9.6 DNA Replication and Chromosome Structure/DNA Structure ILM Flashcards
what are the two prymidines? is this one or two rings?
one ring, cytosine and thymine
how are nucleotides strung together? what kind of bond?
phosphodiester bond
what disease is characterized by abnormally short telomere sequences? affects skin, nails, bone marrow cells. gives effect of premature aging
dyskeratosis congenita
what happens when telomeres become too short?
cells become senescent and stop dividing
telomerase is re-activated in what types of cells?
cancer cells
special repeating segments at the end of DNA
telomeres
What enzyme gets rid of the RNA priming fragments on the lagging strand?
ribonuclease H
what are the two purines? is this one or two rings?
two rings, adenine and guanine
What enzyme combines fragments with the growing strand by joining OH on a 3’ end with a triphosphate on a 5’ end?
DNA ligase
the nucleotides in DNA and RNA are based off a ___ carbon sugar (number)
5
what direction can DNA synthesis occur in?
5’ to 3’ direction
the leading strand in DNA synthesis is replicated __________, while the lagging strand is replicated _____________.
continuously, discontinuous
What enzyme synthesizes telomeres?
telomerase
a nucleotide consists of 3 things. What are they?
a simple sugar, a phosphate group, and a base
in double helix structure, how are the two strands of DNA held together? what force?
hydrogen bonding
What enzyme sits on DNA above the replication fork and ensures correct unwinding of the strand? Making sure there are no knots or anything.
topoisomerase
DNA polymerase does not have inherent affinity for DNA. What complex keeps DNA polymerase attached to DNA?
sliding clamp complex
what are the pairs of nucleotides? (purine and prymidine pairing)
A-T, C-G
there are 4 bases in DNA nucleotides. What are they?
thymine, adenine, cytosine, guanine
what enzyme does most of the DNA synthesis?
DNA polymerase
if RNA, then _____ is replaced by a ______ (nucleotide names)
thymine, uracil
are DNA residues positive or negative?
negative
which is more stable, A-T rich DNA or C-G rich DNA? Why?
C-G rich DNA, they make 3 H bonds between nucleotides (instead of the 2 by A-T)
what site allows duplicated DNA molecules to be pulled apart into daughter cells during cell division?
centromeres
are histone proteins positive or negative?
incredibly positive
DNA polymerase can’t begin synthesis without a primer. There needs to be either a DNA or RNA primer for it to extend synthesis. What enzyme makes the RNA primers for the lagging strand?
DNA primase
when is telomerase enzyme active? (normal, 3 places)
gamete formation, adult stem cells, embryonic stem cells
in DNA, the sugar of the nucleotide is called _____________
deoxyribose
in RNA, the sugar of the nucleotide is called ______
ribose
what unwinds DNA?
DNA helicase
