Micro UNIT Exam 3

Transposition

"Jumping Genes"- move by site-specific recombination from one DNA molecule to another. Composite transposons can carry a variety of genes, including antibiotic resistance genes. induced additional genetic variability

Group IV viruses

(+) sense ssRNA viruses Non-segmented RNA genome that replicated in cytoplasm and synthesizes an RNA dependent RNA polymerase. -Poliovirus -HEP A -Rubivirus-Togaviridae

Group V viruses

(-) sense ssRNA viruses tend to be enveloped, and because (-) sense it cannot serve directly as mRNA to form vital proteins, must be converted to (+) sense. -Influenza Viruses- Orthomyxoviridae Family (Influenza A, B, C) -Rubeola Virus- Red Measles

Topoisomerase

(Gyrase)- alleviate the super coiling that occurs upstream from the replication fork as the double strand is unwinded. (when rep. fork is formed the single strand binding proteins will come in to help keeps fork open).

replication fork/bubble

- A Y-shaped point that results when the two strands of a DNA double helix separate so that the DNA molecule can be replicated - Single fork in Prokaryotic cells - 100s of forks in Eukaryotic cells - Replication will proceed in both directions (form a bubble)

Match the following with the correct cellular process. -Promoter -Origin ( ori) -Ribosome -Bidirectional -P Site -RNA polymerase -Addition of poly-A tail -Lagging strand

-Promoter - Transcription -Origin ( ori)- Replication -Ribosome- Translation -Bidirectional- Replication -P Site- Translation -RNA polymerase- Transcription -Addition of poly-A tail- Transcription -Lagging strand- Replication

Ori C

-origin of replication -site where DNA replication fork starts in a bidirectional direction

Describe the process of DNA replication. Please include all components and the order in which they are used ________

..

List three post transcriptional modifications that are made to eukaryotic mRNA prior to translation. ________________

..

The three post-transcriptional modifications that occur in eukaryotic organisms but not in bacteria.

1. Addition of a 5' 7mG cap to the primary transcript 2. Addition of a 3' poly-A tail to the primary transcript 3. Removal of introns and exon splicing

Put the following stages of a bacteriophage lytic replication cycle in order, from earliest to latest stages.

1. Attachment 2. Penetration 3. Synthesis 4. Maturation 5. Release

Differentiate the bacterial and eukaryotic genome.

1. Bacteria and Archaea typically have one circular chromosome, thus= haploid. Eukaryotes have 2 sets of linear chromosomes = diploid. 2. Bacterial Genome consisted of singular circular dsDNA, located in cytoplasm and supercoils in an area called "Nucleoid"- nucleoid is different than nucleus bc it does not have a plasma membrane. 3. Bacteria may have plasmids 4. Eukaryotic Genome has nuclear chromosomes (located in the nucleus), which means there is a plasma membrane surrounding the genetic material. 5. Histone Proteins are unique to Eukaryotes

Correct sequence representing the Central Dogma of Genetics

1. DNA 2. RNA 3. Protein

What are the three components of a DNA nucleotide?

1. Deoxyribose (5 C sugar) 2. Nitrogenous base (A, T, G, C) 3. Phosphate

Identify 4 practical uses of PCR.

1. Infectious disease diagnosis- amplify genes of microbes that cant be cultured 2. Compare genes between species 3. Diagnosis of inherited disease 4. Forensics 5. Research

Describe the three phases of transcription and translation. How are they similar? How are they different?

1. Initiation 2. Elongation 3. Termination Transcription= copying of a DNA sequence into an RNA sequence. The sequence of DNA is not altered as a result of this process. Translation= mRNA is translated into a sequence of amino acids. Transcription: Initiation: RNA polymerase binds to the DNA at the appropriate site. Once winded- DNA is denatured into a bubble known as "open complex"- separates DNA into template & non-template strands Elongation: synthesis of RNA transcript as RNA polymerase slides along DNA in an open complex. RNA is synthesized in a 5'-3' direction Termination: When the termination sequence is reached RNA polymerase & RNA transcript dissociate from DNA- the RNA transcript can then be used in the process called "TRANSLATION" to make the protein. Translation: Initiation: Which involves binding of mRNA, tRNA, and ribosomal subunits. Elongation: involves adding one amino acid at a time to the polypeptide chain. Termination: occur when the stop codon is reached in mRNA (not recognized by tRNA)

Identify the common viral components and describe their function.

1. Nucleocapsid- consists of the viral genome and the capsid. The capsid is the butter protein coat that surrounds the viral genome (all viruses have this). 2. Genome- can be RNA or DNA and can be single or double stranded. (Viral genome is the primary way to classified/categorize viruses). 3. Capsid- protein structure. Proteins that make up capsid= capsomeres. It encloses the genomes, protects and also determines shape of virus. in some cases, used to attach to host's cells. 4. Tegument- space between nucleocapsid and outer envelope if envelope is present. 5. Envelope- outer phospholipid bilayer, encloses tegument and nucleocapsid. Can help evade detection by host immune system. 6. Spikes: embedded in envelope (can also be extending from capsid without envelope)- they are proteins extensions that typically used for attachment to host cell surfaces.

Short Answer: Describe the four levels of protein organization

1. Primary level of protein structure - sequence of amino acids that make up the protein 2. Secondary level of protein structure - folding of AA chain due to interactions between neighboring AA forming α helix or β pleated sheet conformations 3. Tertiary level of protein structure - interactions that are caused by α helix or β sheet leading to the 3D folding of the polypeptide. Such interactions are include: H-bonds, ionic bonds, hydrophobic interactions or disulfide linkages 4. Quarternary level of protein structure -interactions between multiple subunits (can be the same or different polypeptides) to produce the functional protein

Series of events in that occur during the process of translation in the correct order.

1. mRNA leader sequence (5' UTR) binds to rRNA in small subunit of ribosome 2. tRNA binds to A site of ribosome, based on codon complementarity, adding amino acid to growing peptide 3. tRNA in A site shifts to E site site after the peptide bond is formed between adjacent amino acids 4.Stop codon terminates synthesis of growing peptide chain

Correct order needed to produce a recombinant vector containing a human gene insert

1.Isolate the human gene and the vector DNA using restriction enzymes. 2. Ligate the DNA fragments to produce a recombinant plasmid. 3.Transform bacteria with the recombinant plasmid. 4.Grow bacterial cells on a medium containing a selective agent (such as an antibiotic)

If the sequence of one strand of a DNA molecule was 5' ATGGCAT 3', the complementary strand sequence would be:

3' TACCGTA 5'

Clostridium tetani DNA is 15% G. What percent of its DNA is A?

35%

What is a characteristic shared by both DNA and RNA polymerases?

5' to 3' direction of polymerization

Short Answer: A) Explain what a transgenic organism is. B) Provide two examples of transgenic organisms.

A) A transgenic organism is one that contains genes from other organisms. These genes usually add some special ability or function to the organism. B) Agriculture offers many examples of transgenic organisms. Soybeans have been engineered to contain glyphosate-resistance genes, and other crops have been engineered to grow well in soil with high salt concentrations. Still other plants have been engineered to contain the gene for Bt toxin, a bacterial toxin that kills insect pests that would otherwise feed on and destroy the crop. Not all transgenic organisms represent such extreme genetic modifications, however. Some genetically modified organisms simply represent efforts to improve nutritional content (in the case of plant crops) or to increase food yield (in the case of bovine growth hormone, which is produced by transgenic bacteria and then given to cattle to increase their meat and milk yield).

This type of plasmid has proteins that can be toxic to other bacterial cells: A) Bacteriocins B) F plasmids C) Virulence plasmids D) Ti plasmids

A) Bacteriocins

This is used on cells w/ a thick cell wall & euk cells where access to the nucleus is required: A) Electroporation B) Microinjections C) Liposomes D) Heat shock

A) Electroporation

Genetic info is used within a cell to produce the proteins needed for the cell to function. A) Expression B) Recombination C) Replication D) Transcription

A) Expression

An example of catabolite repression is: A) Lac operon turned off in the presence of glucose B) Lac operon turned on in the presence of lactose C) Lac operon turned off in the presence of lactose D) Lac operon turned on in the presence of glucose

A) Lac operon turned off in the presence of glucose

Which of these would tend to increase the speed that DNA migrates in an agarose gel? A) Shorten the length of the fragment B) Decrease the charge on the fragment C) Decrease the charge gradient D) Increase the amount of agar in the gel

A) Shorten the length of the fragment

Which form of methionine is associated with eukaryotes? A) methionine B) formyl methionine (fMet)

A) methionine

Genetic variation in bacteria can be brought about by (MARK ALL THAT APPLY) A) Mutation B) Conjugation C) Transformation D) Transduction E) Transcription

A, B, C, D

Select all of the true statements regarding DNA replication. (MARK ALL THAT APPLY) A) DNA polymerase joins nucleotides in the 5'-3' direction only B) The leading strand of DNA is made continuously C) The lagging strand of DNA is synthesized as Okazaki fragments D) DNA replication proceeds in one direction around the bacterial chromosome E) Multiple replication forks are possible on a eukaryotic chromosome

A, B, C, E

Which of the following statements are TRUE? (MARK ALL THAT APPLY) A) A genetic mutation may not alter the phenotype B) Because bacteria are asexual they do not exhibit genetic diversity within bacterial species C) The Central Dogma Theory of molecular biology is the flow of genetic information from Nucleic acid to protein D) Chromosomal DNA is replicated prior to transcription and translation E) The base cytosine is complementary to guanine in both DNA and RNA

A, C, E

Select all of the following that are methods for culturing viruses (MARK ALL THAT APPLY) A) Embryonated eggs B) Blood agar plate C) BHI plate D) Tissue culture E) Laboratory animals

A, D, E

Label the following viral structures.

A: Envelope B: Spike C: Capsid D: Genome

Kaposi's sarcoma is often associated with ...

AIDS Patients; Kaposi's sarcoma is a common cancer seen in AIDS patients and is caused by HHV8. This cancer is a devastating condition associated with AIDS.

Ligase Definition

An enzyme that connects two fragments of DNA to make a single fragment; DNA ligase is an enzyme which can connect two strands of DNA together by forming a bond between the phosphate group of one strand and the deoxyribose group on another. It is used in cells to join together the Okazaki fragments which are formed on the lagging strand during DNA replication

Primase definition

An enzyme that joins RNA nucleotides to make the primer using the parental DNA strand as a template.

Differentiate antigenic drift and antigenic shift by influenza virus.

Antigenic drift (minor change of genetic makeup), Antigenic shift (major change of genetic makeup). Antigenic drift-involves the accumulation of a series of minor genetic mutations Antigenic shift- involves "mixing" of genes from influenza viruses from different species (pigs, birds, humans). When shift happens people have little or no immunity against the new virus. While influenza viruses change all the time due to antigenic drift; antigenic shift happens less frequently.

An accidental or unplanned change in the nucleotide sequence is referred to as A) Transduction B) A mutation C) An accident D) A plasmid

B) A mutation

Variation of a gene which has slightly different DNA sequence at the same locus A) Homologus chromosome B) Allele C) Mutation D) Phenotype

B) Allele

What is a variation of a gene which has a slightly different DNA sequence at the same locus? A) Mutation B) Allele C) Gene locus D) Genotype

B) Allele

This type of gene therapy involves a normal gene cloned in retrovirus or adenovirus vectors A) Germline gene therapy B) Ex-vivo therapy C) In-vivo therapy

B) Ex-vivo therapy

Which are spliced together in alternative splicing? A) Introns B) Extrons

B) Extrons

This type of conjugation involves incorporation of a plasmid into a chromosome & is reversible A) F Factor B) F' C) Hfr

B) F'

An example of latent viral infection is A) Polio B) HHV 1 C) Influenza D) Small pox E) Mumps

B) HHV 1

An alpha helix is associated with which level of protein structure? A) Primary B) Secondary C) Tertiary D) Quaternary

B) Secondary

What type of bond holds together sugar-phosphate back bone on a DNA molecule? A) Hydrogen bond B) Strong covalent bond C) Ionic bond D) Peptide bond

B) Strong covalent bond

According to the operon model, for synthesis of an inducible enzyme to occur, the A) End product must not be in excess B) Substrate must bind to the repressor C) Repressor must not be synthesized D) Substrate must bind to the enzyme E) Repressor must be the operator

B) Substrate must bind to the repressor

The tip/ends of eukaryotic linear chromosomes are known as: A) Capsomeres B) Telomeres C) Centromeres D) Histones

B) Telomeres

Why is lysogeny an advantage to a bacteriophage? A) It speeds up the viral infection cycle B) The genetic material of the bacteriophage can be passed on to future generations of cells C) It allows the bacteriophage to destroy the host cells DNA D) It allows the bacteriophage to infect cells it would not normally infect E) It enables the bacteriophage to take over the cell

B) The genetic material of the bacteriophage can be passed on to future generations of cells

Which of the following provides the most significant support for the idea that viruses are nonliving? A) They are not composed of cells B) They cannot reproduce outside host cells C) They cause disease similar to those caused by chemicals D) They are filterable E) They are chemically simple

B) They cannot reproduce outside host cells

This is used to isolate products such as proteins from animal secretions: A) Bioremedeiation B) Transgenic Pharming C) Transformation D) Gene Therapy

B) Transgenic Pharming

A group of three nucleotides in mRNA that encode an amino acid is called a(n): a) anticodon b) codon c) nucleic acid d) gene

B) codon

How is the peptide bond between the amino acids formed? A) lysis B) dehydration synthesis C) condensation D) combustion

B) dehydration synthesis

Compare and contrast the reproductive cycles of animal viruses and bacterial viruses

Bacterial Viruses Replicate: 1. Attachment/Absorption 2. Entry/Penetration 3. Synthesis 4. Assembly/Maturation 5. Release During bacterial phage replication- may one or a few bacteria can adhere to the bacteria, upon release 100's if not 1000s phages are formed (so very different than binary fission where 1 divides into 2 or mitosis). In virus replication- just a. few viruses infect the cell and 100s if not 1000s released. Animal Viruses Replicate: 1. Adhere to host cell using spikes & absorption to plasma membrane of host cell. 2. Penetration- enters host cell 3. UNCOATED- removes capsid- bacterial phages do not have uncaring stage. 4. Synthesis 5. Assembly 6. Release

single strand binding proteins

Bind to DNA at the replication fork= keeping fork open. A protein that binds to the unpaired DNA strands during DNA replication, stabilizing them and holding them apart while they serve as templates for the synthesis of complementary strands of DNA.

List and describe four products produced through recombinant DNA technology.

Biochemical products of recombinant DNA technology in medicine and research include: human recombinant insulin, growth hormone, blood clotting factors, hepatitis B vaccine, and diagnosis of HIV infection -diagnosis and treatment of various diseases -advanced gene therapy for people with disease like cystic fibrosis -vaccine/prevention -Genetic screening (DNA microarrays) -Pharmaceutical-insulin -Pollution Control (bioremediation)

Bacterium with linear chromosome:

Borrelia burgdorferi- Lymes Disease

Helicase

Break the hydrogen bonds between complementary bases separating the double-stranded DNA into single strands

Helicase (definition)

Break the hydrogen bonds between complementary bases separating the double-stranded DNA into single strands. Helicases are a class of enzymes vital to all organisms. Their main function is to unpack an organism's genes. They are motor proteins that move directionally along a nucleic acid phosphodiester backbone, separating two annealed nucleic acid strands such as DNA and RNA, using energy from ATP hydrolysis

The method of exit by an enveloped virion is called ________

Budding

Which of these genetic probes would hybridize to this target sequence? 5' GATCCATATC 3' ? A) 5' GATCCATATC 3' B) 5' CTATACCTAG 3' C) 3' CTAGGTATAG 5' D) 5' GATATGGATC 3'

C) 3' CTAGGTATAG 5'

Which site holds the next amino acid to be added to the lengthening polypeptide? A) E B) P C) A

C) A

Which nitrogenous base is not a pyrimidine? A) Cytosine B) Uracil C) Adenine D) Thymine

C) Adenine

Which enzyme in DNA replication brings in new nucleotides? A) RNA primase B) DNA polymerase I C) DNA polymerase III D) Ligase

C) DNA polymerase III

Select all of these that are components of both DNA and RNA A) Amino acid B) Ribose C) Guanine D) Phosphate E) Uracil

C) Guanine & D)Phosphate

All of the following are caused by prions EXCEPT ... a) kuru b) bovine spongiform encephalopathy c) measles d) Creutzfeldt-Jakob disease e) scrapie

C) Measles

The combination of a virus' protein coat and nucleic acid core is called the A) Nucleus B) Nucleoid C) Nucleocapsid D) Spore coat E) Capsid

C) Nucleocapsid

This amplifies DNA & is capable of making millions of copies of it A) DNA hybridization test B) Fluorescent in situ Hybridization C) Polymerase Chain Reaction D) DNA fingerprinting

C) Polymerase Chain Reaction

An advanced aging disorder that suggests aging is associated with telomere lenth is called: A) Ascites B) Condyloma acuminata C) Progeria's D) Alzheimer's

C) Progeria's

Which component of the structure of an amino acid makes it functional? A) amino group B) Carboxyl group C) R group D) All of the above

C) R Group

This type of mutation is not transmissible to offspring, but is transmissible to daughter cells: A) Wild type B) Induce C) Somatic D) Germline

C) Somatic

Conjugation differs from reproduction since it A) Replicates DNA B) Transcribes DNA to RNA C) Transfers DNA horizontally to cells in the same generation D) Transfers DNA vertically to new cells

C) Transfers DNA horizontally to cells in the same generation

Which form of horizontal transfer entails the uptake of extracellular DNA into the cell? A) Conjugation B) Transduction C) Transformation D) Translation

C) Transformation

A cluster of genes regulated by a common promoter A) repressor B) chromosomes C) operon D) codon

C) operon

Characterize catabolite repression

Cells can use various carbohydrates for metabolism, if glucose is present it will be metabolized first. If glucose and lactose are both present- glucose will be used first and then we will see a brief lag period as the lac operon is being turned on before lactose is used. Catabolite Repression: lac operon is repressed in presence of glucose -Regulation of transcription by both repressors and activators. -Diauxic growth- biphasic growth pattern -lactose is turned off in presence of glucose

HHV 5

Cytomegalovirus (CMV) most common congenital infection in US /asymptomatic transmission: bodily fluid; direct contact

A viroid is A) A complete infectious virus particle B) A capsid without a nucleic acid C) An infectious protein D) A non enveloped, infectious piece of RNA

D) A non enveloped, infectious piece of RNA

Which is the key part of an operon? A) Promoter B) Operator C) Repressor D) All of the above

D) All of the above

Which post-translational modifications may be necessary to make a functional protein? A) Cofactors added B) Join with proteins to form quaternary level of structure C) Glycosylation &/or phosphorylation D) All of the above

D) All of the above

Which of the following viruses are INCORRECTLY matched to the mode of transmission? A) HPV- direct physical contact B) HHV5- vertical transmission C) HHV2- sexually transmitted D) Hep A- blood and bodily fluids E) HHV4- direct oral contact

D) Hep A; blood and bodily fluids

What are the basic stages of transcription? A) DNA, RNA, & Protein B) Regulatory sequence, Promoter, Coding, & Terminator C) Start codon, Elongation, & Stop codon D) Initiation, Elongation, & Termination

D) Initiation, Elongation, & Termination

How is transformation of host cells done? A) Conjugation B) Electroporation C) Freezing D) Microinjection E) Heat shock

D) Microinjection

In the lab you want to determine whether a person has a particular mutant gene. The process involves using primers and Taq. This process is called... A) Translation B) Transformation C) Restriction mapping D) Polymerase Chain Reaction (PCR)

D) Polymerase Chain Reaction (PCR)

This feature of a cloning vector confers drug resistance to the cloning host. A) Origin of replication B) Cloning site C) Promoter D) Selection marker

D) Selection Marker

Which of the following statements about viruses is false? A) Viruses may have DNA or RNA genome, but never both B) Viruses exhibit host specificity C) Viruses use the anabolic machinery of the cell to replicate D) Viruses use their own enzymes to replicate E) Enveloped viruses are surrounded by a phospholipid bilayer F) Viruses are obligate intracellular parasites

D) Viruses use their own enzymes to replicate

Template Parent DNA vs Daughter strands

DNA creates "daughters" by using the parental strands of DNA as a template or guide. Each newly synthesized strand of DNA (daughter strand) is made by the addition of a nucleotide that is complementary to the parent strand of DNA.

Describe the structure of DNA and compare it to the structure of RNA.

DNA is a polymer of nucleotides- they are linked together through a covalent bond "Phosphodiester Bond"(5'-3') located between the phosphate 5' carbon of one nucleotide and the 3' hydroxyl of another. This creates a sugar phosphate backbone. DNA consists of two strands that are hydrogen bonded together, which twists= double helix. The double helix of DNA will fold and bend and interact with various proteins ultimately producing its 3D structure. RNA in contrast are single stranded. RNA contains Uracil, while DNA contains Thymine. RNA has sugar ribosome while DNA has sugar deoxyribose. MAIN features of Watson and Crick's 3D structure of DNA: -hydrogen bonds hold strong together (complementary base pairing) -sugar phosphate backbone -antiparallel strands- forms double helix

Group VII viruses

DNA reverse transcribing viruses genetic information transitions thru an RNA strand as part of their life cycle -HEP B

Conjugation

DNA transfer by conjugation requires intimate cell-cell contact typically initiated by a special pilus (sometimes called a sex pilus) that protrudes from a donor cell. Many but not all species of bacteria have ability to conjugate. Only certain strains of bacterium can act as a donor cell=thus promoting cell-cell contact and synthesis of the conjugation tube/pilus through which the DNA donor will pass. Those cell that are capable of conjugation contain a plasmid termed "fertility factor" or "F factor"

How do the 25,000 or so human genes encode more than 100,000 proteins?

Different combinations; Many of these proteins are produced by alternative intron/exon splicing.

Why does dissemination of Epstein-Barr virus (EBV) often lead to hepatomegaly and splenomegaly?

EBV produces abnormal blood cells that are removed by the liver and spleen.

DNA polymerase III definition

Enzyme that synthesizes the formation of new daughter strand by facilitating the phosphodiester bond between adjacent nucleotides in the growing DNA molecule. Responsible for adding bases to the new DNA chain and proofreading the newly laid down bases in bacteria

HHV 4

Epstein-Barr virus "kissing disease"- oncogenic direct contact/ saliva

Which infection presents as a "slapped cheek" rash?

Erythema infectiosum (fifth disease

How is Eukaryotic and Prokaryotic replication different?

Eukaryotes chromosomes are generally larger than bacteria. The large linear chromosomes therefore require multiple origins of replication to ensure DNA can be replicated in reasonable time. (Bacteria have single origin of replication). Eukaryotes have membrane-bound nucleus house one or more chromosomes. Eukaryotes packed their DNA within the nucleus using proteins called histones. DNA replication is more complex in Eukaryotes & there is more complicated cell cycle regulation occurring. 95% or more of the Eukaryotic genome can be made up of non-coding regions.

Characterize viroids

Even more simple than a virus. Viriod= infectious agent that is composed of a closed, circular, single stranded RNA. There is no capsid and is naked (non-enveloped). -Circular ssRNAs: do NOT encode gene products, copied in nucleus (can only affect Eukaryote). Associated with plant disease (ex: potato spindle tuber disease) Require a host cell, DNA dependent RNA polymerase to replicate

When cells conjugate, the DNA donor is considered to be ________, and the recipient cell is considered to be _______ . The cell that extends the conjugation pilus is ________.

F+; F-; F+ When cells conjugate, the DNA donor is considered to be F+, and the recipient cell is considered to be F-. The F+ cell contains the fertility plasmid, and the F- cell initially does not. After the complete and successful conjugation, both cells leave the event as F+, and both are able to engage in conjugation with other F- cells. The cell that extends the conjugation pilus is F+; the genes encoded on the fertility plasmid are needed for the cell to create the pilus.

True or False? When lactose is present, the operon is "off" (repressed).

FALSE

T/F: DNA released from a dead cell cannot be acquired by a live cell.

False

T/F: Eukaryotic cells have a higher spontaneous mutation rate than Bacteria & Viruses.

False

True or False: "Stop codons" encode an amino acid.

False

True or False: The 5' end of a polypeptide chain is correlated with a carboxyl group.

False

True or false: In Eukaryotes, translation is simultaneous with transcription

False

This includes the genetic information of the entire organism:

Genome

The phenotype of a given trait is dependent upon its _____.

Genotype

Differentiate germline and somatic mutations

Germline Mutations: occurs in gremlin cell- these include cells that give rise to gametes (sperm & eggs). These are inherited to offspring, and is present in every offspring. Somatic Mutations: In somatic cells (body cells). These are not heritable to an individuals offspring. Ex: too much time in the sun that leads to cancer.

What would happen if a colony consisted of one F+ and all the rest were F-?

Given enough time, eventually all of the cells would end up being F+ F+ (donor cell) will remain F+ (UNCHANGED) as all the F- cells are converted to F+

HEP A

Group 4; + sense ssRNA virus ACUTE infection Transmission: fecal-oral (poor sanitation) Resistant to common disinfectants Symptoms are usually response of immune system Prevention: vaccine

The sores on the upper lip in this image are caused by _____.

HHV1

After the F factor shown at the top of this figure becomes integrated into the chromosome of this cell (as shown at the bottom of this figure), the cell is called a(n) ...

Hfr cell; The F-factor plasmid is introduced into a cell during conjugation. If the F plasmid becomes integrated into the chromosome, the cell is called a high frequency of recombination (Hfr) cell. There is a high likelihood that genes on the chromosome in an Hfr cell will be transmitted to a recipient cell during conjugation because the chromosome with the integrated F plasmid essentially acts as an F plasmid. See Section 9.1 in your text for more information.

Describe the three modes of horizontal gene transfer

Horizontal gene transfer: transfer of genes from one organism to another organism without being the offspring (may occur between organisms of the same or different species). 3 Forms of Horizontal Gene Transfer: 1. Transformation 2. Conjugation 3. Transduction

Describe how recombinant DNA is created; discuss its role in gene cloning

How is Recombinant DNA produced? -We need a template DNA (cut your gene of interest from), cloning vector (going to paste the gene into), and a couple enzymes to help. First enzyme we need is restriction endonuclease. Cloning vectors are used to transfer DNA between cells (Types: Plasmids, Phages/Viruses, Cosmids, Artificial chromosomes). Gene cloning: refers to the process of isolating a DNA sequence of interest for the purpose of making multiple copies of it. Recombinant DNA is engineered through the combination of two or more DNAstrands, combining DNA sequences which would not normally occur together.

complementary base pairing

Hydrogen bonding between particular pyrimidines and purines. Adenine & Thymine. Cytosine & Guanine (DNA in RNA Uracil instead of Thymine)

Describe the main difference between an inducible and a repressible operon

Inducible Genes: code for inducible enzymes; enzymes that are needed only in certain conditions and in certain environments. Inducible enzymes often function in catabolic pathways. So inducible enzyme only needed when substrate is present. Repressible Genes: genes that encode proteins that will function in a biosynthetic pathway (anabolic pathway) generally always present unless end product of biosynthetic pathway is available.

List the 3 most important forms of RNA discussed in this unit and the function of each ______

Introns are spliced out, 5' cap and 3' poly A tail are added...........

What is TRUE about the genetic code.

It is non-overlapping It is continuous It is degenerate It is universal

DNA hybridization is a quick test for certain pathogens. A DNA hybridization can detect the presence of DNA when you are unsure if specific bacteria is present. What would happen if you were to use DNA hybridization in a clinical setting, where often what makes the patient sick is a toxin by-product of the bacteria, not necessarily the presence of the bacteria itself?

It would not detect anything; it would need to have the DNA present.

Describe how the lac operon allows the bacteria cells to switch on proteins that will allow the bacteria to utilize lactose. Be sure to label the major components of the lac operon in diagram.

Lac Operon regulates metabolism of Lactose. Structure of Lac Operon: -Operator and Promoter -lacZ- encodes Beta-galactosidase enzyme. Converts disaccharide lactose into glucose & galactose -lacY-specifies the primary structure of permease- this enzyme facilitates entry into bacterial cells -lacA- encodes transacetylase- enzyme that may be involved in removal toxic by-products of lactose digestion. lac operon whose gene products degrade lactose for use as a carbon and energy source. When lactose is provided in media, a form of lactose (called allolactose) binds to the Lac repressor protein (called LacI or LacR), causing the repressor to release from the lac operon. The lac operon, now free to be transcribed, will produce the enzymes needed to degrade lactose. The process is still called induction, even though a repressor protein is involved.

Viral genome enters this inactive stage once the phage genome is integrated. _______

Latency

What enzyme must be used to "glue" the target gene into a cloning vector?

Ligase- used to reform sugar phosphate backbones

HHV 1

Lytic infection and Latent infection latent- epithelial tissue and nervous tissue usually associate with infections of lips, mouth, and face -oral herpes (cold sore) Most common herpes Transmission: nasal/oral secretions HSV1- adulthood 90% will have antibodies against-exposed Treatment: acyclovir, other antivirals

Rotavirus

Most common cause of severe diarrhea among infants and young children. Endemic Virus Transmitted: fecal-oral material complication: dehydration and hypovolemic shock GROUP 3

Short Answer: Explain how mutations are the driving force of evolution.

Mutations are subjective to selective pressure. Mutations are the driving force of evolution as it drives changes in organisms overtime. Mutations might make an organism more fit or less fit in an environment (such an a evolutionary advantage of color/etc), and therefore the individuals that are more fit or less fit in the environment will be more or less likely to be present in the future population. Mutations are an inheritable change in the genetic material. They consist of a change in the nucleotide sequence. They are not good or bad but different. Mutations are the driving force of evolution as they contribute to the success of the individual or population. Mutations make organisms more or less fit for an environment but if the mutation leads to a selective advantage, then that may result in an evolutionary change driven by biological diversity.

Identify the components of a nucleotide and what is it?

Nucleotide= repeating structural unit of both DNA and RNA. Composed of: 1. Phosphate Molecule- that's attached to the 5' Carbon & a 5-Carbon Sugar 2. Pentose: 5 Carbon Sugars (In DNA: deoxyribose; In RNA: Ribose) 3. Nitrogenous Base: DNA: AGCT; RNA: AGCU

Define oncogene and transformed cell.

Oncogene: a gene that has the potential to cause cancer. In tumor cells, they are often mutated or expressed at high levels. Transformed cell: Cells that acquire properties that are distant from the properties of unaffected cells or from infected cells that do not form tumors.

The site where replication of DNA begins is called_________

Origin of replication (OriC)

Influenza Virus

Orthomyxoviruses. Enveloped, ssRNA, w/ segmented genome. Contain hemagglutinin (promotes viral entry) and neuraminidase (promotes progeny virion release). Responsible for worldwide influenza epidemics; pt at risk for fatal bacterial superinfeciton. Rapid genetic changes. Influenza A B and C Transmission: URT secretions/droplets Annual Vaccine GROUP 5

Describe the basic events of PCR

PCR= Polymerase Chain Reaction; PCR rapidly produces copies of DNA in-vitro, and can replicate target DNA from a few copies to billions in a few hours. It is so sensitive, it could detect cancer from a single cell. WHAT'S NEEDED: -template, primers, nucleotides, DNA taq polymerase STEPS: 1. Denaturation: heat to 95C to separate strands, cool between 50-65C. 2. Priming (15-20 Nucleotides long): Annealing- prepares the 2 strands for synthesis 3. Extension: At 72C Taq creates new strands of DNA complementary to template, extends from primer. Amplified DNA can be analyzed, inserted into cloning vectors, etc.

HEP B

Pararetrovirus; Transmission: blood/bodily fluids Clinical signs: liver damage, jaundice, chronic infection Can cause cancer- oncogenic Group 7

Erythrovirus

Parvoviridae- ONLY know Parvo virus to infect humans causes "Fifth Disease" Looks on like pink rash on cheek/face- "slapped cheek" his virus can also cross the placenta leading to damage of blood forming cells of the fetus GROUP 2

Select the statement that accurately describes this figure:

Phage T4 genome will be injected into the bacterium, leaving an empty capsid outside.

F Factor

Plasmid containing a gene for a conjugation pilus. Those with plasmid are F+ Those without plasmid F- The F factor is a conjugated episome=carries genes enabling the transfer of DNA from F+ cell to a F- cell. Episome= circular piece of DNA that can exist as a extrachromosomal element that may integrate host chromosome.

Definition and structure of a prion

Prions are even more unique than viruses or viroids. It is an infectious disease particle. -Cellular PrP Proteins are made by all mammals and they are the product of the prion protein gene found on chromosome 20. -On a normal prion protein-it is composed mainly of alpha helixes. -However, mutant or diseased prions protein results when these alpha helixes are changed into beta pleated sheets. = So interaction with these mutant proteins leads -> causes change in their configuration -> which eventually leads to the death of the neuron. example: "Spongiform Encephalopathy"- tissues with holes in it

Transformation

Process by which bacterium will take up extracellular DNA (could either be DNA released from dead bacterium in natural environment or in a lab experiment and induce transformation). Discovered by Fredrick Griffith 1928 Two Types of Transformation: 1. Natural Transformation: DNA uptake occurs without any help from outside 2. Artificial Transformation: what occurs in lab

Which of the following is currently an important medical application of recombinant DNA technology?

Production of medically useful proteins in microbes; Therapeutic proteins such as insulin are often a result of recombinant technology. The text describes the production of viral proteins in yeast for vaccines. Ribotyping and DNA hybridization do not rely on recombinant DNA technology.

A genetic locus that serves as a recognition site for RNA polymerase attachment. __________

Promoter

Pyrimidines vs Purines

Pyrimidines: Thymine and Cytosine Purines: Adenine and Guanine

Rubeola Virus

Red Measles; paramyxoviridae family HIGHLY contagious Humans are only natural host *Koplik Spots Complication: secondary infections, pneumonia, etc Vaccine: MMR GROUP 5

Ligase

Reforms phospodiester bond between sugar and phosphate after primers are removed and replaced

DNA polymerase III

Responsible for adding bases to the new DNA chain and proofreading the newly laid down bases in bacteria

DNA polymerase I (exonuclease)

Responsible for removing RNA primers, adding DNA nucleotides, and repairing mismatched bases

Topoisomerase

Responsible for supercoiling and untangling of DNA

Explain the role of restriction endonucleases in the process of genetic engineering

Restriction Endonucleases: enzymes that cut the DNA at specific sequences (Blunt or Sticky ends)= result in Restriction Fragment. Sticky ends- accept complimentary tails for gene splicing and can be used to join DNA from different organisms by cutting it with same restriction enzymes- ensuring all fragments have complementary ends. -Recognizes and cuts at recognition sites- Palindromes(sequence read the same front to back: RACECAR) -After DNA is cut from donor, it can be pasted into receipt DNA using ligase (used to reform the sugar phosphate backbones)

The enzyme that is used to cut DNA into smaller pieces is called a _______

Restriction endonuclease

HIV

Retrovirus- replicates only in humans Ultimately destroys the human immune system 1. Begins with acute infection, rapid multiplication 2. Asymptomatic Latent Phase- T cell count decreases and lead to opportunistic infections 3. Chronic Symptomatic Phase- T cell count continually decrease, which results in many illness and cancers 4. AIDS- immune system us no longer able to defend against virus, eventually death There is no cure. Group 6

Group VI viruses

Reverse transcribing viruses they have ssRNA genome and is reversed transcribed into dsDNA -HIV-1

HHV8

Rhadinovirus Direct Contact Kaposi's Sarcoma- skin cancer lesions common in AIDS patients in latent stages of disease.

HHV 7

Roseolovirus; Transmitted: direct contact Usually populates same cells as HHV 6

HHV 6

Roseolovirus; Transmitted: direct contact characterized by pink rash on face, neck, trunk, thighs may make individuals more susceptible to AIDS

Rubivirus

Rubella (German measles)- Togaviridae -Exabthema (skin rash), some call it "3 day measles" Complications: arthritis, congenital rubella syndrome Vaccine: MMR More severe In adults GROUP 4

The method of DNA replication in which each strand of DNA serves as a template for each newly synthesized strand and becomes part of the new molecules. ________________

Semiconservative

Okazaki fragments

Small fragments of DNA produced on the lagging strand during DNA replication, joined later by DNA ligase to form a complete strand.

Primase

Synthesizes the RNA primer

True or False: The R group determines how the amino acid chain will fold to form a 3-D protein.

TRUE

The heat stable polymerase used in PCR that is derived from thermophilic bacteria is called __________

Taq polymerase

These molecules protect the genetic material at the ends of linear chromosomes: _______

Telomeres

Identify two viruses that are teratogenic and two viruses that are oncogenic:

Teratogenic Viruses: anything that induces congenital defect 1. Parvovirus 2. HHV 1 & 2 Oncogenic Viruses: 1. HPV 2. HEP B & C

The bacterial genome is very similar to the eukaryotic genome in that it contains the four basic types of bases [adenine (A), thymine (T), cytosine (C), and guanine (G)] and the order of the base pairs determines the order of the amino acids that form proteins. Using the illustration of a bacterial chromosome, what do you think is the most likely overall morphology of the bacterial chromosome?

The bacterial chromosome shown is circular and unsegmented.

Short Answer: Explain the patterns seen in the HIV titer and T-cell counts in this figure.

The increase in the initial HIV titer infection is fought off by the immune system, while the T-cell count decreases and then rebounds. As time goes on (years +) the HIV titer remains low as the T-cell count continuously declines. The decline of T-cell allows for opportunistic diseases to follow and eventually death.

What is NOT a characteristic of Okazaki fragments?

They are checked for accuracy by DNA polymerase III.

Why are bacterial plasmids problematic for human health?

They can transfer across species. Plasmids are circular and can be manipulated in labs, but that is not problematic for human health. The problem is that plasmids may harbor antibiotic resistance genes that can pass from species to species, leading to the spread of antibiotic-resistant bacteria.

Operon Structure

Think of an assembly line: 1. Promoter (start button) 2. Operator (person in charge- decides if protein need to be produced or not) 3. Structural genes (blueprint for product-dictates the protein that will be made by assembly line)

What type of disease-causing protein is illustrated in this figure? Explain the disease process associated with this type of protein.

This figure represents a prion caused disease. A prion is an abnormal form of a normally occurring brain cell protein. The prion form of the protein acts by binding to normally folded proteins of the same class and altering their conformation of that to the prion. The misfolded protein then alter the conformation of other subunits (on other words recruits normally folded proteins and changes their conformation into abnormal), forming harmful aggregates and eventually killing the cell. In the brain, the prion-induced cell death leads to tissue deterioration and dementia.

What processes increase the genetic diversity of bacteria?

Transduction Conjugation Transformation

Transduction

Transfer of DNA from one bacterium to another via bacteria phage (bacteria phage is a virus specifically infects bacterial cells). When a bacteria phage infects a cell, it can cause host DNA to become fragmented and then pieces can then be packaged within bacteria phage capsids. Bacteria phages can used to transfer DNA to cells via: 1. Specialized Transduction: only a particular genes transferred (at specific site). 2. Generalized Transduction: allows transfer of any bacterial DNA (more random).

The process whereby the primary protein structure is synthesized from an mRNA template ___________

Translation

T/F: If a bacterium is in the presence of both glucose & lactose, it will utilize the glucose first.

True

T/F: Monocistronic & polycistronic refer to the number of proteins that can be encoded.

True

T/F: Plasmids can replicate independently from the cell.

True

True or False: A repressible operon is associated with an anabolic pathway.

True

True or False: The # of chromosomes an organism has doesn't correlate with genetic complexity.

True

True or False: Wobble permits some variation or mutation in the codon w/o altering the message.

True

Lytic and Lysogenic Cycles of Temperate Phages

Virulent phages exhibit lytic cycle only Temperate phages have two reproductive options: 1. Lytic Cycle 2. Lysogenic Cycle- Prophage What is the difference between the lytic and lysogenic cycle? The lytic cycle involves the reproduction of viruses using a host cell to manufacture more viruses; the viruses then burst out of the cell. The lysogenic cycle involves the incorporation of the viral genome into the host cell genome, infecting it from within.

Differentiate a virus from a bacterium and eukaryotic organisms.

Virus= acellular, non-living infectious particles. 1. Metabolically inactive 2. Obligate intracellular parasite 3. Genome= DNA or RNA- all living cells have a genome composed of DNA, but viruses can be DNA or RNA and additionally may be double or single stranded. *A virus can never have both DNA and RNA* 4. Viral genome may be segmented, may be circular and it is enclosed in a protein coat. 5. Genome much smaller than cell's genome 6. Viral genome may encode only 3-4 proteins that are needed to make the viral components 7. TROPISM- viruses are very specific to type of cells they can infect

Describe how viruses are cultured in the lab.

Viruses are difficult to grow- primarily because they need a host for growth (*viruses are obligate intracellular parasites and cannot replicate on their own*)- MUST be grown in a live host. -additionally when injected in a host cell-they generally kill it. Bacteria and archaea viruses are cultivated in bacteria broth or suitable cultures. (Plaques0 clear ones where bacteria have been killed/lysed). Animal viruses may be grown in living animals, tissue culture or in embryonate eggs (chicken/turkey). Viruses are specific- tropism The availability of tissue culture has greatly simplified growth of animal viruses

Leading Strand & Lagging Strand

Within each fork, one DNA strand, called the leading strand, is replicated continuously in the same direction as the moving fork, while the other (lagging) strand is replicated in the opposite direction in the form of short Okazaki fragments. Both leading and lagging strands are extended by a DNA polymerase

What is found at the 5 end of a DNA strand?

a phosphate group

Select ALL of these that are applications of PCR: a. Selectively amplify segments of DNA b. Diagnose infectious disease c.Diagnose inherited diseases d. Monitoring gene expression e. Determine the nucleotide sequence of a gene f. Forensic analysis

a. Selectively amplify segments of DNA b. Diagnose infectious disease c. Diagnose inherited diseases f. Forensic analysis

What is TRUE of bacterial plasmids?

a. They are small circular DNA molecules that can replicate autonomously. b. They may have genes that infer antibiotic resistance. c. They may recombine with the chromosome forming an HFR cell.

What is important to the mechanism by which an internalized influenza virus escapes its envelope?

acidic pH in the lysosome; The low pH of the lysosome facilitates rupture of the influenza envelope. The influenza viral envelope must rupture to release the viral genetic material, and neutral and basic pH will not provide this opportunity. Protons must be able to rush into the viral envelope, and that will only occur in the acidic nature of the lysosome

What would you expect to result in an influenza pandemic?

antigenic shift within a type A influenza virus

HHV 2

associated with genital herpes transmitted sexually treatment: acyclovir

If the hemagglutinin spike were removed from the influenza viral envelope, then the virus would be unable to ...

bind to its surface receptor. Hemagglutinin, a substance that causes red blood cells to stick together to form a mass, is important for binding the influenza virus to its cell surface receptor.

In the bacteriophage life cycle, what can the phage do?

both extract and deliver genes to/from bacterial cells; During the bacteriophage life cycle, the phage commonly extracts DNA from bacterial cells and delivers that DNA to other cells. This is called phage-mediated transduction of genetics. This happens during generalized transduction and specialized transduction. By both of these mechanisms, genes are moved from one cell to another by these types of horizontal gene transfer.

During DNA replication,

both leading and lagging daughter DNA strands are synthesized in the 5' to 3' direction. DNA polymerases can only add new nucleotides onto a free 3' OH, so DNA synthesis always occurs in a 5' to 3' direction (every newly made strand starts with a 5' triphosphate and ends with a 3' OH). Because DNA is antiparallel at each replication fork, there is both a leading and a lagging strand

Which of the following is part of ONLY the lysogenic cycle? a) cell synthesizes phage capsid proteins b) cell replicates phage DNA c) phage DNA integrates into the host genome to form a prophage d) phage lyses the cell

c) phage DNA integrates into the host genome to form a prophage

Which enzyme cuts DNA? a) ligase b) gyrase c) restriction endonuclease d) helicase

c) restriction endonuclease

Mutations always ...

cause a change to an organism's genotype; By definition, a mutation is a change to an organism's DNA sequence—the genotype. The change in genotype may or may not lead to a change in phenotype. Likewise, the mutation may be harmful, helpful, or have no effect at all on the organism

In prokaryotes, transcription occurs in the ________ and translation takes place in the ________.

cytoplasm, cytoplasm

Diseases by Prions

diseases may be transmissible or inherited forms of neurodegenerative diseases. -horizontal transmission- directly or by fomites or by ingestion of contaminated meat. -Difficult to inactivate -Prion diseases are almost always fatal & there is no effective treatment -Prions can only be destroyed by incineration or autoclaving within one normal sodium hydroxide. Diseases: -Creutzfeldt-Jakob disease -Kuru (eating brains of ancestors) -Gerstmann-Straussler Syndrome -Scrapie (goats) -Bovine Spongiform encephalopathy (Mad Cow)

Group I Viruses

dsDNA Viruses -largest group of known viruses -most bacteria phages have dsDNA -Poxviruses, Papoviruses, Adenoviruses -Herpeviruses

Group III viruses

dsRNA viruses -Rotavirus

Semiconservative DNA replication means that ...

each daughter DNA molecule is composed of one original strand and one new strand. DNA synthesis is semiconservative, meaning that newly replicated DNA contains one old strand (the parental strand) and one newly synthesized strand (the daughter strand). Thus, only half of the original DNA strand is present in each new DNA duplex—semiconservative

nucleotide triphosphate

each nucleotide that is added to a growing DNA strand

The ability of the influenza genome to undergo _______ makes it capable of evolving novel strains that cause global pandemics.

gene reassortment (antigenic shift)

Plasmids are circular, extrachromosomal, DNA that some bacteria possess. Plasmids may enter or leave a bacterial cell without changing the bacterial species. According to the table shown, not all bacteria have plasmids, but those that do are subject to what?

genes for advantageous virulence factors, such as antibacterial resistance

Constitutive Gene

genes that are expressed all the time; house keeping genes

Prokaryotic cells are ________

haploid

Hydrogen bonds-

hold strands together of DNA= complementary base pairing

HPV

human papillomavirus- dsDNA with more than 100 strains. Transmitted via direct contract (usually sexual) Infect epithelium and mucous membranes Treatment: Prevention- Gardasil, condoms Most common STD today

Recombinant human insulin is safely produced in bacteria. What is the correct sequence of steps needed to produce such a transgenic bacterium?

hybridize insulin cDNA and plasmid, ligate, transform bacteria

When bacterial DNA is replicated, the newly replicating polynucleotide will always have a 3' ______ group and a 5' ______ group.

hydroxyl; triphosphate

There are two possible infection pathways in a Varicella-Zoster Virus (VZV) infection. In the ________ infection, the virus expresses genes that allow it to produce more viruses. This ultimately kills the cell. In the ________ infection pathway, the virus expresses genes that allow the DNA circle to persist within the cell for decades.

lytic; latent

a) Determine the mRNA sequence encoded by the DNA b) Determine the amino acid sequence of a protein encoded by the DNA 5' C C G A A T T C A A T G G T G C G C G G T G A G T C C T T A G C T C A A C 3 '3' G G C T T A A GT T A C C A C G C G C C A C T C A G G A A T C G A G T T G 5'

mRNA - 5' C C G A A U | U C A | A U G | G U G | C G C | G G U | G A G | U C C | U U A | G C U | C A A | C 3' (Coding region highlighted in yellow) Amino acid sequence - NH3 - Met - Val - Arg - Gly - Glu - Ser - Leu - Ala - Gln - ... C terminus

Koplik spots are a diagnostic indicator of

measles

DNA replication begins at a chromosomal region called the ...

origin

Poliovirus

poliomyelitis non-enveloped, + sense ssRNA virus transmitted: fecal-oral route or direct contact Most are asymptomatic/ mild illness Prevention:: Immunization Almost has been eradicated GROUP 4

What are involved in translation?

rRNA tRNA mRNA

BOTH eukaryotic and prokaryotic DNA replication is...

semi-conservative

The purpose of gel electrophoresis is to ...

separate DNA fragments on the basis of charge and size; Gel electrophoresis separates DNA fragments on the basis of charge and size. The DNA is loaded onto a gel, and an electric current is passed through. DNA migrates toward the positive pole, with shorter fragments moving faster.

Which of the following is involved in the initial phase of HIV interaction with the surface of a T cell?

spike protein;

Group II Viruses

ssDNA Viruses -Parvoviridae -Erythrovirus

The molecule that brings amino acids to the growing polypeptide chain in translation is _______________

tRNA

phosphodiester bond

the phosphodiester bond is the linkage between the 3' carbon atom of one sugar molecule and the 5' carbon atom of another, deoxyribose in DNA and ribose in RNA. Creates sugar-phosphate backbone

bidirectional replication

the process in which DNA replication proceeds outward from the origin in opposite directions

Vaccination for rubella is recommended because ...

there is a high incidence of congenital infections.

The structure of DNA explains both its ability _____ and the way in which it is copied during cell reproduction.

to encode genetic information

The natural role of restriction enzymes in bacteria is ...

to protect the cell from invading phages

The energy required for DNA replication comes from ...

triphosphate deoxyribonucleotides

HHV 3

varicella zoster virus -chicken pox and shingles -shingles is reactivated form of chicken pox Transmission: inhalation of droplets or contact usually mild in children/ more severe in adults Vaccines

A 65-year-old patient presents with a localized painful dermatomal rash traveling along the sensory nerve from his shoulder to his chest. What is the cause of this rash?

varicella-zoster; Shingles is caused by the reactivation of the chickenpox virus, varicella-zoster. Varicella-zoster-specific cell-mediated immunity decreases as the person gets older, which may explain why there is a progressive increase in the incidence of shingles with advancing age.

HPV initiates cancer development through increased expression of ...

viral oncogenes.

The process of DNA synthesis is divided into three phases:

• Initiation, which involves the unwinding of the helix, priming, and loading of the DNA polymerase enzyme complex • Elongation, the sequential extension of DNA by adding DNA nucleotide triphosphates (dNTPs) with release of pyrophosphate, followed by proofreading • Termination, in which the DNA helix is completely duplicated and replication stops