Transcript chapter_3_powerpoint_im

• This will serve as a review of the parts of the cell.
• This also has the notes for the sections in chapter 3
discussed in class on diffusion and osmosis as well as
the cell cycle and mitosis.
• You should be able to identify the organelles in fig.
3.1a on the next slide as well as the functions for the
organelles outlined in table 3.1a and b.
• Refer to the reading of chapter 3 or see me with any
questions.
Fig. 3.1a
Table 3.1a
Table 3.1b
• The cytoskeleton diagrammed on the next slide
functions to help the cell retain and constant shape as
well as helping with movement of the cell.
– Note this is very similar to what our Skelton does for us.
– Composed of three types of filaments or fibers. See
diagram.
• Some cells move by cilia or flagella which are
composed of Microtubules.
Fig. 3.1b
• The plasma membrane is composed of a phospholipid
bilayer.
– This is composed of two layers of phospholipid.
– The polar head oriented outside and inside the cell to
associate with the water (hydrophilic) contents.
– The non-polar tails are situated in-between the two polar
heads and form a non-polar core.
– This arrangement helps control the passage of substances
in and out of the cell.
– There are other molecules located in the cell membrane
such as:
• Proteins
• Cholesterol
– These give the membrane a more rigid structure.
Fig. 3.2
• The nucleus is a prominent structure in the cell and
contains the chromosomes.
• This is surrounded by the nuclear membrane
(envelope) which also has pores in it allow passage of
small molecules in and out.
• The nuclear membrane is continuous with the
endoplasmic reticulum. (ER) See Figure 3.3.
Fig. 3.4
• The ER has two parts:
– Rough ER- Studded with ribosomes which make
proteins. (translation)
– Smooth ER- No ribosomes and this functions in lipid
production.
• The ER functions as highway system of sorts within
the cell to help proteins and other cell products make
their way around the cell and to the outside of the cell.
• Golgi Apparatus:
– Located near the ER usually.
– Consists of stacks of three to twenty sacs.
– Receives products from the ER and other cellular
locations.
– Contains enzymes that change and act on these products.
– Directs their shipment to cellular locations.
• Mitochondria-The Power House of the Cell
• This is bounded by two membranes. Fig 3.6
• Inner membrane is called the cristae and is the site of
ATP synthesis via cellular respiration. See book pg 41.
Fig. 3.6bFig. 3.7Fig.
3.7b
• The plasma membranes helps keep a cell intact.
• It is said to be selectively permeable:
– Only allows passage of certain molecules.
– Functions to control what gets in and out:
– Helps keep the internal cell environment stabile.
• Movement across the membrane is both passive and
active.
• Diffusion:
– Random movement of molecules from a region of high
concentration to an area of low concentration.
• Like perfume in a room.
• Dye in water.
– Some molecules can freely diffuse across the cell
membrane.
• Gasses
• Alcohols
– No energy is required for passive diffusion.
• Osmosis: Specialized Diffusion.
– Diffusion of water across a membrane.
– Occurs when there is an unequal concentration across a
membrane.
– Normally body fluids are isotonic to cell interior.
• Equal conc. of solutes inside and outside of the cell.
• In this case cells retain their shape and size.
• Tonicity.
– Osmotic Pressure
Fig. 3.8a
Fig. 3.8b
Fig. 3.8c
• Transport by Carriers:
– Most substances do not just diffuse across a membrane.
– Most are helped along by passing through protein carriers
with-in the membrane.
– Move from an area of high conc. to an area of low conc.
– No energy is required.
• Movement down concentration gradient.
– Seen with passage of Amino Acids or glucose through
cell membrane.
• Active Transport:
– Movement is against the concentration barrier.
– From an area of low concentration to an area of high
concentration.
– Requires energy.
– Makes use of protein carriers as well.
– See fig 3.9 in book.
Fig. 3.9
Table 3.2
• Cell Cycle:
– Orderly set of stages that take place between the time a
cell divides and when the daughter cells divide.
– Interphase: Period between mitosis events.
• G1: (Gap 1/Growth 1) Period right after division and before
DNA Replication. Cell grows is size.
• S Phase: (Synthesis) Period when DNA is duplicated.
• G2: (Gap 2/Growth) Period when Cell prepares for division.
Fig. 3.10
• DNA replication:
– Review in book on page 47 and figure 3.12
Fig. 3.12
• Protein Synthesis:
– DNA > RNA > Protein.
– Review in figure 3.13 and page 48.
Fig. 3.13
• Mitotic Stage of Cell Cycle:
– Parent cell divides to give two daughter cells.
• Identical Cells.
– 5 stages: Fig 3.14, 3-15 and pg 49-50
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Prophase: Chromosomes condense and form visible structures.
Metaphase: Chromosomes align on equator of cell.
Anaphase: Sister Chromatids separate.
Telophase: Chromosomes separated and cleavage furrow
appears.
– During Telophase cytoplasm and cell organelles divide into both cells.
– Called cytokinesis.
Fig. 3.14Fig. 3.2