Cell Biology Flashcards
(44 cards)
What is an organelle?
An organelle is a smaller, specialised compartment/structure within a cell to carry out a particular function.
What is a cell and how did we find out about them?
Cells are the basic structural unit of all organisms, we only found out about them in the mid 1800s with the creation of the light microscope.
Who did this enable and how?
this = the light microscope
This enabled Robert Hooke due to the light microscope having a higher magnification than the naked human eye to view cells and some larger structures inside more individually.
What is cell theory?
- Plant & Animal tissue is comprised of cells
- Cells are the basic unit of all life
- Cells only develop from existing cells
What is a Eukaryotic cell? Give an example.
‘True nucleus’ - DNA is contained within a nucleus. TYPICALLY larger than a prokaryotic cell.
REMEMBER: EUkaryotic - EU is large!
An example is a plant, fungal or animal cell.
What is a Prokaryotic cell? Give an example.
‘Before nucleus’ - DNA is NOT contained in a nucleus. TYPICALLY smaller than a eukaryotic cell.
REMEMBER: PROkaryotic - [Pro]tests to be heard as you’re small!
An example is a bacterial cell.
Define compartmentalisation.
When organelles have their own individual & distinct membranes and environments within a cell to allow for different reactions to take place (as they may need different conditions).
What is the sum of all reactions (in a cell) called? Examples include reactions for building up and breaking down molecules.
(Cell) metabolism/(Cell) metabolic reactions.
What is the ultrastructure of a cell?
(Smaller) Structures of a cell only available to see under an electron microscope.
Why is an electron microscope better than a light microscope (links to Microscopy!)?
- Higher magnification (from shorter wavelength (thus higher frequency))
Due to this, the beams of electrons can pick up smaller structures inside cells such as the mitochondria.
List all sub-cellular structures/organelles in a plant cell.
- Mitochondria
- Golgi body/apparatus
- Nucleolus
- Nucleus
- Nuclear envelope (+ nuclear pores)
- Centrioles (+ Microtubules)
- Cytoplasm
- Ribosomes
- Plasma (Cell Surface) membrane
- Smooth Endoplasmic reticulum
- Rough Endoplasmic reticulum
- Golgi vesicles
- Lysosome
What are extra organelles in a plant cell?
- Cell wall
- Chloroplast
- Plasmodesmata
- Amyloplast
What is the structure of the Plasma (Cell surface) membrane?
- Phospholipid bilayer
- Contains proteins/protein channels
- Hydrophobic exposed heads
- Hydrophilic hidden tails
What is the function of the Plasma (cell surface) membrane?
- Surrounds external surface of cell
- Regulates movement of molecules in/out of cell
- Partially permeable (Osmosis!)
- Selectively permeable
- Barrier between cell and external environments (which may disrupt cell functions otherwise)
What is the structure of the cytoplasm(/cytosol), and why is it important?
- Jelly-like substance/liquid
- Mostly water (+ filled with proteins)
Being mostly water is important as it can act as a solvent (so substances dissolve) to facilitate many cell reactions (its function).
What is the function of the cytoplasm?
- Organelles sit in the cytosol making it cytoplasm
- Site of many (cell) metabolic reactions, such as anaerobic respiration
What is the structure of the Nucleus?
- Surrounded by nuclear envelope
- Nuclear pores in the nuclear envelope (allow for substances, such as ribosomes or RNAs in/out)
- DNA wound around histone proteins, turned to chromatin, then chromosomes (condensed/coiled DNA) to allow lots of DNA to fit in the nucleus
- Contains the nucleolus, a dark staining region with lots of condensed DNA
What is the function of the Nucleus?
- Control cell activity
- Nuclear envelope seperates nucleus & cytoplasm, regulates movement of molecules in/out of the nucleus
- Nuclear pores allow molecules to move in/out the nucleus (e.g., mRNA leaves through the nuclear pores in the nuclear envelope)
- Contains DNA
- Nucleolus -> Ribosome synthesis
What is the cytoskeleton?
Present throughout the cytoplasm of all eukaryotic cells. A network of fibres necessary for the shape & stability of a cell. It’s also responsible for holding organelles in place as well as cell movement/organelle movements within cells.
What are the 3 main cytoskeleton fibres?
- Microfilaments
- Microtubules
- Intermediate Filaments/Fibres
What protein makes up MICROFILAMENTS?
Actin
What protein makes up MICROTUBULES?
Tubulin
What are Intermediate Filaments made up of?
Rigid fibres/Fibrous proteins that don’t change length.
What do microfilaments do in the cytoskeleton of a cell?
Contractile fibres that are responsible for movement of the plasma membrane & cytokinesis (division of cytoplasm in a Eukaryotic cell to produce 2 daughter cells).
