Composition and Structure of DNA Flashcards
Nucleic acid
acidic substance made up of C,H,O,N,P
What are the 2 types of nucleic acid?
DNA, RNA
What does DNA stand for and where is it found?
Deoxyribonucleic acid, found in nucleus
What does RNA stand for and where is it found?
Ribonucleic acid, cytoplasm
What is DNA made up of?
Repeating units called nucleotides
What does each nucleotide in DNA have?
5-carbon sugar called deoxyribose, phosphate group, nitrogenous base
What are the kinds of nitrogenous bases? How many are there?
Four kinds, adenine, cytosine, guanine, and thymine.
What is a Purine nitrogenous base?
A double ringed one.
What are the Purine nitrogenous bases? How many are there?
2, Adenine and Guanine.
What is a Pyrimidine nitrogenous base?
A single ringed one.
What are the Pyrimidine nitrogenous bases? How many are there?
2, Cytosine and Thymine.
In the nitrogenous bases, what bonds to what?
Each Purine bonds to a Pyrimidine. Adenine and Thymine, and Guanine and Cytosine.
Who were James Watson and Francis Crick?
Scientists who worked for someone else. Using X-Ray photos of DNA, they formed a model of the structure of DNA.
What year were Watson and Crick?
1953
Who took the pictures Watson and Crick used?
Rosalind Franklin.
What did Watson and Crick determine?
DNA was in the shape of a double helix, phosphate and sugar formed the sides, nitrogenous bases the rungs, base pair bonds, complimentary.
Double helix
Twisted ladder
Why are the two strands of the double helix DNA complimentary?
Bc of the nitrogenous base pairings and bonds. If one was AGGTTAC, the other would read TCCAATG
What is DNA replication?
Process of making a copy of DNA
Template
pattern on which each new strand is built
Why does each strand serve as a template?
In order to replicate itself, since each strand is complimentary.
replication forks
areas where double helix separates (called this bc of their y shape)
What is the first step of replication?
The double helix unwinds, and bases on one strand separate from the bases on the other.
DNA polymerase
enzyme that attaches to each strand of the separated DNA during second step of DNA replication
What does the DNA polymerase do?
moves along the strand, reads each base, attaching new complimentary bases according to the base pair rule
When does replication stop?
When all of the DNA has been copied and the polymerases are signaled to detach, one per strand
Conclusion of replication
2 DNA molecules are formed, each composed of a new strand and original strand (called semi conservative replication)
In conclusion of replication, what do the sequences of bases in these two strands look like?
Identical to each other and the original DNA molecule
What may happen during replication?
errors may occur and the wrong bases may be added
What ability does DNA polymerase have that can prevent errors?
Proofread the new DNA strand, backtrack and removing the incorrect nucleotide, replace it w/ the correct one
How many errors occur per nucleotides due to DNA polymerase?
1 error:1 billion nucleotides
