Exam 4 Lectures 21-24

what converts Acetyl-CoA to Malonyl-CoA

Acetyl-CoA carboxylase

what does lipoprotein lipase do

breaks down the triglycerols in the lipoproteins to smaller fatty acids and monoglycerides

what do alpha cells do

secrete glucagon

what do beta cells do

secrete insulin

what do delta cells do

secrete somatostatin

what does somatostatin do

inhibit insulin and glucagon secretion

how does glucose enter beta cells

through GLUT2

what triggers exocytosis

high concentration of Calcium

what is type 1 diabetes

insufficient production of insulin cells

what are characteristics of type 1 diabetes

due to autoimmune destruction of beta cella
develops early in life

what is type 2 diabetes

insulin resistance

what are characteristics of type 2 diabetes

develops in late adulthood
associated with obesity

what are the symptoms of both types of diabetes

blood sugar becomes elevated
body tries to dilute the glucose --> excessive urination and thirst

what is a symptom of type 1 diabetes

fat breakdown is accelerated --> leads to high production of ketone bodies
some of the ketones are ketoacids, raise blood [H+] leads to ketoacidosis

what is a high fasting blood glucose level

126 or higher

what is a low fasting blood glucose level

50 in men or 40

what are the long- term effects of elevated blood sugar

increased risk of CV disease, renal failure, and damage to small blood vessels and nerves

what do adipose tissues release

peptide hormones called adipokines

what do adipokines do

carry information about fuel stores to the brain
includes leptin and adiponectin

what is leptin

an appetite suppressant and stimulates production of anorexigenic hormones

what NT does leptin inhibit

neuropeptide Y

what NT does leptin activate

alpha-MSH

what is neuropeptide Y

an orexigenic
sends signal to eat
levels rise in starvation
inhibited by leptin and insulin

what is alpha-MSH

an anorexigenic
sends signal to stop eating

JAK-STAT mechanism

leptin binds to leptin receptor monomer
activates the dimerization of the the leptin receptor
travels into the nucleus and induce transcription

what percent of diabetes cases are type 2

90%

what are symptoms of insulin resistance

high triglycerides
low HDL
high blood pressure
elevated blood glucose

what are the nucleotide functions

energy for metabolism (ATP)
enzyme cofactors (NAD+)
signal transduction (cAMP)

what are the nucleic acid functions

storage of genetic info (DNA)
transmission of genetic info (mRNA)
processing of genetic information (ribozymes- ribo nucleic acid enzymes)
protein synthesis (tRNA and rRNA)

what is a nucleotide

nitrogenous base
pentose
phosphate

what is a nucleoside

nitrogenous base
pentose

what is a nucleobase

nitrogenous base

what are nucleobases

derivatives of pyrimidine or purine

at what nm do nucleobases absorb

250-270 nm

what are the pyrimidines

C, T, U

what are the purines

A and G

how are nucleotides in the pentose ring attached to the nucleobase

N-glycosidic bond

why is the N-glycosidic bond formed

to position N1 in pyrimidines
to position N9 in purines

what modification is common in eukaryotes but also found in bacteria

5-Methylcytosine

what modification is common in bacteria only

N6-methyladenosine

what are epigenetic markers

way to mark own DNA so that cells can degrade foreign DNA (prokaryotes)
way to mark which genes should be active (eukaryotes)

how many H-bonds to A-T linkages have

2

how many H-bonds to G-C linkages have

3

what does monocitronic mean

one promoter controls expression of one gene

what does polycistronic mean

one promoter controls expression of multiple genes

are eukaryotes monocistronic or polycistronic

monocistronic

are prokaryotes monocistronic or polycistronic

polycistronic

what do palindromic sequences of DNA form

hairpins and cruciforms

how is denaturation of DNA induced

high temperature or change in pH

how is DNA denaturation reversed

annealing

what does a southern blot do

detect DNA from toxins

what does a northern blot do

detect RNA

what does a western blot do

use antibody to detect protein

what are the spontaneous DNA mutations

deamination- very slow reaction
depurination- N-glycosidic bond is hydrilyzed

what are the chemical mutations

oxidative damage- hydroxylation of guanine, mitochondrial DNA is most succeptible
chemical alkylation- methylation of guanine

what are the radiation- induced mutations

UV light- induces dimerization of pyrimidines
ionizing radiation- causes ring opening and strand breaking

what are the RNA viruses

COVID and HIV

what do bacteria contain

extra-chromosomal, double-stranded circular plasmids
plasmid exchange is one way bacteria acquire antibiotic resistance

how many chromosomes do humans have

46 chromosomes

what percent of our DNA encodes for proteins

1.5%

what are viral genomic DNA associated with

capsid proteins

what are exons

expressed sequences of DNA

what are introns

regions of genes that are transcribed but not translated

what are transposons

sequences of DNA that can move around
account for ~50% of the human genome

what are simple sequence repeats

short (10bp or less) sequences repeated millions of times

what is the telomere repeat sequence in humans

TTAGGG

how are telomeres associated with cellular aging

telomeres are shortened after each round of replication
human cells divide about 52 times before losing the ability to divide again

what is chromiatin

fibers of protein and DNA and small amount of RNA

what are histones

small proteins with lots of basic (Lys, Arg) residues

how are histones modified

methylation, acetylation, ADP-ribosylation, phosphorylation, glycosylation, sumoylation, ubiquination

how much DNA is wrapped around a histone

beads are ~146 bp of DNA wrapped around 8 histones

what are the higher order structures of nucleosomes

solenoid model and zigzap model

which way does DNA synthesis occur

addition of new nucleotides to the 3' end

how are Okazaki fragments spliced together

by DNA ligase

what are exonucleases

cleave bonds that remove nucleotides from the ends of DNA

what are endonucleases

cleave bonds within a DNA sequence

what is a primer

short strand complementary to the template
contains a 3-OH' to begin the first DNA polymerase-catalyzed reaction

what is processivity

the number of nucleotides added before dissociation

what does DNA polymerase 1 do

is abundant but is not ideal for replication, primary function is to clean up

what does DNA polymerase 3 do

is the principle replication polymerase

what do DNA polymerases 2, 4, and 5 do

they are involved in DNA repair

what does DNA polymerase 1 also do

moves ahead of the enzyme, hydrolyzes things in its path
does nick translation
this activity is in the Klenow fragment

how many subunits doe DNA polymerase 3 have

10

what is a replisome

the set of enzymes and proteins required for DNA replication in E. coli

what is included in a replisome

helicases, topoisomerases, DNA-binding proteins, primases, DNA ligases

what is oriC

initiation of replication in E. coli
contains A-T rich DNA unwinding elements

what makes the RNA primer

primase

what adds nucleotides to the leading strand

DNA pol 3

does the same DNA pol 3

yes, the DNA of the lagging strand loops around

what brings the okazaki fragments together

DNA ligase

how does replication get terminated

replication forks meet at a region with 20bp sequences: Ter

what is Ter

a binding site for the protein Tus

how quickly does eukaryotic replication occur

slowly, ~50 nucleotides/ sec
20x slower than E. coli

how many DNA polymerases are used in Eukaryotic replication

3

what does DNA polymerase alpha do

probably used to make primers for Okasaki fragments

what does DNA polymerase delta do

used in leading and Okasaki synthesis

what does DNA polymerase epsilon do

used in DNA repair