Test 1 Flashcards
(26 cards)
What is a supramolecular complex?
Structures held together through non covalent bonds.
Categorize these on if they are supramolecular complexes or not, and why.
cell wall, nucleotides, proteins, chromatin, plasma membrane, sugars
Supramolecular complexes: cell wall, chromatin, plasma membrane
Not supramolecular complexes: proteins (peptide bonds), sugars (glycosidic bonds), nucleotides (phosphodiester bonds)
DNA replication is …
semi-conservative: one new and one original strand
When does DNA replication happen
in interphase
name the fours primary enzymes in dna replication and their functions
helicase: unzipping enzyme, breaks hydrogen bonds
dna polymerase: the builder, replicates DNa molecules
primase: the initializer, primer for dna polymerase
ligase: the gluer, glues dna strands together
explain the steps of dna replication
- helicase unwinds dna double helix. SSB proteins keep the strands separated. topoisomerase prevents supercoiling.
- primase makes RNA primers on both strands
- dna polymerase makes complementary dna strands, okazagi fragements get formed on the lagging strand
4.ligase closes the gap between okazagi fragments
whats the direction of dna polymerase
5’ to 3’. remember this is complimentary to the already existing strands
how are okazaki fragments caused? why?
on lagging strans. dna polymerase cna only go 5’ to 3’
what makes up the primary structure of proteins
amino acids held together by peptide bonds to create a polypeptide chain
give the structure of a protein
amino group + carboxyl group + R group
whats the secondary structure of proteins and what causes it?
sheets: alpha or beta. made through hydrogen bonds
whats the tertiary structure of proteins and what causes it?
sheets folded once more because of R-groups (ionic, hydrogen, van der waals, disulphide, hydrophilic and hydrophobic)
whats the quaternary structure of proteins
many peptide chains together
what are chaperones
Chaperones are proteins that guide proteins along the proper pathways for folding. They protect proteins when they are in the process of folding, shielding them from other proteins that might bind and hinder the process.
why is there little allowable rotation around the peptide bond
the partial double bond character (due to resonance between carbonyl and amide groups) makes the peptide bond planar
how many of the 20 common amino acids have rings in their structures? what are they
5: phenylalanine, tyrosine, tryptophan, histidine, proline
aromatic rings: phenylalanine, tyrosine, tryptophan, histdine
non-aromatic rings: proline
*Aromatic rings are rigid and participate in pi-pi stacking interactions.
what are the four stop codons? what about the start
start: aug
stop: uaa, uag, uga
in an amino cid near neutral ph, the carboxylic acid group will be ____ and the amino group will be ______
The carboxyl group will be deprotonated (-COO⁻).
The amino group will be protonated (-NH₃⁺).
This results in a zwitterion, where the amino acid has both a positive charge on the amino group and a negative charge on the carboxyl group, making it electrically neutral overall at physiological pH.
give the steps of a pcr cycle
Denaturation (94-98°C)
Key feature: Heat separates double-stranded DNA into single strands by breaking hydrogen bonds.
2. Annealing (50-65°C)
Key feature: Primers bind (anneal) to complementary sequences on single-stranded DNA.
3. Extension (72°C)
Key feature: Taq polymerase synthesizes new DNA strands by adding nucleotides (dNTPs) in the 5’ to 3’ direction.
Repeat 25-40 times to exponentially amplify the DNA.
Final Extension (72°C for 5-10 min)
Key feature: Ensures complete synthesis of any remaining strands.
Cooling (~4°C)
Key feature: Preserves the amplified DNA for further use.
what is chargaff’s rule
if theres 20% of A, theres 20% of T.
why is dna more stable than rna?
RNA has a hydroxyl (-OH) group at the 2’ carbon of its ribose sugar, whereas DNA has only a hydrogen (-H) at 2’.
This -OH group makes RNA more reactive and allows intramolecular hydrolysis, meaning RNA can self-cleave in alkaline conditions.
DNA lacks this -OH, making it more chemically stable
why do protein absorb light at 280 nm?
aromatic r groups like tyrosine and tryptophan absorb ultraviolet light at 280 nm
which strand does mRNA copy
Antisense is the non-coding DNA strand of a gene. In a cell, antisense DNA serves as the template for producing messenger RNA (mRNA), which directs the synthesis of a protein.
name all the polar neutral amino acids
