Cell Biology

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Cell Theory (3)
living organisms are made of one or more cells, cells are the smallest units of life, all cells come from pre-existing cells
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What are the exceptions to cell theory? (3)
Skeletal muscle, Giant Algea & Aseptate fungi
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Skeletal Muscle
(300 or more mm long) made of fibers that are much larger than normal cells & contain many nuclei
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Giant Algea
(as much as 100mm) consists of many small cells but only has one nucleus
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Aseptate Fungi
consists of hyphae (thread-like structures) have many nuclei in their long threads
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Name the functions of life (7)
Nutrition, Growth, Response, Excretion, Metabolism, Homeostasis, Reproduction
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What happens as a cell grows larger?
surface area to volume ration becomes bigger
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Advantages to being multicellular (2)
1) it can grow to a larger size 2) its cells can differentiate so that different cells do different jobs
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When do emergent properties arise?
when the interaction of individual component produce new functions
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Emergent Properties
new properties that emerge from the interaction of their cellular components (multicellular)
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one of the possible forms of a gene (eye colour: gene for eye colour is the same for booth green and brown eyes BUT allele is different)
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An organisms entire set of genes
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Where can a multicellular organisms genome be found?
In every cell (though some genes may not be used or 'turned off'
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When is a cell 'committed'?
Once it is has gone down a pathway of development and becomes fixed and cannot change to a different pathway
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Stem cells
cells that have the capacity to divide and differentiate along different pathways
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Three examples of stem cells of Stem Cells
embryonic stem cells, adult stem cells (bone marrow skin, liver) & umbilical cord blood or placenta of newborn
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Advantages of using embryonic stem cells over adult stem cells
adult stem cells do not have the same capacity as embryonic stem cells to differentiate along different pathways
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Ethical issues of using stem cells therapeutically
.Newborns cannot consent for stem cells to be harvested from their umbilical cord, .If an embryo dies from the procedure it can be argued as immoral
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Counter-arguments to embryonic stem cell treatment
. Early stage embryo's are just a ball of cells, .They lack a nervous system- feel no pain .left over embryo's from IVF> better used for stem cells than just killed
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examples of therapeutic stem cell use
Stargardt's muscular dystrophy & leukemia
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Stargardt's muscular dystrophy
genetic disease (kids 6-12) Mutation in eye, causes mem. protein used for active transport malfunction Vision becomes worse Experiment done- Embryonic stem cells injected into eye Cells attach to retina and stayed there for 4 months Eyesight improve
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Cancer- abnormal amount of white blood cells produce by bone marrow.
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Stem cell treatment of Leukemia (4)
Large needle inserted into large bone of donor, fluid removed from bone marrow. Stem cells extracted and froze. High doses of chemo (kill cancer cells) .Donors stem cells returned to body.
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organisms whose cells contain a nucleus, associated with histone proteins
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organisms whose cells lack a nucleus, no membrane bound organelles and no associated histone proteins
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Binary Fission
process in which prokaryotic cells divide
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The process of Binary Fission
Bacterial chromosome is replicated. These move to opposite ends of the cell. wall and plasma pull inwards> two identical cell. binary fission can occur every 30 mins
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Eukaryotic cells with a single membrane (5)
Rough endoplasmic reticulum, Smooth endoplasmic reticulum, Golgi apparatus, Lysosomes, Vesicles and vacuoles
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Eukaryotic cells with a double membrane (3)
Nucleus, Mitochondrion, Chloroplast
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Name main organelles of prokaryotes
Cytoplasm, Nucleoid (containing naked DNA), 70S Ribosomes, Pilli, Plasma membrane, Cell wall, Flagellum
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enzymes that hydolosise big molecule
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Golgi apparatus
packages proteins into vesicles
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Rough and Smooth Endoplasmic Reticulum
transports and synthesises proteins
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Pro's and Con's to using adult stem cells
Pro's: fully compatible with adult stem cells, Con's: Difficult to obtain, Less potential than embryonic cells
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Pro's and Con's to using embryonic stem cells
Pro's: Less chance of genetic damage/ mutation, Con's: more potential for tumor formation, chance of regection
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The Davson-Danielli Model
(1930's) Model of membrane structure. There is a bilayer of phospholipids in the center of the membrane with layers of proteins on either side
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Reason for Davson-Danielli Model (3)
1)Chem. analysis of membrane showed they were composed of phospholipids and proteins 2) Evidence suggested there was a phospholipid bilayer 3)Experiments showed layers of protein could act as a barrier
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The Singer-Nicolson Model
(1950s-60s) evidence accumulated and falsified Davson-Danielli Model. Model currently used
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What did the Singer-Nicolson Model show to falsify the Davson-Danielli Model? (3)
1)Micrographs showed globular proteins were in the center of phospholipid bilayer 2)Analysis of mem. proteins showed some parts were hydrophobic 3)Fusion of cells w/ mem. proteins taged w/ coloured markers showed proteins can move in mem. colours mix
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Intergral proteins
embedded in the phospholipid bialyer
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Peripheral proteins
attached to outer surface of the phospholipid bialyer's membrane
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sugar units attached onto the outer surface of the phospholipid bialyer's membrane
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basic component of all biological membranes
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Amphipathic molecule
Part of molecule is attracted to water (hydrophilic) ans part is not attracted to water (hydrophobic)
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What happens when phospholipids are mixed with water?
They naturally become arranged into bilayers, hydrophilic heads facing outwards.
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restricts movement of phospholipid molecules (reduces fluidity and permeability of membrane)
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passive movement of particles from a region of high concentration to a region of low concentration
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Diffusion can occur across a membrane if...
there is a concentration gradient and the membrane is permeable to the particle
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Partly permeable membranes
allow some substances to diffuse through but not others
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Facilitated diffusion
the passive movement of molecules across the cell membrane via the aid of a membrane proteins (channel and carrier proteins)
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Simple diffusion
passive movement along a gradient, which will continue until molecules become evenly dispersed (equilibrium)
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Passive transport
the movement of material along a concentration gradient (high concentration ⇒ low concentration)
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Active transport
the movement of materials against a concentration gradient (low concentration ⇒ high concentration)
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Describe sodium and potassium channel proteins in membranes
They are in the membranes of neurons that open and close, depending on the voltage across the membrane. They are voltage-gated membranes and are used to transmit nerve impulses
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Where in the nervous system are potassium channels contained?
The axons of neurons that are used during an action potential
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Channel proteins
one allow one type of substance to pass through the membrane (specific)
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Function of potassium channels in axons
They are
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Skeletal muscle, Giant Algea & Aseptate fungi

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Skeletal Muscle


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Card 4


Giant Algea


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Card 5


Aseptate Fungi


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