6-1 (8.11.16) Flashcards
chromatin consists of
DNA
histone
non-histone
nucleosome is composed of (NOT the def of complex of histones)
nucleosome core particle (NCP) and DNA
Ribosomes
”” often occur on the ONM
1 stains lightly: its genes are actively transcribing
2 stains darkly: its genes are transcriptionally inactive.
1 Euchromatin
2 Heterochromatin
nuclear pore contain “” channels
what goes thru them
aqueous
ions and small molecules
large proteins enter via active transport and require what
localization signal
lamins are “” filament
intermediate
function of nucleolus
makes ribosome subunits
cell phase eq
G1 + S + G2 + M (mitosis + cytokinesis)
division results in “” (adj) cells
BUT
genetically identical
daughter cells have dif forms
condensation purpose
prevent chromosomes from tangling together in mitosis
chromosomes are maximally condensed at “”
metaphase
disengagement - when does that occur
describe it
G1
centrioles move apart within centrosome
a new centriole is called
PRO centriole
cells at what phase are used for KARYOTYPE analysis
why
metaphase
chromosomes are maximally condensed
what serves as MT organizing center
centrosomes
purpose of astor MT
anchor poles to cell periphery
daughter chromatids are held together at centromere VIA what protein
CO-HESIN
define mitosis
mother -> 2 cells (genetically identical to m)
four steps of mitosis
prophase
metaphases
ana
telo
cytokinesis begins when
ana or telo
purpose of astor microtubules
anchor and pull
”” drives telophase
Dephosphorylation
read: D causes nucleus to reassemble
D causes spindle MT to disappear
D causes chromosomes to decondense
contractile ring forms where
then what forms
last step of contractile ring
bt membranes at anaphase
cleavage furrow
daughter cells break apart
the contraction caused by “” and “” causes cleavage furrow to form
actin
myosin
apoptosis def
programmed cell death
read: apoptosis AVOIDS inflammation
what causes i then
-
necrosis
do prokaryotes have actin, MT, and IMF
NO
prokaryotic version of cilia
flagella
read: P DNA lacks histones
-
dif bt chromatid and chromosome
when chromatids separate, they become chromosome
central dogma is
DNA -> transcription -> RNA -> translation -> protein
types of RNA (5)
rRNA mRNA tRNA snRNA (small nuclear) RNAi (miRNA, siRNA)
tRNA role
transfer amino acid onto polypeptide chain
RNAi role
snRNA role
miRNA - translation inhibit
siRNA - mRNA degrade
RNA splicing (introns, exons) AND telomere maintenance
80% of all cellular RNA is this type of RNA
smallest RNA
15% of all cellular RNA is this
rRNA
tRNA
tRNA
at least 1 tRNA for # AA
20
in eukaryotes, what is a weird thing about mRNA
why
translated mRNA is NOT exact copy of DNA
bc post transcriptional changes
three main steps of RNA synthesis in PROKARYOTES
#1. initiation #2. elongation #3. termination
P RNA synthesis
Initiation steps
-RNA polymerase holoenzyme binds to promoter region
what’s interesting about promoter region
it is NOT transcribed
How does RNA polymerase RECOGNIZE promoter region
in RP, holoenzyme contains a sigma factor
within the promoter region are what
(for PROKARYOTES)
ex (2)
highly conserved consensus sequences
ex:
PRIB-NOW box (10 nucleotides before coding region)
35 hexamer
P RNA synthesis
Elongation steps
read: once RNA transcription begins, sigma factor dissociates
what’s key dif bt RNA and DNA polymerase
RNA P = no proofreading ab
P RNA synthesis
Termination steps
dep
could be RHO dependent or independent
dep
-RHO factor follows RNA P; RHO factor (helicase protein) recognizes rut sequence (termination signal)
Rho-indep termination
newly made RNA has a sequence that allows for creation of hairpin structure
RNA sequence at 3’ end is rich in U’s, which bind weakly to A’s on DNA
new RNA separates from DNA
why does U bind to A’s
A has two H bonds
palindrome def
ABC = BCA
the hairpin loop formed in R-IND termination results bc
palindrome
euk gene expression is regulated by what (dif from P)
PROMOTER plus chromatin enhancer inhibitor
read: also euk RNA is dif bc it is modified after transcription
-
euk transcription initiation - name the 3 dif consensus sequences found in promoters
consensus sequence (in order, closest to farthest)
- TATA/Hogness box
- –similar to Pribnow box
- GC box
- CAAT box
- –much more farther upstream than TATA
the EUK consensus sequences are called what
why
cis acting DNA elements
on the same strand of DNA that is being transcribed
where is enhancer
purpose
region of DNA up/down stream of promoter
transcription factors bind to enhancer AND it stabilizes initiation complex
enhancer is cis acting
while “” is trans acting
enhancer binding transcription factor
read: trans means from dif gene
euk have 3 types of “” polymerases
RNA
clinical: “” found in poisonous mushrooms INHIBITS what
alpha A-MAN-I-TIN
RNA polymerase
euk transcription
steps of gene expression
1. chromatin structure regulates gene expression
what cannot be transcribed vs what can
why
CANNOT: hetero-chromatin
tightly wound
CAN: euchromatin
loosely wound
what kind of DNA Is generally not transcribed
methylated DNA
what relaxes chromatin structure to allow for more gene transcription
acetylation of histones
euk mRNA undergoes modifications…what are they
5’ capping
poly A tail
removal of introns
define intron
mRNA that doesn’t code for protein
what combination permits the start of translation
5’cap
define spliceosome
splices mRNA to remove introns AND joins exons together to yield mRNA
what accounts for 15% of all genetic diseases
mutation at splice sites
read: alternative splicing is a way of diversifying the protein encoding capacity of limited # of genes
-
give ex of alternative splicing
-just give key fact
key: TRO-PO-NIN
read: BUT alternative splicing of its gene sequence results in dif isotypes
look for UP level of cardiac specific troponins if suspect heart damage
what proteins are involved in transport of fats
two forms
why truncated
Apo-lipo-proteins
A B100
- liver
- untruncated
A B48
- small intestine
- truncated
RNA editing made an error; get early stop codon
”” form is the relevant form in mammalian physio
L form
what are the two forms of AA
L and D forms
what’s special about GLYSINE
it is symmetric, therefore does NOT exist in L and D forms
formation of peptide bond results in a loss of charged state of stuff
-
proline disrupts “” structures
more specific
secondary
interrupts alpha-helices
what AA forms disulfide bonds
cysteine
”” “” and “” can accept phosphate groups
why
Serine, threonine and tyrosine
OH
phosphorylated enzyme = spot opens up and substrate can bind
-
define glycosylation
describe the two types
1 Serine or Threonine = 0 glycosylation
addition of oligosaccharide to protein
glycoproteins identity (typical, 2)
secreted (hormones)
receptors
beta and alpha chain in insulin are held together by what
disulfide bonds
alpha helix and beta sheet
-(1/2) structure
secondary
describe secondary and tertiary structure
2: folds into a repeating pattern bc of H bond interactions
3: 3-D folding bc of side chain interactions
read: ex is disulfide bonds
when does quaternary structure arise
proteins have MULTIPLE polypeptide chains
read: don’t occur when protein has just ONE polypeptide chain
what protein aids in protein folding
describe their type
why called this
chaperone
heat shock
chaperone synthesis UP when subjected to higher temp
clinical application of denatured protein (relate to mad cow disease)
-another name for disease
C-Jacob Disease
prion that is a misfolded version of a normal prion -> ab becomes template -> ab ACCUMULATE -> loss function of neurons
HH equation predicts what
AA’s side chain charge
3 classes of proteins
fibrous
globular
membrane
charge of side chains is determined by what
pK
what is the only AA with a NH in a ring?
pro-line
name two post translational modification
- protein phosphorylation
- glycosylation
protein misfolding 2nd example (other than mad cow disease)
AMY…
Alzheimer’s disease
