Lecture 1 - Cell and Organelles Flashcards
The plasma ( cell) membrane
Rough-surfaced endoplasmic reticulum (rER)
Smooth surfaced endoplasmic reticulum(sER)
Golgi apparatus
Endosomes
Lysosomes
Transport vesicles
MEMBRANOUS ORGANELLES
Microtubules
Filaments
Centrioles
Ribosomes
NON MEMBRANOUS ORGANELLES
The membrane bound compartment that contains the genetic information together with the machinery for DNA replication and RNA transcription and processing
Nucleus
The term that means the irreversible condensation of chromatin in the nucleus of a cell undergoing necrosis or apoptosis
Pyknosis
Nucleus is enclosed by nuclear envelope – inner and outer nuclear membrane with an intervening space called what?
Perinuclear cistern
The inner and outer membranes fuse with each other at some places and form circular profiles called ______ that allow communication between the nucleus and the cytoplasm
Nuclear pores
The nuclear pores are guarded by protein assemblies , which together with the nuclear pores are called ______
, providing regulated passageways for the transport of materials in and out of the nucleus
Nuclear pore complexes
The nucleus contains _______ , and is the site for RNA synthesis
Chromatin
The _______ is a non membrane bound spherical structure involved in transcription of genes coding for ribosomal RNA and assembly of ribosomal units
Nucleolus
An important component in the diagnosis and evaluation of genetic disorders and refers to analysis of chromosomes .
Cytogenic testing
- provides a structural and functional barrier between the cell and the outside environment .
- It consists of a phospholipid bilayer with the integral and peripheral proteins and cholesterol embedded in it .
PLASMA MEMBRANE
Functions of which organelle?
- In cell – cell recognition
- In exocytosis and endocytosis
- As a receptor site for signaling molecules such as G proteins
- As an initiator and controller of the secondary messenger system
PLASMA MEMBRANE
Membrane transport protein that
transfer small water soluble molecules
Carrier Proteins
Membrane transport protein where
-Ions and other small charged molecules are transported through the plasma membrane by ion-selective channel proteins
Channel Proteins
3 processes of endocytosis
- PINOCYTOSIS : non specific ingestion of fluid and small protein molecules via small vesicles .
- PHAGOCYTOSIS : uptake of particulate matter
- RECEPTOR –MEDIATED ENDOCYTOSIS : e.g low –density lipoproteins
2 general pathways of exocytosis
Constitutive secretion
Regulated secretion
Type of exocytosis secretion that
substances designated for export are continuously delivered in transport vesicles to the plasma membrane e.g procollagen
Constitutive secretion
Type of exocytosis secretion that
specialized cells such endocrine , exocrine cells and neurons , concentrate secretory proteins and transiently store them in vesicles with in the cytoplasm . A regulatory event ( hormonal or neural stimulus) must be activated for secretion to occur. (as in the release of secretion by the acinar cells of pancreas )
Regulated secretion
Oval or rod shaped structures ~0.5-1.0um in diameter and ~4-9um long .
Are abundant in the cells that generate and expend large amount of energy e.g cells of skeletal muscles and in metabolically active cells e.g liver cells
MITOCHONDRIA
Mitochondria
The outer membrane is smooth and contains _____ , which are large channels that allow larger particles to pass through , hence the composition of intermembranous space is similar to cytoplasm .
Porin
Mitochondria
The inner membrane is folded to form shelf like projections called ______ and encloses a viscous fluid filled space known as the matrix which contains proteins involved in fatty acid oxidation and the Kreb,s cycle
Cristae
Mitochondria
a phospholipid found in the inner membrane , thus making it impermeable to ions , electrons and protons .
Cardiolipin
Mitochondria
has a viscous fluid containing high concentration of proteins some of which are involved in fatty acid oxidation
Matrix
Functions of what organelle?
- Generation of ATP
- Generate heat in the brown fat
- Assist in the synthesis of certain lipids and proteins .
- They possess the enzymes of TCA Cycle (Kreb,s cycle )
- They take part in apoptosis ( programmed cell death)
Mitochondria
Mitochondrial disease can only be passed down by what parent?
Mother
Consists of tubules , sacs and flat sheets of membranes that occupy much of the intracellular space .
Endoplasmic reticulum
ER that
Functions in synthesis of cholesterol & lipids and detoxification of certain drugs and toxins .In the skeletal muscle it is specialized to sequester and release calcium ions
Smooth surfaced endoplasmic reticulum (sER)
ER that
With TEM appears to be a series of interconnected membrane bound flattened sacs called cisterns that have ribosomes attached on the external surface of the membrane .rER functions in the synthesis and modification of proteins that are to packaged , as well as in the synthesis of membrane lipids and proteins
Rough surfaced endoplasmic reticulum (rER )
Is composed of stack of vesicles, tubules and flattened membranous bound cisterns , located near the nucleus
Functions
-Phosphorylation and glycosylation of proteins
Protein sorting
A) incorporated into a unit membrane e.g plasmalemma (integral proteins )
B) immediate release into extracellular space
C) intracellular storage within secretory vesicles to be released later on .
D) incorporated into lysosomes in the cytoplasm .
GOLGI APPARATUS (GA)
TEM reveals the presence of intermediate compartment called _______ concerned with the destruction of endocytosed , phagocytosed or autophagocytosed materials as well as formation of lysosomes
Endosomes
Type of endosome
-are located at the periphery of the cell (close to cell membrane ) and contain receptor- ligand complexes and their acidic pH ( 6) uncouples the receptors from the ligand
Early Endosomes
Type of endosome
-mature into lysosomes and possess a highly acidic pH
Late Endosomes
- are formed by the utilization of late endosomes as an intermediary compartment
- are rich in hydrolytic enzymes e.g proteases , nucleases, lipases etc. responsible for degradation of certain molecules and phagocytosed material
Lysosomes
Disease that occurs mostly in children whose parents are descendants of Northeast European Jews .
-The lysosomes are unable to catabolize GM2 ganglioside due to hexoaminodase deficiency their neurons accumulate large amount of ganglioside in endolysosomes The enlarged endolysosomes obstruct neuronal function .
Tay- Sachs disease
are single membrane bound organelles that contain oxidative enzymes e.g urate oxidase , catalase, D- amino glucosidase .All oxidative enzymes produce hydrogen peroxide (H₂O₂), which is a toxic substance. The catalase present in these regulates the amount of hydrogen peroxide thus protecting the cell .
Peroxisomes
Is an inherited autosomal recessive disorder that interferes with normal peroxisomal functions which lead to early death
Zellweger,s syndrome
Are small non membranous organelles that exist as individual particles until protein synthesis begins .
There are 2 subunits of unequal size and constitution , composed of proteins and r-RNA. The large sub unit is 60 S in size and the small unit is 40 S
Ribosomes
is composed of filamentous proteins that act not only as the structural framework of the cell but also to transport material within the cell and provide it with the capability of motion and cell division .
- It consists of :
- Microtubules
- Microfilaments
- Centrioles
Cytoskeleton
Part of cytoskeleton
-Consist of alpha and beta tubulins arranged in 13 protofilaments
Microtubules
(actin) and microfilaments , help in the movement of cell from one place to another , as well as movement of the regions of cell with respect to itself .
Thin filaments
help in providing a structural framework to the cell and resist mechanical stresses on the cells
Intermediate filaments
are composed of myosin and interact with thin filaments thereby providing movement
Thick filaments
Allow the organelles , vesicles and other components of the cytoskeleton to bind to microtubules
Two important MAPs ______ and ______ are motor proteins that facilitate movement
kinesin, dynein
Are paired structures visible under light microscope as short rod like structures built from nine microtubule triplets.
Usually found close to the nucleus often partially surrounded by Golgi apparatus .
Provide basal bodies for cilia and flagella and align the mitotic spindle during cell division
Centriole
