1.1 Flashcards
Outline cell theory
All living organisms are made up of cells
Cells are the smallest unit of life
All cells must come from pre-existing cells
What are caveats to cell theory?
Striated muscle - challenges the idea that cells only have one nuclei
Giant algae - challenges idea that cells are the smallest unit of life (can be ≈7cm big)
Aceptate fungal hyphae - challenges the idea that cells are single/individual units
How do you calculate magnification?
Image size
Magnification Actual size
magnification= image size / actual size
!!!1 µm = 1000cm!!!!
Describe all the functions of life:
Metabolism - all chemical reactions taking place in a cell
Reproduction - either sexual or asexual production of offspring
Homeostasis - maintaining relatively constant conditions
Growth - increasing in size or number of cells
Response - ability to react to change in internal or external environment
Excretion - removal of waste products from metabolic reactions
Nutrition - consuming or producing food
List the functions of life in Paramecium:
Metabolism - reactions taking place in cytoplasm
Reproduction - reproduces asexually via mitosis
Homeostasis - vacuoles control cells water content to be expelled through plasma membrane
Excretion - cell membrane allows oxygen entry for respiration, diffusion of products is when excretion occurs
Nutrition - organisms consumed in cytoplasm to provide energy & materials for growth
List the functions of life for Chlamydomonas:
Metabolism - enzymes speed up reactions in cytoplasm
Reproduction - reproduces sexually and asexually by dividing fused nuclei
Homeostasis - water content released by flagella through vacuoles to keep water content tolerable
Response - beating movement of flagella moves it along, has light sensitive “eye spot” to detect light
Excretion - oxygen diffuses across cell membrane
Nutrition - CO2 converted into what’s needed for growth, cell membrane can absorb other organisms in the dark
Explain what cell size is limited by:
As cell size increases, SA:Vol ratio decreases; so materials & heat cannot be exchanged fast enough across plasma membrane to sustain the needs of the cells metabolism
Outline emergent properties
Emergent properties are the result of interactions between component parts rather than the individual components themselves
What does cell differentiation involve?
It involves the expression of some genes and/or the silencing of others in a cell
Outline key features of stem cells:
They retain the ability to divide
They have the ability to differentiate
Stem cells can be harvested from 3 main sources, briefly describe them:
Embryonic stem cells: harvested from early stages of human embryo, are pluripotent
Cord blood stem cells: harvested from umbilical cords, easily stored, are multipotent
Adult stem cells: difficult to harvest, less growth potential, are unipotent
Discuss the use of stem cells to treat Stargardt’s disease and one other named condition:
Stargardt’s:
A mutation that causes macular degeneration
Embryonic stem cells divide & differentiate into retinal cells, then injected into retina
Leukaemia:
A cancer of the blood
stem cells harvested from bone marrow, chemo destroys diseased cells then stem cells are transplanted into bone marrow
Discuss the ethics of the therapeutic use of stem cells from specially created embryos, from the umbilical cord blood of a newborn baby and from an adult’s own tissues.
Embryonic stem cells:
Pros - undifferentiated, less chance of genetic damage, unlimited growth potential
Cons - involves killing of embryo, more risk to become tumour cells
Cord blood stem cells:
Pros - easily obtained, umbilical cords would be discarded anyway, collected commercially
Cons - limited stem cells from 1 umbilical cord, limited capacity to differentiate
Adult stem cells:
Pros - harvesting doesn’t kill adult, less chance of tumour, fully compatible with adult tissues
Cons - limited ability to differentiate, less growth potential, difficult to obtain
