Transcript 1.1.8 Calculate linear magnification of drawings. Drawings

1.1.1 Discuss the theory that living organisms
are composed of cells.
– Note: Skeletal muscle and some fungal hyphae are
not divided into cells but have a multinucleate
(many nuclei) cytoplasm. Some biologists consider
unicellular organisms to be acellular.
1.1.2 State that a virus is a non-cellular
structure consisting of DNA or RNA
surrounded by a protein coat.
1.1.3 State that all cells are formed from other
cells.
– This is the ‘Cell theory’.
1.1.4 Explain 3 advantages of using a light
microscope
Answer: see things in color, large field of view,
easily prepare sample material, portable, could
possibly see a living thing or a moving thing.
1.1.5 Outline the advantages of using electron
microscopes.
Higher resolution (you can see the difference
between two things at a smaller
distance.)Higher magnification.
1.1.6 Define organelle.
An organelle is a discrete structure within a cell,
and has a specific
function.
1.1.7 Compare the relative sizes of molecules,
cell membrane thickness, viruses, bacteria,
organelles and cells, using appropriate SI
units.
molecules (1 nm),
thickness of membranes (10 nm), viruses (100 nm),
bacteria (1 μm),
organelles (up to 10 μm), most cells (up to 100 μm). The
three-dimensional nature/shape of cells should be
emphasized.
1.1.8 Calculate linear magnification of drawings.
Drawings should show cells and cell ultrastructure
with scale bars
eg. Magnification should also be
stated, eg × 250.
Cell lab:
10 different specimens on 100 or 430 power.
• of the 10specimens, 3 of them (at least) need to be fresh
slides –there will be onion etc… on Monday.
Each specimen gets 5 points:
1. BIG Drawing of 2 or 3 cells (only) with 3 things labeled = 3
points
2. Magnification labeled
3. Scale bar that tells the size of the cells.
1.1.9 Explain the importance of the
surface area to volume ratio as a factor
limiting cell size.
• The cell has to exchange materials with the environment.
• Surface area is the area in direct contact with the environment.
• Surface area doesn’t grow as quickly as volume when the cell
gets bigger.
• For a 1 cm cube the SA:Vol = 6:1
• For a 10 cm cube the SA:Vol = 0.6:1
• SO! Cells can’t be too big, or they don’t get the nutrients from
the environment!!!
1.1.10 State that unicellular organisms
carry out all functions of life.
1.1.11 explain that cells in multicellular organisms
differentiate to carry out specialized functions by
expressing some of their genes but not others.
• Every cell has all of the body’s DNA… but only some of it is
activated.
• Differentiation: When a cell is specialized to be one type of cell
like a nerve cell or muscle cell.
•1.1.12 Define tissue, organ and organ system
tissue: group of similar cells performing a particular task (blood
cells, epithelial,muscle tissue… note that one cell doing a task
is meaningless.)
Organ: structural unit made of a group of tissues which work
together to perform a function (liver, heart)
Organ system: several organs working together (digestive,
circulatory)
1.2.1 Draw a generalized prokaryotic
cell as seen in electron micrographs.
These guys use
mesosomes for cell
division… the inner
membrane forms a curl…
1.2.2 State one function for each of the following:
• Cell wall: made of amino
sugars, protection and
strength
• Slime capsule: protection
from drying out, makes
cells stick to stuff and
other cells
• Membranes: control of
what comes in and out
• Cytoplasm: contains
ribosomes, DNA,
• Mesosome: curl of
membrane that makes
the capsule and moves
DNA in cell division
Quiz and Notebook check Friday
1.1.1 to 1.2.2