Lecture 1: Cells and organelles I Flashcards
The space between the inner and outer membrane is continuous with
the lumen of the rough ER.
Histones are
small proteins containing a lot of amino acids (arginine and lysine) that facilitate the binding to the negatively charged part of DNA.
POLG deficiency
-many mutations in mtDNA, promotes aging and apoptosis of cells.
Chloroplasts contain three membrane-limited internal compartments (T/F)
True, the intermembrane space, stroma and thylakoid lumen.
Chloroplasts are the largest and most characteristic organelles in plants (T/F)
True.
What are NADH and FADH2
They are coenzymes that have the ability to transfer electrons.
function of outer mitochondrial membrane
contains enzymes that convert lipid substrates in which are metabolized by the matrix.
Molecular medicine: Nuclear lamina diseases
Emery-Dreifuss muscular dystrophy; neck becomes stiff, heart problems.
Hutchinson-Gilford progeria; premature aging.
Sub-organelle of the nucleus is
the nucleolus: where cell ribosomes assemble.
All cells contain DNA as a store of
genetic information.
unicellular organisms fall under what two categories?
unicellular prokaryotes and eukaryotes.
ETC during photosynthesis
(1) PSII: chlorophyll absorbs light, following the hydrolysis of H2O forming molecular 1/2O2 + 2H+ + e-. (2H+)
(2) PQ.
(3) Cyt b: able to transport H+ from stroma to lumen.
PSI: provided additional energy by sun to push electrons. (1H+)
(4) NADP reductase: converting NADP to NADPH.
-2H+ in stroma +3H+ in lumen: the lumen has 5H+ in excess)
(5) excess protons in lumen drives ATP synthase, thermodynamically favoured.
Morphology of mitochondria
mitochondrial network is very dynamic. can appear as highly branched, interconnected tubular network.
Chromosomal DNA is packed into
chromatin fibers with the help of special proteins.
complex I, II, III
- electrons from NADH and FADH2 are transferred through several electron protein complexes.
- this creates proton gradient, which powers amazing enzyme ATP synthase.
- produces the most ATP.
The balance between fission and fusion is a major determinant of mitochondrial morphology (T/F)
True.
Chloroplasts also contain an extensive internal system of interconnected membrane-limited sacs called
thylakoids.
Matrix contains
(2) identical copies of circular mitochondrial DNA
(3) mitochondrial ribosomes.
(4) enzymes responsible for expressing mitochondrial genome.
mitochondria arise from
pre-existing mitochondria by fission.
10^10=
1 angstrom.
“Dark” reaction in plants stroma will
convert CO2 into carbohydrates (CO2 fixation).
LBR and Emerin keep
lamina close to the inner membrane.
examples of unicellular eukaryotes
FUNGI and YEAST.
prokaryotes comprise a single
membrane-limited compartment.
nuclear lamina diseases are caused by
a mutation in two genes:
(1) coding for emerin (inner nuclear membrane protein, lamin-binding protein); emerin unable to hold nuclear lamina.
(2) coding for lamina; lamina unable to interact with DNA in LBR.
Ultimately, repressing transcription of certain genes.
Cellular respiration
consuming oxygen and releasing carbon dioxide (similar to breathing).
Accumulation of mutation in mitochondrial DNA promotes
aging.
viruses use reverse transcriptase (T/F)
True.
In plants, how does the chloroplast and mitochondria collaborate to provide ATP?
-cells that lack chloroplasts and therefore cannot produce their own ATP, rely on an export of sugars from its chloroplasts to the mitochondria that are located in all cells of the plants .
• Most of the ATP needed by the plant is synthesized in these mitochondria.
Levels of organisation of chromatin
DNA–>nucleosome core particles; core histones (8 subunits), H1–> filament (10nm)–>30nm fiber–>looped domains–>metaphase chromosome.
Cells are made up of
70% water, inorganic ions such as Na+ K+ Mg2+ Ca2+ Cl-, organic molecules such as (1) carbohydrates (2)lipids (3)nucleic acids such as RNA and DNA (4)proteins.
Robert Hook invented the first light microscope in
1665.
Molecular Medicine: mitochondrial disorders
(1) Myoclonic Epilepsy and Raged Red Fibers (MERRF).
(2) POLG
prokaryote cell structure
(1) cell wall: outer membrane.
(2) plasma membrane: inner membrane.
(3) cytoplasm: contains ribosomes, site of protein synthesis, region of the cell lying outside the nucleoid.
(4) nucleoid: single circular DNA molecule which is not surrounded by a membrane separating it from the cytoplasm.
the nucleus is surrounded by;
a nuclear envelope (double membrane).
The cell is the fundamental unit of life (T/F)
True it is the underlying building block from which all organisms are constructed.
Mitochondrial disorders are due to
abnormal proliferation of mitochondria that have decreased cytochrome c oxidase (complex IV) activity.
DNA is wrapped around histones
(1) H2A,H2B,H3,H4 in nucleosome core particles and sealed with H1.
(2) non-histone proteins binds to linker DNA between nucleosome core particles.
difference between the structure of a plant and animal cell
(1)plant cell does not contain a centriole.
(2)animal cell does not have a cell wall, chloroplast, or vacuole.
Exception: unicellular eukaryotic organisms have a cell wall.
cells are the smallest units exhibiting the characteristics of life (T/F)
true because they are able to reproduce themselves by their own efforts.
the nuclear lamina;
is a fibrous network providing structural support to the nucleus.
How mitochondria produces ATP
(1) pyruvate is converged to Acetyl CoA
(2) acetyl CoA is oxidized by TCA cycle which produce 6NADH, 2FADH2 and 2 ATP.
(3) oxidative phosphorylation uses electrons from NADH and FADH2 to generate proton gradient.
(5) gradient is formed driving ATP synthase.
The nucleus contain molecules
of DNA, long polymers that encode the genetic specification of the organism.
What happens to the sugars synthesized in the chloroplast?
they move into the cytoplasm where they are converted to pyruvate through glycolysis and then transported into the mitochondria of the root.
As a cell prepares to divide its chromatin condenses into chromosomes (T/F)
True.
How are small molecules imported in the nucleus?
small molecules have sufficient size and molecular weight that fit through nuclear pores without extra energy.
Two types of cells:
(1) prokaryotic cells: DNA is not segregated within a defined nucleus, do not contain internal membranes.
(2) eukaryotic cells: DNA is segregated within a defined nucleus, contain extensive internal membranes enclosing organelles separating them from the cytosol.
How are ribosomes assembled in the nucleolus?
(1) ribosomal proteins imported from the cytoplasm.
(2) brought to nucleolus and assemble on pre-rRNA (pre ribosome RNA).
(3) pre rRNA cleaved to form several pieces of rRNAs.
(4) ribosomal proteins and rRNA assemble to form 40s and 60s subunits (relative rate of movement).
(5) subunits exported to cytoplasm.
The outer nuclear membrane is continuous with
the rough endoplasmic reticulum (ER).
Cell biology investigates how
cells grow, divide, operate, communicate, control their activities, and die.
The absorption of light and ETC takes place
thylakoid membrane.
Role of mitochondria (simple explanation)
- oxidize carbohydrates and lipids to produce ATP by the process of oxidative phosphorylation.
- performs cellular respiration.
Chromatin contain
(1) twice as much DNA as protein.
(2) histones are their major protein.
The inner and outer membrane are joined at nuclear pore complexes (T/F)
True.
Chloroplasts perform
photosynthesis during the day thereby producing ATP and NADPH, which in turn in used CO2 into sugars.
The basic structural unit of chromatin is called
the nucleosome.
Organization of leaf and roots
(1) leaf produces sugars transported to root cells.
(2) root cannot synthesize chloroplast because they are not exposed to the light or do not have chloroplasts.
types of proteins transported into the nucleus
(1) DNA-binding proteins; histones, non-histones, activators, repressors of transcription.
(2) m-RNA.
(3) components of the nucleus such as laminas.
(4) ribosomal proteins.
(5) shutting nuclear transport receptors (importins); deliver other proteins to nucleus.
what is the diameter of a eukaryotic cell, bacterium, and frog egg?
eukaryotic: 0.005-0.02 mm
bacterium: 0.001 mm
frog egg: 1 mm
the nucleus communicates with the cytosol;
via nuclear pores that perforate the envelope.
Five pairs of high energy electrons are transferred to NAD+ and FAD and then passed through ETC for production of ATP (T/F)
True.
Viruses are not the smallest units exhibiting the characteristics of life (T/F)
True because they are not able to reproduce themselves by their own efforts; they use reproductive machinery of cells they invade.
There are five major types of histones:
H1,H2A,H2B,H3,H4
Chromatin contains an equal mass of non-histone chromosomal proteins (T/F)
True.
organization of the mitochondria organelle
(1) double-membrane separated by inter membrane.
- inner membrane forms folds of cristae, which extend into the matrix.
- due to folds with cristae surface area is increased.
organelles are the smallest units exhibiting the characteristics of life (T/F)
False, they are not able to reproduce themselves by their own efforts, outside of host cells.
function of inner mitochondrial membrane
synthesis of ATP.
the nuclear pore complexes;
the only channels where molecules are able to travel from the nucleus to cytoplasm.
“Light” reaction in plants thylakoid membrane will
(1) Absorb light by green pigment attached to proteins.
(2) electron transport chain.
(4) synthesize ATP and NADPH.
how are proteins transported into the nucleus?
by means of passive diffusion where energy is required made through ATP hydrolysis.
LBR stands for
Lamin B Receptor.