Chapter 2.4 - Eukaryotic Cell Structure Flashcards
Ultrastructure and function of eukaryotic cell components Importance of cytoskeleton Interrelationship between organelles involved in production and secretion of proteins
Definition of cells
Basic unit of all living things
Two fundamental types of cell
Prokaryotic
Prokaryotes are single celled organisms with a simple structure of just a single undivided internal area called cytoplasm (made up of salts, water and organic molecules)
Eukaryotic
These cells make up multicellular organisms (animals, plants and fungi)
Complicated internal structure containing nucleoplasm and cytoplasm
Contains many membrane bound cellular components
What are chemical reactions
Fundamental processes of liye and in feuds requires enzymes and specific reaction conditions
Definition of metabolism
synthesis and breaking down of molecules. Different sets of reactions take place in different regions of the ultrastructure of a cell.
where do reactions take place
Cytoplasm
Purpose of cell surface membrane
Separates cell cytoplasm from external environment
Definition of organelles
Different membrane bound compartments divided in cell cytoplasm
Purpose of membrane bound compartments
Provide distinct environments and conditions for different cellular reactions
Features of membranes
Selectively permeable - control movement of substances (cells and organelles)
Effective barriers
Fragile
Nucleus
Contains coded genetic information in the form of DNA molecules
DNA directs synthesis of all proteins required by the cell
Controls metabolic activities
Often biggest organelle
DNA
Contained within double membrane - nuclear envelope (protects DNA from damage in cytoplasm)
Envelope has nuclear pores for molecules to move through nucleus
DNA too large to leave to site of protein synthesis
Transcribed into RNA
Associates with histones to form chromatin
Chromatin coils and condenses to form chromosomes
Become visible when cells are about to divide
Nucleolus
Produces ribosomes
Composed of proteins and RNA
RNA produces rRNA
rRNA combines with proteins to form ribosomes
Mitochondria
Small amount of DNA
Site of final stage of cellular respiration
Produces ATP so energy stored in bonds of complex organic molecules is made available for cell to use
Double membrane
Inner membrane folds to form cristae. Contains enzymes for aerobic respiration
Fluid interior is matrix
Produces own enzymes and reproduce themselves
Vesicles
Membranous says
Storage and transport
Single membrane with fluid inside
Lysosomes
Specialised vesicles Hydrolytic enzymes Break down waste material Break down pathogens that have been ingested by pathogens Cell death or apoptosis
Definition of cytoplasm
Network of fibres necessary for shape and stability of cell.
Controls cell movement and movement of organelles within the cell
Microfilaments
Formed by protein actin
Contractile fibres
Cell movement and cell contraction
Cytokinesis
Microtubules
Globular tubulin proteins polymerise. Form tubes that form scaffold like structure that shape cell
Tracks for movement
Spindle fibres made up of microtubules have role in physical segregation of chromosomes
Intermediate fibres
Mechanical strength
Help maintain integrity
Centrioles
Not present in flowering plants and most fungi
Composed of microtubules
2 associated centrioles form centrosome - involved in assembly and organisation of spindle fibres during cell division
Position flagella and cilia
Flagella
Whip like Protrude from some cell types Longer than cilia Enable cells motility Sensory organelle detecting chemical changes in cells environment
Cilia
Stationary - present on cell surface. Sensory (nose)
Mobile - beat in rhythmic manner creating current
Cause fluids or objects adjacent to move (trachea moving mucus away from lungs keeping airways clean)
Fallopian tubes to move egg cells from ovary to uterus
Contains two central microtubules surrounded by 9 pairs
Pairs of parallel microtubules slide over each other causing cilia to move in beating motion
Endoplasmic reticulum
Network of membranes enclosing flattened sacs called cisternae
Connected to outer membrane of nucleus
Smooth Endoplasmic Reticulum
Lipid and carbohydrate synthesis
Storage
Rough endoplasmic reticulum
Ribosomes bound to the surface
Responsible for synthesis and transport of proteins
Secretory cells
Releases hormones or enzymes
More Rough Er than cells that don’t release proteins
Ribosomes
Site of protein synthesis
Either free floating or attached to endoplasmic reticulum
Not surrounded by membrane
Constructed of RNA molecules made in nucleolus
Golgi apparatus
Modified and packages proteins into vesicles (e.g. secretory vesicles if leaving or lysosomes if staying)
Similar in structure to smooth ER
Compact structure formed of cisternae
No ribosomes
Steps of protein production
Synthesised on ribosomes bound to ER
Pass into ERs cisternae and packaged into transport vesicles
Vesicle goes to Golgi apparatus via cytoskeleton
Vesicle fuses with cis face of Golgi apparatus
Protein enters Golgi apparatus
Protein is structurally modified
Leaves through trans face after being packaged into vesicle
Vesicle fuses with cell - exocytosis
Some form lysosomes - contain enzymes for use in the cell
