Cell structure Flashcards
What is a eukaryotic cell?
A cell with membrane-bound organelles
Which organelles are found in both animal and plant cells?
- Cell surface membrane
- Lysosomes
- Ribosomes
- Rough/smooth endoplasmic reticulum
- Nucleus
- Nucleolus
- Golgi apparatus
- Cytoplasm
- Mitochondria
Which organelles are only found in plant cells?
- Vacuole
- Chloroplasts
- Cell wall (cellulose)
- Plasmodesmata (strands of proteins)
How are algal cells different to plant cells?
Chloroplasts are a different shape/size
How are fungal cells different to plant cells?
- Don’t have chloroplasts
- Cell walls are made from chitin instead of cellulose
What is the structure and function of mitochondria?
Structure: Double membrane (inner membrane folded to form cristae which increase surface area for attachment of enzymes involved in respiration), matrix (enzymes for respiration, DNA, ribosomes)
Function: Carry out aerobic respiration, produce ATP
What is the structure and function of the cell surface membrane?
Structure: Made up of phospholipids, proteins and carbohydrates arranged into fluid-mosaic model, microvilli formed from folding (increase surface area)
Function: Controls passage of molecules in/out of cell
What is the structure and function of a chloroplast?
Structure: Double membrane (inner membranes called thylakoids which contain chlorophyll, stacked to form grana), grana (increase surface area for absorption), stroma (fluid contains enzymes for photosynthesis)
Function: Site of photosynthesis
What is the structure and function of the cell wall?
Structure: Rigid, made up of cellulose, fully permeable
Function: Supports the cell
What is the structure and function of a vacuole?
Structure: Tonoplast (surrounding membrane), cell sap (sugar/salt solution)
Function: Helps to maintain pressure inside cell (keeps it turgid), involved in isolation of unwanted chemicals inside cell
What is the structure and function of the nucleus?
Structure: DNA, pores (substances can move between nucleus and cytoplasm), nucleolus
Function: DNA codes for proteins, ribosome synthesis in nucleolus
What is the structure and function of ribosomes?
Structure: Made up of RNA and protein, 2 sub-units (small and large)
Function: Protein synthesis
What is the structure and function of endoplasmic reticulum?
Structure: Forms enclosed, flattened sacs (cisternae) - 2 types (rough, smooth)
Function: rough - Synthesises and transports protein through cell, smooth - synthesises and transports lipids
What is the structure and function of Golgi apparatus?
Structure: Can form lysosomes (fluid-filled membrane sacs)
Function: Processes, modifies and packages proteins into vesicles for transport out of cell
What is the structure and function of lysosomes?
Structure: Vesicles with bilayer, cell surface membrane, proteins and enzyme complex
Function: Hydrolyse invading pathogens in white blood cells
What is a prokaryotic cell?
Cell with no membrane-bound organelles (bacteria)
How do prokaryotic cells differ from eukaryotic cells?
- Slime capsule for protection
- Single circular loop of DNA instead of nucleus
- Plasmids (small loops of DNA)
- Flagella for movement
- Cell wall made up of murein instead of cellulose or chitin
- Smaller ribosomes
What is a virus?
Acellular (not a cell), non-living
How does a virus differ to prokaryotic/eukaryotic cells?
- No cell surface membrane, cytoplasm or ribosomes
- Much smaller
- Capsid (protein coat)
- Attachment proteins (complementary to infected cell)
- Lipid envelope
What is cell fractionation?
Separation of cell organelles by density and mass
What are the conditions for cell fractionation and why?
- Ice cold (reduces enzyme activity)
- Buffered pH (prevents enzymes from denaturing)
- Isotonic (stops osmosis from occurring so cell doesn’t burst)
What are the steps for cell fractionation?
- Tissue broken using homogeniser to release organelles
- Filtration - removes cell debris
- Spun at LOW speed in centrifuge - forms pellet of nuclei (heaviest)
- Supernatant (remaining liquid) removed and spun for faster and longer so smaller organelles form a pellet - chloroplasts then mitochondria
- Repeated for smaller organelles - lysosomes, endoplasmic reticulum then ribosomes
What order do the organelles go in during cell fractionation?
- Nuclei
- Chloroplasts –> mitochondria
- Lysosomes –> endoplasmic reticulum
- Ribosomes