Lecture 6 Flashcards
Lysosomes
- Like the cells stomach (acidic- pH 4.5 breaks things down)
-it’s enzymes only function at acidic pH so great examples of Compartmentalization
- hydrolyses both internal and external stuff
- internal: organelles that are old/not functioning correctly (autophagy)
*external: bacteria and debris engulfed by phagocytosis
- internal: organelles that are old/not functioning correctly (autophagy)
- not present in plants (they use lytic vacuoles)
Vacuoles
-Present in plants and fungi
-filled with fluid
-Some protein/ also have specialized vacuoles called contractile vacuoles that pomp excess water out of the cell
Vacuole function
- turgid pressure for cell enlargement
- storage of nutrients
- digest waste products (similar to lysosomes)
- pigmentation
Nuclear envelope quick
Control in/out of nucleus
Rough ER quick
Protein synthesis/ folding
Smooth ER quick
Lipid synthesis / detox
Golgi quick
Protein modification and sorting into vesicles
Vesicles quick
Carry thing between compartments
Lysosomes quick
Stomach of the cell
Vacuoles quick
Turgid pressure and other diverse roles
Plasma membrane quick
Surround cell, control in/out
Semi-autonomous organelles why aren’t they part of Endomembrane system
Although surrounded by membranes, they aren’t part of Endomembrane system bc they don’t send or receive vesicles
Semi autonomous organelles example
Mitochondria
Chloroplasts
What do mitochondria and chloroplasts have in common
Involved in generation of bioenergy
Both use electrochemical reactions to make energy
Both have internal membranes with extensive folding to increase the surface area of the energy producing machinery
How does mitochondria converts into energy
Sugars > respiration > ATP
How do chloroplasts make energy
CO2 > photosynthesis > sugars
Why semi autonomous
- Each arose from ancient prokaryotic symbionts that gradually evolved to rely on host cell and can’t live independently anymore
- each have their own genome (small. Circular. Like plasmids)
- most of the genes were lost or transferred to the host
- have own ribosomes and make proteins
- but most proteins come from host cell
-replicate on their own by division
* uses essentially same division machinery as modern prokaryotes
-have double membranes like modern prokaryotes
-have similar shapes and sizes as modern prokaryotes
Mitochondria
- the source of all cellular respiration. Which creates the bulk of the cells energy in the form of ATP
- 2 membranes
* inner one has folds called cristae
-matrix is the cytoplasm
Chloroplasts
-Perform photosynthesis
-2 boundary membranes + internal thylakoid membrane
- stroma is the “cytoplasm”
-stacks of thylakoids are called grana (singular=granum)
-photosynthetic reactions occur in thylakoids and stroma
Other plastid types
Several others which defended from chloroplasts
Roles in storage and pigmentation
-chromoplast- holds pigment for organ coloration
- leucoplasts- no pigments
* Amyloplast: starch storage
* Proteinoplast: protein storage
Cytoskeleton is what? And what types
Filamentous protein polymers
Types
* microtubules
* intermediate filaments
* microfilaments
Cytoskeleton functions
- cell shape
- cell polarity
- cell division
- cell movement and migration
- intracellular transport and cytoplasmic organization
Microtubules
- polymers made of tubulin
- made of 13 protofilaments
- have plus and minus ends which gives them an inherent polarity
- switch between growing (polymerization)/ and shortening (depolymerization)
- most growth/ shortening occurs at plus ends
Microtubules functions
Cell shape and movement
Cell division
Provide tracks for intercellular organelle movement
Microfilaments
Polymers of actin
Two protofilaments form a helix
Also have plus and minus ends, which give them an inherent polarity
Also grow by polymerization and shorten by depolymerization
Also most growth/ shortening at + ends
Microfilaments functions
Cell shape and migration
Cell division (mostly during cytokinesis)
Organelle movement and cytoplasmic streaming in plants
Components of contractile elements in muscle fibres
Intermediate filaments
Polymers of intermediate filament proteins (many types)
Varied composition depending on cell type
Do not have polarity and dynamic like MTs/MFs
Can be both inside and outside of the cell
Intermediate filament functions
-structure/ support/ adhesion
Examples:
-extracellular matrix in mammals
-collagen (structural component of skin and connective tissues)
-keratin (hair nails and claws)
- nuclear lamins (line inner surface of nuclear envelope In Animals)
Why don’t plants and fungi have intermediate filaments
They have cell walls instead of
Prokaryotic cytoskeleton
Have ancestral versions of both microtubules and microfilaments
Similar functions to MTs and MFs
*cell shape
*cell division
