Cells: Eukaryotic Structure And Organelle Functions Flashcards
Plant cell aspects
- A cellulose cell wall with Plasmodesmata channels for exchanging substances between adjacent cells
- A vacuole (fluid filled compartment)
- Chloroplasts
10 key eukaryotic organelles
- Cell Surface Membrane
- Nucleus
- Mitochondria
- Chloroplasts
- Golgi apparatus + Golgi vesicles
- Lysosomes
- Ribosomes
- Rough endoplasmic reticulum + Smooth endoplasmic reticulum
- Cell Wall
- Cell Vacuole
Function of rough endoplasmic reticulum
Proteinsynthesis, folds and processes proteins made at ribosomes
Fungal cell aspect
- Can be unicellular (yeast) or multicellular (mushroom)
- Cell wall made up of chitin not cellulose
- No chloroplast, as they do not photosynthesise
Membrane-bound
Surrounded by a membrane (phospholipid bilayer)
Functions of the nucleus
- Site of DNA replication and transcription (making mRNA)
- Contains the genetic code for each cell
Organelles
Sub-cellular structure with a specific function
Ultrastructure of a eukaryotic cell (12)
- Cell membrane
- Golgi apparatus + Golgi vesicle
- Nucleus
- cytoplasm
- Mitochondria
- Nuclear envelope
- Nuclear pore
- Rough endoplasmic reticulum
- Ribosomes
- Smooth endoplasmic reticulum
- Lysosome
- Nucleolus
Structure of endoplasmic reticulum
- Both Rough and Smooth Endoplasmic reticulum have folded membranes called cisternae
- RER have ribosomes on the cisternae
Algal cell aspect
- Can be unicellular (chlorella) or multicellular (seaweed)
- Cellulose cell wall
- Chloroplasts have a different shape and size
- Some algal cells have one large chloroplast compared to several smaller chloroplasts
Structure of the nucleus
- Nuclear envelope (double membrane
- Nuclear Pores
- Nucleoplasm (granular, jelly-like)
4.Chromosomes (Protein bound, linear DNA) - Nucleolus (smaller sphere inside which is the site of ribosomal RNA production. It also makes Ribosomes)
Lysosome function
Contain hydrolytic enzymes to destroy surplus organelles or body cells and tissues if released. They can release enzymes for four purposes:
1. Breakdown material/ pathogens ingested by phagocytes
2. Destroy material outside the cell by releasing enzymes to the outside of the cell
3. Digest worn out organelles
4. Break down cells when they have died - Apoptosis
Ribosome function
Small granules found in all cells, occur either free in the cytoplasm or associated with RER
Two types: 80 s: found in the eukaryotic cells, 25nm in diameter
70 s: found in prokaryotic cells, mitochondria and chloroplasts
Made up of two sub-units (large and small), ribosomes are made of protein and rRNA
Golgi Apparatus/Body function
-Folded membranes (cisternae)
-Secretory vesicles pinch off from the cisternae
-Adds Carbohydrates to Proteins to form glycoproteins
-Processes and packages new lipids and proteins
-Produces secretory enzymes
-Secretes Carbohydrates (e.g cellulose in plants)
-Makes Lysosomes
Rough Endoplasmic Reticulum function
Large surface area for protein synthesis
Pathway to transport protein through the cell
Chloroplast structure and function
Present in plant and algal cells and surrounded by two membranes forming an envelope
-The Stroma: contains water, enzymes and other substances
-Thylakoids: intricate series of. membranes that form interconnecting enclosed spaces, contains the chlorophyll
-Grana: stacks of thylakoids
-Lamellae: connects adjacent Grana
- The site of photosynthesis. This occurs partly in the Grana and partly in the Stroma
Mitochondria structure and function
Surrounded by two membranes (outer membrane and highly folded inner membrane)
-The Matrix: central fluid filled space, contains enzymes that catalyse reactions during some stages of respiration
-The Cristae: intricate folds inner membrane that have a large internal surface area and holds the enzymes involved in the final stage of respiration
-Contains circular DNA and Ribosomes
- Site of aerobic respiration
- Produces the energy carrier molecule ATP
- Higher numbers of mitochondria and cristae in metabolically active cells e.g Epithelial cells in the intestine
Vacuole function
Filled with fluid and surrounded by a single membrane called a tonoplast
- Makes cells turgid and therefore provides support
- Temporary store of sugars and amino acids
- The pigments are responsible for coloured petals
- Stops the plant wilting and is involved in the isolation of unwanted chemicals inside the
Nucleolus function
Synthesis of Ribosomal RNA (rRNA)
Cell Wall structure and function
A rigid structure that surrounds cells in plants, algae and fungi.
- In plants and algae cells it is made up of microfibrils of cellulose polymer there is a thin layer called the middle lamella, which cements adjacent cells together
-In fungi, it is made of chitin, a nitrogen containing polysaccharide
- Provides mechanical strength to the cell
- Prevents the cell from bursting under the pressure created by osmosis
Smooth Endoplasmic Reticulum structure and function
A tubular extension of the nuclear membrane. Synthesises, stores and transports lipids and carbohydrates
