LECTURE 7 Flashcards
Cytosol
The fluid portion of the cytoplasm. (Without structures or membranes)
Cytoplasm
Interior of a prokaryotic or eukaryotic cell.
Organelle
Any membrane-bound structure in a eukaryotic cell,
Prokaryotic cells have
- No nucleus
- DNA in an unbound region called nucleoid
- no membrane-bound organelles
- cytoplasm bound by plasma membrane
- cell walls (bacteria and archaea, but composition is different)
Why did eukaryotes evolve membrane outs organelles
They evolved a way to fold their membranes to increase the surface area.
One simple model of endosymbiosis
1) ancestral cell that’s anaerobic
2) membrane folding
3) cell size increases
4) produces oxygen
5) aerobic prokaryotic ingested
6) bacterium not destroyed, developed into mitochondria. ( all non-photosynthetic eukaryotes)
7) photosynthesis bacterium ingested (chloroplast) ( all photosynthetic eukaryotes)
The endosymbiosis hypothesis
- mitochondria and chloroplast arose in eukaryotes by endosymbiosis
0 mutually beneficial relationship derived form one cell living inside another cell.
Mitchochondria are descended form an ancient ________. And it closely related to
Bacterium. a-proteobacteria (gram negative)
Chloroplasts are descended form an an don’t
Cyanobacteria (photosynthetic bacterium)
Evidence for endosymbiosis
Mitochondria and chloroplasts :
- have their own DNA (circular)
- genes are organized like prokaryote genome
- have their own ribosomes
Ribosomes are big compels of
Proteins and RNA molecules
Eukaryotes and prokaryote ribosomes differ in
Size and components
The endowment and system contains
- nuclear membrane
- endoplasmic reticulum
- vacuoles
- Vesicles
- lysosomes
- golgi
- plasma membrane
All of the endomembrane systems are related by either :
1) physical continuity
2) vesicles that transfer from one to another.
What membrane-bound organelles are not part of the endomembrane system
- peroxisomes
- mitochondria
- chloroplasts
The nucleus
- stores DNA, is a site for transcription
- contains multiple linear chromosomes
Nuclear envoleop
- double membrane ( each membrane has a phospholipid bilayer)
- separates the nucleoplasm form the cytoplasm.
Nuclear pore complexes
- span both bilayers
- regulates movement of substances in and out of nucleus
Nuclear lamina
- Provides structural support of the nucleus
What is the nuclear lamina composed of?
Intermediate filament called lamin, which assembles on the inner surface of the nuclear envelope.
Nuclear envelope membrane order
- inner membrane
- outer membrane
- neculear pore
Chromatin
DNA and proteins ( associated together because of electrostatic interaction)
DNA is ________ charged, and histones are ________ charged
Negatively . Positively
Why package DNA?
- organism the nucleus
- protect DNA form damage
- make it easier to move replicated DNA into daughter cell during cell division
4 hi stone proteins assemble into a
Larger 8-subunit complex ( his tone octamer
What are the four proteins that assemble into a large 8-sub into complex ?
H2A, H2B, H3, H4
Histone H1 provides
Stability and protection to DNA, involved in packaging of nucleosomes
Nucleolus (ribosome production factory)
- this is a visible sub-compartment of the nucleus ( not bound by membrane)
- site of ribosomal RNA (rRNA) synthesis
- site of assembly of ribosome protein subunits (each half of the ribosome enter the nucleus separately via nuclear pores)
Steps to nucleolus (ribosomes production factory)
1) each subunit ( made in cytoplasm) must enter nucleus
2) ribosomal subunits associate with 4 different RNA molecules
3) final assembly occurs in the cytoplasm
The tow types of endoplasmic reticulum ER
Smooth and rough
Cells that provide a lot of proteins will tend to have more
Rough ER
Cells that provide a lot of lipids (fats) will tend to have more
Smooth ER
Are both types of ER found in both plants and animals
YES
RER ribosomes are associated with the
Translation of proteins that aren’t destines for the endomembrane system
Function of the rough ER
- site of protein synthesis and assembly
- site of quality control
Ribosomes (protein factories)
- particles made of ribosomal RNA and protein
- assemble all peptides
Where does the ribosomes assemble all peptides
- in the cytosol (free ribosomes)
- on the outside of the endoplasmic reticulum (bound ribosomes)
Smooth ER functions
- ion storage
- phospholipid, steroid synthesis
- detox of drugs and alcohol
- carbohydrate metabolism
The Golgi apparatus
- Shipping and receiving
- contains cisternae
- cisternal maturation
- cis face / trans face
Cistercian’s
Golgi apparatus consists of flattened membranous sacs called cisternae
Cis face
“Receiving” side of the golgi (faces nucleus)
Trans face
“Shipping” side of the golgi (faces away from nucleus)
Golgi apparatus functions
- modifies products of the ER
- sorts and packages material into transport vesicles
- it manufacturers some macromolecules
Inclusion cell disease
Involves the loss of a modification in the golgi
- proteins that should go to the lysosome instead get sent outside the cell.
