Molecular Basis of Inheritance Flashcards
________ is DNA and not RNA, proteins or any other biological compound
The genetic material
Genetic material was shown in a series of experiments between what years?
1928-1952
DNA is composed of:
-one sugar, 2-deoxyribose
-four nitrogenous bases:
purines A and G
pyrimidines T and C
-phosphate groups
Sugar + base + phosphate =
= nucleotide
Nucleoside consists of a ___ + _____
sugar and base
A phosphate group consists of ____ + ___
1 P and 4 O’s
What are the nitrogenous bases?
A, G, C, T
The phosphate is attached to the –OH on the ____
no. 5 carbon of the sugar, the 5´ C
The –OH on the no. 3 carbon of the sugar, the 3´ C,
is free
Sugar in DNA
deoxyribose
Sugar in RNA
Ribose
the purines in DNA and RNA
adenine (A) & guanine (G)
the pyrimidines in DNA and RNA
cytosine (C), thymine (T) in DNA & uracil (U) in RNA
DNA and RNA are polynucleotides made by linking nucleotides end-to-end by what process?
dehydration synthesis
The covalent bonds linking the adjacent sugars are called _____
phosphodiester bonds
The chain has a regular _____ backbone
sugar-phosphate
One end has a phosphate on ____
a 5 carbon end
The other end has an –OH on ____
a 3´ carbon
____ is exclusively double-stranded, com-posed of two polynucleotide chains
DNA
____ may be either single-stranded or double-stranded
RNA
DNA forms a double helix, first proposed by who and when?
Watson and Crick in 1953
helix is ___ handed
right
bases are located where on DNA?
Center
They are flat and stacked like rungs in a twisted ladder
Bases
What is the DNA backbone?
The “backbone” is (deoxyribose-phosphate)n
The bases on the opposite strands form ______ with each other
H bonds
what are A to T with 2 (A=T), G to C with 3 (G=-C)?
Base pairs
A&T and G&C must be what to eachother?
complementary
- The 2 strands have the opposite orientation
- One runs 5´ to 3´, the other 3´ to 5´
Anti-parallel
There are ___ base pairs in one complete turn of the helix
10
The helix makes one turn every __ nm (__ Å
3.4, 34
The distance between adjacent base pairs is thus __ nm (__ Å)
0.34, 3.4
The diameter of the helix is __ nm (__ Å
2.0, 20
The two strands separate and each serves as the template for the synthesis of a new strand during what phase?
S Phase
Each “daughter” double helix consists of one ____ strand and one ____ strand
“old”, “new”
DNA replication is thus said to be ____________
semiconservative
_____ are added to the 3´ end of the chain
dNTPs
The chain grows in the _____ direction
5´ to 3´
enzymes that add dNTPs to the growing chain are called:
DNA polymerases
In E. coli, there are three types of enzymes, called:
DNA polymerases I, II and III
All three enzymes add _____ to the 3´ end of the chain, extending it in the 5´ to 3´ direction
dNTPs
Most of the new DNA is made by:
DNA polymerase III
On the _____, new DNA is made as one long continuous strand
leading strand
On the lagging strand, however, new DNA is made in pieces called:
Okazaki fragments
_______ was a pioneer Japanese molecular biologist, known for his pioneer research onDNA replication
Reiji Okazaki
Ultimately, the Okazaki fragments are joined into one long continuous strand by the enzyme called:
DNA ligase
DNA replication starts at a point on the DNA called the:
origin of replication
Replication proceeds in what direction?
both
The place where replication is occurring is called:
-There will be 2 moving away from origin
the replication fork
On one side of each replication fork, DNA is made in the same direction the fork moves;
The new DNA made on this side of the fork is called:
the leading strand
The new DNA made on this side of the fork is called the lagging strand;
The new DNA made on this side of the fork is called:
the lagging strand
The lagging strands must be made in segments called:
Okazaki fragments
Okazaki fragment 1 is made, the fork moves…..
….fragment 2 is made, and so on
Eventually all the Okazaki fragments will be joined to make one long continuous strand by an enzyme called:
DNA ligase
DNA polymerases cannot add the first dNTP in a new strand;
That’s done by an enzyme called ___ which makes a short primer of RNA
primase
Eventually, the primer is removed by _____, which replaces it with DNA
DNA polymerase I
