Exam 3 Questions With 100% Complete
Solutions
Nucleus - CORRECT ANSWER-A part of the cell containing DNA and RNA and
responsible for growth and reproduction
-average diameter = 6 micro meters, volume up to 40 micrometers ^3 is about 8% of
cell volume.
-found in eukaryotes
-orgin: membrane surrounded an early prokaryotes nucleoid.
-Mesosome: folded invaginations in the plasma membrane of bacteria that are produced
by the chemical fixation techniques used to prepare samples for electron microscopy.
components of the nucleus - CORRECT ANSWER--Nuclear Envelope: double
membrane bound organelle, composed of an outer membrane, an inner membrane and
a perinuclear space.
-Nuclear Pore Complexes = has about 2000/nucleus and some 450+ nucleoproteins(30
diff kinds).
-chromatin - the genetic stuff inside of the nucleus is.
DNA complexed with histone proteins and acidic nuclear proteins, heterochromatin
(condensed and inactive - dark in EM's)
,euchromatin(less dense and active - greyish in EM's)
Nucleolus - a dense spherical structure... the site of rDNA genes which make rRNA. in
the humane genome there are 5 chromosomes with nucleolar rDNA genes.
Nucleoplasm - soluble phase of the nucleus that contains enzymes, RNAs, solutes,
chromatin, etc.. similar to cytoplasm.
Nuclear pore structure - CORRECT ANSWER-- Elaborate structure of about 100
proteins
- Small water soluble molecules pass unimpeded
- Larger molecules pass only with "approval"
- OUTWARD- completed mRNA, assembled ribosomal subunits
-Cytosilic fibrils are long string like structures, nuclear lamina is right under the innner
nuclear membrane, water and small molecules come in and aout, but proteins gets
trapped inside, nuclear basket at the bottom.
Nuclear Transport - CORRECT ANSWER-1960s - Feldherr injects gold particles in
unicellular amoebas, TEMs showed particles congregating at pores within a minute;
within 10 min gold was in nuelcoplasm.
1970's - used fluorescent tagged proteins - showed proteins of less than 60,000 MW
passed.
1980's - ron laskey studied a nuclear transport protein.. nucleoplasmin and radioactivley
tagged it and used audiography to follow its movement.
,- in the experiment panel a shows nucleoplasmin (head and tail regions) enters the
nucleus and suggest proteins has an aa sequence that helps mobility. panel b - where
is signal in head or tail? - they split and tagged tail entered nucleus, thus it holds aa
sequence. Panel c- where in the tail - cut tail into pieces and spliced to a non-nuclear
cytoplasmic protein..
Result: nucleoplasmin holds a 17 amino acid sequence that targets transport into
nucleus, it is known as the nuclear localization sequence. suggests a likely mechanism
for nuclear protein transport.
Chromatin - CORRECT ANSWER-heterochromatin (condensed & inactive - dark in
EM's) euchromatin (less dense & active - greyish in EM's)
Nucleolus - CORRECT ANSWER-Site of transcription and processing of rRNA and of
assembly of preribosomal subunits. Thus it consists of ribosomal DNA genes, RNA, and
ribosomal proteins, including RNA polymerases, imported from the cytosol.
Nucleoplasm - CORRECT ANSWER-viscous fluid enclosed by the nuclear envelope
chromosome structure - CORRECT ANSWER-this goes from a DNA molecule in a
double helix to a "beads-on-a-string" structure consisting of strings of DNA wrapped
around beads of nucleosomes. These get coiled, then form a single fiber hollow
cylinder, and then go onto a chromosome.
Mitochondria - CORRECT ANSWER-site of: cellular respiration - aerobic [redox rx's]
oxidation of CH2O --> CO2 + H2O, gas exchange in cell - CO2 is released and O2 is
taken up and reduced to H2O. KREBS cycle - an aerobic pathway that oxidized
pyruvate CO2 + H2O
ETC chain, ATP snythase, oxidative phosphorylation which makes atp
, role of conversion of covalent bond energy in food molecules into celluar atp energy.
couples redox transfers of e- and H+ protons... via ATP synthase to make atp.
parts of mitochondria - CORRECT ANSWER-Janus green-B colorizes when it is an
oxidizng agent and accepts hydrogens produced by mitochondrial cellular respiration.
parts are best seen via fluorescent dyes, TEMS and false colorized EMS
-it is a double membrane bound organelle: Has an inner membrane and an
outermembrane. Outermembrane contains transport protein porin (passage of
moleucles up to 5K MW). inner membrane is very selectivley permable(not permeable
to most molecules)
-peri-mitochondrial space = area where H+ accumulates
-cristae - inner membranes that hold the respiratory assemblies of ETC
-mitoplasm = aqueos compartment = dna, ribosomes, KC enzymes, etc
structure: elongate cylinders to oblate spheroids, 3-5 micrometers long
number: 20 to 1000 per cell; the more active a cell = the greater number
contents: has its own circular dna - 16,569 nucleotide pairs, about 37 genes, has its
own ribosomes and protein synthesizing abilities, holds enzymes for cellular respiration