Unit 1 Cell Biology Flashcards
Cell Theory States that:
All living things are composed of cells
The cell is the smallest unit of life
Cells come from pre-existing cells
Cells multiply though division
Exeptions From Cell Theory:
Striated Muscle Cells
Aseptate Fungal Hyphae
Giant Algae
Stiated Muscle Cells are:
Multinucleated
Long fibres (300mm)
Surrounded by a single plasma membrane
Aspeptate Fungal Hyphae are:
not a single unit very long continuous cytoplasm along multiple cells Multinucleated cell walls composed of chitin
Giant algae are;
- Complex structure
- Large size (5-100mm)
- Nucleus is located in the rhizoid
MRHGREN
metabolism response sensitivity homeostasis growth reproduction excretion nutrition
Differentiation
All diploid cells contains the entire set of genetic materials. BUT not all genes are activated in all cells
Stem Cell Pathways
Stem cells are unspecialised
Can continuously divide and replicate
Differentiate into specialised cell types
Totipotent
Pluripotent
Multipotent
Unipotent
Toti - Differentiate into any cell
Pluri - Differenciate into many types of cells
Multi - Differentiate into few closely related types of cells
Uni - regenerate but can only differentiate into their associated cell type
State Mitochrondria Structure and purpose
Double membrane
folded (cristae) inner membrane
Site of ATP production by aerobic respiration
State structure and purpose of 80s ribosomes
Larger than 70s
No membrane
Synthesises proteins to function in the cytoplasm for use within the cell.
State structure and purpose of Rough ER
Consists of flattened membrane sacs (cisternae)
Often located near nucleus
80S ribosomes attached to outside of cisternae.
Synthesise proteins which are transported by vesicles to the golgi for modification before secretion outside the cell
Golgi Aparatus structure and purpose
Cristernae, like rER
No ribosomes attached
often close to plasma membrane.
Cristernae are shorter and curvier.
Modifies proteins from rER and then are packaged by vesicles for secretion
Visicle structure and purpose
Single membrane with fluid inside
Very small in size
larger than ribosomes.
used to transport materials inside the cell
Lysosomes structure and and purpose
spherical with singular membrane formed from golgi vesicles.
Contain digestive enzymes
high concentration of enzymes cause organelle to stain heavily (appears dark on micrographs)
Vacuoles structure and purpose
Single membrane with fluid inside.
plant cell vacuoles are large and permanent, often occupying majority of cell volume.
Flagellum
Thin projection from cell surface
Contain microtubules
Used to move cell
Only in animal cells
Cilia
Thin projections from cell surface
Contain microtubules
Used to either move the cell or to move the fluids next to cell
Only animal cells.
Microtubules
Small cylindrical fibres
Vary in functions
Eg. Plays a role in cell division.
Centrioles
Consists of two groups of nine triple microtubules.
Are mainly found in animal cells.
Not present in vascular plants or fungi.
Chloroplast
Site of photosynthesis
Where glucose is produced
Plant cells only
Binary Fission
Prokaryotes Reproduce asexually
- DNA is replication semi conservatively
- Two DNA loops attach to membrane
- Membrane elongates and pinches off (cytokinesis) forming two separate cells
- Two daughter cells are genetically identical (clones)
Calculate Magnification
Scale bar measurement / scale bar label
Prokaryotes
Smaller than eukaryotes Came first in terms of evolution. E. Coli example of prokaryote Some strains are toxic to humans and can cause food poisoning. Ultrastructure of prokaryotes
Compartmentalised
Efficiency Metabolism - enzymes and substrates localised, much more concentrated
Localised conditions - pH and other factors can be kept at optimal levels.
Optimal pH differs per cell (can be Toxic/damaging)
Substances can be isolated (Digestive enzymes) and stored in lysosomes
Numbers and locations of organelles can be changes dependent on the cell’s requirements.
Electron Microscopes
Can see ultrastructure of cells
Phospholipids
Has a hydrophillic head and hydrophobic tail
Amphipathic
Form double layers in water
Proteins in lipid bilayer
Many different proteins embedded in lipid bilayer
These proteins determine most of membrane specific functions.
Cholesterol
Disturbs clost packaging of phospholipids
Helps to regulate membrane fluidity
Important for membrane stability
Potassium Channels
Voltage gated in axons
Enable facilitated diffusion of potassion of on axon
1. More positive charges inside
2. This voltage charges, causes potassium channels to open, allows potassium ions to diffuse out of axon
3. Once voltage conditions change, channel rapidly closes again.
Osmotic Control
Hypertonic (plasmolyzed) - higher concentration outside cell
Isotonic (flaccid) - equil inside and outside cell
Hypotonic (Turgid) - higher concentration inside cell
Phospholipid bilayer
Selectively permeable
Small molecules can diffuse easily from simple diffusion or facilitated diffusion
Larger particles need active transport
Large molecules undergo endo/exocytosis
Endocytosis
Takinging in external substances by inward punching of plasma membrane, forming a vesicle.
Exocytosis
Secreation of substances when a vesicle joins cell plasma membrane.
Vesicles
Small, spherical packages that form from RER and Golgi
Carry proteins produced by ribosomes on RER to Golgi
Prepared for export from cell via another vesicle.
Prophase
Centosome move to opposite poles of cell and spindle fibres begin to form between them
DNA supercoils - chromatin condense and become sister chromatids
Nucleus membrane breaks down and disapears
Cyclins
Protein
- Cells cannot progress to next stage of cell cycle unless specific cyclin reaches its threshold
- Cyclins bind to enzymes celled cyclin dependent kinases
- These kinases then become active and attach phosphate groups to other proteins in the cell
- Attachment of phosphate triggers other proteins to become active and carry out tasks (specific to one of the phases of the cycle.
Nucleus
Spherical
double membrane with pores
Contains genetic info in DNA double helix
Mitochondria
Double membrane
Folded inner membrane
Folds referred to as cristae, variable in shape.
Site of ATP production by aerobic respiration
Ribosomes
80S ribosomes larger than 70S ribosomes
No membrane
Synthesises proteins to function in cytoplasm
Use within the cell.
Rough ER
Flattened membrane sacs (cisternae)
Located near nucleus
80S ribosomes attached to outside of cristernae
Synthesise proteins which are transported by vesicles to golgi for modification before secretion outside cell.
Golgi Apparatus
Flattened membrane sacs called cisternae, like rER
No attached ribosomes
Close to plasma membrane
Cisternae - shorter and curvier
Modifies proteins from rER and then repackaged by vesicles for secretion.
Vesicles
Single membrane Fluid inside Very small in size Larger than ribosomes Used to transport materials inside cell
Sodium-Potassium Pump
Interior of pump opens to inside of axon; 3 sodium ions enter pump and attach to binding sites.
- ATP transfers a phosphate group from itself to pump; this causes pump to change shape and interior is then closed.
- Interior of pump opens to outside of axon and 3 sodium are released.
- Two potassium ions from outside can then enter and attach to their binding sites.
- Binding of potassium causes release of phosphate group; this causes pump to change shape again so it only opens to inside of axon.
- Interior of pump opens to inside of axon and 2 potassium ions are released. Sodium ions can now enter and bind to the pump again (1).
Metaphase
Spindle Fibres from each end of centromere attach to sister chormatids
Anaphase
Continued contraction of microtubule
Spindle fibres cause separation of sister chromatids
Chromosomes move to opposite poles
Telophase
Chromosomes uncoil and decondense
Chromosomes arrive at poles
New membranes form
