Unit 1 Cell Biology Flashcards
Define Cell
the basic unit of life
Define Differentiation
the change in a cell to become more specialized
Define Emergent Properties
properties that appear in a complex system but do not appear in the individual units
Define Stem Cells
cells that are capable of differentiation
Function of Life
1.nutrition
2.metabolism
3. growth
4.response
5.excretion
6.homeostasis
7. Reproduction
Equation to calculate the size of a cell
actual width of cell = size of image/size of magnification
How does the surface area to volume ration affect the function of a cell
if the ratio is too small the exchange of substances will be too slow, waste substances will accumulate and heat will not be lost efficiently
Cell size is limited by…
Surface area to volume ration
Differentiation involves…
expression of some genes and not others in a cell’s genome
what is necessary for embryonic development
stem cell division and differentiation
Cell Theory
Living organisms are composed of cells (one or more) – that is, cells are the building blocks of organisms.
Cells are the smallest units of life – that is, a cell is the basic unit capable of carrying out all the functions of a living organism.
Cells come from pre-existing cells (omni cellulae e cellula) – that is, cells do not show spontaneous generation.
Why are striated muscles an exception to Cell Theory
Striated muscle tissue is composed of repeated units called sarcomeres. These show a characteristic striped (striated) pattern when viewed under the microscope. This challenges the idea that a cell has one nucleus, as the muscle cell (fibre) has more than one nucleus per cell.
Why are giant algae an exception to Cell Theory
As a single-celled organism, Acetabularia challenges two widely accepted notions about cells: that they must be simple in structure and small in size.
Why are Fungal hyphae an exception to cell theory
This challenges the idea that a cell is a single unit as the fungal hyphae have many nuclei, are very large and possess a continuous, shared cytoplasm.
Describe the use of stem cells to treat Stargardt disease and one other example
Stargardt Disease - Patients are given retinal cells derived from human embryonic stem cells, which are injected into the retina. The results obtained have been quite positive as the inserted cells attach to the retina and become functional, suggesting that it may be possible to restore sight to affected individuals using stem cells.
Leukemia -Treatment in this case involves harvesting hematopoietic stem cells (HSCs), which are multipotent stem cells. HSCs can be taken from bone marrow, peripheral blood or umbilical cord blood. The HSCs may come from either the patient or from a suitable donor. The patient then undergoes chemotherapy and radiotherapy to get rid of the diseased white blood cells. The next step involves transplanting HSCs back into the bone marrow, where they differentiate to form new healthy white blood cells.
Why are stem cells seen as unethical
But, given that some of the methods of obtaining stem cells may involve destruction of an embryo, ethical issues are raised. People question whether it is morally right to promote therapeutic use of stem cells.
Define Magnification
how much an image has been enlarged
Define Resolution
the minimal distance at which two points that are close together can be distinguished
Characteristics of a Prokaryotic cell
no nucleus or membrane bound organelles
cell walls
pili
flagella
plasma membrane containing cytoplasm that has 70S ribosomes
Characteristics of Eukaryotic cells
plasma membrane enclosing cytoplasm that has 80S ribosomes
nucleus
mitochondira
other membrane-bound organelles
Characteristics of Eukaryotic cells
plasma membrane enclosing cytoplasm that has 80S ribosomes
nucleus
mitochondira
other membrane-bound organelles
Electron Microscopes
higher resolution than light microscopes allowing observation of the ultra structure of cells. Can magnify up to x10,000,000
Binary Fission
Binary fission is a means used by prokaryotes to reproduce asexually. It involves the following steps:
The chromosome is replicated semi-conservatively, beginning at the point of origin (shown in red in Figure 2).
Beginning with the point of origin, the two copies of DNA move to opposite ends of the cell.
The cell elongates (grows longer).
The plasma membrane grows inward and pinches off to form two separate, genetically identical cells.
Membranes are formed by
Phospholipids, cholesterol, proteins, lipoproteins, and glycoproteins
Cell membranes are formed by…
double layers of phospholipids
Phosolipids are…
amphipathic meaning they have a hydrophilic part and a hydrophobic part. The hydrophilic heads face both the outside and inside of the cell while hydrophobic parts are in the middle of the bilayer
Define Transmembrane proteins
integral membrane proteins that span across the membrane making it hard to separate them form the membrane
Define Integral Proteins
embedded in the phospholipid bilayer and protrude on only one side of the membrane and are difficult to separate form the phospholipid bilayer
Define Peripheral Proteins
are temporarily attached either to the surface of the phospholipid bilayer or to integral proteins and can be separated from the membrane using salts
Explain the fluidity and permeability of plasma membrane
phospholipids have a low melting point because of the kinking of the long chain of fatty acids occurring at unsaturated bonds which explains why some are found in liquid states and others are found in a solid state, making the membrane fluid. In animal cells, cholesterol embedded in this double layer will control this fluidity and permeability to some solutes
Define Passive Transport
movement across the membrane without the use of energy
Define Facilitated Diffusion
passive transport of molecules or ions across the cell membrane through specific transmembrane proteins
Define active transport
the movement across the membrane requiring energy in the form of ATP
Define Osmosis
The passage of water through a selectively permeable membrane from a higher water potential to a lower water potential
Osmolarity
the measurement of the solute concentration of a solution expressed as the total mass of solute per litre of solution
Isotonic solution
shares the same concentration as the tissues or cells it it bathing
hypertonic solution
has a higher solute concentration that the tissues it bathes
hypotonic solution
lower solute concentration than the tissue is bathes
endosymbiotic theory
mitochondria and chloroplasts were themselves prokaryotes that were taken in by larger prokaryotes by endocytosis. Instead
Have double membranes, as expected for cells taken in by endocytosis. (see Figure 1 below)
Have circular naked DNA, as in prokaryotes.
DNA is formed as single chromosomes.
Have 70S ribosomes, as in prokaryotes.
Divide by binary fission like prokaryotic cells.
Are susceptible to some antibiotics.
Interphase
stage of cell division before mitosis.
the cell grows, formes organelles(G1 stage), DNA is duplicated (S stage) and synthesis of proteins that are involved in nuclear division occur
Mitosis
nuclear division consisting of four stages: prophase, metaphase, anaphase, and telophase
Prophase
The stage where chromatin condenses and associates with histones forming chromosomes, the nuclear membrane disappears and spindle fibres are formed. Chromosomes attach to spindle fibres
Metaphase
The stage where chromosomes are aligned in the equator of the cell
Anaphase
where sister chromatids are separated to the opposite poles of the cell
Telophase
the last stage of mitosis where a nuclear membrane forms around each set of chromosomes that being to uncoil
Cytokinesis
a process that occurs along with telophase. The cytoplasm of the parental cell divides into two daughter cells. Cytokinesis in animals is produced by cell strangling whole in plants it is by formation of a plate
Define Centomere
the stucture of the chromosome that holds together both chromatids and is the point of attachment to the spindle fibres
Define Mitotic Index
Number of cells in mitosis divided by total number of cells seen under the microscope
