UNIT 3 Flashcards
What is the name of the sit at which replication begins?
origin of replication
Which molecule seperates the two strands of DNA during replication?
Helicase
The primer laid down by primase is made of what molecule?
RNA
Which molecule produces the vast majority of DNA during replication?
DNA polymerase III
Which molecule removes the RNA primers and replaces them with DNA
DNA polymerase I
When DNA Polymerase III has to move in the opposite direction of helicase, it results in what?
discontinuous replication
What molecule forms the final covalent bond between nucleotides during replication?
DNA ligase
What molecule is synthesized during transcription?
RNA
Where does transcription take place in eukaryotic cells?
in the nucleus
what enzyme performs transcription?
RNA polymerase
what is the name of the sequence of DNA bound by RNA polymerase during initiation?
promoter
for eukaryotic cells to initiate transcription, _____ in the initiation complex recruit ___ _____
proteins; RNA polymerase
for prokaryotic cells to initiate transcription, ___ ______ is directly attracted to ____ sequences
RNA polymerase, promoter
termination of transcription typically requires what structure to form in newly made RNA?
step-loop
during RNA splicing, what special regions of RNA are removed from the primary transcript?
introns
The point at which the two strands of DNA are separated to allow replication of each strand
replication fork
protein that binds to and stabilizes single stranded DNA until it can be used as a template
single strand binding protein
a single DNA strand that, during DNA replication, is replicated in the 5′ – 3′ direction
lagging strand
short sequences of DNA nucleotides which are synthesized discontinuously and later linked together by the enzyme DNA ligase to create the lagging strand during DNA replication.
okazaki fragments
protein that unwinds parental double helix at replication forks
helicase
protein that synthesizes an RNA primer at the 5’ end of leading strand and of each okazaki fragment of lagging strand
primase
protein that using parental DNA as a template, synthesizes new DNA strand by covatently adding nucleotides to the 3’ end of a pre existing DNA strand or RNA primer
DNA polymerase III
protein that removes RNA nucleotides of primer from the 5’ end and replaces them with DNA nucleotides
DNA polymerase I
protein that joins 3’ end of DNA that replaces primer to rest of leading strand and joins okazaki fragments of lagging strand
DNA ligase
the process by which DNA directs protein synthesis, includes transcription and translation
gene expression
the synthesis of RNA under direction of DNA
transcription
synthesis of a polypeptide under the direction of mRNA
translation
site of translation
ribosomes
intital RNA transcript from any gene
primary transcript
protein that pries the DNA strands apart and hooks together the RNA nucleotides
RNA polymerase
mediates the binding of RNA polymerase and the initiation of transcription
transcription factors
the completed assembly of transcription factors and RNA polymerase II bound to a promoter
transcription initiation complex
promoter that is crucial in forming the initiation complex in eukaryotes
TATA box
removes introns and joins exons, creating an mRNA molecule with a continuous coding sequence
RNA splicing
what is the sequence of the start codon in the genetic code
AUG
where would you NOT find functional ribosomes
in the nucleus
what component of translation is the last to join the initiation structure?
large ribosomal unit
in what site to tRNA molecules carrying a single amino acid enter the ribosome?
A site
scientists believe that the majority of mutations in humans are caused by…
mistakes during DNA replication
how does the mismatch repair mechanism recognize an incorrect base pair?
it recognizes a change in width between DNA strands
how does the mismatch repair mechanism distinguish the old and new strands of DNA?
the old strand is methlylated and the new strand is not
loosening chromatin structure will result in what?
higher rates of transcription
repressor proteins work by binding DNA sequences called what?
operators
repression works by blocking which step?
elongation of transcription
noncoding regions of RNA
introns
change in DNA sequence
Mutation
chemical changes in just one base pair of a gene
point mutations
replaces one nucleotide and its partner with another pair of nucleotides
base pair substitution
mutation that has no effect on the amino acid produced by a codon because of redundancy in the genetic code
silent mutation
mutation that still codes for an amino acid, but might be the wrong one
missense mutation
mutation that changes an amino acid codon into a stop codon, almost always leading to a nonfunctional protein
nonsense mutation
mutation that alters the reading frame
frameshift mutation
cancer cells remain localized
benign mass
tumor cells invade other tissues
malignant tumor
the tumor cells induce secondary tumors at other locations in the body
metastasis
acetyl groups are attached to positively charged lysines in histone tails
histone acetylation
looks at DNA/protein patterns and how they affect expression
epigenetics
blocks elongation of transcription
repression
increases rate of initiation
induction
entire stretch of DNA that includes the operator, the promoter, and the genes that they control
operon
protein that can switch off an operon
repressor
repressor is a product of a separate gene called what
regulatory gene
molecule that cooperates with a repressor protein to switch an operon off
corepressor
small single stranded RNA that can bind to mRNA
micro RNA
phenomenon of inhibition of gene expression by RNA molecules
RNA interference
RNAi is caused by what
small interfering RNAs (siRNAs)
physical expression of a trait
phenotype
unit of inheritance that encodes a trait
gene
alternative form of a single gene
allele
genetic makeup of an individual
genotype
both alleles are the same
homozygous
alleles are different
heterozygous
determines if individual displaying dominant phenotype is homozygous or heterozygous for that trait
testcross
two pairs of contrasting traits
dihybrid cross
unit factors (traits) assort independently during gameate formation
independent assortment
what organism did mendel use in his studies?
pea plants
what term is used to express the combination of alleles an individual possesses for a trait?
genotype
a single gene trait where heterozygotes have intermediate phenotype is an example of what?
incomplete dominance
a single gene trait where heterozygotes exhibit a mixed phenotype reflecting each parent is…
codominance
what is the name of a molecule that is recognized by the immune system?
antigen
