Lecture 9: Nucleic Acids Flashcards
What stores the genetic information?
What mediates the expression of genetic information?
DNA
RNA
______________ sugar molecule + nitrogenous base
Nucleoside
What type of sugar is in DNA vs RNA
DNA: deoxyribose
RNA: ribose
Which are purine vs pyrimidines
Purines: A, G
Pyrimidines: C, U, T
What are the 3 structural components of DNA and RNA
Phosphate backbone
Sugar
Nitrogenous Base
______________:
Formed between the OH group on C3 of one sugar and the C5 on the next one. This bond linked the nucleotides together forming the backbone of RNA and DNA polymers
3-5 phosphodiester bond
______________ formed between the nitrogenous bases and C1 of sugar
N glycosidic bonds
In terns of DNA and RNA what groups are on the 5’ and 3’ end
5’: phosphate group
3’: hydroxyl group
What is the backbone of DNA _____________
How are bases bound to one another?
2 deoxyribose phosphate backbone
N bases bound to one another by hydrogen bonds
What are the types of double helix
-Right handed (A and B form)
-Left handed (Z form)
What is Chargaff’s rule for double stranded DNA molecules
t-a and c-g
%A=%T, %G=%C
How do you remove RNA from a DNA solution?
add an alkaline solution
How can you separate nucleotides?
heating the DNA solution
GC have a higher melting point then AT as a result of an addition hydrogen bond
In terms of chromatin:
Which one is active? and Which one in inactive?
Euchromatin: related, transcriptionally active
Heterochromaton: highly condensed inaccessible for transcription
When are chromosomes visible
only during metaphase
All cells within an organism have the same DNA but different ______________ which determines tissue specific function
chromatin structure
Modification:
_________________ of the DNA
_________________ of the Histones
Methylation
Acetylation
What are some characteristics of mitochondrial DNA
✓ Circular, double-stranded
✓ Contains ~17kb
✓ Encodes its own proteins
✓ Contains very few untranslated
sequences
✓ Genetic code differs slightly from the
standard code
✓ High mutation rate
✓ Used to provide evidence for the
evolutionary origins of species
What are some characteristics of RNA structure?
✓ Single-stranded linear molecule
✓ 5’→3’ direction
✓ Uracil instead of Thymine
✓ Can fold back on themselves forming
intramolecular double-stranded
regions known as hairpins
What is the function of mRNA
carries genetic information from DNA to the DNA to the Ribosomes for use in protein synthesis
What is the function of tRNA
Present amino acids AA to the ribosomes for synthesis of the polypeptide chain
What is the function of rRNA
together with the ribosomal proteins form the ribosomal subunits
mRNA is the most diverse group in length and base sequence. What are 3 common modifications of mRNA?
-5’ Cap and 3’ poly A Tail
-Splicing of introns
-5’ and 3’ UTRs
What type of RNA has a high percentage of unusual bases
tRNA
What are some facts about rRNA
-80% of all RNAs
-Four different sizes in eukaryotic cells.
-Produced from larger precursors in the
nucleolus and modified subsequently:
What is the function of nuclease?
participate in the processing of rRNA, tRNA, and mRNA
What is the function of peptide transferase?
part of the large ribosomal subunit catalyze the condensation of amino acids to form polypeptides
What is the function of a ribozyme?
catalytic activity
What are some non coding RNAs
Small nuclear RNA they participate in the formation of spliceosomes, mediate splicing and removal of introns, transposons silencing, directing chromatin, modifications
___________ participate in the formation of spliceosomes and mediate splicing and removal of introns
snRNA’s
______________ participate in the processing of rRNA guiding chemical modifications of nucleotides
snoRNAs
__________ transposon silencing, directing chromatin modifications (role in epigenetic)
piRNA’s
