Chapter 3: From Genes to Proteins Flashcards
What are the base of nucleic acids?
purines and pyrimidines
What is the difference between RNA and DNA in their bases?
RNA contains uracil rather than thymine
Difference between nucleoside and nucleotide
nucleoside is made of sugar and base, and nucleotide is a nucleoside with one or more phosphate groups attached
How do nucleotides link?
connected via phosphodiester bonds
Describe which of the nucleotide bases held together
adenine and thymine form 2 H-bonds
guanine and cytosine form 3 H-bonds
Chargaff’s rule
the amount of A + G = C+ T
two methods for deducing high-resolution protein structures
- X-ray crystallography (dominant method)
2. Cyro-electron microscopy
X-ray cyrstallography
- x-rays scatter as they pass through crystallized protein
- resulting waves interfere with each other, creating a diffraction pattern from which the position of atoms is deduced
Cryo-electron microscopy
- beam of electrons is fired at a frozen protein solution
- the emerging scattered electrons pass through a lens to create a magnified image on the detector, and the structure can then be deduced
Can DNA be denatured and/or renatured?
it can be both denatured and renatured
List the three predominant forces stabilizing DNA
hydrophobicity, base stacking and entropy
Other forces that stabilizing DNA (excluding predominant forces)
hydrogen bonding and ionic interactions
Describe the renaturation process of DNA
DNA is heated at high heat and melts, and the strands separate. Then either option can occur (a) cooling to 20-25C below Tm can cause renaturation (i.e. DNA strands will reassemble), (b) rapid cooling to temperature much lower than Tm will result in improper base pairing, however next the rewarming to 20-25C below Tm can lead to renaturation (i.e. DNA strands will reassemble)
What are genes?
sequences of DNA
What does replication?
copying DNA
What does transcription?
converting DNA into RNA
What does reverse transcription?
converting RNA into DNA
What does translation?
making proteins from an RNA template
Is DNA replication natural in vivo?
- yes, DNA must be copied in order to sustain life but excessive DNA replication can be indicative of cancer
What technology replicates DNA in vitro?
technology such as the Polymerase chain reaction (PCR)
Is the RNA transcript complementary to the coding template strand or the noncoding template strand?
noncoding template strand
three types of RNA
mRNA, tRNA, and rRNA
mRNA
encodes for polypeptide sequences
tRNA
carries amino acids to ribosome
rRNA
aids in polypeptide synthesis
Two ways in which genes are identified
- Scan for open reading frame (start and stop)
2. Comparison with known genes
Gene number is often correlated with ___________.
organismal complexity
What parts of a DNA do restriction enzymes normally cut?
palindromic, double stranded DNA, sticky ends, blunt ends, restriction digest, and restriction fragments
What is the role of restriction enzymes?
aid in defense for bacteria
Which restriction enzyme is used to selectively cut DNA?
type II
characteristics of type II restriction enzymes
- cleave 4-8 bp segment of dsDNA
- palindromic recognition sequences
- they form blunt or sticky ends
