3.2.1.1 Flashcards
Describe the structure of the cell surface membrane
-‘fluid mosaic’ phospholipid bilayer
-with extrinsic and intrinsic proteins embedded
Describe the function of the cell surface membrane
-Isolates cytoplasm from extracellular environment
-Selectively permeable to regulate transport of substances
-Involved in cell signalling
Explain the role of cholesterol, glycoproteins & glycolipids in the cell surface membrane
Cholesterol :
-steroid molecule connects phospholipids and reduces fluidity
Glycoproteins :
-cell signalling, cell recognition (antigens) and binding cells together
Glycolipids :
cell signalling and cell recognition
Describe the structure of the nucleus
-surrounded by nuclear envelope, a semi permeable double membrane
-nuclear pores allow substances to enter/exit
-dense nucleolus made of RNA and proteins assembles ribosomes
Describe the function of the nucleus
-Contains DNA coiled around chromatin into chromosomes
-controls cellular processes: gene expression determines specialisation and site of mRNA transcription, mitosis, semiconservative replication
Describe the structure of a mitochondrion
-surrounded by a double membrane, folded inner membrane firms cristae: site of electron transport chain
-fluid matrix: contains mitochondrial DNA, respiratory enzymes, lipids, proteins
State the function of mitochondria
-site of aerobic respiration to produce ATP
Describe the structure of a chloroplast
-vesicular plastid with double membrane
-Thykaloids: flattened discs stack to form grana; contain photosystems with chlorophyll
-Intergranal lamelle: tubes attach thykaloids in adjacent grana
-Stroma: fluid filled matrix, contains starch grains
State the function of chloroplasts
-site of photosynthesis to convert solar energy to chemical energy
Describe the structure of the golgi apparatus
-planar stack of membrane-bound, flattened sacs or cisternae with small rounded hollow structures called vesicles
Describe the function of the golgi apparatus
-modifies and packages proteins
-synthesises glycoproteins
Describe the structure of a lysosome
-sac surrounded by single membrane
-membrane-bound organelle that releases hydrolytic enzymes
-embedded H+ pump maintains acidic conditions
-contains digestive hydrolase enzymed
-glycoprotein coat protects cell interior
Describe the function of a lysosome
-digests contents of phagosome
-exocytosis of digestive enzymes
Describe the structure of a ribosome
-formed of protein and rRNA
-free in cytoplasm or attached to ER
Describe the function of a ribosome
Site of protein synthesis via translation :
-large subunit: joins amino acids
-small subunit: contains mRNA binding site
Describe the structure and function of the endoplasmic reticulum
-cisternae: network of tubules and flattened sacs extends from cell membrane through cytoplasm and connects to nuclear envelope
-Rough ER : many ribosomes attached for protein synthesis and transport
-Smooth ER: lipid synthesis
Describe the structure of the cell wall(plants)
-made of cellulose microfibrils
-plasmodesmata: allows molecules to pass between cells
-middle lamella - acts as boundary between adjacent cell walls
State the function of the cell wall(plants)
-mechanical strength and support
-physical barrier against pathogens
-part of apoplast pathway to enable easy diffusion of water
Describe the structure of the cell vacuole in plants
-surrounded by a single membrane called the tonoplast
-contains cell sap: mineral ions, water, enzymes, soluble pigments
Describe the function of the cell vacuole in plants
-controls turgor pressure
-absorbs and hydrolyses potentially harmful substances to detoxify cytoplasm
Explain some common cell adaptions
-folded membrane or microvilli increase surface area eg: for diffusion
-many mitochondria = large amounts of ATP for active transport
-Walls one cell thick to reduce distance of diffusion pathway
State the structures in a eukaryotic cell that cannot be identified with an optical microscope
-mitochondria
-ribosomes
-ER
-lysosome
-cell surface membrane
How are chloroplasts adapted to their function
-granal membranes: provide large surface area fir the attachment of chlorophyll, electron carriers and enzymes that carry out the first stage of photosynthesis
-the fluid of the stroma posses all the enzymes needed to make sugars in the second stage of photosynthesis
-chloroplasts contain both DNA and Ribosomes so they can manufacture some of the proteins needed for photosynthesis
Outline the roles of organelles in the production, transport and release of proteins from eukaryotic cells
-DNA in nucleus is code for protein
-Ribosomes/RER produce protein
-mitochondria produce ATP for protein synthesis
-golgi apparatus packages/ modifies proteins
-Vesicles transport proteins
What is the cell wall component of:
-plants
-algae
-fungi
-prokaryotes
Plants: cellulose
Algae: cellulose
Fungi: chitin
prokaryotes: murein
