Eukaryotic Cell Flashcards
Cells consist of two main components and animal cells lack a
-nucleus
-cytoplasm
-animal cells lack a cell wall
The nucleus (2) and contains (3):
-largest structure
-essential
Contains:
-DNA and chromosomes
-Nucleoproteins (for DNA and RNA synthesis and folding of DNA)
-newly synthesized RNA
Two forms of DNA are:
-Heterochromatin (dark, clumped peripherally)
-Euchromatin (light, scattered)
Which form of DNA is involved in RNA synthesis?
Euchromatin
Which form of DNA is silenced (ie. NOT involved in RNA synthesis)
Heterochromatin
Nuclear morphology is used to
Identify cells that are neoplastic (large and multi-nucleated)
The nuclear envelope (4)
-contains the nucleus
-composed of an inner and outer membrane
-continuous with the Endoplasmic Reticulum
-consists of Nucleoporins (allow movement between nucleus and cytoplasm)
The Nucleolus (3) and consists of (2)
-roughly spherical in shape
-may be more than one present
-involved in ribosomal RNA (rRNA) synthesis and ribosome assembly
Consists of:
-Nucleonema (partially assembled ribosomes)
-Pars amorpha (DNA coding for rRNA)
The Cytoplasm (2)
-aka Cytosol
-consists of a number of organelles (ER, Golgi apparatus, ribosomes, mitochondria, lysosomes, centrioles) within a fluid medium
Endoplasmic Reticulum (3)
-network of membranes (“RETE” in Latin = net)
-connected to nuclear envelope
-two types (rough and smooth)
Rough Endoplasmic Reticulum (rER): (2)
-ribosomes on outer surface involved with protein synthesis (translate mRNA into protein)
-modification and packaging of proteins BEFORE transported to Golgi
Which Endoplasmic Reticulum is closest to the nucleus?
Rough
Smooth Endoplasmic Reticulum (sER): (4)
-NO ribosomes
-involved in synthesis and/or storage of phospholipids, cholesterol, glycerides, glycogen, and steroids
-drug detoxification
-Calcium storage in muscle
Ribosomes (2)
-consist of rRNA and proteins
-responsible for protein assembly (structure, chemical messengers, and enzymes)
An increased protein production requires more
Ribosomes
Ribosomes are synthesized in the ____, assembled in the ____, and transferred to the ____
Nucleus, Nucleolus, Cytoplasm
Golgi Apparatus (3)
-consists of a series of membranous sacks called Cisternae
-located close to the nucleus and ER
-communicates with ER and cell surface via Vesicles
3 major functions of the Golgi Apparatus are
-modification and packaging of secretory products (hormones and enzymes)
-synthesis of glycoproteins and glycolipids for cell membrane
-packages enzymes for use within the cell
Mitochondria (5)
-have their own DNA (can self replicate)
-supply the cell’s energy
-consists of an outer and inner membrane folded into Cristae to increase surface area
-ATP formed within the matrix
-regulate Apoptosis (cell death)
Lysosomes (3)
-produced by the Golgi Apparatus
-round, membrane bound vesicles
-contain ~50 types of acid hydrolyses (ie. digestive enzymes)
Three functions of Lysosomes
-degrade defunct organelles
-digest carbohydrates, lipids, proteins, and nucleic acids
-kill intracellular microorganisms
Primary Lysosome (2)
-inactive enzymes
-fuse with damaged organelle via Autophagy and become a Secondary Lysosome
Secondary Lysosome (2)
-phagocytosis of damaged organelle
-activated enzymes
Residual Body (3)
-exhausted lysosome
-filled with undigested debris
-either extruded from the cell or remain as Lipofuscin Granules
Centrioles (3)
-usually two aligned at right angles near the nucleus in the centrosome
-cylindrical structure composed of Microtubules (9 microtubule triplets = 27 in total)
-used for cell division and formation of cytoskeleton
Lipofuscin are
Defunct lysosomes
The cytoskeleton is ___ and consists of (3)
-a framework of several types of proteinaceous filaments and tubules within the cell
Consists of:
-micro filaments
-microtubules
-intermediate filaments (mainly keratin)
Biological Membranes (3)
-contain the organelles within the cell
-functionally polarized
-permeable to lipid soluble molecules but NOT lipid insoluble
6 main functions of Biological Membranes
-protection
-absorption and transport
-adherence
-compartmentalisation
-provide internal surface area
-cell-to-cell communication
Phospholipid Bilayer (4)
-two layers
-semi fluid
-hydrophobic tails
-hydrophilic heads
Membrane protein functions (5)
-anchoring of cells to one another or structures
-cell recognition (prevents immune attack on self)
-enzymes to catalyze intra- or extra-cellular reactions
-carriers to move substances across the membrane
-channels that move water and ions across the membrane
Proteins associated with the Plasma/Cell Membrane (2)
Integral Proteins
-embedded in the bilayer
-movement of compounds across the membrane
-can be transmembrane proteins (ie. span across the entire width of the membrane)
Peripheral Proteins
-bound to the inner or outer surface of the membrane
Extracellular surface of the membrane contain (2)
-Glycoproteins
-Glycolipids
___ molecules are embedded within the _____
Cholesterol; hydrophobic region of the bilayer
Carbohydrate chains extend into the extracellular environment to form the
Glycocalyx
Four functions of the Glycocalyx
-Cell recognition
-adhesion
-adsorption of molecules (binding of specific molecules to alter cell function)
-mechanical and chemical protection (forms a viscous layer that lubricates and protects)
Three specializations of the Plasma Membrane
-tight junctions
-desmosomes
-gap junctions
Tight Junctions (3):
-located immediately beneath the apical surface of the cell
-blocks the passage of solutes into the intercellular space
-each tight junction forms a band around the apical portion of the cell, creating the Zonula Occludens
Desmosomes (6):
-adhering/anchoring junctions
-bind to adjacent cell
-linked to cytoskeleton
-strong, resistant to stretching/twisting
-continuous band below tight junction
-hemidesmosomes between the basal portion of cell and basement membrane in epithelial cell
Gap Junctions (2):
-two cells locked together by Connexins (membrane proteins)
-form channels for the movement of ions, nutrients, and signalling chemicals
Microvilli (4)
-short, finger-like projections of plasma membrane
-increases surface area for absorption
-mostly found in gut (epithelial cells of small intestine)
-aka Brush Border
Cilia (3)
-long
-wave-like, synchronous motility that propels fluid
-found in oviduct and airways
Stereocilia (3)
-increase surface area for absorption
-long microvilli, NOT cilia
-found in epithelial cells of the epididymis
Passive Diffusion (3)
-movement down the concentration gradient
-no energy needed
-small molecules
Facilitated Diffusion (3)
-movement of large, hydrophilic molecules down the concentration gradient
-no energy required
-rate of transport is determined by the number of carrier proteins present
Active Transport (2)
-transport of molecules against the concentration gradient
-requires energy (ATP)
Endocytosis (2)
-bulk transport INTO the cell
-cell membrane bulges inward to form pseudopodia and pinches off to form a vesicle which will fuse with lysosomes
Three types of Endocytosis
-Pinocytosis: extracellular fluid
-Phagocytosis: extracellular solid material (ex. Bacteria)
-Receptor-Mediated Endocytosis: receptors within a clathrin-coated pit on the cell surface bind to specific molecules
Exocytosis (4)
-bulk transportation OUT of cell
-expulsion of waste products or secretory products
-steroids/lipids leave via Passive Diffusion OR are stored until bulk release
-proteins released via Constitutive Secretion (continuously) OR Regulated Secretion (stored in vesicle until signalled for release)
Apoptosis (5)
-genetically programmed cell death
-response to genetic error
-absent in tumour cells
-common in embryonic tissue
-intrinsic (stress, UV radiation, DNA damage etc activates a signalling cascade within mitochondria) or extrinsic (initiated via death ligands)
Necrosis (3)
-uncontrolled cell death (lysis of cells)
-cells are exposed to conditions that they cannot tolerate and die
-creates an inflammatory response
