Cell membranes contain proteins that transport molecules across the membrane. Simple diffusion allows small, nonpolar molecules to pass through, while protein channels called ion channels rapidly transport ions down their concentration gradients. Carrier proteins also transport molecules via facilitated diffusion or active transport. Facilitated diffusion uses carrier proteins to transport molecules down their concentration gradients without direct input of energy. Active transport transports molecules against their gradients by carrier proteins that change conformation in an energy-requiring process.
Digestion of proteins, absorption of amino acids, synthesis of amino acids, catabolism of amino acids and synthesis of specialised non-protein compounds from amino acids for undergraduates
Proteoglycans are proteins that are heavily glycosylated*. The basic proteoglycan unit consists of a "core protein" with one or more covalently attached glycosaminoglycan (GAG) chain(s).
Isoenzymes (or isozymes) are a group of enzymes that catalyze the same reaction but have different enzyme forms and catalytic efficiencies. Isozymes are usually distinguished by their electrophoretic mobilities.
Glycosylation, the attachment of sugar moieties to proteins, is a post-translational modification (PTM) that provides greater proteomic diversity than other PTMs.
synthesis and lipolysis is explained in detail. enzymes involved and their differences are tabulated. adipose tissue metabolism is also included. Fatty liver causes are explained in detail. obesity is briefly described.
Digestion of proteins, absorption of amino acids, synthesis of amino acids, catabolism of amino acids and synthesis of specialised non-protein compounds from amino acids for undergraduates
Proteoglycans are proteins that are heavily glycosylated*. The basic proteoglycan unit consists of a "core protein" with one or more covalently attached glycosaminoglycan (GAG) chain(s).
Isoenzymes (or isozymes) are a group of enzymes that catalyze the same reaction but have different enzyme forms and catalytic efficiencies. Isozymes are usually distinguished by their electrophoretic mobilities.
Glycosylation, the attachment of sugar moieties to proteins, is a post-translational modification (PTM) that provides greater proteomic diversity than other PTMs.
synthesis and lipolysis is explained in detail. enzymes involved and their differences are tabulated. adipose tissue metabolism is also included. Fatty liver causes are explained in detail. obesity is briefly described.
structure of human cell: human cell is the basic structural and functional unit of life which having a cytoplasmic region, nucleus and a plasma membrane . the word cell is coined by the scientist Robert Hook in the year of 1665 . cell organelles and their functions . function of the cell and each organelles functions
Cytoplasm. Within cells, the cytoplasm is made up of a jelly-like fluid (called the cytosol) and other structures that surround the nucleus. Scientists concluded that the average human body contains approximately 37.2 trillion cells
Cell Structures and Functions In pathology.pptxVictory120660
Cell structure and function are fundamental to understanding biology. Here's a broad overview:
1. **Cell Structure:**
- **Cell Membrane:** Acts as a barrier, controlling the passage of substances in and out of the cell.
- **Cytoplasm:** Gel-like substance within the cell where organelles are suspended.
- **Nucleus:** Contains genetic material (DNA) and controls cell activities.
- **Organelles:** Structures within the cell with specific functions, such as mitochondria (energy production), endoplasmic reticulum (protein synthesis), Golgi apparatus (protein packaging), and lysosomes (digestion).
2. **Cell Function:**
- **Metabolism:** Cells carry out metabolic processes to maintain life, including energy production, nutrient breakdown, and waste removal.
- **Reproduction:** Cells can reproduce through processes like mitosis (cell division) or meiosis (reproductive cell division).
- **Homeostasis:** Cells maintain a stable internal environment by regulating processes like temperature, pH, and nutrient levels.
- **Communication:** Cells communicate with each other through chemical signals, allowing coordination within tissues and organ systems.
- **Differentiation:** Cells specialize into different types with specific functions during development, forming tissues and organs.
- **Response to Stimuli:** Cells can respond to external stimuli, such as light or chemicals, through processes like movement or changes in gene expression.
Understanding cell structure and function is crucial for comprehending biological processes at all levels, from the functioning of individual organisms to the interactions within ecosystems.
Cell Anatomy and physiology ( structure and function for NEET asparients, Biology, MBBS, BPT, Allied, nursing , medical and paramedical students. This is the easiest form of slide share to understand the context better.
Cell structure slideshare.pptx Unlocking the Secrets of Cells: Structure, Fun...ananyagirishbabu1
Dive into the intricate world of cells with our detailed Slideshare presentation. This educational resource is designed to provide a thorough understanding of cells, the fundamental building blocks of all living organisms. Ideal for students, educators, and biology enthusiasts, this presentation covers:
Introduction to Cell Theory: Discover the historical development of cell theory and its significance in modern biology.
Types of Cells: Compare and contrast prokaryotic and eukaryotic cells, highlighting their unique features and functions.
Cell Organelles and Their Functions: Explore the various organelles within a cell, such as the nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, and more, each described with their specific roles.
Cell Membrane Structure and Function: Learn about the composition and function of the cell membrane, including its role in regulating the movement of substances in and out of the cell.
Cell Division and Reproduction: Understand the processes of mitosis and meiosis, key to cellular replication and genetic diversity.
Specialized Cells: Investigate the diversity of cell types, including muscle cells, nerve cells, and blood cells, and their specialized functions in multicellular organisms.
Interactive Diagrams and Visual Aids: Engage with detailed diagrams and illustrations that clarify complex concepts and enhance learning.Introduction to Cell Theory: Discover the historical development of cell theory and its significance in modern biology.
Types of Cells: Compare and contrast prokaryotic and eukaryotic cells, highlighting their unique features and functions.
Cell Organelles and Their Functions: Explore the various organelles within a cell, such as the nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, and more, each described with their specific roles.
Cell Membrane Structure and Function: Learn about the composition and function of the cell membrane, including its role in regulating the movement of substances in and out of the cell.
Cell Division and Reproduction: Understand the processes of mitosis and meiosis, key to cellular replication and genetic diversity.
Specialized Cells: Investigate the diversity of cell types, including muscle cells, nerve cells, and blood cells, and their specialized functions in multicellular organisms.
Interactive Diagrams and Visual Aids: Engage with detailed diagrams and illustrations that clarify complex concepts and enhance learning.
This Slideshare presentation is a valuable educational tool, offering clear explanations and engaging visuals to help you grasp the essential concepts of cellular biology. Whether preparing for exams, teaching a class, or simply exploring the microscopic foundations of life, this resource provides a comprehensive overview of the fascinating world of cells. Explore the fascinating world of cells with our comprehensive SlideShare presentation. This educational resource delves into the fundamental unit of life,
Similar to cell,subcellular organelles,and transport (20)
Prix Galien International 2024 Forum ProgramLevi Shapiro
June 20, 2024, Prix Galien International and Jerusalem Ethics Forum in ROME. Detailed agenda including panels:
- ADVANCES IN CARDIOLOGY: A NEW PARADIGM IS COMING
- WOMEN’S HEALTH: FERTILITY PRESERVATION
- WHAT’S NEW IN THE TREATMENT OF INFECTIOUS,
ONCOLOGICAL AND INFLAMMATORY SKIN DISEASES?
- ARTIFICIAL INTELLIGENCE AND ETHICS
- GENE THERAPY
- BEYOND BORDERS: GLOBAL INITIATIVES FOR DEMOCRATIZING LIFE SCIENCE TECHNOLOGIES AND PROMOTING ACCESS TO HEALTHCARE
- ETHICAL CHALLENGES IN LIFE SCIENCES
- Prix Galien International Awards Ceremony
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
Knee anatomy and clinical tests 2024.pdfvimalpl1234
This includes all relevant anatomy and clinical tests compiled from standard textbooks, Campbell,netter etc..It is comprehensive and best suited for orthopaedicians and orthopaedic residents.
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
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Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
Ethanol (CH3CH2OH), or beverage alcohol, is a two-carbon alcohol
that is rapidly distributed in the body and brain. Ethanol alters many
neurochemical systems and has rewarding and addictive properties. It
is the oldest recreational drug and likely contributes to more morbidity,
mortality, and public health costs than all illicit drugs combined. The
5th edition of the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5) integrates alcohol abuse and alcohol dependence into a single
disorder called alcohol use disorder (AUD), with mild, moderate,
and severe subclassifications (American Psychiatric Association, 2013).
In the DSM-5, all types of substance abuse and dependence have been
combined into a single substance use disorder (SUD) on a continuum
from mild to severe. A diagnosis of AUD requires that at least two of
the 11 DSM-5 behaviors be present within a 12-month period (mild
AUD: 2–3 criteria; moderate AUD: 4–5 criteria; severe AUD: 6–11 criteria).
The four main behavioral effects of AUD are impaired control over
drinking, negative social consequences, risky use, and altered physiological
effects (tolerance, withdrawal). This chapter presents an overview
of the prevalence and harmful consequences of AUD in the U.S.,
the systemic nature of the disease, neurocircuitry and stages of AUD,
comorbidities, fetal alcohol spectrum disorders, genetic risk factors, and
pharmacotherapies for AUD.
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
Pulmonary Thromboembolism - etilogy, types, medical- Surgical and nursing man...VarunMahajani
Disruption of blood supply to lung alveoli due to blockage of one or more pulmonary blood vessels is called as Pulmonary thromboembolism. In this presentation we will discuss its causes, types and its management in depth.
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New Drug Discovery and Development .....NEHA GUPTA
The "New Drug Discovery and Development" process involves the identification, design, testing, and manufacturing of novel pharmaceutical compounds with the aim of introducing new and improved treatments for various medical conditions. This comprehensive endeavor encompasses various stages, including target identification, preclinical studies, clinical trials, regulatory approval, and post-market surveillance. It involves multidisciplinary collaboration among scientists, researchers, clinicians, regulatory experts, and pharmaceutical companies to bring innovative therapies to market and address unmet medical needs.
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
Recomendações da OMS sobre cuidados maternos e neonatais para uma experiência pós-natal positiva.
Em consonância com os ODS – Objetivos do Desenvolvimento Sustentável e a Estratégia Global para a Saúde das Mulheres, Crianças e Adolescentes, e aplicando uma abordagem baseada nos direitos humanos, os esforços de cuidados pós-natais devem expandir-se para além da cobertura e da simples sobrevivência, de modo a incluir cuidados de qualidade.
Estas diretrizes visam melhorar a qualidade dos cuidados pós-natais essenciais e de rotina prestados às mulheres e aos recém-nascidos, com o objetivo final de melhorar a saúde e o bem-estar materno e neonatal.
Uma “experiência pós-natal positiva” é um resultado importante para todas as mulheres que dão à luz e para os seus recém-nascidos, estabelecendo as bases para a melhoria da saúde e do bem-estar a curto e longo prazo. Uma experiência pós-natal positiva é definida como aquela em que as mulheres, pessoas que gestam, os recém-nascidos, os casais, os pais, os cuidadores e as famílias recebem informação consistente, garantia e apoio de profissionais de saúde motivados; e onde um sistema de saúde flexível e com recursos reconheça as necessidades das mulheres e dos bebês e respeite o seu contexto cultural.
Estas diretrizes consolidadas apresentam algumas recomendações novas e já bem fundamentadas sobre cuidados pós-natais de rotina para mulheres e neonatos que recebem cuidados no pós-parto em unidades de saúde ou na comunidade, independentemente dos recursos disponíveis.
É fornecido um conjunto abrangente de recomendações para cuidados durante o período puerperal, com ênfase nos cuidados essenciais que todas as mulheres e recém-nascidos devem receber, e com a devida atenção à qualidade dos cuidados; isto é, a entrega e a experiência do cuidado recebido. Estas diretrizes atualizam e ampliam as recomendações da OMS de 2014 sobre cuidados pós-natais da mãe e do recém-nascido e complementam as atuais diretrizes da OMS sobre a gestão de complicações pós-natais.
O estabelecimento da amamentação e o manejo das principais intercorrências é contemplada.
Recomendamos muito.
Vamos discutir essas recomendações no nosso curso de pós-graduação em Aleitamento no Instituto Ciclos.
Esta publicação só está disponível em inglês até o momento.
Prof. Marcus Renato de Carvalho
www.agostodourado.com
3. Cell
Cell
is the
Basic Structural and Functional Unit
of all Living Organisms
• Therefore,
Evolution of cell
is a crucial milestone
in the
evolution of life.
5. Cell
• Subcellular organelles are bathed by cytosol
and include –
nucleus, mitochondria,
endoplasmic reticulum, ribosomes
golgi apparatus (golgi complex),
lysosomes, peroxisomes,
and cytoskeleton.
22. Cell
• Diversity of cell types serves the function of
the particular tissues and organs in which they
are present.
• Depending on the function,
different cell types
differ in their organelle content,
or
their organelles may contain
different amounts of
particular enzymes or structural molecules.
24. Cell Membrane
• thin hydrophobic sheet
in fluid state which envelopes the cell
• made up of lipid bilayer (two layers)
• containing also proteins
• Lipid and Protein molecules are bound to
each other by non-covalent bonds
• Carbohydrates, found in lesser amounts
are bound to lipid and protein molecules
by covalent bonds
25. Cell Membrane
Membranes
• Define the external boundaries of
cells and organelles
• Maintain their integrity
and
• Serve to compartmentalize functions within the
cells.
26. Salient features of Cell Membrane
• Membranes are
flexible (because they are fluid),
elastic
and
self-sealing
• flexibility
permits the shape changes that accompany cell
growth and movement of cells, gives stability
Also enables the cell to perform exocytosis and
endocytosis
27. • Membranes are selectively permeable to
molecules.
-Being hydrophobic membranes are permeable to
only lipid soluble/hydrophobic substances and
impermeable to hydrophilic/polar substances.
-However, membranes have transport systems
(made of proteins) to permit and regulate the
movement of polar compounds across its
thickness.
28. Functions of Cell Membrane
1. Cell Membranes maintain the shape and size
of the cells.
2. Protects the cytoplasm and the cell
organelles from the external environment
3. The intracellular membranes serve to
compartmentalize functions within the cells.
4. Membranes regulate the transport of
substances like
nutrients, ions, gases, water, various
products, wastes into and out of cells and
their organelles.
29. 5.Membranes bound enzymes carry out metabolic
reactions near the inner surface of the cell
membrane. Egs:Succinate dehydrogenase .
6.Membranes are involved in signal transduction;
i.e. proteins in membranes detect specific
signals
transmit such signals to the cell interior by
specific chemical events.
7. Membrane mediates cell-to-cell communication
between adjacent cells by gap-junctions.
8. Membrane regulates the flow of information
between cell and its environment
30. Structure of Cell Membrane
Membranes are
sheet-like complex structures
composed of • Lipids
• Proteins
and
• Carbohydrates
31. Structure of Cell Membrane
• Lipid bilayer conformation
is the basic structure of all biological
membranes.
• lipid bilayer
is made up of
amphipathic lipid molecules
(having both hydrophilic or polar part and a hydrophobic or
non-polar part)
crucial in the formation of membrane structure
32. Structure of Cell Membrane
Fluid Mosaic Model
proposed by Singer and Nicolson
to explain the structure of cell membrane
According to this,
• membrane is a
fluid lipid bilayer
with
a mosaic of embedded proteins
34. In 1972, S.J. Singer & G. Nicolson
proposed that membrane proteins are
inserted into the phospholipid bilayer
It’s like a fluid…
It’s like a mosaic…
It’s the
Fluid Mosaic Model!
AP Biology
35. Structure of Cell Membrane
In other words,
the model is compared to
icebergs (membrane proteins)
floating in a sea ( predominantly
phospholipid molecules)
36. Structure of Cell Membrane
Membranes are
5-8 nm thick
and
appear trilaminar
when viewed through an electron
microscope
37. Structure of Cell Membrane
• Different membranes within the cell
and between cells have different
compositions
• This difference reflects the diversity
of biological roles of these
membranes
38. Structure of Cell Membrane
For e.g.
• myelin sheath of neurons,
which acts as an electrical insulator,
is rich in lipids
whereas
• inner mitochondrial membrane
in which many enzyme-catalyzed processes take place
contains
more proteins than lipids
39. Lipids
All Lipids present in cell membrane are –
Amphipathic Lipids
Compound Lipids and
Cholesterol (Free Cholesterol)
Phospholipids Glycolipids
conceived as having a –
polar head
and a
non-polar tail.
41. Lipids
Amphipathic lipids
self-assemble in aqueous medium
into bilayer sheets (lipid bilayer)
with their hydrophobic parts (non-polar tails) of each
layer
facing and interacting with each other forming a
hydrophobic membrane core
and
hydrophilic parts (polar heads)
facing towards the two surfaces
interacting with the aqueous medium
44. Lipids of cell membrane
Ampipathic lipids such as
• phospholipids
(e.g. lecithin,cephalin,sphingomyelin)
• glycolipids and
• cholesterol.
45. Lipids
Specific type of lipid
may be present in particular tissues
Example:
• Nerve tissues
have large quantity of
glycolipids and sphingomyelins.
• Mitochondrial membrane
rich in cardiolipin.
46. Proteins
• Make up about 50% of total membrane mass
In a typical cell
• Distributed
Asymmetrically
in the
lipid bilayer
47. Proteins
• Membrane proteins are of 2 types.
1.Peripheral membrane proteins
attached to the lipid bilayer on either surface
E.g.
succinate dehydrogenase (TCA Cycle),
endoplasmic reticulum enzymes, etc
2. Integral membrane proteins
deeply embedded in the lipid bilayer.
– Some integral membrane proteins may completely
span the lipid bilayer –
–transmembrane proteins
e.g. receptor proteins, transport proteins, channel
proteins, etc).
48. Cell Membrane proteins
Peripheral
membrane proteins
Integral
Transmembrane proteins
membrane proteins
Examples
Integral membrane proteins
•Receptor proteins
• Transport proteins
• Channel proteins
49. Many Functions of Membrane Proteins
Outside
Plasma
membrane
Inside
Transporter
AP Biology
Enzyme
activity
Cell surface
receptor
Cell surface
identity marker
Cell adhesion
Attachment to the
cytoskeleton
50. Membrane Carbohydrates
• relatively minor components
5-8% of the total membrane mass.
• covalently linked to lipids and proteins as
glycolipids and glycoproteins.
• Located on the extra cellular side of the
membrane, which forms a loose outer
carbohydrate coat called Glycocalyx
51. Functions of Glycocalyx
• Gives a net negative surface charge
and repel from other electrically negative
particles.
• Cell to cell attachment is possible.
• Part of receptor substances for binding
hormones such as insulin
• Some of the carbohydrate moieties
enter into immune reaction.
62. Fluidity of Membranes
Membrane consists of
a mosaic of lipids and proteins
that can move laterally (so fluid)
in the plane of the membrane.
fluidity makes the membrane
• flexible (which in turn permits the shape changes that
accompany cell growth and cell movements),
• increases permeability ,gives stability
and
enables them to
• invaginate or evaginate
allowing them to ingest or to expel materials.
63. Factors Affecting the Fluidity
• Unsaturated cis-fatty acids
• Short chain fatty acids and
• High temperature
Increase the membrane fluidity.
Whereas,
Cholesterol
decreases
the
membrane fluidity
64.
65. Specialised Membrane Structures
• Tight Junction
• seen in epithelial cells, where the lateral membrane
of a cell is fused with lateral membrane of adjacent
cell. This prevents the movement of molecules
through the gap between the cells. This ensures
that, molecules move only through the luminal side
to the serosal side.
E.g.: Seen in gastrointestinal epithelial cells.
• Myelin Sheath
Specialized structure for the conduction of nerve
impulse, rich in lipids.
66. Specialised Membrane Structures
• Synaptic membranes:
Cell membranes associated with synapses.
Required for the release or reception of
neurotransmitters.
• Microvilli:
Hair like projections produced by the membrane
evagination, which increases absorptive surface
area.
Eg: intestinal epithelial cells.
67. Specialized Membrane Structures
Tight Junction
Tight Junction
Eg: gastrointestinal epithelial cells
For cell to cell communication
Microvilli
Eg: gastrointestinal epithelial cells
Enhance absorption of food
Myelin sheath
Myelin Sheath
Eg: neurons
For conduction of nerve
impulse
Synaptic membrane
Eg: neurons
Transmit information between
neurones
69. Cell membrane is the boundary between
inside & outside…
separates cell from its environment
Can it be an impenetrable boundary?
NO!
OUT
IN
food
carbohydrates
sugars, proteins
amino acids
lipids
salts, O2, H2O
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OUT
IN
waste
ammonia
salts
CO2
H2O
products
cell needs materials in & products or waste out
70. Transport Across
Cell Membrane
• Membranes act as effective barrier for the passage of
molecules,
thereby keeping some substances inside the cell and
others out.
• Yet they also contain transport systems
which confer on membranes the important property of
selective permeability
by allowing specific molecules to be taken up
and
unwanted compounds to be removed from the cell
71. Transport Across
Cell Membrane
•
As the membrane core is hydrophobic in
nature
hydrophobic molecules move more readily
across the membrane
than hydrophilic ones.
• As the membrane fluidity increases,
permeability to hydrophilic substances also
increases
72. Transport across cell membrane
What molecules can get through directly?
fats & other lipids
inside cell
NH3
What molecules can
lipid
salt
NOT get through
directly?
polar molecules
H 2O
outside cell
sugar aa
H 2O
ions
salts, ammonia
large molecules
starches, proteins
AP Biology
73. Transport across cell membrane
Membrane becomes semi-permeable
with protein channels
specific channels allow specific material
across cell membrane
inside cell
NH3
AP Biology
salt
H 2O
aa
sugar
outside cell
74. Classification of Transport Across Cell Membrane
Membrane Transport
Small Molecules
Passive transport
(Energy independent)
Simple Diffusion
Macromolecules & Particles
Active transport
(Energy dependent, Carrier mediated)
Facilitated Transport
(Carrier mediated)
Ion-channels
Endocytosis
Eocytosis
75. Another Way to Classify
Transport of Small Molecules
Non-mediated transport
(no carrier proteins)
Simple Diffusion
Facilitated Transport
(Passive transport)
Carrier mediated
Ion-channels
Active transport
(Energy dependent,)
76. Contents
•Transport of Small Molecules
o Non-mediated transport (no carrier proteins)
-- Simple Diffusion
-- Ion-channels
o Carrier mediated
-- Facilitated Transport(Passive)
-- Active transport(Energy dependent)
•Macromolecules & Particles
77. Non-mediated Transport
(no carrier proteins)
Simple Diffusion
Very Small molecules (like water) and gases (CO2,O2)
enter the cell by this method.
It is a very slow process.
Doesn’t require energy (energy independent/passive).
It is a non-mediated transport
(no carrier proteins involved).
Molecules diffuse from
a region of higher concentration
to a region of lower concentration
(down the concentration gradient)
diffusion occurs through a membrane opening or through
intermolecular spaces.
78. Simple diffusion
Eg:
a) Respiratory exchange of gases between
pulmonary alveolar membrane
and
tissue capillary wall
b) Intestinal absorption of
pentoses, some mineral ions and water-soluble
vitamins
and
c) renal reabsorption of urea
79. Ion-channels
• specialized protein molecules
that span the membranes
& permit the rapid transport of ions such as
Na+, K+, Cl-.
• The channels generally remain closed
but in response to stimulus,
open allowing rapid flux of ions
down the gradient
80. Carrier Mediated Transport
• specific carrier molecules are required
• protein in nature.
• Have specific binding sites
for the molecules to be transported
• Transport is dependent on
availability of free binding sites on the carrier
protein
• more rapid than simple diffusion.
81. Classification of
Carrier Mediated Transport
There are 2 Ways of Classification
1. Depending upon
Number of Molecules Transported
and
Direction of Transport
2. Depending upon
Whether Energy is Required or not
82. Classification of
Carrier Mediated Transport
1.
• Uniport
• Co-transport
- Symport
and
- Antiport
2.
• Facilitated Transport(Passive)
• Active transport(Energy dependent)
83. Carrier Mediated Transport
• Uniport
Movement of one molecule from one side to another
E.g.: movement of glucose from the cells of GIT to ECF.
• Co-transport
Movement of one molecule depends on
simultaneous or sequential transfer of another molecule
Co-transport may be
- Symport
Two molecules move in the same direction
E.g.: Na+/Glucose transport.
-Anti-port
Two molecules move in opposite directions
E.g.: Cl- – HCO3- exchange in RBCs
121. Carrier Mediated Transport
• Based on energy need,
carrier-mediated transport are of
two types:
--Facilitated Transport (energy independent/passive)
and
-- Active transport (energy independent/active)
122. Facilitated Transport
• It is passive transport and carrier mediated.
• Here transport is down the concentration gradient.
• Once the molecule binds to the biding site,
a conformational change occurs in the carrier
making the binding site exposed to the opposite direction
Now the molecule is released from the carrier.
Another conformational change in the carrier
leads to the exposure of the binding site to the region
where free molecules to be transported are present.
• Structurally similar solutes can
inhibit the entry of one another by competitive inhibition.
E.g. There are four different facilitated carrier systems for
carbohydrates and five for amino acids.
123. Facilitated transport
Diffusion through protein channels
channels move specific molecules across
cell membrane
facilitated = with help
no energy needed
open channel = fast transport
high
low
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“The Bouncer”
125. Active Transport
• Transport is
carrier mediated
against the concentration gradient
and hence
energy-dependent.
• Transport occurs only in one way,
against the concentration gradient.
• The energy comes usually from
hydrolysis of ATP molecules
• About 40% of the total energy of the cell is used for
the active transport.
126. Active Transport
Cells may need to move molecules against
concentration gradient
shape change transports solute from
one side of membrane to other
protein “pump”
conformational change
“costs” energy = ATP
low
ATP
high
AP Biology
“The Doorman”
127. Active Transport
E.g.
• Na+–K+ pump or Na+-K+ ATPase
is the best example for active transport
because virtually all cells have it.
Other examples
• Ca+–dependent ATPase
(in sarcoplasmic reticulum of skeletal muscles),
• H+–dependent ATPase
located in the membrane of epithelial cell lining the
stomach
and has the function of acid (H+) secretion
128. Na+-K+ ATPase
• Na+-K+ ATPase establishes and maintains
a high intracellular K+ concentration
and
a low Na+ concentration
compared to their concentrations in ECF.
• The Na+ – K+ ATPase,
expels 3 Na+ ions
and
brings 2K+ ions from outside to inside
with a concomitant hydrolysis of ATP.
Drugs like digitalis (a cardiac glycoside)
and ouabain inhibit Na+ – K+ ATPase.
131. Classification of active transport
• based on the source of energy
1. Primary active transport - Transport of
molecules is directly linked to the hydrolysis of
ATP, which provides energy.
E.g. Na+–K+ pump or Na+-K+ ATPase
2.Secondary active transport- Transport of
molecules is indirectly linked to the hydrolysis of ATP.
Eg: Glucose and galactose are absorbed from the
intestine by secondary active transport.
Concentration gradient of Na+ is maintained by Na+ – K+
ATPase.
132. Physiological importance of active
transport
• -Responsible for the generation of the resting membrane
potential, basis for excitability in nerve and transmission of
nerve impulse
• -Na+ pump is driving force for several secondary active
transport of nutrients into the cell. For example, glucose is cotransported with sodium into the cell
• -Calcium pump (Ca++ dependent ATPase): found in
sarcoplasmic reticulum of skeletal muscles. It transports
calcium from the cytosol to the sarcoplasmic reticulum. It
regulates muscle contraction
• -Proton pump (H+ dependent ATPase): located in the parietal
cells of the stomach . It is responsible for the secretion of Hcl
into stomach lumen, to maintain the highly acidic pH essential
for gastric digestion.
133. • Clinical application:
Cardiotonic rugs like digitalis (a
cardiac glycoside) and ouabain
inhibit Na+ – K+ ATPase. They are
used in treatment of heart
failure.
134. Transport of
Macromolecules & Particles
-transported by
Endocytosis
and
Exocytosis
-Macromolecules such as
proteins, polysaccharides, hormones and
particles like viruses, bacteria etc are
transported by these mechanisms.
136. Transport Across Cell Membrane
Endocytosis: Process by which cells take up the large
molecules
137. Phagocytosis (Gk: Phagein = to eat)
•
•
•
•
Occurs in specialized cells such as macrophages
and
granulocytes.
ingestion of large particles such as
viruses, bacteria, cells or debris.
• endocytic vesicle (phagosome)
fuses with the lysosome.
hydrolytic enzymes of lysosomes
break down the macromolecular contents
released in to the cytosol
reused or further catabolized
138. Pinocytosis(cell drinking)
•
Cellular uptake of fluid and fluid contents
containing small particles.
E.g.: -Intake of chylomicron
by the hepatocytes;
-internalization of LDL by LDL receptor
139. Exocytosis
extrusion of particulate or macromolecular
materials,
which can’t pass out through the intact membrane.
• secretory vesicle is pinched off from the Golgi
apparatus;
• moves towards and fuses with the plasma
membrane.
• E.g. a) Release of Trypsinogen by pancreatic
acinar cells.
b) Release of Insulin by -cells of Langerhans.
• c) Release of acetylcholine by pre-synaptic
cholinergic nerves.
140. Transport Across Cell Membrane
Exocytosis: Process of extrusion of a macromolecule
from the cell
141. Disorders of
Membrane Structure and Transport
Abnormality in membrane structure or transport
can cause diseases.
• Respiratory distress syndrome
Defect in biosynthesis of dipalmitoyl lecithin
(lung surfactant)
• Familial hypercholesterolemia
Mutations in the gene encoding LDL receptor
Cystic fibrosis
Mutations in the gene encoding Cl- transporter
144. Nucleus
• largest sub-cellular organelle.
• double membrane –
nuclear membrane,
surrounds it.
• At intervals nuclear membrane has
nuclear pores,
permit the passage of molecules
in and out of the nucleus.
• nucleus of eukaryotic cell contains
a dense body known as
nucleolus
rich in rRNA.
145. Nucleus
• Nucleoplasm
– ground material of nucleus
rich in enzymes such as,
DNA polymerases, RNA polymerases, etc.
• Nucleus of an interphase (non-dividing) cell filled
with a diffuse material
– chromatin.
– During the cell division, chromatin condenses to form
chromosomes.
– Humans have 23 pairs of chromosomes compactly
packed in the nucleus.
146. Nucleus –Functions
• Nuclear DNA --the repository of genetic information
serves two purposes -i) By DNA replication
provides genetic information to
offspring or daughter cells
during cell division., thus it is blue print of life.
ii) By transcription (RNA synthesis)
provides information for the synthesis of all
protein molecules of the cell.
Both replication and transcription
take place in the nucleus.
Function of nucleolus:
-Synthesis of rRNA and ribosomes
147. Mitochondria
spherical, oval or rod like bodies.
have two membranes –
outer and inner membrane.
outer membrane is smooth
while the inner membrane is for folded to form
cristae
components of
electron transport chain (ETC) and
oxidative phosphorylation
buried in the inner mitochondrial membrane.
149. Mitochondria
• The central cavity of the mitochondrion
contains
the matrix
• Matrix contains enzymes and chemical
intermediates of -TCA cycle
Heme synthesis
Urea cycle, etc.
Also present in the matrix are, mitochondrial
DNA, RNA and ribosomes.
150. Functions
• ETC and oxidative phosphorylation-- situated in
inner mitochondrial membrane are involved in ATP
synthesis, hence mitochondria are regarded as
‘powerhouse of the cell’
• Some of the major pathways operate in the
mitochondria. They are, TCA cycle, -Oxidation of
fatty acid, ketone bodies
formation, gluconeogenesis (partly), urea cycle
(partly), heme synthesis (partly), pyrimidine
synthesis (partly) .
• Mitochondrial DNA codes for some of the
mitochondrial proteins involved in oxidative
151. Endoplasmic Reticulum (ER)
network of membrane-enclosed spaces
extends throughout the cytoplasm.
• classified into
rough and
smooth ER
rough appearance (when observed under electron
microscope) is
due to ribosomes attached to the cytoplasmic
side of the membrane.
smooth ER does not have ribosomes.
152.
153. Functions of ER
• Rough ER : involved in synthesis of proteins
(lipoproteins, glycoproteins)
• Smooth ER:
I. Metabolism of drugs and toxic compounds
(cyt P450 monooxygenases are present in
liver cell smooth ER)
II. Synthesis of lipids
(TAG, phospholipids, cholesterol) and
III. Ca2+ storage in skeletal and cardiac
muscle.(note- sarcoplasmic reticulum of
muscle is a modified ER)
154. Golgi Complex/Golgi Apparatus
• group of membrane bound
flattened tubes or sacs
placed one over another
in a pile or stack.
155.
156. Golgi Apparatus - Functions
Main functions of Golgi apparatus are
protein sorting, packaging and secretion.
• newly synthesized proteins are
handed over to the Golgi apparatus, which
catalyze the addition of
carbohydrates, lipids or sulfate moieties
to the proteins.
157. Lysosomes
membrane bound vesicle
containing various hydrolytic enzymes
(hydrolases.
• Lysosomal enzymes
are capable of digesting
proteins, carbohydrates, lipids and nucleic acids
• pH inside the lysosomes is less than that of
cytosol necessary for its digestivse function
158.
159. Lysosomes -Functions
• hydrolases breakdown complex molecules
brought into the cell by
endocytosis, phagocytosis or
worn-out organelles from the cells own
cytoplasm. Lysosomes - termed as ‘suicide-bags’
as their lysis can lesad to
digestion and death of the cell
Sphingolipidosis –
group of disorders in which
excess of sphingolipids accumulates in lysosomes
161. Peroxisome - Functions
Free radicals
formed by peroxidation of PUFA
capable of damaging
cell membranes, tissues, and genes
Such reactions are implicated in
inflammatory diseases, ageing process
malignant transformation.
and
• Catalase and peroxidase enzymes destroy such
unwanted peroxides and other free radicals
162. Ribosomes:
nucleoproteins
present either freely in cytosol or
bound to ER
• Function:
provide necessary infrastructure for
mRNA, tRNA & amino acid
to interact with each other for
translation process.
163. Cyto skeleton
Made up of
microtubules and actin filaments
role in maintaining the
cellular structure,
mobility and
cell division.
Hereditary spherocytosis
due to mutations in
genes encoding
spectrin or other structural proteins in
red blood cell membrane,
leading to excessive hemolysis
164. Organelle
Nucleus
Function
Provides genetic information to offspring
RNA transcription, directs protein
synthesis
Mitochondria Energy production from the oxidation of
food substances and the release of
adenosine triphosphate
Endoplasmic Translation and folding of new proteins
reticulum
(rough endoplasmic reticulum), synthesis
of lipids (smooth endoplasmic reticulum)
165. Golgi
appartus
Sorting, packaging, and modification of
proteins
Endoplasmic Translation and folding of new proteins
reticulum
(rough endoplasmic reticulum), synthesis
of lipids (smooth endoplasmic reticulum)
Lysosome
Breakdown of large molecules
Peroxisome
breakdown of metabolic hydrogen
peroxide and free radicals
167. Sub-Cellular Fractionation
isolation of an organelle
in a relatively pure form
in order to study its
functions
Cell membrane is disrupted usually by mechanical means
called
homogenization
• subcellular organelles
can then be separated from the homogenate by
differential centrifugation
using the instrument
ultracentrifuge