Which of the following removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of Okazaki fragments?
DNA POL 1
Which of the following statements is true of chromatin?
Heterochromatin is highly condensed, whereas euchromatin is less compact.
Which of the following techniques could help a researcher inhibit the expression of a target gene?
RNAi
how many base pair codons do we have total
64
Shine-Dalgarno sequence is
upstream from AUG
A polysome could be best described as
an active site for protein biosynthesis
Identify the false statement regarding the control and secretion of insulin
High intracellular ATP opens the ATP-sensitive potassium ion channel.
DNA replication occurs ( ), while transcription and protein translation take place ( ), respectively
in the nucleus, in the nucleus and on ribosomes
Binding of high level of insulin molecules to their receptors will () - in regards to appetite
inhibit the production of appetite-stimulating neuropeptide Y and induce the production of appetite-suppressing -MSH
Insulin stimulates glucose uptake in
muscle and adipose where glucose is converted to glucose 6 phosphate
insulin in liver activates
glycogen synthase and inactivates glycogen phosphorylase, so that much of the glucose-6-phosphate is channeled into glycogen.
lipoprotein lipase breaks down
triglycerols in the lipoproteins to smaller fatty acids and monoglycerides that are transported into your tissues and either burned for fuel or re-assembled into triglycerides for storage
specialized pancreatic cells that secrete important hormones:
alpha- glucagon beta cells- insulin delta- somatostatin
somatostatin inhibits
insulin and glucagon
where are the alpha beta and delta cells found
the islets of Langerhans in pancreas
beta cells secrete what in response to increasing blood glucose levels
insulin
glucose enters what cells via what
enters beta cells via GLUT2 -glycolysis, ATP increases
ATP binds to
ATP gated K+ channels then K+ channels close depolarizing plasma membrane
the closing of K+ channels triggers opening of
Ca2+ voltage gated ion channels and theres an increase of Ca2+ in cytosol through exocytosis
maturation of insulin
-24 AA−long signal sequence targets proinsulin into the endoplasmic reticulum where the storage vesicles form -formation of disulfide bonds occurs within storage vesicles -Ca2+ activated proteases that cleave C-peptide from proinsulin -tests of insulin levels measure C-peptide
1 glucose forms how many ATP
30-32
Ca2+ is also released from
endoplasmic reticulum in response to initial elevation of Ca2+ levels in cytosol
depolarizing the membrane
internal is less positive
process of fuel metabolism due to prolonged fasting or type 1
leads to CAC inhibition, ketone body formation, and eventual coma/death due to ketoacidosis -glycolysis isn’t stimulated leading to muscle and fat breakdown, so the oxaloacetate produced is used to send glucose to your brain -without oxalo staying in CAC it’s inhibits so the fat broken down remains acetyl coa and is used for ketone bodies which provide some fuel also for the brain but accumulate in your kidneys
Fuel Use Over Four Hours of Normal Human Metabolism
right after eating- glucose rises -insulin stimulates glycolysis and glycogen synthesis -two hours after eating blood glucose drops- glycogen secreted liver glycogen releases glucose -four hours after eating more glucagon from pancreatic alpha cells, more TAG hydrolysis, FA becomes fuel for muscle and liver
two forms of diabetes
type 1- insufficient production of insulin: -due to autoimmune destruction of B-cells -develops early in life -genetic -ie insulin dependent or juvenile diabetes type 2- insulin resistance -worse type -more common -develops in late adulthood -associated with obesity -cells dont respond appropriately to insulin
diabetes symptoms
in both forms of diabetes, blood sugar becomes elevated body tries to dilute glucose and this causes excessive urination and thirst
in type 1 diabetes fat breakdown is accelerated which leads to
high production of ketone bodies this raises H+ and leads to ketoacidosis Bicarbonate buffering system activated, leads to altered breathing Breakdown of ketone body acetoacetate produces acetone, which is expelled via the breath Untreated diabetes leads to dramatic weight loss
Physiological Effects of Blood Glucose Levels
Blood glucose is normally determined after several hours of fasting High fasting blood glucose level (126 or higher) is a warning sign for diabetes Low fasting blood glucose level below 50 (in men) or 40 are warning signs of various hypoglycemic conditions Blood glucose levels after meal (postprandial) are typically higher (up to 145 mg/100 mL is normal)
long term effects on elevated blood sugar
Compromises O2 delivery, especially in extremities (feet, etc.) Increases risk of cardiovascular disease, renal failure, and damage to small blood vessels and nerves
adipose tissue releases
peptide hormones called adipokines which carry info about fuel stores to brain
hormones that control eating
alpha MSH suppresses appetite- eat less metabolize more neuropeptide Y (NPY)- inceat more metabolize less
Both leptin and insulin are peptide hormones both trigger production of ( ) and act upon what cells
acts on anorexigenic neurosecretory cells to increase production of alpha MSH
Leptin and insulin also act on orexigenic neurosecretory cells to inhibit the release of
NPY
leptin
Stimulates production of anorexigenic (appetite-suppressing) hormones Stimulates sympathetic nervous system Triggers cascade that regulates gene expression May be involved in hard-wiring of neuronal circuits during development
neuropeptide Y
orexigenic (appetite-stimulating) hormone Sends signal to eat Levels rise in starvation Levels rise in ob/ob and db/db mice Inhibited by leptin and insulin
alpha melanocyte stimulating hormone (a-MSH)
is an anorexigenic (appetite-suppressing) hormone Sends signal to stop eating Release is stimulated by leptin Acting through melanocortin 1 receptor, α-MSH stimulates the production and release of melain, by melanocytes in skin and hair.
leptin increases transcription of gene yielding
a-MSH
what happens to leptin receptor when leptin binds
it dimerizes and JAK phosphorylates 2 Tyr in receptor dimer
after JAK is phosphorylated in the receptor dimer what happens
Receptor becomes docking site for STAT3, STAT5, STAT6 (Signal Tranducers and Activators of Transcription) STATs are phosphorylated by the same JAK
once that STATs dimerize they
move the nucleus stimulate transcription of gene for precursor to anorexigenic a-MSH
JAK-STAT mechanism of leptin signal transduction
folic acid helps treat
stroke and heart attacks
high blood glucose levels cause hemoglobin to become
glycosylated
insulin also inhibits appetite by interacting with
hypothalamus
The orexigenic neurons have insulin receptors to Regulate
wakeful appetite
insulin binding to orexigenic neurons
Inhibits release of appetite-stimulating NPY Stimulates appetite-suppressing a- MSH
there can be cross talk between
insulin and leptin pathways
Leptin makes liver and muscle more sensitive to
insulin common 2nd messenger may enable leptin and insulin to trigger same downstream pathways
type 2 diabetes epidemic
90% of diabetes cases are type 2 300 million diagnosed cases world-wide and growing Hallmark is resistance to insulin Initially, the body responds by making more insulinOver time, some individuals have to supplement with insulin
type 2 diabetes syndrome
Believed to affect 27% of adult U.S. population Cluster of symptoms along with insulin resistance:Abdominal obesity High triglycerides (TAGs) Low HDL Good high-density lipoprotein (HDL) cholesterol They act as cholesterol scavengers, picking up excess cholesterol in your blood and taking it back to your liver where it's broken down. The higher your HDL level, the less "bad" cholesterol you'll have in your blood. High blood pressure Elevated blood glucose (but may not be full-blown diabetic) Often includes other signs of inflammation
functions of nucleotides
Energy for metabolism (ATP) Enzyme cofactors (NAD+) Signal transduction (cAMP)
functions of nucleic acids
Storage of genetic info (DNA) Transmission of genetic info (mRNA) Processing of genetic information (ribonucleic acid enzymes) Protein synthesis (tRNA and rRNA)
central dogma
replication - DNA- transcription- RNA- translation- protein
nucleotide=
nitrogenous bases pentose phosphate
nucleoside=
nitrogenous base pentose
nucleobase=
nitrogenous base
pentose in nucleotides
beta-D-ribofuranose in RNA beta-2-deoxy-D-ribofuranose in DNA
nucleobases
Derivatives of pyrimidine or purine Nitrogen-containing heteroaromatic molecules Planar or almost planar structures Absorb UV light around 250–270 nm
pyrimidine bases
Cytosine is found in both DNA and RNA Thymine is found only in DNA Uracil is found only in RNA
purine bases
adenine guanine
B-N-glycosidic bond
in nucleotides the pentose ring is attached to the nucleobase through this bond bond is formed to position N1 in pyrimidines and to position N9 in purines bond is stable toward hydrolysis especially in pyrimidines
how does B-N-glycosidic bond get cleaved
catalyzed by acid
nucleotide and nucleic acid nomenclature
what minor nucleoside (modification done after DNA synthesis) in DNA is common in eukaryotes, also found in bacteria
5-Methylcytosine
what minor nucleoside (modification done after DNA synthesis) in DNA is common in bacteria, but not found in eukaryotes
N6-Methyladenosine
epigenetic marker
Way to mark own DNA so that cells can degrade foreign DNA (prokaryotes) Way to mark which genes should be active (eukaryotes) Could the environment turn genes on and off in an inheritable manner? Foreign DNAs (not methylated) that are introduced into the cell are degraded by sequence-specific restriction enzymes and cleaved
DNA can be methylated in
epigenetic
hydrogen bonding between what base pairs is easier to break and why
AT because it has 2 H bonds while CG has 3 bonds
mRNA - messenger RNA
Is synthesized using DNA template Contains ribose instead of deoxyribose Contains uracil instead of thymine One mRNA may code for more than one protein Together with transfer RNA (tRNA) transfers genetic information from DNA to proteins
gene expression control in Eukaryote-
Monocistronic- one promotor controls expression of one gene
gene expression control in prokaryotes-
polycistronic- one promotoer controls several genes
Palindromic sequences can form
hairpins and cruciforms
Different strands are read like
a palindrome read in reverse
same strands are read like
mirror- they repeat
When only a single DNA (or RNA) strand is involved, the structure is called
a hairpin
Tm of DNA
heat denaturation of DNA it depends on pH and ionic strength and on the size and base composition of the DNA. Tm= 50% of DNA becoming single stranded
factors that affect DNA denaturation
The midpoint of melting (Tm) depends on base composition High CG increases Tm
Tm depends on DNA length Longer DNA has higher Tm Important for short DNA
Tm depends on pH and ionic strength High salt increases Tm
what bases melt at a lower temp
AT
increase C and G nucleotides what happens to Tm graph
the temp increases linear
Molecular Mechanisms of Oxidative and Chemical Mutagenesis
Oxidative damage Hydroxylation of guanine Mitochondrial DNA is most susceptible
Chemical alkylation Methylation of guanine
Cells have mechanisms to correct most of these modifications
alkylating agent
chemical agents that cause DNA damage S-adenosylmethionine nitrogen mustard dimethylsulfate dimethylnitrosamine
which alkylating agent acts enzymatically
S-adenosylmethionine
molecular mechanisms of radiation induced mutagenesis
UV light induces dimerization of pyrimidines; this may be the main mechanism for skin cancers.
Ionizing radiation (X-rays and y-rays) causes ring opening and strand breaking . These are difficult to fix.
Cells can repair some of these modifications, but others cause mutations. Accumulation of mutations is linked to aging and carcinogenesis.
deamination is removal of
NH group
depurination is removal of
prune group through hydrolysis
process by which DNA gets unwound from histones
acetylation
start codon
AUG (RNA)
stop codon
UAA UAG UGA (RNA)
what other amino acid only has one codon - and what is the code
Trp - UGG
bacteria also contains extra chromosomal double stranded circular
plasmids about 2000-10000 base pairs
E. coli
4,639,675 DNA 1 chromosome about 4400 genes
true or false: circular plasmids can be swapped easily in bacteria
true
what is one way bacteria can acquired antibiotic resistance
plasmid exchange
eukaryote DNA is in
multiple discrete chromosomes
composition of human genome
-only a small fraction (1.5%) of the total genome encodes for proteins -Some DNA regions directly participate in the regulation of gene expression (promoters, termination signals, etc.) -Some DNA encodes for small regulatory RNA with poorly understood functions -Some DNA may be junk (pieces of unwanted genes, remnants of viral infections
exons
are expressed sequences (translated into amino acid sequence) Exons account for only 1.5% of human DNA!
introns
are regions of genes that are transcribed but not translated They do not encode polypeptide sequence
introns are removed after
transcription and the exon mRNA sequences are spliced together and creates “mature transcripts”
transposons are
sequences that can move within genome