Name:________________________________________ Biol 2420 Fa15 Exam 3 Study Guide

This guide is not guaranteed to include everything that will be on the exam. Please review your class notes, class slides, homework assignments, and supplement with the class text as needed. I also recommend that you read the article “The Challenge of Antibiotic Resistance” by S. Levy if you need further clarification on antibiotic resistance.

1.) What are the substrates required for each of the following processes?

Transcription – DNA

Translation – mRNA

2.) What are the enzymes required for each of the following processes?

Transcription –RNA polymerase

Translation- tRNA and ribosomes

3.) What are the products of each of the following processes?

Transcription- mRNA

Translation- proteins

4.)a.) Which region on DNA is required to initiate transcription? promoter

b.) Which enzyme binds to this region of DNA? RNA polymerase

c.) How are the strands of DNA separated for transcription to occur? RNA polymerase

d.) How many DNA strands are used as the template for transcription of a single gene? 1

e.) Does RNA exist in double-stranded or single-stranded form? Single-stranded

5. a.) Where does prokaryotic transcription occur?
Cytoplasm
b.) Where does eukaryotic transcription occur? nucleus 6.)a.) There are three types of RNA molecules. What are they?
Messenger, transfer, and ribosomal
b.) Which one of the three types of RNA molecules is translated? messenger 7.)a.) What are ribosomes composed of?
Proteins and trna
b.) Where does eukaryotic and prokaryotic translation occur? cytoplasm 8.)a.) Diagram a tRNA molecule and label the anticodon region and the amino acid attachment site. pairing of an anticodon on tRNA with a codon on mRNA.

b.) Diagram pairing of an anticodon on tRNA with a codon on mRNA.

c.) Which codons initiate and terminate translation? Aug is start and stop

d.) Describe the following types of mutations?

missense- change in a single base pair that changes amino acid

silent- change in a single base pair that does not change amino acid

nonsense- change in base pair that adds in early stop codon

frameshift- an insertion or deletion of 1 or 2 or more nucleotide bases

9.)a.) By what process do spontaneous point mutations arise? replication

b.) Why are spontaneous mutations rare in living organisms? Because DNA polymerase has proofreading capabilities

c.) Based on your knowledge of bacterial reproduction, if a parent cell has a mutation, does it’s progeny also have that mutation? yes

d.) This type of mutation transfer is referred to as ___________vertical gene________________________ transfer.

10.)a.) Differentiate between horizontal and vertical transfer of mutations in bacteria.

Horizontal is when mutations occur between related or unrelated species through transformation, transduction, conjugation, or transposition. Vertical gene transfer occurs between parent and progeny.

b.) Describe/define plasmid DNA. Can plasmid DNA be horizontally transferred?

Plasmid DNA is an extra chromosomal genetic material that can be horizontally transferred through conjugation or more specifically, rolling circle replication.

11.) Name and describe three mechanisms of horizontal gene transfer. Be sure to include whether cells, DNA in the environment or bacteriophages are required.

mechanism - definition

a. transformation- free floating genetic material is brought into the cell by endocytosis and recombined homologously into the DNA

b. transposition- transposons (or jumping genes) are used to insert DNA into recipient cell DNA

c. transduction- bacteriophages will attack the recipient cell and use either the lytic cycle to create more phages or lysogeny to insert themselves into the DNA of the cell

12.) Which cells do bacteriophages infect? bacterial

13.a.) List three characteristics of antibiotics.
Small, organic compounds that inhibit growth of microorganisms

b.) What type of microbe do antibiotics target?

Bacteria cells

14.) What are the various modes of action of antibiotics?

a. peptidoglycan synthesis

b.folate pathway synthesis

c. replication and transcription

d. cell membrane and protein synthesis

15.) How do antibiotic resistant strains of bacteria arise? What two things are required for a primarily antibiotic sensitive population to become an antibiotic resistant population? Explain.

Mutations and selective pressure

16.) Antibiotic resistance genes allow bacterial cells to resist antibiotics. How? What are the cellular mechanisms that bacteria use to resist antibiotics?

a. target alteration

b. degradation of antibiotic

c. efflux pumps

d. alteration of antibiotic

e. altering of cell membrane permeability

17.)a.) What is the function of the enzyme beta-lactamase?
To cleave beta lactam drugs in the cell wall
b.) What is the function of the enzyme chloramphenicol acetyltransferase (encoded by the cat gene)?

To cleave chloramphenicol and it affects protein synthesis
19.) Diagram and label a naked animal virus and an enveloped animal virus.

20.) What are the steps of a general viral lifecycle? List them in order.

a. enter cell

b. create genomic material

c. create protein

d. assemble virus into proper tertiary structure

e. exit cell

21.) A virus requires a host cell to reproduce. Why? What does the host cell provide to the virus that the virus does not have?

It provides ribosomes and energy

22.) There are so many viruses and they are all different. How do they vary? Give six characteristics of viruses that are variable.
Size, shape, mode of transmission, naked, enveloped, and type of genomic material

23.a.) Which structures on a virus mediate attachment to host cells? Spike proteins

b.) Do these structures bind to specific receptors or to any receptor? Bind to specific

24.) Enveloped viruses can enter a host cell by two mechanisms. What are they?
Membrane fusion and endocytosis

24.)a.) What is the genome of HIV composed of?

b.) Which enzymes are required for the lifecycle of HIV? Name them and state their function and/or the chemical reactions that they perform. enzyme - function/chemical reaction

c.) Which cells are targeted by HIV? immune d.) Which enzymes/proteins/processes in the HIV lifecycle do anti-HIV medications target?
Reverse transcriptase and protease

e.) Differentiate between a person that is HIV+ and a person that has AIDS.

25.)a.) What is the genome of influenza composed of? 8 rna strands

b.) Which enzyme is required for replication of the influenza genome?

c.) What are the substrate and the product of this enzyme? Write out the reaction with the substrate on the left, the enzyme on the right and the enzyme over the arrow.

26.) Do viral replication enzymes typically have proofreading ability? No
27.) Differentiate between antigenic shift and antigenic drift among influenza viruses.

28.) Differentiate between acute, latent and chronic viral infections with respect to duration, presence of the virus and replication of the virus and provide an example virus type of infection duration viral presence viral replication example virus latent Several months or years Low numbers After latent period HIV chronic Long-lasting and permanent High Constantly acute Several days High Until it runs its course cold

29.) What are the possible fates of the cells that animal viruses infect?
Lysing

30.) Complete the following table to compare viruses and bacteria. bacteria viruses

size ability to grow without a host sensitivity to antibiotics ability to generate energy presence of nucleotides
& enzymes for trancription presence of amino acids and ribosomes for translation type/composition of genome presence of unique replication
enzymes