KH1 Flashcards
Define polymer
Covalent bond-linked chain of monomers
What is an informational polymer?
Polymer with more than 1 kind of monomer, where the sequence of monomers is the information needed.
What’s the common generic structure of a monomer in an informational biopolymer?
They have a common element which will form the backbone of the polymer through covalent bonds. They have a “characteristic” element which forms the side-chains.
How many monomers can you connect with 1 joining site?
2
How many joining sites (minimum) do you need to make a polymer?
2
What do you need for further chain growth?
Joining sites exposed at ends.
What happens when you have 3 joining sites?
Branched polymers
Are informational biopolymers branched?
No.
Example of branched polymers?
Complex carbs
Can cells make branched polymers?
Yes.
How many ends do informational biopolymers have?
2
Why do cells use linear biopolymers and not branched ones?
To be able to pack and handle them better.
Describe the DNA molecules of bacteria in terms of biopolymers and structure.
They have a circular but unbranched form because the two ends of linear informational biopolymers have been joined.
How can you describe the symmetry of the monomers of informational biopolymers?
Asymmetric
Describe both joining ends in relation to each other.
They are chemically distinct.
How do informational biopolymer backbones connect?
To the opposite end.
What drives the asymmetry of the polymer?
The asymmetry of the monomers.
In which way does polymer growth occur?
In 1 direction. Unidirectional.
What are the 2 major types of biopolymers and their respective monomer units?
Nucleic acids: nucleotides
Protein: Amino acids
Order DNA, RNA and Protein in order of chain length >
DNA > RNA> Protein
What is the characteristic element of nucleotides?
Heterocyclic base
What is the common element of a nucleotide?
Pentose sugar phosphate
What are the 2 joining sites on a nucleotide?
The 5’ phosphate and the 3’ OH
How do nucleic acid polymers grow?
By addition of monomers to the 3’ end.
What’s the difference between ribose and deoxyribose sugars?
Absence of 2’ hydroxyl in deoxyribose.
What is the consequence of the lack of -OH on deoxyribose?
DNA is more resistant to chain cleavage by hydrolysis.
What are the purines?
adenine and guanine
What are the pyrimidines?
uracil, thymine, cytosine
What is the consequence of having T instead of U in DNA?
Chemical damage is easier to repair.
Difference between U and T?
The methyl group on c5 in thymine.
What is the link between adjacent nucleotides & why?
A phosphodiester bond. Cause the phosphate is joined in an ester bond to the 5’OH of the downstream nucleotide and another ester bond with the 3’OH of the nucleotide upstream.
Will nucleotides be newly joined to the phosphate group?
No. It is the 5’ end and not the 3’ end.
What is the characteristic element of amino acids?
R side chains
What’s the common element in amino acids?
Alpha carbon linked to a COOH (carboxyl) group and a NH2 (amino) group.
Which stereoisomer of amino acids is used in protein sythesis?
L structure
Polymer growth happens at which joining site in proteins?
At the carboxyl terminus.
What’s the bond between adjacent amino acids?
peptide bonds
How are amino acids added to the polymer chain?
The monomers are energized when a nucleoside triphosphate brings the amino acids to the chain and then 2 phosphate groups are kicked out
What is the high energy form of amino acid monomers?
Amino acyl-tRNA esters
What is the part of the high energy form of amino acids is kicked out to help amino acid incorporation?
the tRNA
Can energized monomers grow a chain by themselves?
No.
What do energized monomers need in order to grow chains?
Enzymes.
How does the enzyme help monomers grow into chains
The enzyme is associated with a template biopolymer that directs the enzyme to incorporate the correct type of monomer.
What would you say causes the sequence?
The template.
Enzyme for DNA construction
DNA polymerase
Enzyme for RNA construction
RNA polymerase
Enzyme for protein construction
Ribosome
Which biopolymers exists as single polymer chains?
RNA and protein
DNA strands are held together by:
Weak H-bonds between complementary bases
What’s another name for complementary bases
Watson-Crick base pairs
Describe the helix of DNA
right-handed helix called “B” DNA, the 2 strands are antiparallel, sugar-phosphate backbones on the outser side, base-pairs on the inside
How are base-pairs in the interior of DNA structures read?
Bye DNA-binding proteins binding to major and minor grooves to identify specific sequences without separating strands.
How can denatured strands be renatured?
By forming H-bonds between complementary base-pair sequences.
Example of when we need renaturation and denaturation.
During DNA replication and transcription, molecular biology and genomic processes
What’s Tm?
The temperature at which the DNA is 1/2 melted
Tm depends on:
the DNA’s base composition
What kind of DNA would have a higher Tm? Why?
DNA with a higher proportion of G-C pairs because they have 3 h-bonds (more h-bonds)
Relationship between Tm and G-C content
As G-C base pair content increases, Tm increases.
T or F: DNA bends along its horizontal axis
F: DNA bends along its long axis.
Why does DNA need to bend?
For DNA-protein interactions and it’s needed in the folding of DNA into compact structures.
Example where DNA bending is used?
Chromosome formation
