Chromatin, Operons, & DNA Replication Flashcards
progeria: interruption with
nuclear lamina
we know about proteins due to the … that occur with them
proteins
heterochromatin is a … version of chromatin
densely packed
heterochromatin leads to … of genes by inhibiting … at these locations, prevents access of … necessary for transcription
inactivation; transcription; enzymes
euchromatin are … chromatin –> … occurs in these regions
loosely packed; transcription
chromatin consists of … and .., namely DNA wrapped around … to form … that are held together either as “… on a …” (…) or as a structure of … in width (…)
DNA; proteins; histones; nucleosomes; beads; string; euchromatin; 30 nm; heterochromatin
about .. base pairs of DNA wrap around complexes of … histones, composed of … of each of the four different types: …, …., …, …
150; 8; two; H2A; H2B; H3; H4
Nucleosomes are joined together by way of
linker DNA
chromosomes are formed during …, when the cell is undergoing …
mitosis; cellular division
in …, chromatin begin to condense, which is when the chromosome becomes visible. During …, in which the cell is not dividing, the chromatin is in its … state, allowing for … to occur
prophase; interphase; least condensed; transcription
modification of the … regulates gene expression
histone tail
…. of the histone (addition of an … group) … the coils
…. (addition of a … group) … the coils
acetylation; acetyl; loosens; methylation; methyl; tightens
…. reduces the space needed for DNA within the cell. It reduces the … on the molecule by allowing it to … around itself. It can also regulate …
supercoiling; helical stress; twist; transcription
positive supercoiling: DNA is … –> …-handed twisting of the DNA
negative supercoiling: DNA is … (most DNA like this) –> …-handed twisting of the DNA, makes it easier to … the DNA strands
overwound; left; underwound; right; separate
epigenome refers to the … that regulate gene expression (e.g. …, …, etc.)
can be influenced by … factors
chemical compounds/modifications; DNA methylation; histone methylation; environmental
operon –> grouping of
genes
prokaryotes have to control which genes will be expressed, based on the … that they are in
environment
E.coli cells in environment with glucose, maltose and lactose would select … first in their metabolic genes, breaking it down by way of … (which involves … enzymes, leading to a net yield of … ATP). They would then select either maltose or lactose, building the enzymes responsible for breaking them down.
glucose; glycolysis; 9; 2
repressor proteins sit on top of …. and block …
gene segment; transcription
glucose is the …, … energy source
preferred; universal
operons are named after their … (what they act on)
substrate
lac operon –> used for …. –> …, inducer is … (…)
lactose; inducible; lactose; allolactose
permease enzyme allows lactose to …, and beta galactosidase … to glucose and galactose
enter the cell; hydrolyzes lactose
trp operon is used for … (an ….) –> …, tryptophan is the …
tryptophan; amino acid; repressible; repressor
prokaryotes make tryptophan and don’t need to … it BUT if it is in solution/agar that they are plated on, they don’t make it so that they don’t waste …, …, etc –> gene segment for tryptophan would be …
consume it; energy; resources; turned off
operons allow for prokaryotes to
regulate gene expression
(differences between trp and lac operon) trp operon leads to an … pathway whereas lac operon leads to a … pathway
anabolic; catabolic
(differences between trp and lac operon) lac is … whereas trp is ….
inducible; repressible
(differences between trp and lac operon) lac is controlled by the abundance of the … whereas trp is not dependent on the conditions of the …, although it can be repressed by these conditions
substrate; environment
(differences between trp and lac operon) trp is deactivated by the presence of … whereas lac is activated by the presence of …
tryptophan; lactose
(differences between trp and lac operon) the trp repressor is …, whereas lac is … Also, the trp repressor cannot bind to the …, but the lac repressor can
inactive; active; operator region
generating permeases leads to more …, more lactose in less …
efficiency; time
interaction between … and … regulates gene expression
repressor; inducer
regions of operon (gene segments): ... ... ... ...
operator; repressor; promoter; regulatory region
repressor sits on top of the
operator
the lactose repressor … after the binding of lactose, preventing the repressor– the … gene — from binding to the …. This allows … to attach to the …, which has been exposed by the binding of a … complex to a … binding site such that the … can fully bind to it. Transcription follows, by which enzymes necessary for lactose metabolism are produced
changes shape; regulatory; operator; RNA polymerase; promoter; CAP; CAP; RNA polymerase;
DNA replication occurs in three steps: …, …., and …
unwinding; complementary base pairing; joining
unwinding is the process by which the parental strands, also known as the … strands, are separated by way of a …
template; helicase enzyme
the point at which helicase begins separating the strands is known as the … At this point, helicase begins breaking the … between the .., forming two … – the two exposed strands of DNA that will undergo base pairing–which constitute a … that will grow as replication proceeds
origin of replication; hydrogen bonds; base pairs; replication forks; replication bubble
… stabilize the separated strands to ensure that the hydrogen bonds will not reform between the base pairs
single stranded binding proteins
before complementary base pairing can occur, …, an …., generates an … at the origin of replication because DNA polymerase can only attach new nucleotides to an … of nucleotides
primase; RNA polymerase; RNA primer; existing strand
Free nucleotides that were produced and stored in the cell prior to replication are then paired with nucleotides on the parental strands by way of …
DNA polymerase
the parental strands that are part of the fork ran … to one another, and the new strands being formed must also be … to the template strands
antiparallel; antiparallel
replication must occur in the … to .. direction, as nucleotides can only be added to the … group at the … end of the chain. This requirement leads to the formation of the … and … strands
5’; 3’; -OH; 3’; leading; lagging
the parental strand that is in the 3’ to 5’ direction is termed the … strand, and the parental strand that is in the 5’ to 3’ direction is termed the … strand
leading; lagging
replication in the leading strand occurs in the … direction that the fork is moving, while replication in the lagging strand occurs in the … direction that the fork is moving.
same; opposite
the lagging strand is replicated in segments called …. due to the fact that DNA polymerase must stop and restart due to the … of synthesis
Okazaki fragments; direction
the strands are … to ensure that no mistakes are made and … are removed by DNA polymerase and replaced with …
proofread; RNA primers; DNA nucelotides
… then joins the fragments to form the … molecules that are comprised of one parental and one new strand
DNA ligase; daughter DNA
Both prokaryotes and eukaryotes exhibit … replication, but some prokaryotes can exhibit … replication
bidirectional; unidirectional
in prokaryotes, there is …. point of origin, but in eukaryotes replication occurs at many different ….
only one; replication bubbles
… is the site of replication in prokaryotes. … is the site of replication in eukaryotes
cytoplasm; the nucleus
eukaryotes have … types of DNA polymerase, whereas prokaryotes have … types of DNA polymerases, but eukaryotic polymerases work … than prokaryotic polymerases
4; 2; slower
prokaryotes have only … site of termination, while eukaryotes have .. than one site of termination. Eukaryotes also face the problem of having some DNA that does not get …, which is solved by the presence of …–non-coding, repetitive sequences of DNA
one; more than one; replicated; telomeres
