Download Cell membrane

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Key Points:
1. Structure (and importance) of cell
membrane
2. Structure (and function) of organelles
3. Interconnections between cells to
maintain structural stability in body
tissues.
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Typical cell
1. Cell membrane
2. Cytoplasm
Cytosol
Organelles
Membranous
Non membranous
Vault- large ribonucleoproteins; transport
mRNA from nucleus to cytoplasm
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Cell membrane (plasma membrane)
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Fill in the blanks
•The ________ ________ model describes the structure of the
plasma membrane.
•In this model the membrane is seen as a bilayer of
______________ in which protein molecules are embedded.
Name the functions of cell
membrane proteins
1. _____________
2. _____________
3. _____________
4. _____________
5. _____________
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Cytosol (hyaloplasm)
• The liquid component of the cytoplasm
surrounding the organelles and other
insoluble cytoplasmic structures.
• It is the site of various chemical reactions.
Eg : glycolysis
• It consists of water (aqueous), organic
molecules and dissolved ions.
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Cytosol
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Membranous
Organelles
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The Nucleus
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•The nucleus is the control center of the cell.
• It is the largest organelle in the cell and contains the
DNA.
•Nucleolus is inside the nucleus.
•It is responsible for synthesizing ribosomes.
•The fenestrations (openings) on the surface of the
nucleus are the nuclear pores, through which molecules
move in and out of the nucleus.
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 The DNA of all cells is made up of ___________.
 DNA + _________ proteins = Nucleosome
 ____________ + Linker DNA = Chromatin
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Mitochondrion
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• Cellular power plants - generate Adenosine Tri-Phosphate(ATP) as
a source of chemical energy.
• There are more mitochondria in more active cells.
Eg: Skeletal muscle cells, cardiac muscle cells.
Q : From which gametocyte does the
mitochondrion inherit its genome?
A : Ovum
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Smooth (SER) & Rough (RER) Endoplasmic
Reticulum
•ER is a network of
membranes
throughout the
cytoplasm of the cell.
•There are two types
of ER
Function : Synthesis
Storage
Transport
of proteins
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Fill in the blanks
•When ______________are attached it is called RER and SER when there
are no ______________ attached.
•The RER is where most ________________ occurs in the cell.
•The function of the SER is to synthesize __________in the cell.
•The SER also helps in the ___________of harmful substances in the cell.
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Golgi Apparatus
•Packaging and shipping of proteins
•Cell membrane renewal
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Lysosomes
• The recycling compartment of the cell.
• Engulf cellular and endocytosed proteins, lipids that need digestion.
• The resulting metabolites are transported either as vesicles or directly across
the membrane.
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Name A , B, C & D
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Non-membranous Organelles
1. Cytoskeleton
2. Microvilli
3. Centrioles
4. Ribosomes
Cytoskeleton
Q. Name the 4 protein
components:
1. ________________
2. ________________
3. ________________
4. ________________
Q. What is its function:
____________
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Direct formation of mitotic spindle.
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Centrosome
• An area in the cell where microtubles are produced (microtubule
organizing center).
• It is composed of 2 centrioles, each made up of a ring of 9 groups of
microtubules -3 fused microtubules in each group.
• One centriole is perpendicular to the other.
• During cell division, the centrosome divides and the centrioles replicate
(make new copies).
• It results in two centrosomes, each with its own pair of centrioles.
• The two centrosomes move to opposite ends of the nucleus, and from
each centrosome microtubules grow into a spindle.
• It is responsible for separating replicated chromosomes into the 2
daughter cells.
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Ribosomes
Q:
•Eukaryotic ribosomes are made
up of 60% _______ & 40%
_______.
•They are active in _______
synthesis.
A:
•There are 2 types of ribosomes
60% RNA + 40% Protein
1. __________
Active in protein synthesis
2. __________
There are fixed (on RER) and
free ribosomes
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Intercellular Attachments
1) Gap Junctions
•channel proteins interlock and
form pores
Q: Where are they abundantly seen?
A: in cardiac and smooth muscle
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2) Tight Junctions
• Interlocking membrane
proteins
Q: Where are they abundantly
seen?
A: surface of epithelial cells
lining the digestive tract
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3) Desmosomes
• Proteoglycan layer reinforced by transmembrane proteins (cell
adhesion molecules)
• 3 types - Belt, button & hemi-desmosomes
Q: Where are they abundantly seen?
A: Found in superficial layers of skin
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ANSWERS
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•The fluid mosaic model describes the structure of the plasma
membrane.
•In this model the membrane is seen as a bi-layer of phospholipids in
which protein molecules are embedded.
Functions of cell
membrane proteins
1.
2.
3.
4.
5.
6.
Cell adhesion
Carriers
Pumps
Ion channels
Receptors
Enzymes
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• The DNA of all cells is made up of nucleotides.
• DNA + Histone proteins
= Nucleosome
• Nucleosome + Linker DNA = Chromatin
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Answer
•When ribosomes are attached it is called RER and SER when there are no
ribosomes attached.
•The RER is where most of the protein synthesis occurs in the cell.
• The function of the SER is to synthesize lipids in the cell.
•The SER also helps in the detoxification of harmful substances in the cell.
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The 4 protein components are,
1. Microfilaments (mostly actin)
2. Intermediate filaments
3. Thick filaments (composed of myosin subunits)
4. Microtubules (composed of tubulin subunits)
Function:
•
Maintain cell shape & integrity
•
Support & move cellular structures & materials
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THE END
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