| What are the 3 principles of cell theory? | all living things are made of cells
cells are the smallest unit of life
cells only come from pre-existing cells |
| How is striated muscle fibres an exception to cell theory? | individual cells fuse to form long multinucleated fibres = challenges the idea that cells always work as autonomous units |
| How is aseptate fungal hyphae an exception to cell theory? | Hyphae may be connected with a continuous cytoplasm (no cellular partitions = challenges the idea that living cells are made of separate cells |
| How is giant algae an exception to cell theory? | certain species are very large = challenges the idea that organisms are always made of many microscopic cells |
| What are the 7 functions of life? | Metabolism = undertakes important chemical reactions
Reproduction = produces offspring sexually/ asexually
Sensitivity = responsive to internal / external stimuli
Homeostasis= maintain a stable internal environment
Excretion= remove toxic waste products
Nutrition = exchanges materials with the environment
Growth: changes shape / size / position |
| What are the functions of life in paramecium (heterotroph)? | Metabolism: food particles enclosed in vacuoles with enzymes for digestion
Reproduction: divides asexually (mitosis)
Sensitivity: cilia responds and detects stimuli
Homeostasis: gases enter and exit with diffusion
Excretion: waste products removed by anal pore and liquids pumped out with contractive vacuoles
Nutrition: engulf food with feeding grove
Growth: cilia helps move the cell |
| What are the functions of life for chlorella (Autotroph)? | Metabolism = chlorophyll makes organic molecules with photosynthesis
Reproduction = asexual (mitosis)
Sensitivity = sensitivity towards light (phototaxis)
Homeostasis: keeps equilibrium inside
Excretion + Nutrition = exchange gases by diffusion
Nutrition: photosynthesis
Growth: Non-motile |
| Differences between light and electron microscope (2) | light: uses visible light to views living specimen in colourand has lower resolution and magnification
Electron: dead specimens in black and white, higher resolution and magnification |
| How to calculate magnification? | M = Image size / actual size |
| What does the surface area and volume of a cell affect? | volume = metabolism rate (larger cells need more energy to function)
Surface area = material exchange rate (large membrane surface = more material movement) |
| What are the two different types of gene packaging? (3) | euchromatin: active genes that are packaged in an expanded and assecible form
heterochromatin: inactive packaged in condensed and inaccessible form |
| What are stem cells? (3) | unspecialized cells that can:
self renew (continuously divide and replicate)
potency (capacity to differentiate into specialized cell types) |
| What are the 2 main types of stem cells? (2) | embryonic stem cells (totipotent / pluripotent) can form any cell type
adult stem cells (multipotent / unipotent) limited capacity for differentiation |
| What are all 4 types of stem cells? | totipotent: form any cell type and placental tissue (zygote)
pluripotent: form any cell type (embryonic)
multipotent: differentiate into a number of closely related cell types (Adult)
unipotent: can't differentiate, but can self renew (muscle stem cells_ |
| What is the process of stem cell therapy? | stem cells are extracted from embryos, umbilical cord blood or certain adult tissues (bone marrow)
biochemical solutions trigger differentiation
new cells are implanted into host tissue
immune system is suppressed to stop rejection
new cells are monitored to see that they aren't cancerous |
| What are 2 specific diseases that SCT is used with? | Stargardts disease: it is an inherited form of juvenile macular degeneration = blindness
Treated by replacing dead cells in retina with functioning ones
Parkinsons disease: degenerative disorder caused by the death of dopamine secreting cells (CNS)
treated by replacing dead cells in midbrain with functioning ones
show tremors and rigidity and slow movement as dopamine is an NT used for smooth movements |
| What are the ethical considerations with the use of stem cells? | embryos are specially created with the highest potency however it is the highest risk of developing into a tumor and involves destruction of an embryo
Umbilical cord blood is easy to extract but it has a lower potency and the cells must be stored from birth at a cost
Adult tissues are cells that can be taken at any life stage but it has the lowest potency and could be difficult and painful to extract |
| What are 2 methods of artificial stem cell production? | Somatic cell nuclear transfer (SCNT) = creating embryonic clones by fusing a diploid nucleus with a enucleated egg cell
more embryos than needed are created = raises ethical concerns of excess embryos
Nuclear reprogramming: cause a change in gene expression profile of a celll = different cell type (transdifferentiation)
Uses oncogenic retroviruses and transgenes = cancer |
