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Eukaryotic cell structure (Eukaryotic cell (Nucleus (Contains coded…
Eukaryotic cell structure
Cells
Basic unit of all living things
Prokaryotic and eukaryotic cells
Prokaryotes: single-celled organisms with single undivided internal area (cytoplasm) composed of cytosol (made of water, salts, organic molecules)
Eukaryotes: multicellular organisms (e.g. animals, plants, fungi) complicated internal structure containing membrane bound nucleus, (nucleoplasm) and cytoplasm with membrane-bound cellular components
Compartments for life
Chemical reactions require enzymes and specific reaction conditions
Metabolism involves synthesis and breakdown of molecules
Reactions take place in cytoplasm
Cell cytoplasm seperated from external environment by cell-surface membrane
Reactions take place in the cytoplasm
Cytoplasm separated from the external environment by cell-surface membrane
Eukaryotic cells: cytoplasm divided into many different membrane-bound compartments called organelles
Membranes are selectively permeable/ control movement substances into and out cell and organelles
Eukaryotic cell
Vesicles and lysosomes
Lysosomes are responsible for breaking down pathogens ingested by phagocytic cells
Lysosomes responsible for apoptosis
Lysosomes break down waste material in cells e.g. organelles
Lysosomes specialised forms of vesicles contain hydrolytic enzymes
Transport materials inside the cell
Vesicles are membrane sacs that have storage and transport roles
Cytoskeleton
Network fibres responsible shape/ stability of cell
Organelles held in place by cytoskeleton/ controls cell movement and movement organelles within cells
Present in cytoplasm
Has 3 compartments:
Microfilaments
Contractile fibres formed from actin
Responsible for cell movement/ contraction during cytokinesis (cytoplasm single eukaryotic cell divided form 2 daughter cells)
Microtubules
Globular tubulin proteins polymerise form tubes used form scaffold-like structure determines shape cell
Tracks for movement organelles e.g. vesicles around cell
Spindle fibres (physical segregation chromosomes in cell division) composed of microtubules
Intermediate fibres
Mechanical strength to cells help maintain integrity
Mitochondria
Double membrane bound: inner membrane folded form cristae and fluid interior called matrix
Membrane forming cristae contains aerobic respiration enzymes
Site of final stage of cellular respiration where energy molecule ATP can be used
Contain mitochondrial (mt)DNA
Centrioles
Component of cytoskeleton in eukaryotic cell except flowering plants/ fungi
Composed of microtubules
2 associated centrioles form centrosome involved in assembly/ organisation spindle fibres during cell division
Position flagella/ cilia
Nucleolus
Area within nucleus
Responsible producing ribosomes
Composed of proteins and RNA
RNA used produce ribosomal RNA (rRNA) which combines proteins form ribosomes necessary protein synthesis
Flagella and cillia
Flagella longer than cilia BUT cilia greater number
Flagella enable cell mobility OR sensory organelle that detect chemical changes in cell's environment
Flagella (whip-like) and cilia (hair-like) extentions that protrude from cell types
Cilia can be mobile or stationary
Stationary cilia present surface cells and function in sensory organs
Mobile cilia beat in rhythmic manner creating current cause fluids/ objects next cell move e.g. trachea move mucus away lungs/ fallopian tubes move egg cells from ovary to uterus
Each cilium contains 2 central microtubules surrounded by 9 pairs microtubules arranged 'wheel'
Pairs parallel microtubules slide over each other causing cilia move beating motion
Nucleus
Contains coded genetic information as DNA molecules
DNA directs synthesis proteins required by cell
DNA controls metabolic activity of cell (e.g. proteins are enzymes needed for metabolism to occur)
Biggest single organelle
DNA contained within double membrane called nuclear envelope to protect from damage in cytoplasm
Nuclear envelope contains nuclear pores allow molecules move into and out nucleus
DNA too large leave nucleus transcribed into RNA molecules (exported through nuclear pores)
DNA and histones form chromatin
Chromatin coils and condenses form chromosomes
Organelles of protein synthesis
Key function cell synthesis proteins for internal use/ secretion
Ribosomes, endoplasmic reticulum, Golgi apparatus coordinate production proteins and cytoskeleton coordinate protein synthesis
Endoplasmic reticulum
Endoplasmic reticulum (ER) network membranes enclosing cisrernae and connected to outer membrane nucleus
Smooth endoplasmic reticulum responsible lipid/ carbohydrate synthesis and storage
Rough endoplasmic reticulum has ribosomes bound surface/ responsible synthesis and transport proteins
Secretory cells release hormones/ enzymes have more RER than cells that do NOT release proteins
Ribosomes
Constructed of RNA molecules made in nucleolus cells
Site of protein synthesis
Not surrounded by membrane
Mitochondria and chloroplasts contain ribosomes
Free-floating in cytoplasm or attached endoplasmic reticulum forming RER
Golgi apparatus
Modifies proteins and 'package' into vesicles
Secretory vesicles if proteins destined leave cell OR lysosomes stay in cell
Compact structure formed of cisternae does NOT contain ribosomes
Protein production
Proteins pass into cisternae and packaged into transport vesicles
Vesicles containing synthesised proteins move towards Golgi apparatus via transport function cytoskeleton
Proteins synthesised on RER
Secretory vesicles carry proteins: move towards and fuse with cell-surface membrane releasing contents by exocytosis (some vesicles form lysosomes- enzymes for internal use)
Vesicles fuse with cis face Golgi apparatus and proteins enter, proteins structurally modified and leave Golgi apparatus in vesicles from trans face