DNA and RNA- Biology Flashcards
“message carrying” molecule, coding for the creation of proteins in our bodies.
DNA
ADENINE pairs with
THYMINE
THYMINE pairs with
ADENINE
GUANINE pairs with
CYTOSINE
CYTOSINE pairs with
GUANINE
DNA resides in cell, except in what case?
Mitosis/Meiosis when nuclear membrane breaks down
Chromosomes are made up of organized bundles of what?
DNA
DNA is a double helix. What does that mean.
Two strands spiraling around each other.
DNA’s monomer
Nucleotide
what does DNA stand for?
deoxyribonucleic acid
The backbone of DNA is made of what?
Deoxyribose and phosphate
Strands run anti parallel. Name order.
5’ -> 3’ and 3’ -> 5’
Three parts of nucleotide:
Phosphate group, pentose sugar, nitrogenous base.
Only exists in RNA
Uracil
When does DNA replication occur?
Happens in S-phase of Interphase
Enzymes
speed up chemical reactions
Main purpose of DNA replication
Prepare cell for Mitosis by copying DNA
Replication Fork
When the double helix is unwound, leaving both strands open for replication.
Supercoiling
DNA getting tangled
Primers
Signals for DNA polymerase III to come in and add nitrogenous bases.
Complementary
When nitrogenous bases are added off of chargaff’s rule A-T, C-G
5’- 3’
the direction DNA is synthesized in
Leading Strand (template)
The strand being, one continuous strand
Lagging strand (complementary)
The strand being synthesized in fragments because it is running antiparallel to the leading strand.
Okazaki Fragments
The fragments of DNA on the lagging strand that are synthesized.
Whats is the goal of initiation?
Prepare DNA for copying
What are the steps of initiation?
Topoisomerase (prevents supercoiling), helicase (unzips DNA), SSB (bind to separate DNA, preventing them from combining), primase (adds RNA to each strand, acting as a starting point for DNA synthesis)
What is the goal of elongation?
Build the new DNA strands through DNA Polymerase III.
What does DNA polymerase III do?
Adds complementary DNA nucleotides to the 3’ end of each RNA primer. Also synthesizes the leading strand and the lagging strand in okazaki fragments
What is the goal of Termination?
clean up and finalize the new DNA strands.
What are the steps in Termination?
Exonuclease, DNA polymerase I, and Ligase
EXONUCLEASE
Works alongside DNA polymerase I and removes RNA primers form newly synthesized DNA.
Ligase
Seals the gaps between okazaki fragments on the lagging strand by forming phosphodiester bonds, completing the sugar-phosphate backbone.
DNA polymerase I
Fills the gap where the RNA primers were with DNA nucleotides.
Gyrase
relieves tension on the DNA strand while its being unwound
what would happen if ligase did’t do its job
DNA fragments would remain unconnected
Single Stranded Binding proteins
Coat the DNA around the replication fork to prevent rewinding of the DNA
Primase
Synthesizes RNA primers complementary to the DNA strand
DNA polymerase III
Extends the primers, adding on to the 5’-3’ direction.
Exonuclease
Removes RNA primers
DNA polymerase I
Adds DNA to the gaps that were created when the primers were removed
DNA ligase
Seals the two new DNA strands
