Operons have a promoter and an operator region. What is the function of each?
Promoters PROMOTE transcription
Operators BLOCK transcription
What happens at the promoter region?
RNA polymerase binds and transcribes the operon
What happens at the operator region?
Repressor and maybe a co-repressor binds and blocks transcription
When is the Lac operon gene is “on”?
It turns on when lactase is present in the cell. Some lactase binds to the lac repressor
When the Lac operon turn “off”?
When lactase is not present in the cell (no metabolism needs to happen). Lac repressor binds to the operator, blocking transcription.
3 _______ required for this reaction are coded for by which 3 genes?
enzymes, 3 genes are Lac Z, Lac Y and Lac A
What does the trp operon do? How many genes code for the 5 enzymes needed to regulate this reaction? What are they?
Makes the amino acid tryptophan. 5 genes are needed to code for the 5 enzymes. They are Trp A-E
When is the Trp operon turned on? When is it turned on?
Trp turned on when tryptophan is absent in the cell, and turned off when trp is present
When lactase is present, some of it binds to the __________, (acts as an _________). It does not bind to the operator. ____ _________ binds to the promoter, allowing transcription to happen.
represser, inducer, RNA polymerase
Unlike lac, when RNA polymerase binds to the promoter in the trp operon, the repressor is automatically ________. It does not need an ________.
Inactive, inducer
To stop making trp, what needs to bind to the inactive trp represser to make it active?
A tryptophan corepressor
What is genetic engineering?
The science of altering/ cloning genes to make a new trait or biological substance. It involves removing the gene of one organism and placing it into another
Restriction enzymes are found in ________. They cut ______ DNA into smaller pieces.
bacteria, viral
Restriction enzymes _____ at specific locations. They cut at __________ sequences.
cut, palindromic
Restriction enzymes cut up viral DNA. Why isn’t bacterial DNA also cut up?
It is methylated (contains methyl groups, CH3)
Restriction enzymes are named for the organism from which they were first isolated. Ex. ______ is isolated from E. coli strain RY13. Eco is the _______ and ______ is the species. R is the the strain. 1 means it was the first ______.
EcoR1, genus, coli, enzyme
Restriction _____ are also known as palindromic sequences. They posses two-fold ________ symmetry (same forward and back)
site, rotational
DNA digestion (also known as DNA _________) is done with a series of restriction ________. DNA fragments are separated by ______ during ____ ______________.
fragmentation, enzymes, size, gel electrophoresis
What does endonuclease cleavage do to a piece of DNA?
Cuts a polynucleotide chain by separating nucleotides other than the two end ones.
What are restriction maps used for?
To characterize and unknown DNA
All bacteria have ___ chromosome. It is circular and made up of approx ____ million base pairs and _____ genes.
1, 4 million base pairs, 1000 genes
A plasmid is a small piece of DNA in the shape of a ______, found in SOME bacteria. Usually, plasmid genes produce genes that give the bacteria _______ to an antibiotic.
circle, immunity
for ex, the amp’r gene gives immunity to the antibiotic _______
the tet’r gene gives bacteria immunity to the antibiotic ________.
ampicilin, tetracyline
Gel ___________ is a tool for plasmid mapping.
- Restric enzymes cleave _______ into smaller fragments
- DNA segments are located into ____ of the gel at the _______ end. The gel floats in a _______ solution.
- When an electric current is passed through the gel, segments move toward the _______ charged cathode.
- ______ DNA move faster than large.
electrophoresis,
- DNA
- wells, negative, buffer
- positively
- smaller
To have matching ______ ends, a bacterial plasmid and piece of _____ must have been cut with the same _________ enzyme. The _______ and DNA are joined by DNA _____ and inserted into a bacteria. The structure is called a _________ _______.
sticky, DNA, restriction, plasmid, ligase, recombinant plasmid
Bacteria take up a __________ plasmid by means of a ______ shock. We cannot see the plasmid, so how do we know which bacteria were transformed and which were not?
recombinant, heat. Place ALL bacteria into a petri dish with agar gel and ampicillin. Ampicillin kills the non-resistant bacteria.
What gene allows the plasmid to survive antibiotics? Each surviving bacterium gives rise to a group of new bacteria, all with the same ________. What is this called?
The antibiotic resistance gene. plasmid, colony
Once a colony with the correct plasmid has been found, we can give them a ________ signal to make a target ______. Churning out large amounts of protein, they are similar to _______.
chemical, protein, mini factories
Once the protein is produced, bacterial cells can be ______ open to _______ it. Since the cell has other contents, we must ______ the protein using _________ techniques.
split, release, purify, biochemical
What are the two types of immune genes? What are they immune to?
amp^r gene: immune to the antibiotic ampicillin
tet^r gene: immune to the antibiotic tetracycline
What does PCR stand for? It is an automated process developed by Kerry Mullis that does what?
PCR: Polymerase Chain Reaction
Purpose: amplify or clone DNA
What are 3 applications of PCR?
- Amplify small amount of DNA at crime scene, to create a DNA “finger print”
- Parental testing
- Cancer gene research
What are the 4 materials required for PCR?
- DNA sample
- Free nucleotides (A,C,T,G)
- DNA primers (short, single-strand DNA)
- TAQ polymerase (used to cool DNA to prevent denaturation)
Explain the 3 main steps of PCR
- ___________: Heat DNA fragment to 94C and denature into _______ strands.
- ___________: Cool the mixture to 50-65 C to ______ to ______ to the ends of their complementary strands. TAQ synthesizes the new strand
- __________: Heat to 72 for DNA _______ to extend primers using free-floating nucleotides
- Denaturation: Heat DNA fragment to 94C and denature into single strands.
- Annealing: Cool the mixture to 50-65 C to anneal the primers to the ends of their complementary strands. TAQ synthesizes the new strand
- Elongation: Heat to 72 for DNA polymerase to extend primers using free-floating nucleotides
What does VNTR stands for? How is it used to distinguish between individuals.
VNTR stands for Variable Number of Tandem Repeat. VNTR is a single strand of DNA where there is a tandem reset sequence. There are different numbers of repeats between individuals.
VNTR can be classified as mini or micro satellite. What is the difference?
mini: each repeat is 10 nucleotides
micro: each repeat is 2-5 nucleotides
VNTR does not undergo the two Ts. What are they?
They are not transcribed or translated
What does RFLP stand for? What is it used to create?
RFLP stands for “restriction fragment length polymorphism” it used to create a DNA fingerprint
Describe RFLP
- DNA is fragmented by ________ enzymes
- DNA fragments are separated by agarose gel __________
- DNA fragments are denatured to single _____ using an ________ solution.
- DNA is transferred to _______ paper by applying pressure.
- ________ probe complementary to DNA attaches
- Autoradiography exposes the film to form an _______ of the DNA
- DNA is fragmented by restriction enzymes
- DNA fragments are separated by agarose gel electrophoresis
- DNA fragments are denatured to single strands using an alkaline solution.
- DNA is transferred to nitrocellulose paper by applying pressure.
- Radioactive probe complementary to DNA attaches
- Autoradiography exposes the film to form an image of the DNA
Sanger DiDeoxy DNA Sequencing uses ____________ to stop replication.
Di-nucleotides
How do dideoxynucleotides stop DNA replication?
Dideooxynucleotides lack the C3-OH group required by DNA polymerase to add the next nucleotide
Phosphodiester bond cannot be made
If this DNA strand was placed in a test tube with 4 normal nucleotides and dideoxycytosine, how many fragments are produced?
TCGAAAAGAT
3 potential strands!
- AGC
- AGCTTTTC
- ACFTTTTCTA (normal)
What is the difference between regular Sanger dideoxynucleotide sequencing and automated?
the products are labeled with flurosecnt dye rather than radioactive markers. it is excited by lasers. sequencing determined by a computer
what is sequencing?
the order of nucleotides
