DNA Flashcards
What does DNA stand for?
Deoxyribonucleic acid
What are the sub-units of DNA called?
Nucelotides
What is each nucleotide made up of?
A sugar called deoxyribose, a phosphate group, and a nitrogen base
What is ribose?
A sugar, like glucose, but with only five
carbon atoms in its molecule
What is deoxyribose?
Almost the same as ribose but lacks one
oxygen atom
What are the organic bases of DNA?
Adenine (A), Thymine (T), Cytosine (C), Guanine (G)
What is a molecule of DNA formed by?
Millions of nucleotides joined together in a long chain
DNA usually consists of a _______ strand of nucleotides?
Double
The strands are held together between the bases by what kind of bond?
Chemical
What are the pairs of bases?
- Adenine and thymine
- Cytosine and guanine
The paired strands are coiled into a spiral called?
Double helix
The helix makes one complete twist every ____ nucleotides?
10
What is the length of a complete twist?
3.4 nanometers
Who discovered the chemical structure of DNA?
Watson and Crick
True or false, replication can occur at different sites within one DNA molecule at the same time?
True
What are enzymes?
Proteins that perform a function
What does DNA girase do?
Relaxes the DNA molecule
What does DNA helicase do?
Attaches at the “origin of replication site”, then breaks the hydrogen bonds holding the strands together
True or false, DNA replication occurs on both strands simutaneously, but the processes are slightly different?
True
True or false, DNA strands are anit-parralel?
True
What does RNA primase do?
Searches for a specific DNA target sequence that instructs the enzyme to attach, then adds a short 10-60 sequence of base pairs called an RNA primer
What does DNA Polymerase III do?
Searches for and attaches at the RNA primer site. Then begins adding free, matching nucleotides to the original 3’ strand
What does DNA Polymerase I do?
Moves in and replaces the RNA primer
What does DNA ligase do?
Seals the gap
Replication occurring on the 5’ strand is known as?
Lagging strand
Newly added nucleotide sequences are called?
Okazaki fragments
How many new identical copies of the original DNA strand are there in the end?
Two
What type of bond forms between the deoxyribose sugar and the nitrogen base?
Gycosyl
The carbons of a deoxyribose sugar are number 1’ to 5’. Which carbon is attached to the nitrogen base?
1’
In the ladder-like model of DNA, what do the steps/rungs consist of?
Nitrogen bases
How many primers are required on the leading strand during DNA replication?
1
DNA replication occurs in what direction?
5’ to 3’ direction only
