Cells Topic 2 Flashcards
(16 cards)
Describe the Structure and function of the cell-surface membrane
- Phospholipid bilayer with embedded proteins etc.
- 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. 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 and salts. Surrounding membrane is called the tonoplast.
Maintains 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
Describe how prokaryotic cells differ from eukaryotic cells
- Prokaryotic cell cytoplasm contains no membrane bound organelles e.g. mitochondria WHEREAS eukaryotic cell contains membrane bound organelles
- Prokaryotic cell has no nucleus / contains free floating DNA WHEREAS eukaryotic cell has a nucleus containing DNA
- Prokaryotic DNA is circular and isn’t associated with proteins WHEREAS eukaryotic DNA is linear and is associated with proteins
- Prokaryotic cell wall contains murein and peptidoglycan WHEREAS eukaryotic cell wall is made of cellulose
- Prokaryotic cells have smaller 70s ribosomes WHEREAS eukaryotic cells have larger ribosomes
- Prokaryotic cells may have…. one or more plasmid, a capsule, and/or one or more flagella
Explain why viruses are considered as non-living
- Acellular → not made of or able to be divided into cells
- Non-living → unable to exist/reproduce without a host cell
Compare and contrast the Optical microscope with the Scanning electron and Transmission electron microscopes
Optical microscope
*uses light
*2d image
*longer wavelengths of light
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