Comparmentalization Of Cells Flashcards by Bianca vermontte

Catalyze mostly by membrane-bound enzymes

Lipid metabolism

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Both require a membrane to couple the transport of H+ to the synthesis of ATP

Oxidative phosphorylation and photosynthesis

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Provide increased membrane area, they also create enclosed compartments that are separate from the cytosol, thus providing the cell with functionally specialized aqueous spaces.

Intracellular membrane systems

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Responsible for the import and export of specific metabolites

Membrane transport proteins

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Mechanism of each organelle

> Importing

>incorporating into the organelle

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Contains the main genome and is the principle site of DNA and RNA synthesis.

Nucleus

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Consists of cytosol and organelles suspended on it.

Cytoplasm

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Site of protein synthesis and degradation, also performs most of the cells intermediary metabolism - the many reactions by which some small molecules are degraded and others are synthesized to provide building blocks for macromolecules.

Cytosol

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Has many ribosomes bound to its cytosolic surface, they are engaged in synthesis of both soluble and integral membrane proteins, most of which are destined either for secretion to the cell exterior or for other organelles.

Endoplasmic reticulum

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Translocated into the ER as they are synthesized. This explains why ER membrane is unique in having ribosomes tethered to it.

Proteins

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Produces most of the lipid for the rest of the cell and functions as a store CA2+ ions.

Endoplasmic reticulum

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Consists of organized stacks of disc like compartments. Receives lipids and proteins from the ER dispatches them to a variety of destinations, usually covalently modifying them en route.

Golgi Apparatus

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Disc like compartments

Golgi cistern

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Generate most of the ATP used by cells to drive reactions that require an input of free energy.

Mitochondria and chloroplasts

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Specialized version of plastids, functions as storage of food and pigment molecules.

Chloroplasts

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Contain digestive enzymes that degrade defunct intracellular organelles, as well as macromolecules and particles taken in from from outside the cell endocytosis.

Lysosomes

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Endocytosed materials must first pass through these series of organelles.

Endosomes

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Small vesicular compartments that contain enzymes utilized in a variety of oxidative reactions.

Peroxisomes

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Form during development of chloroplasts from proplastids in the green leaves of plants.

Thylakoid vesicles

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Small pre cursor organelles that are present in all immature plant cells.

Proplastids

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Harbors all of the chloroplast’s photosynthetic machinery.

Thylakoid

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Surrounded by a double membrane, remain isolated from the extensive vesicular traffic that connects the interiors of the most of the other membrane-enclosed organelles to each other and to the outside of the cell.

Membrane and plastids

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Intracellular compartments in eukaryotic cells

Nucleus and cytosol
Organelles that function in the secretory and endocytosis pathways.
Mitochondria
Plastids

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Direct their delivery to locations outside the cytosol.

Siting signals

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Protein traffic between the cytosol and nucleus occurs between topologically equivalent spaces, which are in continuity in the nuclear pore complexes.

Gated transport

Function as selective gates that actively transport specific macromolecules and macromolecule assemblies but also follow free diffusion of small molecules.

Nuclear pore complexes

Membrane bound protein translocation directly transport specific proteins across the membrane from the cytosol into the space that is topologically distinct.

Transmembrane transport

Membrane enclosed transport intermediates, pericarp like transport vesicles or larger irregularly shaped organelle, ferry proteins from one compartment to another.

Vesicular transport

Removes the finished proteins that are typically 15-60 residues long.

Signal peptidases

Used to direct proteins from the cytosol to the ER, mitochondria, chloroplasts and peroxisomes, they are also used to transport proteins from the nucleus to the cytosol and from the Golgi to the ER.

Signal sequences

Sorting signals that direct proteins into the nucleus from the cytosol.

Signal patches

Direct newly synthesized degrading enzymes that to the lysosomes

Signal patches

Proteins for initial transfer to the ER.

Signal sequence at N terminus

Recognized as ER residents

Four amino acids at their c terminus

Proteins destined for mitochondria

Positively charged amino acids alternate with hydrophobic ones.

Sufficient for protein targeting

Signal sequences

Proteins destined for peroxisomes

Signal peptide of three characteristic amino acid on their C terminus

Guides proteins to their appropriate destination, sorting signals are recognized by this.

Sorting receptors

Passed from one parent cell to progeny cell in a form of the organelle itself.

Epigenetic information

Encloses the DNA and defines compartment

Nuclear envelope

Specific proteins that acts as a binding site for chromatin and for protein mesh work or nuclear lamina.

Inner nuclear membrane

Provides structural support for nuclear membrane

Nuclear lamina

Studded with ribosomes engaged in protein synthesis

Outer nuclear membrane

Space between inner and outer nuclear membrane

Perinuclear space

Occurs continuously between cytosol and nucleus

Bidirectional traffic

Small water soluble molecules can passively diffuse through this

Aqueous channels

Selectivity of the nuclear process resides in this, present only in the nuclear proteins

Nuclear localization signals

Nuclear localization signals must be recognized by this

Nuclear import receptors

Serve as a binding sites for the import receptors

FG repeats

These receptors bind both the export signal and nucleoporins to guide their cargo through the pore complex to the cytosol

Nuclear export receptor

Found in both cytosol and nucleus, required both the nuclear import and export systems

Ran

Become bound to proteins that are loaded into the RNA transcription and splicing proceed.

Messenger RNA

Recognized by export receptors that guide RNA out of the nucleus through nuclear pore complexes.

Nuclear export signals

Interconnected protein subunits

Nuclear lamins

Meshwork of interconnected protein subunits

Nuclear lamina

Special class of intermediate filament proteins that polymerize into a two-dimensional lattice

Lamins

What happens to the nuclear lamina when the nucleus disassembles during mitosis?

It depolymerizes

Double membrane enclosed organelles

Mitochondria and chloroplast

Forms intensive invaginations

Inner membrane of mitochondria

Encloses the matrix space

Mitochondrial crustal

Part of mitochondria that is in contact with the cytosol

Outer membrane of mitochondria

Mitochondrial proteins are first fully synthesized as precursor proteins in the cytosol and then translocated into the mitochondria by this mechanism

Posttranslational mechanism

Multi subunit protein complexes that function as a protein translocator across the outer membrane

TOM complexes

Function across the inner membrane

TIM23 & TIM22

Mediates insertion of inner membrane proteins that are synthesized within the mitochondria

OXA complex

Contact sites of matrix space

Storms

Surrounded by only a single membrane, all of the proteins of this organelle must be imported.

Peroxisomes

Present in all eukaryotic cells, contain oxidative enzymes, catalase and urate oxidase

Peroxisomes

Utilizes hydrogen peroxide generated by other organelle to oxidize a variety of other substrates

Catalase

Process of breaking down fatty acid molecules

Beta oxidation

Most abundant class of phospholipids in myelin

Plasmogens

Uses up O2 and liberates CO2

Photorespiration

Conversion of fats to sugars

Glyoxylate cycle

A defect in importing proteins into peroxisomes, individuals that contain "empty" peroxisomes

Zellweger syndrome

Organized into a netlike labyrinth of branching tubules and flattened sacs throughout the cytosol

Endoplasmic reticulum

Central role in lipid and protein synthesis

Endoplasmic reticulum

Partly translocated across ER and and become embedded in it.

Transmembrane proteins

Fully translocated across the ER membrane and release into the ER lumen.

Water soluble proteins

Contain ER exit sites.

Smooth ER

A cell that is abundant with smooth ER

Hepatocyte

Specialized smooth ER, sequesters Ca2+ from the cytosol by mean of Ca2+ ATPase that pumps Ca2+ ions into the lumen

Sarcomas mic reticulum

Small closed vesicles that form when ER breaks into fragments when being disrupted.

Microsomes

ER resident protein, catalyze sa free sulfhydryl groups on cysteines to form disulfide bonds

Protein disulfide isomerism

Can be formed in three steps: choline, two fatty acids, and glycerol phosphate

Phosphatidylcholine

Made by condensing the amino acid serine with fatty acid to form an amino alcohol sphingosine.

Ceramics