DNA and DNA Replication Flashcards
What is DNA?
Deoxyribonucleic acid. A double stranded helical molecule with genetic information.
What is a chromosome?
Long threads of genetic material found in the nucleus. Made of DNA and protein
What is the basic structure of DNA?
A double helix. The two sides are anti parallel and are composed of repeating units called nucleotides.
What composes a nucleotide?
A five carbon sugar (deoxyribose), a phosphate group, and one of 4 nitrogen bases.
What are the 4 nitrogen bases and which bonds to which?
Adenine, thymine, guanine, and cytosine. Adenine==thymine. Cytosine===guanine.
What are the pyramidines?
Thymine and cytosine. Single ring structure
What are the purines?
Guanine and adenine. Double ring structure
What is chargaffs rule?
The number of adenine is equal to thymine. The number of guanine is equal to the number of cytosine.
What is RNA?
It is a single ring structure similar to DNA
What are three structural differences between DNA and RNA?
RNA is single strand, not double.
RNA uses a ribose backbone instead of deoxyribose.
RNA replaces thymine with uracil
What are the three kinds of RNA?
mRNA-messenger
tRNA-transfer
rRNA-ribosomal
What is DNA replication?
When DNA makes a copy of it self. It “unzips”. The new DNA is composed of 1 old strand and one new strand
What is helicase?
Helicase is the enzyme that opens up DNA at various locations called origins forming “replication bubbles”. At either end of the bubble is the “replication fork”
What are the three jobs of polymerase?
1) form the sugar phosphate backbone
2) replaces RNA primer with the DNA nucleotides
3) proofreads DNA and corrects errors
Which direction can DNA replicate in?
The 5-3 direction. The leading strand works non-stop. The lagging strand works in fragments
What are the Okazaki fragments?
The lagging strand during replication works in small fragments from the 5-3 direction. At the starts there is a small section of RNA at the start of each fragment
What does RNA primer/primase do?
Puts the RNA primer at the start of the Okazaki fragment
What does ligase do?
It’s the DNA glue. It puts the Okazaki fragments in place
What is elongation?
Extending a new strand of DNA
What is DNA sequencing?
Determining the exact nucleotide order in a section of DNA.
What is a gene?
A unit or section of hereditary material located on a chromosome
