Unit 3 - Exam Review

Question 1

4.1 7 Historical figures in the discovery of DNA + discoveries

Answer 1

Frederich - puss, nuclein
Hammerling - algae cap, nuclein location
Griffith - mice, DNA transforming principle
Hershey/Chase - bacteriophage, DNA contains info not protein
Chargaff - nucleotides, A=T C=G
Rosalind/Wilkins - xray, DNA double helix
Watson/Crick - stole info to create 3D model

Question 2

4.2 DNA vs RNA

Answer 2

DNA - double helix, CGAT, deoxyribose
RNA - single stranded, CGAU, ribose

Question 3

4.3 Conservative vs. Semi-Conservative replication

Answer 3

Conservative - One daughter molecule is unchanged, parent strands recombine

Semi-Conservative - Each daughter cell is half parent and half new dna

Question 4

4.3 3 Steps of DNA replication

Answer 4

Initiation, elongation, termination

Question 5

4.3 What happens during DNA initiation + 3 enzymes

Answer 5

HELIICASE seperates 2 strands of double helix, creating a replication fork.

SSBs prevent parent DNA from reannealing

GYRASE untwist strands and relieve tension

PRIMASE adds RNA primers

Question 6

4.3 What happens during DNA elongation + 3 enzymes

Answer 6

DNA POLYMERASE III brings nucleotides into the replication fork from 3’-5’ starting at primers

DNA POLYMERASE I replaces RNA primers with correct nucleotides

DNA LIGASE joins Okazaki fragments by phosphodiester bonds

Question 7

4.3 What happens during DNA termination

Answer 7

Daughter DNA rewind. DNA POLYMERASE III and I exonuclease (proof read) new strands and splice out any mistakes and replace the correct nucleotide.

Question 8

5.2 What happens during transcription and translation

Answer 8

Transcription - RNA POLYMERASE synthesizes mRNA by copying DNA, similar to DNA replication. mRNA leaves the nucleus.

Translation - mRNA clamps between the small subunit and large subunit of the ribosome, starting in the P site. Strand shifts left and tRNAs are added until a stop codon is reached. EPA site order

Question 9

5.5 Types of mutation

Answer 9

Point (silent, nonsense, missense)
Frameshift (substitution, deletion)
Chromosomal (Abnormal Structure - Deletion, Inversion, Duplication, Translocation)(Abnormal Number - Nondisjunction, Polyploids)

Question 10

5.7 Prokaryotes vs Eukaryotes
Genome
Transcription
Translation

Answer 10

Prokaryotes - Small and circular, all coding but promoters&operators, operons (genome), with translation, no excision (transcription), formylmethoinine, ShineDalgama binding site, small ribosomes (translation)

Eukaryotes - large chromosomes, coding and non coding, no operons (genome), in nucleus, splicing (transcription), methionine, 5’ cap binding site, cytoplasm, big ribosomes (translation)

Question 11

5.8 Gene organization smallest to biggest

Answer 11

200 nucleotides + 8 histones -> nucleosomes -> chromatin -> chromosomes

Question 12

6.1 Explain - Plasmids, restriction enzymes, vectors

Answer 12

Plasmid: circular pieces of bacteria DNA
Restriction Enzyme: protects against phages
Vectors: used to transport foreign DNA, usually plasmids

Question 13

6.1 Explain - Gel electrophoresis, cloning

Answer 13

Gel electrophoresis: bacteria is shocked in a gel to loosen up cell wall allowing a vector to enter
Cloning: desired gene added to DNA vector, then added to bacteria, transformed bacteria is isolated and cultured

Question 14

6.3 Explain – polymerase chain reaction, Sanger dideoxy method, CRISPR method + examples

Answer 14

PCR - Used to make copies of a gene with a small amount of DNA, fingerprinting

SDM - determine base pairs that makeup genes, human genome project

CRISPR - molecular scissors (Cas9) cut DNA to add or remove sections, treat diseases

Question 15

6.4 Name 2 medical uses, agricultural uses, and forensic uses of cloning/DNA replication

Answer 15

Medical: gene therapy, gene screening
Agricultural: Bt toxin herbicide, Ti plasmid
Forsenic: fingerprinting, PCR investigations