CH 16: The Molecular Basis of Inheritance Flashcards
nucleotide
a pentose sugar attached to a nitrogenous base and to a phosphate group.
what are the 4 different nitrogenous bases in DNA?
Thymine, Adenine, Cytosine, and Guanine.
Which two are single-ring pyrimidines?
Thymine and Cytosine
Which two are double-ring purines?
Adenine and Guanine
DNA is ___ and ___
antiparallel and complimentary
Helicase
unwinds the two DNA strands at the origin of replication by temporarily breaking the hydrogen bonds. CREATES REPLICATION FORKS
Single stranded binding proteins
binds to the newly separated DNA strands that were broken down by helicase to prevent them from re-forming the hydrogen bonds between them.
Topoisomerase
relieves the overwinding in the DNA double strand caused by helicase’s unwinding the two strands.
Primase
attaches a primer of RNA nucleotides that signal for DNA replication to begin at the location of the primer.
DNA Polymerase III (3)
adds nucleotides to create new DNA strands using each separated strand as a template.DNA Polymerase III corrects most errors as they occur
DNA Polymerase I (1)
replaces RNA nucleotide primers with DNA nucleotides.
DNA Ligase
functions in the lagging strand to join the Okazaki fragments into one continuous DNA strand.
DNA + histone =
nucleosome
chromatin
DNA & proteins are organized as cylindrical fibers
chromosomes are made up of
DNA and protein
DNA is a polymer of
nucleotides
there are _ different types of nucleotides
4
A =
T
G =
C
in 1952,
Alfred Hershey and Martha Chase showed that DNA was responsible for genetic heredity
___ is responsible for genetic heredity
DNA
what accounts for all the genetic diversity on earth?
the order of the four (A,T, C, G) nucleotides
what makes an organism what it is?
the combination and sequence of nucleotides in DNA provide the blueprint for making proteins that makes an organism what it is
DNA Replication
the parent DNA strand unwinds and two new strands are created, using the base pairing rules. The result is two strands (sister chromatids) of DNA that each have one parent strand and one newly synthesized strand
Prokaryote DNA is circular, ___
circular, round, and only have one replication origin. Replication proceeds in both directions
Eukaryotic DNA (linear)
have many replication origins, replication proceeds in both directions
new nucleotides can only be added to the __’ end of the new DNA strand that is being built
3’
Nuclease
repairs DNA damage and synthesis errors. Example: when we get a sunburn, we hurt our DNA, nuclease goes in and pulls this error region in and DNA Polymerase III can fix it, and DNA Ligase seals the ends together.
Mutations
can be passed down from one generation to the next. It is an error. Some can be harmful and some can be beneficial
Telomeres
do NOT code for genes, they are short, repetitive nucleotide sequences.
Telomerase
In ovary and teste cells, telomerase catalyzes the lengthening of telomeres so that genes are not lost. Good for germs cells, but not for somatic cells.
The 5ꞌ end of a DNA strand always has a free __________ group while the 3ꞌ end always has a free __________ group.
phosphate, hydroxyl
In DNA replication, the next nucleotide is incorporated into the growing polymer at the __________ of the molecule by an enzyme called __________.
3ꞌ (hydroxyl) end; DNA polymerase
DNA polymerase adds nucleotides to the __________ of the leading strands, and to the __________ of the lagging strands (Okazaki fragments).
3’ end; 3’ end
Replication of the lagging strand of DNA is accomplished by repeatedly making __________ followed by 1,000–2,000 nucleotide segments called __________.
short RNA primers; Okazaki fragments
DNA and RNA are….
nucleic acids
prokaryotic DNA is found in the
cytoplasm
eukaryotic DNA is packed into the
nucleus of the cell
