Ap Biology

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AP ESSAY ANSWERS: 16-20
1. Information transfer is fundamental to all living organisms. For TWO of the following examples, explain in detail, how the transfer of information is accomplished. A) The genetic material in one eukaryotic cell is copied and distributed to two identical daughter cells. B) A gene in a eukaryotic cell is transcribed and translated to produce a protein. C) The genetic material from one bacterial cell enters another via transformation, transduction or conjugation. 16 total pts possible

A) max 8 pts combined (4 pts max each part – Part a is looking for “copy and distribute”)
“copy”= DNA replication
-when DNA is copied- interphase, S phase of cell cycle
-recognition of origin site on DNA
-concept of unwinding enzyme (helicase)
-RNA primer (RNA primase)
-DNA polymerase- adds complementary nucleotides to DNA template strand
-concept of complementary relationship among bases-semiconservative antiparallel backbones
and 5’ -> 3’ generation of new segments
-DNA ligase- hooks Okazawki fragments together
-Other- telomere replication, proofing by DNA polymerase
“distribute”=Mitosis
-concept of chromatid pairs or doubled chromosomes
-prophase- condensation of chromosomes, spindle formation
-metaphase-alignment of chromosomes
-anaphase- separation of chromatids or equivalent statement
-telophase/cytokenesis- nuclear membrane reforms, division to two cells-cell plate or furrow,
-other- cell cycle control, cell surface area/volume ratio and mitosis B) max 8 pts combined (4 pts max each part- Part B is looking for transcription and translation
Transcription
-functional definition- DNA sequence to RNA sequence
-promoter recognition
-RNA polymerase- adds complementary RNA nucleotides to DNA template
-complementary relationships (T changes to U)
-5’-> 3’- growth of new strand
-start site/termination sequences
-introns/exons with general explanation
-caps/tails for mRNA processing
-other- transcription factors, spliceosomes, enhancers
Translation
-functional definition- mRNA base sequences to amino acids
inititation
-sequence of events- complex includes mRNA, small unit of ribosome, first tRNA
-structure of ribosomes- complete description- two subunits, 2 action sites, rRNA and proteins
Elongation
-tRNA structure- amino-acyl (A) site and anticodon
-complementary- codons to anticodons, mRNA base sequence to tRNA base sequence
-peptide formation- amino acids joined together by peptide bonds to form polypeptide Termination
-stop codon & release polypeptide +& release ribosomes
-other- triplet code, recognition segments, wobble (redundancy) *one point can be granted to either section of part b for describing the movement of RNA from the nucleus to the cytoplasm

C) max 8 pts- choose one only
Transformation
-functional definition- uptake of naked DNA from environment into bacteria
-competency- cell membrane permeable to fragments
-how to make competent- Calcium chloride, heat shock, cold stability, gene gun, electroporation
-parameters for individual DNA segments- size, double helix
-description of Griffiths/Avery expt- information transfer emphasis
-other- recognition of transfer thru gene technology, plasmid description, antibiotic resistance
(can get 2 pts for this)

Transduction
-functional definition- viral vector (bacteriophage) that goes from bacteria to bacteria, transfers bacterial DNA
(can get two points for this)
-lytic cycle-describe, makes many copies of virus fast, released (can get two points for this)
-lysogenic cycle- describe, incorporates viral DNA into bacterial DNA, replicates, reproduces
when induced, goes to lytic cycle (can get two points for this)
-excision
-other- prophage, oncogene, gene technology (can get two points for this)
Conjugation
-functional definition-...
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