Anatomy of the Cell Flashcards
What are the components of a cell
Water, Protein, Lipid, Carbohydrate and Inorganic
What are Eukaryotic Cells Features
Outer Membrane
Inner Cytosol
Cytoskeleton
Membrane bound organelles (In Cytosol)
Inclusions
What is an Inner cytosol made of
Solution of proteins, electrolytes and carbohydrates with fluid and gel-like properties
Cytoskeleton function and composition
Determines shape and fluidity of cell
Made of thin and intermediate filaments & microtubules
What is the plasma membrane function
Separates the cytoplasm from the outside environment
What is the composition of plasma membrane
Bimolecular layer of amphipathic phospholipid molecules
What is the composition of a phospholipid molecule
Hydrophilic head (At outer and inner surface)
Hydrophobic tail (Facing toward middle of 2 layers)
What proteins are found in plasma membrane and what do they function as
Integral proteins which can be receptors, channels, transporters and enzymes
What is exocytosis and endocytosis
Exo- cell shifts materials into extracellular space through plasma membrane
Endo-Cell brings substances into the cell vis vesicles through plasma membrane
Why is it good for cell membrane to have a fluid quality
As it can change shape easily and diffusion occurs laterally
What does ‘selective permeability’ of cell membrane mean
Highly permeable to water, oxygen and small hydrophobic molecules.
Impermeable to charged ions e.g Na
What are Organelles
Small, intracellular organs with specific function and structural organisation
Essential to life
What Organelles are in the Cytoplasm
Mitochondria - (energy production)
Rough endoplasmic reticulum - (protein synthesis)
Smooth endoplasmic reticulum - (cholesterol & lipid synthesis/detoxification)
Golgi apparatus - (modification & packaging of secretions)
Lysosomes – (hydrolytic enzymes for intracellular digestion)
Nucleus – (contains genetic code)
What are Inclusions
Other structures within cytoplasm
May or may not be bound by membrane
Inclusions are dispensable and may only be present a short time/transient
What inclusions are in a cell
Pigment
Glycogen stores
Lipid droplets
Pre-secretion product
Endocytosis Vesicle
What are the 3 main classes of filaments in cytoskeleton
Microfilaments
Intermediate filaments
Microtubules
What are microfilaments composed of
Protein Actin (7nm diameter)
What are Intermediate filaments composed of
Six main proteins varying in cell types (>10nm diameter)
What are microtubules composed of
2 tubulin proteins- Alpha and Beta (25nm in diameter) Tubulin originates from centrosome
What proteins are important in movement of components in a cell with long processes
Kinesin and Dynein
Both ATPase moving towards cell periphery (K) and Centre(D)
What is structure of nucleus
Enclosed by nuclear envelope
Inner and outer nucleus membrane
Nuclear pores, continuity with cytoplasm
Contains chromosomes
What is on outer nuclear membrane
Ribosomes, continuous with cytoplasmic RER
Where does RNA synthesis occur
In the nucleus as this is where mRNA and tRNA are transcribed
What types of DNA are found in the nucleus
Euchromatin (Dispersed and actively undergoing transcription)
Heterochromatin (Highly condensed and not undergoing transcription)
What are ribosomes
Made up of a small subunit which bind to RNA and a large subunit (to catalyse peptide bond formation)
What is the endoplasmic reticulum ER
Forms a network of interconnecting membrane bound compartments
2 types rough and smooth
Inactive cells have little ER
What is the rough endoplasmic reticulum RER
Studded with ribosomes, vital role in protein synthesis and initiates glycoprotein formation
What is smooth endoplasmic reticulum SER
Lacks ribosomes, plays a vital role in lipid synthesis
What is the Golgi complex
Golgi apparatus composed of flattened membrane bound cisternae
Vesicles enter is from RER/SER
What is function of cisterns
Modify and package macromolecules that were synthesised in the ER
-Add sugars
-Cleave proteins
-Sort macromolecules into vesicles
What are mitochondria
Power generators of the cell, generate ATP through oxidative phosphorylation and synthesise lipids and proteins
What is mitochondria composition
Outer and inner membrane
Inner membrane folded= cristae, increases surface area
Oblong cylindrical organelles
Contain own DNA and system for protein production
What are intercellular junctions
Specialised membrane structures linking individual cells together into a functional unit- prominent in epithelia (3 Types)
What are the 3 types of intercellular junctions
Occluding junctions
Anchoring junctions
Communicating junctions
What are occluding junctions
Prevent diffusion and appear as a focal region of close apposition between adjacent cell membranes
(Also known as tight junctions or zonula occludens)
What are anchoring junctions
Link submembrane actin bundles of adjacent cells (also known as zonula adherens)
Desmosomes function
link submembrane intermediate filaments of adjacent cells (Called macula adherens) Common in skin providing mechanical stability
What are communicating junctions
Allow selective diffusion of molecules between adjacent cells (also known as gap junctions)
Circular patch studded with pores which produce connexon proteins
What is a junctional Complex
Close association of many junctions found in certain epithelial tissues
How is material transported in and out of cells
Diffusion
Via transport proteins (pumps or channels)
Vesicular transport
What are the types of vesicular transport
Phagocytosis
Endocytosis
What is endocytosis
Material from extracellular space incorporated into the cell. Cell membrane invaginates forming endocytotic vesicle. Receptor mediated
What is phagocytosis
Bacterium binding to cell membrane is engulfed creating phagosome. Phagosome binds with lysosome carrying digestive enzymes creating phagolysosome.
