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Title: Eukaryotic and Prokaryotic cells
Description: Describes about the structure and function of eukaryotic cells and Prokaryotic cells and all cell organelles
Description: Describes about the structure and function of eukaryotic cells and Prokaryotic cells and all cell organelles
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2022
LECTURE 1
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CELL PHYSIOLOGY
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DR
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03
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Introduction
CLASSES
LECTURES
• ARE IN CLASS (INSITE)
• ARE ONLINE
• STUDENTS WRITE CLASS
TESTS
• END WITH FINAL TEST
• STUDENTS NEED TO PASS
THE CLASSES TO TAKE THE
FINAL TEST
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• Introduction
TOPICS
• Cell physiology
• Nucleus and cell cycle
• Homeostasis and fluids
• Plasma membrane
• Transport across plasma membrane
• Membrane potentials
CELL
• The basic living unit of the body is the cell
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• Each type of cell is specially adapted to
perform one or a few particular functions
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CELL
• The different substances that make up the cell
are collectively called protoplasm
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• Many cellular chemicals are dissolved in the
water
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Ions
• The most important ions in the cell are:
– potassium,
– magnesium,
– phosphate,
– sulfate,
– bicarbonate,
– and smaller quantities of sodium, chloride, and
calcium
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03
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• These can be divided into two types:
– structural proteins
– functional proteins
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03
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– filament = long chain of proteins
• A prominent use of such intracellular filaments is to form
microtubules (polymers of protein – tubulin) that provide
the "cytoskeletons" of such cellular organelles as cilia,
nerve axons, the mitotic spindles of mitosing cells
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Functional proteins
• The functional proteins are mainly the enzymes
of the cell
• The functional proteins are often mobile in the
cell fluid
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Lipids
• Lipids are several types of substances that are
grouped together because of their common
property of being soluble in fat solvents
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Lipids
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Carbohydrates
• Carbohydrates have little structural function in
the cell except as parts of glycoprotein
molecules, but they play a major role in nutrition
of the cell
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• Also, a small amount of carbohydrate is virtually
always stored in the cells in the form of glycogen,
which is an insoluble polymer of glucose
– GLYCOGEN = POLYMER OF GLUCOSE
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Physical Structure of the Cell
• The cell is not merely a bag of fluid, enzymes,
and chemicals
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Physical Structure of the Cell
• Most organelles of the cell are covered by
membranes composed primarily of lipids and
proteins
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03
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• Where these are present, the reticulum is called
the granular endoplasmic reticulum
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03
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• This part is called the agranular, or smooth,
endoplasmic reticulum
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03
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• It usually is composed of four or more stacked
layers of thin, flat, enclosed vesicles lying near
one side of the nucleus
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Lysosomes
• Lysosomes are vesicular organelles that form by
breaking off from the Golgi apparatus and then
dispersing throughout the cytoplasm
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• The lysosome is surrounded by a typical lipid bilayer
membrane and is filled with large numbers of small
granules, which are protein aggregates of as many as
40 different hydrolase (digestive) enzymes
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• They contain oxidases rather than hydrolases
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– Hydrogen peroxide is a highly oxidizing substance and is
used in association with catalase (oxidase enzyme) to
oxidize many substances that might otherwise be
poisonous to the cell
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Mitochondria
• Mitochondria are present in all areas of each
cell's cytoplasm
• Their total number per cell varies from less than
a hundred up to several thousand, depending on
the amount of energy required by the cell
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• Indeed, the mitochondria contain DNA similar
to that found in the cell nucleus
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• Introduction
TOPICS
• Cell physiology
• Nucleus and cell cycle
• Homeostasis and fluids
• Plasma membrane
• Transport across plasma membrane
• Membrane potentials
Nucleus
• The nuclear membrane, also called the nuclear
envelope, is actually two separate bilayer
membranes, one inside the other
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• The nucleus contains large quantities of DNA –
in the form of chromosome
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03
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03
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• Essentially all organs and tissues of the body
perform functions that help maintain these
constant conditions
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Extracellular Fluid
-The "Internal Environment"
• About 60 per cent of the adult human body is fluid,
mainly a water solution of ions and other substances
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• This extracellular fluid is in constant motion throughout
the body
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Differences Between
Extracellular and Intracellular Fluids
• The extracellular fluid contains large amounts
of:
– sodium,
– chloride,
– bicarbonate ions
– nutrients for the cells, such as oxygen, glucose,
fatty acids, and amino acids
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milliequivalents per litre
(mEq/L)
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A milliequivalent is onethousandth of an
equivalent
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03
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TOPICS
• Rules and regulations
• Cell physiology
• Nucleus and cell cycle
• Homeostasis and fluids
• Plasma membrane
• Transport across plasma membrane
• Membrane potentials
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The membrane structure,
transport trough membrane (diffusion,
active transport)
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The protein molecules in the
membrane have different properties for
transporting substances:
- channel proteins – they are penetrating the lipid bilayer, but have watery
spaces all the way through the molecule and allow free movement of water
as well as selected ions or molecules
- carrier proteins – they are penetrating the lipid bilayer
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Conformatial
changes in the protein molecules then move the substances through the
interstices of the protein to the other side of the membrane (for example
transmembrane pumps)
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• Introduction
TOPICS
• Cell physiology
• Nucleus and cell cycle
• Homeostasis and fluids
• Plasma membrane
• Transport across plasma membrane
• Membrane potentials
Transport through the cell membrane, either directly
through the lipid bilayer or through the proteins,
occurs by one of two basic processes:
• DIFFUSION
• ACTIVE TRANSPORT
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Diffusion
• Diffusion involves simple movement through the
membrane caused by the random motion of the
molecules of the substance
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DIFFUSION:
• through the cell membrane is divided into two subtypes
called:
– simple diffusion – is the movement of molecules or
ions through a membrane channels or through
membrane „spaces” without any actions with carrier
proteins in the membrane
– facilitated diffusion -requires interaction of a carrier
protein
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Postulated mechanism for facilitated diffusion
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• of water and other lipid-insoluble molecules through protein
channels
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– Other lipid-insoluble molecules can pass through the protein pore channels
in the same way as water molecules if they are water soluble and small
enough
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DIFFUSION through protein channels and „gating”
of these channels
The protein channels are distinguished by two important
characteristics:
they are often selectively permeable to certain substances, for
instance sodium channels
many of the channels can be opened or closed by gates
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– For instance a strong negative charge on the inside of the cell membrane
could cause the outside sodium gates are tightly closed, but conversely,
when the inside of the membrane loss its negative charge, these would
open suddenly and allow of sodium to pass through the sodium pores
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03
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Also shown are conformational changes in the protein molecules
to open or close „gates” guarding the channels
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– This causes a conformational or chemical bonding change in the protein
molecule that opens or closes the gate
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• it uses ENERGY,
• it is against the concentration gradient
• the substances that are transported by primary
active transport are sodium, potassium, calcium,
hydrogen, chloride and a few other ions
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Postulated mechanism of the sodium-potassium pump
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Vesicle transport
• Very large particles enter the cell by a
specialized function of the cell membrane
called endocytosis
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Vesicle transport
• Pinocytosis means ingestion of minute
particles that form vesicles of extracellular fluid
and particulate constituents inside the cell
cytoplasm
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Phagocytosis
• Phagocytosis occurs in much the same way as
pinocytosis, except that it involves large
particles rather than molecules
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(extension of the cytoplasm)
Osmosis
• Movement of the water through cell membrane
• Normally the amount that diffuses in the two
directions is balanced so precisely that zero
movement of water occurs
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Osmosis at a cell membrane when a sodium chloride solution is
placed on one side of the membrane and water is placed on the
other side
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03
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• In still other types of cells, such as glandular cells,
macrophages and ciliated cells, local changes in
membrane potentials also active many of the
cells functions
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MEMBRANE POTENTIALS
of neuron
NEURON POTENTIALS
-RESTING STAGE, this is the resting membrane potential before the action
potential begins
-ACTION POTENTIAL INCLUDES:
DEPOLARIZATION STAGE, at this time, the membrane suddenly
becomes very permeable to sodium ions
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Ten rapid diffusion of
potassium ions to the exterior re-establishes the normal negative
resting membrane potential
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• THANK YOU!
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Title: Eukaryotic and Prokaryotic cells
Description: Describes about the structure and function of eukaryotic cells and Prokaryotic cells and all cell organelles
Description: Describes about the structure and function of eukaryotic cells and Prokaryotic cells and all cell organelles