DNA structure part 2 Flashcards
what is the backbone of nucleotides or DNA
phsophate group
nucleotides are linked together by what type of bond
phosphodiester bonds
what is the distance of one complete turn of double helix
3.4nm
what is distance between each base pair
0.34
two strands create a ladder with alternating ______ and _______ as the sides of the ladder and the _________ bonded base pairs as rungs of the ladder
sugar and phoshpate
H bond
know the diagrams of all
yes sir
Why is complementary base pairing important
allows the base pairs to be arranged in the most energetically favourable way
- it is essential in forming the helical structure of DNA.
It is also important in replication as it allows semiconservative replication.
describe the structure of Double helix
Two single strands join through H bonds via complementary bases.(pyrimidine and purine)
Phosphate group(spine) and deoxyribose sugar act as the sides of the DNA strands while complementary bases act as the rungs of the ladder which are bonded together by H bonds in the middle of the two strands.
Imagine you were looking at a double helix, what are three unique things you would see about this DNA structure
-antiparallel
- twisting
- complementary bases
What bonds link together nucleotides and what does it occur between
phosphodiester bonds which occurs between the phosphate group of one nucleotide and the deoxyribose sugar of another nucleotide
why is 5’ to 3’ written instead of 3’ to 5’
because if the leading template strand 5’to 3’ contains the genetic information of the 3’ to 5’ as it is the inverted form 3’ to 5’, furthermore DNA polymerase 3 usually builds DNA in the 5’ to 3’ direction anyways
fill in the blanks: ALL human genome is organized into __________-
__________ consists of protein and DNA called ________
DNA is coiled to fit inside the nucleus every ____, ________ the dna double strand is coiled around a _________,________________ which is held together by another _______
compelx of histones coild by DNA is called a ____________
The DNA double helix strand is _______________ and is therfore strongly attracted to ____________
series of _____________ coil to form chromatin fibres
chromatin fibres fold to form ____________
chromosomes
Chromosomes chromatins
200 nucleotides, central histone histone
nucleosomes
negativity charged histone
nucleosomes
histones
supercoil
Why is it important that hydrogen bonds between DNA are easy to break?
DNA replication
Purpose of junk DNA?
There is a bunch of junk DNA in between genes (referred to as “coding DNA”) for the purpose of protecting the DNA from mutations. By having sections of “junk” in between genes, the cell increases the chance that if a mutation were to occur, then there is a good chance it will happen in this non-coding, “junk” DNA, instead of within an important gene the cell needs for survival.
If the OH group of CH2 group is on the top of the one DNA strand the strand is running
if phosphate is on bottom of strand and strand is upside down (doesnt need to mention)
if phosphate is on top
if OH is on bottom
3’to 5’
3’ to 5’
5’ to 3’
5’ to 3’
