Cell nucleus, structure and functions.ppt

Cell Nucleus

1. 1
Cell Nucleus
•Control center of the cell
• Nuclear envelope
• Porous double membrane
• Separates nucleoplasm from
cytoplasm
• Nucleolus
• Dense collection of RNA and
proteins
• Site of ribosome production
• Chromatin
• Fibers of DNA and proteins
• Stores information for synthesis of
proteins
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Nucleus
Nucleolus
Chromatin
(a)
Nuclear
pores
Nuclear
envelope

2. 2
3.3: Movements Into
and Out of the Cell
Passive (Physical) Processes
• Require no cellular
energy and include:
• Simple diffusion
• Facilitated diffusion
• Osmosis
• Filtration
Active (Physiological) Processes
• Require cellular energy and
include:
• Active transport
• Endocytosis
• Exocytosis
• Transcytosis

3. 3
Simple Diffusion
• Movement of substances from regions of higher concentration to
regions of lower concentration
• Oxygen, carbon dioxide and lipid-soluble substances
Time
Solute molecule
Water molecule
A B A B
(2) (3)
Permeable
membrane
A B
(1)
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4. 4
Animation: How Diffusion Works
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5. 5
Facilitated Diffusion
• Diffusion across a membrane with the help of a channel or carrier
molecule
• Glucose and amino acids
Region of higher
concentration
Transported
substance
Region of lower
concentration
Protein carrier
molecule
Cell
membrane
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6. 6
Animation: How Facilitated Diffusion Works
Please note that due to differing
operating systems, some animations
will not appear until the presentation is
viewed in Presentation Mode (Slide
Show view). You may see blank slides
in the “Normal” or “Slide Sorter” views.
All animations will appear after viewing
in Presentation Mode and playing each
animation. Most animations will require
the latest version of the Flash Player,
which is available at
http://get.adobe.com/flashplayer.