Structure of DNA and Replication Flashcards
What is DNA?
Long molecule made up of units called nucleotides
What are the 3 basic components that make up a nucleotide?
Deoxyribose, phosphate group, and a nitrogen base
What are the 4 kinds of nitrogen bases in DNA?
Adenine, guanine, thymine, and cytosine
What is Chargaff’s Rule?
- The A (adenine) and T (thymine) pair together
- The G (guanine) and C (cytosine) pair together
What did Watson and Cricks discover with DNA?
-Discovered that hydrogen bonds could form between the nitrogenous bases and provide just enough force to hold the two strands together
What is replication?
Before a cell divides, it duplicates the DNA to ensure each cell has a set of DNA molecules
Each DNA molecule from the replication has what? (two things)
one original strand
-one new strand
How do enzymes carry out DNA replication?
It is carried out by a series of enzymes that “unzip” a molecule of DNA
What is DNA Helicase?
Breaks down hydrogen bonds between the base pairs and the two strands of the molecule unwind
What is the principle enzyme in DNA replication?
DNA polymerse, because it joins individual nucleotides to produce a DNA molecule
- It also proofreads each new DNA strand
- Facilitates hydrogen bond between nucleotides in a new DNA molecule
What is Ligase?
Seals up the sequence of DNA into two continuous double strands
-Connects sugar phosphate backbone in DNA molecules
After replication the DNA winds into a _____
double helix
Where is DNA found?
- In prokaryotes it is found in the cytoplasm
- In Eukaryote it is found in the nucleus
List the 3 basic steps of DNA replication
- Helicase opens up helix by breaking hydrogen bonds
- DNA polymerse adds complimentary bases to the original strand
- DNA polymerse proof reads the strand
What does Adenine + guanine produce?
Purines
