Cells Flashcards
Describe the cell surface membrane
- Made up of ‘fluid mosaic’ phospholipid bilayer
- Isolates cytoplasm from extracellular environment
- Selectively permeable to regulate transport of substances
- Involved in cell signalling/ cell recognition
- Receptor molecules on it —> allow it to respond to chemicals like hormones
Explain the role of cholesterol, glycoproteins and 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 and function of the nucleus
- Nuclear enevelope —> surrounds nucleus and is a semi permeable double membrane
- Nuclear pores —> allow substances to move between cytoplasm and nucleus (eg. RNA)
- Dense nucleolus —> made of RNA and site of ribosome production
- Controls cell activities by controlling transcription of DNA
- DNA contains instructions to make proteins
Describe the structure and function of a mitochondrion
- Surrounded by double membrane + folded inner membrane (cristae)
- Site of ATP production during aerobic respiration
- Cristae provide a large surface area for attachment of enzymes and other proteins involved in respiration
- Fluid matrix —> contains enzymes needed for respiration + proteins, lipids, ribosomes, DNA for production of their own proteins
- Found in large numbers in cells that are very active and require a lot of energy
Describe the structure and function of a chloroplast
- Surrounded by double membrane
- Thylakoids —> flattened discs that contain complexes of pigments like chlorophyll in membranes —> absorb light for light dependent reaction
- Grana —> stacks of thylakoids
- Lamellae —> membranous extensions that connect thylakoids
- Stroma —> fluid surrounding thylakoids
- Starch grains —> store sugars
- Ribosomes —> protein synthesis
- Contain DNA —> genes that code for proteins involved in photosynthesis
- Site of photosynthesis
- Absorb light energy —> chemical energy
Describe the structure and function of the endoplasmic reticulum
Rough endoplasmic reticulum:
- System of membranes enclosing a fluid filled space
- Ribosome coating
- Proteins processed (from ribosomes) —> larger SA for more reactions
Smooth endoplasmic reticulum:
- No ribosome coating
- Enzymes catalyse metabolic reactions
- Synthesise, store and transport lipids
Describe the structure and function of the golgi apparatus
- Group of fluid filled membrane bound flattened sacs
- Processes and packages new lipids and proteins
- Makes lysosomes
Golgi vesicle:
- produced by Golgi apparatus
- Small fluid filled sac in cytoplasm
- Surrounded by membrane
- Stores lipids and proteins made by Golgi apparatus
- Transports them out of cell via cell surface membrane
Describe the structure and function of a lysosome
- Round organelle surrounded by membrane
- Contains hydrolitic enzymes —> separate from cytoplasm by surrounding membrane
—> digests invading cells / break down worn out components of cell
Describe the structure and function of a ribosome
- Small organelle that floats free in cytoplasm or attached to RER
- Made up of proteins and RNA
- Consists of a small and large subunit
- Site of protein synthesis
- Eukaryotic cells have bigger ribosomes (80s) than prokaryotic cells (70s)
Describe the structure and function of the cell wall
- Made up of cellulose
- Found in plants, algae and fungi (made up chitin in fungi)
- Contains channels (gaps) called plasmodemata
- Supports cell and prevents it from bursting —> cell can withstand high osmotic pressures
- Plasmodemata allows for the exchange of substances between neighbouring cells
Describe the structure and function of a cell vacuole (plants)
- Membrane bound
- Found in cytoplasm
- Contains cell sap ( weak solution of sugar and salts)
- Has a surrounding membrane called a tonoplast (selectively permeable membrane)
- Helps to maintain pressure inside cell and keep it rigid
- Stops plants wilting
- Involved in isolation of unwanted chemicals inside cell
What organelles are found in an animal cell?
- Cell surface membrane
- Rough / Smooth endoplasmic reticulum
- Nucleus
- Nucleolus
- Nuclear enevelope
- Lysosome
- Ribosome
- Golgi apparatus
- Cytoplasm
- Mitochondrion
What organelles are found in a plant and algal cells?
- Cell surface membrane
- Rough / Smooth endoplasmic reticulum
- Nucleus
- Nucleolus
- Nuclear enevelope
- Ribosome
- Golgi apparatus
- Cytoplasm
- Mitochondrion
- Cell wall
- Vacuole
- Chloroplasts
What organelles are found in fungal cells?
- Cell surface membrane
- Rough / Smooth endoplasmic reticulum
- Nucleus
- Nucleolus
- Nuclear enevelope
- Ribosome
- Golgi apparatus
- Cytoplasm
- Mitochondrion
- Cell wall
- Vacuole
What is the difference between plant and algal cells?
The chloroplasts in algal cells are different shapes and sizes to plant chloroplasts.
Eg. Some algae have one large chloroplast rather than several smaller ones
