Structure of Eukaryotic Cells Flashcards
Describe the Structure and function of the cell-surface membrane
1- Phospholipid bilayer with embedded proteins etc.
2. Selectively permeable – enables control of passage of substances in and out of cell
- Barrier between internal and external environment of cell
Describe the Structure and function of the nucleus
- Nuclear envelope, nuclear pores, nucleolus, DNA / chromatin
- Controls the cells activity though transcription on mRNA
- Nuclear pores allow substances e.g. mRNA to move between the nucleus and cytoplasm
- Nucleolus makes ribosomes which are made up of proteins and ribosomal RNA
Describe the Structure and function of the mitochondria
- Double membrane – inner membrane folded to form cristae.
- Matrix containing small 70S ribosomes, small circular DNA and enzymes involved in aerobic respiration (glycolysis).
- Site of aerobic respiration producing ATP for energy release
Describe the Structure and function of the Golgi apparatus
- 3 or more fluid filled membrane bound sacs with vesicles at edge
- Receives protein from rough endoplasmic reticulum
- Modifies/processes protein e.g. add carbohydrates/sugars
- Packages into vesicles e.g. for transport to cell surface membrane for exocytosis
- Also makes lysosomes
Describe the Structure and function of the lysosomes
- Type of Golgi vesicle containing lysozymes – hydrolytic enzymes
- Release of lysozymes to break down / hydrolyse pathogens or worn out cell components
Describe the Structure and function of ribosomes
- Float free in cytoplasm or bound to rER. 2. Not membrane bound. Made from 1 large and 1 small subunit.
- Site of protein synthesis, specifically, translation.
Describe the Structure and function of the rough endoplasmic reticulum
- Ribosomes bound by a system of membranes
- Folds polypeptides to secondary / tertiary structure
- Packages to vesicles, transport to the Golgi apparatus etc.
Describe the Structure and function of the smooth endoplasmic reticulum
- Similar to RER but without ribosomes – system of membranes
- Synthesises and processes lipids
Describe the Structure and function of chloroplasts (plants and algae)
- Thylakoid membranes are stacked up in some parts to form grana, which are linked by lamellae. These sit in the stroma (fluid) and are surrounded by a double membrane. Also contains starch granules and circular DNA.
- (Chlorophyll) absorbs light for photosynthesis to produce organic substances
Describe the Structure and function of the cell wall (plants, algae and fungi)
- Made mainly of cellulose in plants and algae, and of chitin in fungi
- Rigid structure surrounding cells in plants, algae and fungi. Prevents the cell changing shape and bursting (lysis)
Describe the Structure and function of the cell vacuole (plants)
- Contains cell sap – a weak solution of sugars, salts and pigments.
- Surrounding membrane is called the tonoplast.
- Maintains turgor pressure in the cell (stop wilting)
- Stores/isolates unwanted chemicals in the cell
Describe how specialised cells are organised in complex multicellular organisms
- Specialised cell – the most basic structural/functional subunit in all living organisms; specialised for a particular function
- Tissue – Group of organised specialised cells; joined and working together to perform a particular function; often with the same origin
- Organ – Group of organised different tissues; joined and working together to perform a particular function
- Organ system – Group of organised organs; working together to perform a particular function
Explain how epithelial cells in the small intestine are specialised for efficient absorption.
Villi and microvilli increase surface area.
Lots of mitochondria to provide energy e.g. for active transport
