structure and physiological of cell

1. University of karbala
College of medicine
First stage
PBL Week 1
Zaid Hashim Yousif

2. Structure and physiological of cell

3. Contain 3 basic cell
structures:
•Cell Membrane
•Cytoplasm with organelles
•Nucleus

5. Cell or Plasma Membrane
• Surrounds outside of ALL cells
• Composed of double layer of phospholipids
,proteins and other compound
• It has highly selective permeability properties
• Controls what enters or leaves the cell
• Provides structural support for cell and tissues
• Allows for communication
• Creates separation between ECF vs. ICF

6. • Each phospholipid molecule consists of an enlarged
head in which the phosphate portion is located; and
of two thin tails.
• The head end is called the polar end , hydrophilic
Heads contain glycerol & phosphate The tail end is
the non-polar end, hydrophobic made of fatty acids

7. • Proteins help move large molecules or aid in cell
recognition
• Some proteins occupy the entire thickness of the
membrane and may project out of both its
surfaces.
• These are called transmembrane proteins
• Peripheral proteins are attached on the surface
(inner or outer)
• Integral proteins are embedded completely
through the membrane

8. Functions of transmembrane proteins
1. Transport function
2. Enzyme function
3. Gated Ion channel formation
4. Receptor function/signal transduction

9. Peripheral Protein Functions
• Enzyme function
Mediate chemical reactions
• Structural
Mediate attachment
• Transporters
Between/among cell membrane proteins
• Electron carriers
In electron transport chain
• Regulators
Such as apoptosis (programmed cell death)

10. Other phospholipid bilayer membrane
components
• cholesterol
• sphingolipids
• Glycoconjugates

11. Sphingolipids
• Group of membrane lipids with larger “heads”
Involved in
• cell signal transduction by forming caveolae
• cell-cell communication
• Endocytosis & uptake of viruses and bacteria
• Form “lipid rafts” – more cholesterol

12. Glycoconjugates
• Includes glycolipids & glycoproteins
• Form a glycocalyx on the exoplasmic surface
(covering that surrounds the cell
membranes of some bacteria, epithelia and
other cells)
• Many functions
• Integrated with other membrane
molecules/structures such as sphingolipids

13. • Functions of glycocalyx:
– Protection
• Cushions the plasma membrane and protects it from chemical injury
– Immunity to infection
• Enables the immune system to recognize and selectively attack foreign
organisms
– Defense against cancer
• Changes in the glycocalyx of cancerous cells enable the immune system
to recognize and destroy them
– Transplant compatibility
• Forms the basis for compatibility of blood transfusions, tissue grafts, and
organ transplants
– Cell adhesion
• Binds cells together so that tissues do not fall apart
– Inflammation regulation
• Glycocalyx coating on endothelial walls in blood vessels prevents
leukocytes from rolling/binding in healthy states
– Fertilization
• Enables sperm to recognize and bind to eggs
– Embryonic development
• Guides embryonic cells to their destinations in the body

14. Cytoplasm of a Cell
• Jelly-like substance enclosed by cell membrane
• Provides a medium for chemical reactions to take
place
• Cytoplasm is divided functionally into
Cytosol
• Site of many chemical reactions
Inclusions
Membranous Organelles
• Functional units of the cell

15. Cytosol
Cytosol functions (many in conjunction with other
processes)
• Cell signaling
• Cytokinesis ( division of cytoplasm of a
single eukaryotic cell divides into two daughter
cells)
• Protein synthesis
• Glycolysis (conversion of glucose into pyruvate)
• gluconeogenesis

16. Inclusions
• The Inclusions
– Direct contact on the cytosol
• Ribosomes
–Involved in synthesis of proteins
• Proteasomes
–Involved in protein degradation
• Protein fibers
–Provide structure and movement within the
cell
»Actin
»Intermediate filaments
»microtubules

17. The cytoskeletal
help to
1. Maintain cell shape
2. Organize the internal compartment of the
cell
3. Provide transport routes within cells
4. Aid in creation of tissues from cells
5. Create movement

18. consist of the following:
• ‰‰Microfilaments
• ‰‰Microtubules
• ‰‰Intermediate filaments

19. Centrioles
• Paired structures near nucleus
• Made of bundle of microtubules
• Appear during cell division forming mitotic
spindle
• Help to pull chromosome pairs apart to
opposite ends of the cell

20. Cytoskeleton
20
MICROTUBULES
MICROFILAMENTS

21. Mitochondria
Consist of
• Outer membrane
• The inner membrane is highly folded on itself
forming incomplete partitions called cristae.
• The space bounded by the inner membrane is
filled by a granular material called the matrix
This matrix contains
1. numerous enzymes.
2. some RNA
3. dioxyribonucleic acid (DNA).

23. • Converts energy stored in food into usable
energy (ATP) therefore call “Powerhouse” of
the cell

24. Endoplasmic Reticulum - ER
• It forms an interconnected network of
flattened, membrane-enclosed sacs or tube-
like structures known as cisternae.
• Connects to nuclear envelope & cell
membrane

25. • There are two types of endoplasmic reticulum:
• rough endoplasmic reticulum is studded
with ribosomes that are the sites of protein
synthesis.
• The smooth endoplasmic reticulum lacks
ribosomes and functions in lipid manufacture
and metabolism, the production of steroid
hormones, and detoxification.

27. Ribosome
• Made of PROTEINS and rRNA
• “Protein factories” for cell
• Join amino acids to make proteins
• Process called protein synthesis
Can be attached to
Rough ER
Be free (unattached) in the cytoplasm

28. Golgi Bodies
• Stacks of flattened sacs
• Receive proteins made by ER
• Transport vesicles with modified proteins
pinch off the ends
• Modify, sort, & package molecules from ER for
storage OR transport out of cell
• Materials are transported from Rough ER to
Golgi to the cell membrane by VESICLES

29. • into three regions
• The region nearest the nucleus is the cis face
(or cis Golgi).
• The opposite face (nearest the cell
membrane) is the trans face
• The inter mediate part (between the cis face
and the trans face) is the medial Golgi

31. Nucleus
• Usually the largest organelle
• Controls the normal activities of the cell
• Contains the DNA in chromosomes
• Bounded by a nuclear envelope (membrane)
with pores
• Each cell has fixed number of chromosomes
that carry genes
• Genes control cell characteristics

32. • All cells in the body contain nucleus, except
mature red blood cells (RBCs) in circulation
Functions
• Gene Expression
• Can only happen if material is allowed in &
out of the nucleus
• Processing of pre-mRNA

34. Nuclear Envelope
• Double membrane surrounding nucleus
• Also called nuclear membrane
• Contains nuclear pores for materials to enter
& leave nucleus
• Connected to the rough ER
• Nuclear membrane compartmentalizes the
nuclear material from the rest of the cell
allowing control on both sides

35. Nucleolus
• Cell may have 1 to 3 nucleoli
• Disappears when cell divides
• Makes ribosomes that make proteins

36. Thank you