dna strycture 2
TRANSCRIPT
Stores and passes on genetic information from one generation to another.
DNA DEOXYRIBONUCLEIC ACID
DNA STRUCTURE
THE DNA STRUCTURE IS SHAPED LIKED A SPIRAL STAIRCASE, OR TWISTED LADDER.
DNA STRUCTURE(An Overview)
DNA has three main components:• Deoxyribose ( pentose sugar)•Base (there are four different ones)•Phosphate group
The deoxyribose sugar of the DNA backbone has 5 carbons and 3 oxygens.
DNA STRUCTURE
DNA STRUCTURE
THE STEPS OF THE LADDER ARE MADE OF PAIRS OF NITROGEN BASES.
DNA STRUCTURE
They are divided into two groupsPyrimidines and purines
Pyrimidines (made up of 6 atoms 4 carbon 2 nitrogen rings)ThymineCytosine
Purines (larger of the two bases; made up of 9 atoms that make up the fused rings 5 carbon, 4 nitrogen )AdenineGuanine
DNA STRUCTURE
1. ADENINE = A2. GUANINE = G3. CYTOSINE = C4. THYMINE = T
They are represented by their capital letter.
DNA STRUCTURE
There is only one way the nitrogen bases can form
ADENINE pairs with THYMINEGUANINE pairs with CYTOSINE
DNA STRUCTUREQUESTION ?
CAN C JOIN WITH A
AND G JOIN WITH T
YES
NO
CORRECT
MOVE ON
SORRY REVIEW MORE
DNA STRUCTURENucleotides Nucleotides are formed by the condensation of a pentose sugar, phosphate and one of the 4 basesThe following illustration represents one nucleotide
CIRCLE = Phosphate
PENTAGON= Deoxyribose
Rectangle= Base
DNA STRUCTUREDNA Double Helix and Hydrogen Bonding
•Made of two strands of nucleotides that are joined together by hydrogen bonding•Hydrogen bonding occurs as a result of complimentary base pairing
Adenine and thymine pair upCytosine and guanine pair upEach pair is connected through hydrogen bondingHydrogen bonding always occurs between one pyrimidine and one purine
DNA STRUCTURE•Adenine always pairs with thymine because they form two H bonds with each other
•Cytosine always pairs with guanine because they form three hydrogen bonds with each other
DNA STRUCTUREAntiparallel strands
The strands run opposite of each other.
The 5’ end always has the phosphate attached. ’
SAMPLE QUESTION
Which of the following nucleotide base sequences complements the section of DNA modeled above?F. 5′UTCGCA3′G. 5′TTAGCG3′H. 5′GCGATT3′J. 5′TTUCGC3′
3′AATCGC 5′
SAMPLE QUESTION
The Correct Answer: G
G is the right answer because A (adenine) always pairs with T (thymine) and C (cytosine) always pair with (guanine).