Transcript Cell Structure and Function

2.1
The Structure & Functions of
Eukaryotic Cells
Chloroplasts
• Derived from photosynthetic bacteria & has DNA
• A double membrane bound, solar energy capturing organelle
• Internal thylakoid membrane is stacked (grana) and has
pigments for photosynthesis.
• Liquid medium around thylakoid called stroma.
Chloroplast Micrograph
Photosynthesis
• It takes place in the thylakoid membranes and
stroma
• Pigments like chlorophyll capture solar energy to
make cellular food (ie: glucose)
• Cyanobacteria closely related to chloroplasts in
higher plants.
Mitochondria
• Have their own DNA
• A double membrane bound organelle
• Internal cristae membrane is folded for increased
surface area.
• Aerobic cellular respiration
occurs in the cristae and
the matrix
• The liquid medium inside
the cristae is called
the matrix.
Mitochondria Micrograph
Mitochondria
• Breaks down high-energy organic molecules (cellular
respiration) to store in chemical bonds as chemical
potential energy.
• In addition to glucose, it can
also use lipids and proteins
• The released energy is
stored in the form of
ATP
Cell Walls
• It is found in plants, fungi, & many protists
• Surrounds cell membrane for support and protection (ie:
Turgor Pressure in plants)
• Made of either polysaccharides, glycoproteins or both.
• It is porous and does little to control access to the cell.
Cytoskeleton
• It is an internal network of
protein fibres
• It’s made of 3 fibre types
– Microfilaments
– Microtubules
– Intermediate filaments
• 3 functions:
– mechanical support
– anchors organelles
– help move
substances
Microfilament Micrograph
Cell Movement
• Microtubules & microfilaments
- slide against one another for
internal cell movement
• Cilia
– Short
– Used to move substances
outside human cells
• Flagella
– Whip-like extensions
– Found on sperm cells
Cilia & Flagella Structure
•
•
•
•
Both are extensions from the cell membrane.
They’re bundles of microtubules
Cilia are short and in large numbers for movement.
Flagella are few but longer for locomotion.
Cell (Plasma) Membrane
• It wraps the cell contents & it’s semi-permeable.
• It’s a double layer of phospholipids & embedded proteins
• This “fluid mosaic model” has the hydrophillic heads
oriented to the outside and hydrophobic tails to the
inside. This controls access in & out of the cell.
• Includes cholesterol, glycoproteins and glycolipids.
Cell Membrane Micrograph
Phospholipids
• They are lipid
molecules with one
glycerol, 2 fatty acids
and a phosphate
group.
• The polar head is
hydrophyllic head and
the non-polar tail is
hydrophobic.
• Most of the fatty acid
chains are saturated.
Membrane Proteins
1. Channels or transporters
– Move molecules in one direction
2. Receptors
– Recognize certain chemicals
Membrane Proteins
3. Cytoskeleton
– Microtubules & microfilaments
4. Enzymes
– Catalyze production of substances
End Part 3