2.1 Eukaryotic and prokaryotic cell structure + function Flashcards
What is the unifying concept of cell theory?
1) Cells - smallest unit of life.
2) All cells derived from division of pre-existing cells.
3) Within cells are the sites of all chem reactions of life.
What is the meaning of cell theory?
- Cells fundamental unit of structure, function + organisation in all living organisms.
What is the definition of a unicellular organism?
- Organism composed of a single cell.
What are cells organised into in complex organisms?
- Tissues, organs + organ systems.
What is the definition of a multicellular organism?
- Organism composed of many cells.
- Cells differentiate to become arranged into tissues, organs + systems that carry out different functions.
What is the process of differentiation?
- Developmental process - structure of cells in a multicellular organism specialise, becoming adapted for a specific function.
What happens to specialised cells?
- No longer able to divide.
- Cells show great variety in shape + structure.
What is the definition of a tissue?
- Group of cells w common origin + similar structure that work together to perform a single function.
What is an example of an animal tissue and an example of a plant tissue?
- Animal tissue –> blood.
- Plant tissue –> xylem.
What is the definition of an organ?
- Structure made of more than one type of tissue, that work together to perform a specific function.
What is the definition of an organ system?
- A group of organs + tissues that perform a particular function.
What is an example of an organ system?
- Circulatory system –> heart, together with blood vessels + blood.
What is the definition of a prokaryotic cell?
- Microorganisms, typically unicellular + have fundamentally different structure to eukaryotes.
What are the examples of prokaryotes?
- Bacteria + Cyanobacteria (photosynthetic bacteria).
What are the distinctive features of prokaryotes?
- Size –> exceedingly small - about size of ribosomes/chloroplasts in eukaryotic cells.
- Absence of (membrane-bound) nucleus.
Do prokaryotic cells have a membrane-bound nucleus?
- Single circular DNA molecule molecule (nucleoid).
- Unlike eukaryotic, DNA in nucleoid is not associated w protein.
What is the definition of a nucleoid?
- Circular DNA molecule found in prokaryotic cells.
- Don’t refer to as chromosome - the DNA in neither linear nor associated w histones.
Which structures are found in all prokaryotic cells?
- Cytoplasm, plasma membrane, ribosomes, nucleoid, cell wall.
Which two structures are only found in some prokaryotic cells?
Pili + Flagella.
What are plasmids + what is their function?
- Circular DNA molecules (in addition to nucleoid).
- usually only contain a few genes - usually conferring resistance to antibiotics.
What are 70s ribosomes?
- Involved in protein synthesis, but smaller than 80s ribosomes in eukaryotic cells.
What is found in the cytoplasm of prokaryotic cells?
- Lack of membrane-bound organelles.
- No mitochondria, chloroplasts, golgi apparatus or endoplasmic reticulum.
What are the functions of cell walls in all prokaryotic cells?
- Protects cells from rupture caused by osmosis + possible harm from other organisms.
What does a mesosome look like?
- In-tuckings of the cell membrane.