BIOLYMPICS

Ch16.1

100

What are the two main characteristics of DNA structure? Is DNA charged?

Double helix and antiparallel. 

Yes, Negative

200

What is a nucleotide made of? What is the backbone called?

Phosphate group, deoxyribose (sugar), nitrogenous base. 

Sugar-phosphate backbone.

300

What nitrogenous bases are purines? Which are pyrimidines? What types of bond binds them? Who pairs with who? How many bonds are in each? 

Purines: G, A. Pyrimidines: T, C, U (RNA).

Hydrogen bonds. 

A=T (2 H bonds), C=G (3 H bonds)

400

What are the three models of DNA replication? Which one do we think is correct nowadays?

Conservative, semiconservative, dispersive

500

Difference between DNA and RNA

1. RNA has a ribose, while DNA has deoxyribose sugar

2. RNA single-stranded, DNA double-stranded 

3. RNA has Uracil, rather than Thymine in DNA

Ch16.2

100

Proteins used in the initiation of replications and their functions? 

Topoisomerase: Relieves overwinding strain ahead of replication forks. 

Helicase: Unwinds parental double helix at replication forks by breaking H bonds.

Single-Stranded Binding proteins: Binds to and stabilizes single-stranded DNA until it is used as a template

Primase: Synthesizes an RNA primer at 5′ ends of the leading strand and at 5′ ends of each Okazaki fragment of a lagging strand

200

What is the leading strand template direction and lagging strand direction

Leading Template: 5' --> 3'

Leading strand: 3' --> 5'

Lagging Template: 3' --> 5'

Lagging strand: 5' --> 3'

300

Remaining enzymes for actual replication and their functions? 

DNA Polymerase III: synthesizes new DNA strands by adding nucleotides to the RNA primer. 

DNA Polymerase I: Removes RNA nucleotides of primer from 5′ ends and replaces them with DNA nucleotides added to 3′ ends of the adjacent fragment

DNA Ligase: Joins Okazaki fragments of lagging strand; on the leading strand, joins 3′ end of DNA that replaces primer to rest of leading strand DNA

400

You have a drug that blocks the activity of Primase. How will this drug affect DNA replication? 

Synthesis of both complete lagging and leading strands will stop. 

500

Two types of mistakes repair of DNA replication

Mismatch repair: other enzymes remove and replace incorrectly paired nucleotides.

Nucleotide excision repair: a nuclease (DNA-cutting enzyme) removes and correctly replaces damaged segments of DNA. 

Ch17

100

What are the steps of gene expression for Eukaryotic cells? Where does each step take place? 

NUCLEUS Transcription: DNA --> pre-mRNA

NUCLEUS RNA processing pre-mRNA: --> mRNA

CYTOPLASM Translation: mRNA --> Protein

200

Things needed for transcription? In what direction is the RNA strand created? 

1. Promoter sequence (TATA Box) + Transcription factors + RNA Poly II = Transcription Initiation Complex                                        

DNA 3' --> 5' 

mRNA 5' --> 3'                   

300

Is the termination for transcription the same for Eukaryotes and Prokaryotes? 

NO 

For prokaryotes: terminator sequence stops RNA poly II

Eukaryotes: Polyadenylation signal.  Protein-bound to this poly-A-Tail cuts the mRNA from the polymerase. 

400

Three things to remember about RNA processing (What is added to both ends and what is actually changed)

Addition of a 5' cap (modified guanine) 

Poly-A-tail: 50-250 A sequence to 3' end

RNA splicing: RNA cut and paste

500

What are the binding sites of the ribosomes in translation? 

EPA sites

Ch18

100

What is an operon?

A unit of genetic function found in bacteria and phages. Consisting of a promoter, operator, and regulatory section of a gene. 

200

What are the repressor and the corepressor? 

repressor: inhibits gene transcription. Bind near the promoter.

Corepressor: binds to the repressor and changes its shape allowing it to bind to the operator. 

300

What is Euchromatin and Heterochromatin? 

Euchromatin: a less condensed form of chromatin; available to transcribe. 

Heterochromatin: chromatin is very condensed; NOT available to transcribe. 

Chromatin: complexes (nucleosomes) of DNA wrapped around histone proteins (positively charged proteins)

400

How can chemical modifications regulate gene expression?  

1. Histone acetylation: addition of acetyl group to histone tails (neutralize the positive charge of histones); promotes transcription by opening chromatin up. 

2. DNA Methylation: addition of methyl group on DNA bases (mostly C); promote or inhibit translation 

500

Inducible vs Repressivble

Inducible operons: off can be turned on. (i.e. lac operons (metabolism starts when allolactose is detected); catabolic (break down)

Repressive: on but can be turned off when the corepressor binds to the repressor; anabolic (building up)