1.1 Cell Biology Flashcards
State the cell theory
- cells are the basic units of life
- cells make up all living organisms
- cells are produced by existing cells
______ carry out all the functions of life, what are the functions of life.
cells
M etabolism R response H omeostasis G rowth R eproduction E xcretion N utriton
explain metabolism and rate of material exchange
metabolism - function of its mass/volume
material exchange - function of its surface area
why does _____ _____ ___ ______ ______ limits cell size ?
the surface area to volume ratio
as a cell grows bigger, volume increases faster than surface area leading to a decreased SA:V ratio.
If metabolic rate exceeds the rate of exchange of vital materials and wastes (low SA:Vol ratio), the cell will eventually die
Hence growing cells tend to divide and remain small in order to maintain a high SA:Vol ratio suitable for survival
Differentiation
unspecialised cell develop into cells with a more distinct structure and function.
It leads to a development or the organism, involves expressing some genes and not other’s in a cell genome
multicellular organisms display ______ _______
Define it
emergent properties
whole organism can do more things than individual cells are capable of, cuz of the interaction between different parts
Genome
complete set of genes
How does the Striated muscle cell defy the cell theory ?
challenges the idea that a cell has one nucleus and all living organisms are made of cells
Muscle Cells called fibres can be very long (300mm)
They are surrounded by a single plasma membrane but they are multinucleated
This does not conform to the standard view of a small single nuclei within a cell
How does giant algae : Acetabularia challenge the cell theory ?
Acetabularia is a single-celled organism challenges both the idea that all organisms are made of cells and that they must be simple in structure and small in size
Gigantic in size (5 – 100mm)
Complex in form
The single nucleus is located in the rhizoid
How does the aseptate fungal hyphae challenge the cell theory ?
challenges the idea that a cell is a single unit and organisms are made of many cells
Fungal hyphae very large, multinucleated with a continuous cytoplasm
They have cell walls composed of chitin
The cytoplasm is continuous along the hyphae with no end cell wall or membrane
What are stem cells
an undifferentiated cell of a multicellular organisms that can form more cells of the same type indefinitely or other kinds of cell via differentiation
What are the different type of stem cells and explain them
Totipotent - can differentiate into any type of cell and can give rise to an organism
Pluripotent - can differentiate into all body cells but can’t give rise to an organism
Multipotent - can only differentiate into a few closely related type of body cells
Unipotent - can only develop into their associated cell
type
How is stem cell used to treat the Stargardt’s disease
Stargardt’s diseases is an inherited disease of the retina, deterioration of the tissue at the back of the eye photoreceptor cells
it is treated by injecting retina cells into the retina
How is stem cell used to treat leukemia
type of cancer in the blood where caused by high levels of abnormal white blood cells
treatment - harvesting hematopoietic stem cells which can be extracted from bone marrow,peripheral blood or umbilical cord blood
patient undergoes chemotherapy and
radiotherapy to get rid of the diseased
white blood cells
then transplanting the HSCs to the bone marrow where they differentiate to form new healthy white blood cells
Ethical issues with stem cells and arguments supporting it
some methods of obtaining stem cells may require the destruction of an embryo
arguments supporting it :
cells may be used in cell therapy which can be used to cure serious diseases and disabilities
transplant can be easily obtained without another humans death
stem cells are harvested at the early stage of the embryo where the embryo has not developed a nervous system and won’t feel any pain
