General Exam IV Qs Flashcards
What is the defining organelle of euks?
(and what it contain?)
The nucleus!
Contains genomic DNA
What is the role of the nucelus?
Stores and protects genetic information, regulated expression, maintains it and so forth
-also forces spatial and temporal separation of transcription and translation
Bacterial gene expression:
what happen go!
(bonus for how different from euks)
-purple chain mRNA
-RNA polymerse main circle
-ribosome second big circle (ribosome will attach and start transcbing)
-growing peptide
9 RNA polymerases
-blobs at top are ribosomes and peptides theyre producing
-transcriptiona nd translation happening at same time messenger RNA is being synthesized
dear god do see the slide Unit III pg 4
Gene expression in a euk cell:
Transcription and
Translation: __________
and ___________
separated”
Transcription and
Translation: spatially
and temporally
separated”
For Gene expression in euks, what occurs in the nucleus and what occurs in the cytoplasm?
Transcription and Processing occur in the nucleus
Translation occurs in the cytoplasm
Describe transcription in euks
(where happen, and what make?)
Occurs in Nucleus
makes pre-mRNA (bacs dont do this)
Describe Processing (in gene transcription) in euks
(where happen, and what make?)
in nucleus,
makes mRNA,
mRNA reads
5’-cap
5’ (backwards G)———- 3’ (poly A tail, added by polyA polymerse, As not encoded in DNA)
Protein looks for those 3 backwards Gs
Both must be there to help them become mRNA
There are sections of exons in the sequence, and introns
The introns then gotta be removed (splicing)
So then exons are joined together to form coding sequence
5’ cap
-poly A tail
-removal of introns (all three happening at same time)
**do see slide Unit III pg 5
Are exons or introns removed before the remaining join together to form the coding sequence?
(bonus for the name of this event)
The introns then gotta be removed (splicing)
So then exons are joined together to form coding sequence
Describe Translation in euks
(where happen and what is synthesized?)
Occur in cytoplasm
Translation -> proteins synthesized!
DNA scattered through nucleus, there’s a nucleolus, area of intense transcription activity
-nucleoolis appears as large stain, due high trsanscription to ribosomal proteins
(do review slide for visual, unit III pg 5)
What is the nucleolus?
(do what and look like what on microscope slide?)
area of intense transcription activity
-appears as large stain, due high transcription to ribosomal proteins
How does a euk nucleus package its DNA?
(bonus for how bacs do it)
Use of histone protein complexes
forms a histone octomer (2 units each)
one additional histone
-bacs use (something omg sorry I forgot!) cations!
Histone proteins form an _________
octomer
Histone proteins form an octomer,
how many times does DNA wrap around this octomer, what is this called, and what attracts DNA to the octomer?
A lot of positively charged amino acids
-DNA naturally attracted
-DNA is wrapped around octomer to form nucleosome (wraps twice)
Name for histone octomer/DNA complex?
Nucleosome
How many bps of DNA make direct contact with the histone proteins (core)?
~160 base pairs of DNA make direct contact with the histone proteins (core)
Name of histones, and which one is unique?
(how many form the main octomer complex?)
H2A-
H2B-
H3-
H4-
H1- special, not in the main complex, binds at the conjunction where one strand comes in/out to twist a little bit
Nucleosome:
What is this?
and ~how many bps will one form?
basic unit of DNA packaging
-About every 200 base pairs, another nucleosome will form
Why do all this histone business?
-All done to make DNA shorter, you gotta make it shorter
What’s special about H1 histone protein?
(hint: histone not in the complex)
Histone H1 binds at the conjunction where one strand comes in/out to twist a little bit
“11nm fiber”
the 11nm fiber is kinda first stage of supercoiling of DNA (after nucelosome complexes of histone proteins and DNA form), later forms the 30 nm fiber
What little structure enables formed nucleosomes to reach out and coil together tightly?
(bonus: forming the what?)
-There’s a little tail protein branching out from the nucleosomes so they can interact with each other and pull tighter forming the 11nm fiber
Unit III pg 7
Why called 11nm fiber?
the diameter of the fiber structure formed by the coiling and packing of nucleosomes in the process of DNA compaction. It be one of the early stages in the hierarchical organization of DNA
11 nm fiber then compacts further to form the _______
30 nm fiber,
11nm fibers associate with each other and coil up together to from the 30 nm fiber (diameter)
Then protein scaffold formed to make look like WWWWWWW (sorta, review slides
Unit III pg 7
Finally, 30 nm fiber is condensed to what structure?
Packing ratio how many times shorter?
Eventually that loop gets fully packaged down to mitotic chromosome,
packing ratio ~8,000x shorter
Starting with strand of DNA, then adding histones etc, describe the levels of compaction
(in euks)
-DNA wraps twice around octomer of histones to form nucleosome (H1 at end for twisting outside complex)
-nucleosomes be pulling each other near with little tail proteins forming the 11nm fiber
-The 11nm fiber then coils tightly to form the 30nm fiber
-Finally, the 30 nm fiber then compacts to form mitotic chromosome
(packing ratio ~8,000x shorter )
Nucleur pore:
What it do?
-very tightly controlled protein complex that makes the gate
-usually closed, needs ATP to open it up, only does that when mature RNA knocks on the door
**review slides omg unit III pg 8
Name of the guys that carry things in and out of the nuclear pore?
-exportons and importons will bind and carry things through the pore
Nuclear pore/Nucleus?:
What is the physical structure?
(hint membranes, how many and look like what)
two membranes: between each nuclear pore, interconnected like pancake that folded
-Perinuclear space in the middle
-lining the inside of membrane nuclear lamina (made of lamins long protein filaments that are interwoven)
This one is cloth like, lining the inside, maintaining integrity
What is the lining of the inside of the nucelus’s like/composed of?
(right outside/inside depending on perspective of inner membrane I think????)
-lining the inside of membrane nuclear lamina (made of lamins long protein filaments that are interwoven)
This one is cloth like, lining the inside, maintaining integrity
unit III pg 8
Rough endoplasmic reticulum-
Found where, covered in what, and do what?
-Found right outside nucleus
-covered in little dots of ribosomes
-just an extension of the nuclear membrane
-Very different proteins and functions to the nucleus (proteins about translation, inside nucleus about protecting the DNA)
Mitochondrion: (singular)
basic components/function
-blue stuff inside mitochondrion: matrix
-pink infoldings of membrane are cristae (infolds bc it gives more surface area for the ATP synthesis)
-want as many proteins in inner membrane as possible to make that ATP
-outer membrane is stuff sac like for sleeping bag
**see unit III pg 12
What is the membrane structure for a mitochondrion?
Double membrane structure (not connected, cant take a stroll inside like the double nuclear membrane)
mitochonrion has its own __________
and how many are usually found in each cell??
genome- singular circular chromosome
-each cell has a lot of mitochondria (skin couple hundred, muscle thousands probably)
How do mitochondrions replicate?
(similar to how what other dudes do it?)
-most organelles tied to mitosis
BUT mitochondria can replicate autonomously whenever it feels the cell needs more energy
-replicates automonously within the cell to meet cellular energy demands
(bacs use binary fission to replicatie, same with mitochondria)
What are mitochondrions real specilaized at
-Specialized in energy production (ATP) via an electron transport chain
What does the mitochondrion electron transport chain for ATP synthesis look like?
**dear god do review slide unit III pg 13
-enzymes for glycolysis in cytoplasm (EMP, same as bacs)
2 pyruvtars to inside matrix to acetyl COA
NADHs go to electron transport chain to be recycled (inner membrane)
80% protein
-NADH drop off electrons at complex I, protons pumped outward to cytoplasm
-concentraiton of Hs is really low inside matrix, hence proton gradient is formed (even though outer concentration aint that high, higher than in matrix)
-Water binds H, and then only way the Hs can get back in is through ATP synthase, shaft turns, ATP produced
Where does the Krebb’s cycle occur in a mitochondrion?
-Krebbs cycle is in matrix in the mitochondrion
What’s the deal with the H’s in the mitochondrion ?
(what area most concentrated of the gradient, and what is the only way for Hs to get back in the cell)
-concentration of Hs is really low inside matrix, hence proton gradient is formed (even though outer concentration ain’t that high, higher than in matrix)
-Water binds H, and then only way the Hs can get back in is through ATP synthase, shaft turns, ATP produced
Chloroplasts! How many membranes they got?
3 membranes (outer and inner, and then thylakoids)
Thylakoid membrane holds the chlorophyll
Chloroplasts!
How many membrane, genome what, and replicates how?
3 membranes (outer and inner, and then thylakoids)
Thylakoid membrane holds the chlorophyll
-Chrolopast genome (circle like the bacs)
-replicate autonomously to meet energy demands of cell
What are chloroplasts totally fire at doing?
-Specialize in converting solar energy into cellular energy (ATP) and reducing power (NADPH) that can drive the fixation of carbon dioxide into organic molecules
20/10 would recommend reviewing the chloroplast membrane/cell structure
Unit III pgs 15-17
What is the stroma in a chloroplast?
-fluid-filled region encased by the inner membrane of the chloroplast.
(It be hostin’ various enzymes and substances that be crucial for the process of photosynthesis, the magical conversion of sunlight into energy.)
What’s the deal with the chloroplast proton gradient?
-Protons are pumped inward into the thylakoid (every protron accounted for and trapped in there)
-chloroplasts more efficient (than mitochondrions?)
What happens to the pH inside the thylakoid with the addition of light?
bonus: name of this inside space
-pH inside the thylakoid drops with addition of light
(becomes more acidic bc more H’s poppin in)
Thylakoid lumen (inside) Hs accumulate
How can H’s leave the thylakoid lumen ?
(chloroplasts)
ATP synthase channel only exit for Hs
ELectron chain for mitochondrions vs chloroplasts
Where the electrons come from? And how
-Electron that goes through mitochondrial ETC comes from NADH (from krebbs & glycolysis)
-Electron through ETC in chloroplast comes from H2O (releases O2)
How are electrons refilled with m n m energy in chloroplasts?
-Energy from sun charges up the empty electrons, fills up to then pump the protons
Photosystems II and I,
What happens, and who goes first?
**review slides, unit III pg 18
Photosystem II- absorbing photons and stripping electrons from water molecules, releasing oxygen in the process.
These energized electrons then go through electron transport chain.
Photosystem I- takes electrons that have traveled through the electron transport chain and further boosts their energy. PSI then passes these high-energy electrons to another carrier, eventually contributing to the formation of NADPH
protein pigment complexes
(they be catching the sunlight, giving enough energy to drive otherwise thermodynamically unfavorable reactions)
Do there be energy to be got from H2O?
Noo ain’t no energy to be got from H2O, they’re very low energy electrons
Photosystem II:
absorbing photons and stripping electrons from water molecules, releasing oxygen in the process.
These energized electrons then go through electron transport chain.
Photosystem I:
takes electrons that have traveled through the electron transport chain and further boosts their energy. PSI then passes these high-energy electrons to another carrier, eventually contributing to the formation of NADPH
What is Endosymbiotic theory?
The theory that nucleii mitochondria, and chloroplasts originated as separate cells who were inducted into cells to form euks
Nucleus probably used to be a(n) _________
(endosymbiotic theory)
Archea
-All nucleus related genes closest to archeal genes (DNA polymerase, RNA, histone proteins etc)
-Cytoplasm related genes closest to bacteria: (krebbs, cycle, glycolysis enzymes, genes in detoxification, stress response etc suff like that)
-Archea was so effective at protecting dna/expressing it etc, that eventually the archea lost their metabolic genes but retained nucleus-related genes
Why would archea develop into the nucelus?
-Archea was so effective at protecting dna/expressing it etc, that eventually the archea lost their metabolic genes but retained nucleus-related genes
-Suggestive evidence: archea have histones -> nucleosomes
-Archeal gene expression very similar to euks, different to bacs
-protein binds to promotor and start codon, then starts transcribing
-Archeal proteins:
-dna polymerase, rna polymerase, transcription factors
What is RNA polymerase like in euks and archea?
RNA polymerase in euks and archea is real blind, gotta be forced into there
(Bacterial RNA polymerase can find and do)
Endosymbiotic theory of how mitochondria and chrolorplasts came to be cell homies?
Endocytosis (they got engulfed)
What evidence supports endocytosis in endosymbiotic theory?
-Double membranes bb
(of the nucleus, endocytosis
-taken into an endosome **review slides if you can, basically cell is engulfing another cell for food usually) unit III pg 30
-outer membrane comes from host, inner membrane from bacterium (captured cell)
-engulfed bacterium loses some genes, so initially obligate parasites, but eventually established as an organelle
Idk man just talk about why make sense that chloroplasts/mitochondria were incorporated via endocytosis
(for ex. Mitochondria suddenly provided energy or nutrients if let cell live in engulfed state rather than chopping it down)
Mitochondrion and chloroplast, got engulfed through endocytosis
-bc engulfed bacterium better at making energy than host cell
DNA of mitochondria and chloroplasts look like what? (resemble what? Endosymbiotic theory)
-modern non-photosynthetic euks born due to the mitochondria poppin in (DNA is unique and circular like bacterial)
-mitochondria makes its own ribosomes, then it makes it own proteins and genes are transcribed using ribosomes (so we can use the SSU rRNA gene to sequence mitochondria)
Comes up as alpha-proteobateria
Closely related to bacteria called richettsia (intracellular parasite)
What is REFERED TO as first endosymbiotic event
when a eukaryotic cell engulfed a prokaryote
10/10 gotta review the endosymbiotic slides
unit III slides 30-34ish
Bacterial flagella vs euk flagella quick differences?
Bacs it’s a motor, flagella is external of plasma membrane
Euks it’s much more complex, flagella is technically intracellular structure (not outside membrane)
-Both grow from distil end, for bacs comes from inside hollow tube, for euks travels up side before joining to end
Eukaryotic flagella structure
(hint 4 main components, though one is empty space basically)
**see slides omg, unit III pg 43
Basal body- anchor
Plasma membrane- outside
Axoneme- middle thingy
Space for
intraflagellar
transport- yea
and cytoplasm down below ig
Axoneme-
who’s a part of this, and how it work?
-Dynein motors
-microtubules
-nexin
-inner sheath
who prolly the og chloroplasts?
Cyanobacs og chloroplasts
Do bacterial or eukaryotic flagella grow from the distil end?
-Both grow from distil end, for bacs comes from inside hollow tube, for euks travels up side before joining to end
-Dynein motors (little blue circles)
what are and do what?
the little feet of the dynein motors be walking along the microtubule (propels euk flagellar movement)
Little feet can move anolng microtubule, head is anchored
What powers euk and bacterial flagella to move?
-ATP powers euk flagella, motion is whipping back and forth (as dynein motors walk down, flips one over the other.)
-bac flagella proton gradient, propelling motion,
both grow through distil end but by different mechanisms
How many motors on a euk vs bacterial flagelluar motor?
Who is more rigid in structure, and who is most powerful?
-convergent evoltuon
-euk thousands of little motors, bac only have the one motor, euk more ridid structure so more power when it flips
For structure of axoneme rod (euks flagella)
unit III pg 44
What’s the deal with microbe euks and cell walls?
-Some always have a cell wall
-Some never have a cell wall
-Some only have a cell wall in certain life stages (like giardia wowow)
The Cell Wall:
made of what for bacs/euks
-peptioglycan (bacterial cell wall)
Euks:
-Cellulose
* Silica
* Chitin
* Carbohydrate-modified proteins
do most euk microbes have a cell wall?
-Not all euk mircobes have cell wall
-Most bacs do tho
Cell wall-
in euks and bacs, does what?
-support structure, shape to cell
-protects from chemicals /physical stresses/osmotic stresses
-hypertonic allows for full extension for plant cell, for ours they pop
What can euk cell walls be made from?
- Cellulose
- Silica
- Chitin
- Carbohydrate-modified proteins
Cellulose
(cell wall euk strucural compoent, look like what?)
- Linear polysaccharide chains of glucose linked via β
-1,4 glycosidic bonds
α-D-glucose β-D-glucose
β (14) glycosidic bond
CelluloseStarch
**see slide unit III pg 49-50
fibrils filled with microfibrules
Who has cell walls made of cellulose?
(and who in this group is the exception?)
Most algae have cell walls of cellulose
(Exception: Diatoms)
-also water molds and slime molds (microfungii)
Who has cell walls made of silica?
Diatoms bb