DNA & Biotechnology Flashcards
What is the difference between nucleosides & nucleotides ?
Nucleosides: composed of pentose & nitrogenous base (covalently linked @ C1)
Nucleotide: amount of phosphate groups attached to nucleoside (attached @ C5)
What is the difference between ribose & deoxyribose?
Ribose has -OH @C2 while deoxyribose has -H @C2
What is the overall charge of DNA & RNA, & why ?
Negative due to phosphates
Which bases are classified as purines & pyrimidines and how do they differ ?
Purines: adenine, guanine (2 ring structures)—> both found in RNA & DNA
Pyrimidines: cytosine, uracil, thymine (1 ring structures)—-> C in both but U only in RNA & T only in DNA
What properties are needed for a molecule to be considered aromatic ?
- Planar
- Cyclic
- Conjugated
- 4n +2 pi electrons (Huckel’s rule)
How are nitrogenous bases paired via complementary base pairing ?
A-T (2 H+)
C-G (3H+)—> stronger due to more bonds
The idea that the total amount of purines will be equal to the total amount of pyrimidines based on complementary pairing is based on what ?
Chargaff’s rules
What is the difference between nucleosome and chromatin ?
Chromatin is a whole structure of complex DNA and proteins while nucleosome is a basic unit of chromatin
What is the difference between heterochromatin & euchromatin ?
Heterochromatin is a small part of chromatin that remains compact during interphase & often consists of DNA w/ highly repetitive sequences.
Euchromatin is dispersed and contains genetically active DNA
What does the replisome/replication complex function as ?
Assisting proteins to DNA polymerases
What is the enzyme responsible for unwinding DNA ?
Helicase
Proteins that hold single stranded DNA apart to prevent rekindling or degradation are known as ?
Single-stranded DNA-binding proteins
What enzyme works ahead of helicases to add negative supercoils to relieve the torsional strain that comes with the positive supercoiling effect due to DNA unwinding ?
DNA topoisomerases
The enzyme responsible for reading the DNA template in the 3’-5’ direction and synthesizing new DNA from it is known as ?
DNA polymerases
Primase consists of what type of sequences ?
RNA
What are the functions & differences between the DNA polymerases ?
B, E, & S: work together to synthesize new DNA on both the leading & lagging
S: fills in gap left after removal of RNA sequence/primer
Y: replicates mitochondrial DNA
B & E: essential for DNA repair
S & E: assisted by PCNA protein to strengthen interaction between polymerases and template strand
*RNase H: removes rna primer sequence
Prokaryotes:
III: synthesis of DNA
I: replaces RNA primer sequence with DNA sequence
Mutated genes that cause cancer are known as ?
Oncogenes (referred to as proto-oncogenes BEFORE mutated)
Tumor suppressor genes that function to stop tumor progression are known as ?
Antioncogenes (Ex: p53 or Rb)
Genomic libraries consist of what ?
Large fragments of DNA that include both exons (coding region) & introns (noncoding region) of the genome.
cDNA libraries consist of ?
Reverse-transcribed mRNA & include only genes that are expressed in the tissue they were derived from
The joining of 2 single stranded sequences is a tool known as ?
Hybridization
How do transgenic and knockout mice compare ?
Transgenic mice are altered @germ line via fertilized ova or embryonic stem cells
Knockout mice intentionally have a deleted gene
Both are useful for studying human diseases
