Download Organelles in EUKARYOTIC CELLS

Organelles in EUKARYOTIC CELLS
Pages 4 – 5: cell membrane, cytoplasm/cytosol, cytoskeleton,
nucleus, chromatin/chromosomes, and centrioles
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Use the info on the following slides to complete pages 4
– 5 in your notes.
You do not have to draw pictures. We will do that in
class.
For location, you may circle plant, animal, or both. If there
is other info for location, be sure to write it in the box.
Cell membrane
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aka plasma membrane or phospholipid bilayer
Location
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Outer layer of the cell
Both plant and animal cells
Function
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Controls what moves in/out of cell (thus helps maintain
homeostasis)
Structure
Composition:
1. Phospholipid bilayer
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Made of 2 layers of phospholipids
Main component (largest part)
2. Steroids
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Cholesterol
Give cells some strength
3. Carbohydrates
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Help cells stick together
Serve as recognition sites
4. Proteins (2 types)
A. Integral = embedded within membrane; used to TRANSPORT
things in and out of cell
B. Peripheral = attached only to inner/outer surface; used in
RECOGNITION
What does fluid mosaic mean?
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Phospholipid bilayer behaves more like a fluid than a solid
Lipids/proteins move freely
If we break down the words…
Fluid = parts not stationary
Mosaic = made up of lots of pieces put together
Cell membrane is selectively permeable!
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It will only allow certain things to pass in or out
Cell membrane
Cell membrane
Cytoplasm vs. cytosol
Cytoplasm
Cytosol
• area in cell
• gel-like aqueous
between nucleus and fluid inside cell
cell membrane
• contains all of the
cells organelles
Cytoskeleton
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Function
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Maintain cell shape
Makes cells strong and resistant to damage
Aids in moving organelles and molecules around the cell in a
process called cytoplasmic streaming
Location
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Spans the cytoplasm
Both plant and animal cells
Structure (in your book on pg. 84)
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What are the parts of the cytoskeleton? It’s made of
three types of protein fibers.
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Microtubules – thick protein cords (tubulin)
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used in cell movement – make up cilia and flagella
used in chromosome movement – make up centrioles and spindle
fibers
maintain cell shape; hold organelles in place
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Intermediate filaments – protein fibers in between thickness,
coiled into cables
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used to maintain shape and support cell
anchor nucleus and other organelles, maintain shape of nucleus
Microfilaments – thin protein strands (actin)
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used in cytoplasmic streaming, cell movement, cell shape, and muscle
contractions
Cytoskeleton
Nucleus
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Function
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Remember…DNA → RNA → proteins
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Where DNA is housed/protected (control center)
Where RNA is transcribed
it’s the DNA that tells the cell what proteins to make, when to
make them, how much to make, where they should go, etc.
DNA never leaves the nucleus – it’s too risky! So the
nucleus is also the site of DNA’s info being copied into
RNA – a process called transcription
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Location:
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Usually centrally located
Both plant and animal cells (largest organelle in animal cells)
Structure
4 parts:
1. Nuclear matrix = protein skeleton that helps nucleus to
maintain its shape
2. Nuclear envelope = surrounds the nucleus; it’s actually a
double lipid bilayer
3. Nuclear pores = small holes in nuclear envelope where
RNA passes from nucleus to cytosol
4. Nucleolus = inside nucleus; site where ribosomes
assembled before they move to cytosol
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Pictures
So DNA is in the nucleus?
YES! But we actually call it different things
depending on what it looks like!
Chromatin
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Long, thin, stringy DNA
State of DNA in a
nondividing cell
Stretched out for genetic
code to be interpreted by
proteins
Chromosomes
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Coiled up and condensed
DNA
State of DNA in dividing
cell
Packaged to be easily
moved to opposite ends
of the cell for cell division
Centrioles
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Location
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Structure
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Animal cells only!
Cytoplasm near nuclear envelope (in centrosome)
Cylinder-shaped organelles made of short microtubules
arranged in a circle
Occur in pairs and are perpendicular to each other
Function
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Organize microtubules of cytoskeleton during cell division
Organize microtubules to form cilia and flagella
Centriole
Centriole