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Studying and measuring cells

Viewing Cells:
Magnification the size of an object is larger than the object itself
Resolution to distinguish between two objects that are close to each other (higher the resolution
= higher the detail)

You must add a stain, as most biological matter is transparent, stains…

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Mitochondria Aerobic respiration Folded internal membrane to give large surface

Chloroplast Photosynthesis Stacks of membranes for large surface area for
Nucleus Contains genetic info of Separated by nuclear envelope with pores for
chromosomes communication

Nucleolus Production of ribosome Dark staining area in nucleus

Ribosome Amino acid assembled On…

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Lysosome Enzymes kill of Membrane keeps enzymes separate from rest
pathogens of the cell

Cilia Moves materials
alone tubes
Cilia and undulipodium have the same internal
structure arrangement of 9+2

Undillipodium/Flagellum Moves sperm cells
and gametes of some

Cytoskeleton supports structure and moves organelles around eukaryotic cells

Prokaryote and…

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bond, Carbohydrates are attached to protein and lipid and face the outside of the cell. All this makes
the fluid mosaic model.

Why fluid mosaic?
Fluid: phospholipids are liquid and free to move
Mosaic: lots of components put together like a mosaic


of Cell
Phospholipids Form a…

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Diffusion occurs passively ­ no ATP is needed as substances move down the concentration
gradient. Molecules such as oxygen and carbon dioxide diffuse easily across the bilayer as they are
small and uncharged

Osmosis is a form of diffusion. Although water molecules are polar they are small enough…

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Cell signalling and investigating cell membranes

Cell signalling
Cells communicate with one another by cell signalling, three ways in which to do so are:

Neurones they transmit information electronically over long distance
Hormones endocrine secrete hormones into the bloodstream, they have effects on target cells
which are the only cells…

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S stage - replicates DNA
G stage ­ cells build up energy reserve and makes new membranes

As a result of mitosis: the number of chromosomes stay the same, genetic info passed on is
identical in the daughter cells, two nuclei are formed, and no genetic variation occurs


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Distances from the surfaces to the centre are too great

Surface area to volume ratios

An example of that are the alveoli, they have a large surface area and thin layer that has a short
distance for diffusion, a good supply of blood in the capillaries to absorb and/or deliver…

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Ciliated cells Squamous eplitilihum
Move mucus up the airways towards the Gives short diffusion pathway for oxygen and
mouth carbon dioxide in the alveoli

Measuring lung activity

Tidal volume ­ volume breathed into the lungs in one breath
Vital capacity ­ maximum volume of air that can be breathed out…

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Very small = large surface area

Vein Walls are thin, as blood pressure is low
Walls stretch to accommodate large volumes of blood
Veins have semilumar valves ensuring blood travel
towards heart
Lined by endothelium cells

Semilunar valves in veins Muscles of body contract and squeeze veins, pushing
blood to…


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