THE LIFE OF THE LIFE OF THE CELLTHE CELL

REQUIREMENTS OF A CELLREQUIREMENTS OF A CELL

1.1. Genetic materialGenetic material that permits the production that permits the production of identical cells ~ Deoxyribonucleic acid of identical cells ~ Deoxyribonucleic acid (DNA) – “blueprint” of a specific species. (DNA) – “blueprint” of a specific species.

2. Metabolic machinery 2. Metabolic machinery for the maintenance of for the maintenance of life-sustaining activities.life-sustaining activities.

3. Cell membrane 3. Cell membrane which enables the cell to which enables the cell to exchange materials with its environment.exchange materials with its environment.

METABOLISM AND ITS PHASESMETABOLISM AND ITS PHASES

1. Anabolism 1. Anabolism – aka “– aka “constructive phaseconstructive phase” ~ all ” ~ all chemical reactions that result into the chemical reactions that result into the formation of bigger or complex molecules formation of bigger or complex molecules from smaller or simpler molecules from smaller or simpler molecules (synthesis).(synthesis).

MetabolismMetabolism - refers to the sum total of all the - refers to the sum total of all the chemical reactions which occurs within a living chemical reactions which occurs within a living cell e.g. cell e.g. Respiration, Digestion, ExcretionRespiration, Digestion, Excretion, etc., etc.

Two Phases of Metabolism:Two Phases of Metabolism:

All anabolic activities are All anabolic activities are “endergonic” ~ “endergonic” ~ energy-energy-storing e.g. Photosynthesis in plants and synthesis of storing e.g. Photosynthesis in plants and synthesis of carbohydrates, lipids, proteins, etc in animals. carbohydrates, lipids, proteins, etc in animals.

2. Catabolism 2. Catabolism – aka “– aka “destructive phasedestructive phase” ~ all ” ~ all chemical reactions that result into the chemical reactions that result into the breakdown of bigger or complex molecules breakdown of bigger or complex molecules into smaller or simpler molecules (analysis).into smaller or simpler molecules (analysis).

All catabolic activities are All catabolic activities are “exergonic” ~ “exergonic” ~ energy-energy-releasing e.g. Respiration among animals.releasing e.g. Respiration among animals.

ENTRY AND EXIT OF MATERIALS ENTRY AND EXIT OF MATERIALS IN CELLSIN CELLS

““The ability of cells to exist and maintain life-The ability of cells to exist and maintain life-sustaining activities depends on its ability to sustaining activities depends on its ability to take in (food and nutrients) and get rid of take in (food and nutrients) and get rid of

substances (wastes or toxins).” substances (wastes or toxins).”

Major Process in the Entry and Major Process in the Entry and Exit of MaterialsExit of Materials

1. Active Transport 1. Active Transport – involves carrier molecules – involves carrier molecules and cellular energy ~ requires or makes use of and cellular energy ~ requires or makes use of energy e.g. energy e.g. ExocytosisExocytosis and and EndocytosisEndocytosis

2. Passive Transport 2. Passive Transport – does not involve carrier – does not involve carrier molecules and cellular energy ~ happens molecules and cellular energy ~ happens naturally therefore, no amount of energy is naturally therefore, no amount of energy is used. used.

ACTIVE TRANSPORTACTIVE TRANSPORT

Requires the cell to spend energy stored in the Requires the cell to spend energy stored in the chemical bonds of chemical bonds of Adenosine triphosphateAdenosine triphosphate (ATP) (ATP) and a system of carrier molecules.and a system of carrier molecules.

ATPATP - compound which by its breakdown in the - compound which by its breakdown in the body (to body (to Adenosine diphosphateAdenosine diphosphate) provides ) provides energy for physiological processes such as energy for physiological processes such as muscular contraction.muscular contraction.

CYTOPLASM

OUTSIDE THE CELL

SOLUTE

CARRIER PROTEIN

CYTOPLASM

OUTSIDE THE CELL

SOLUTE

CARRIER PROTEIN

CYTOPLASM

OUTSIDE THE CELL

SOLUTE

CARRIER PROTEIN

SOLUTESOLUTE

CYTOPLASM

OUTSIDE THE CELL

CARRIER PROTEIN

CYTOPLASM

OUTSIDE THE CELL

CARRIER PROTEIN

SOLUTESOLUTE

CYTOPLASM

OUTSIDE THE CELL

CARRIER PROTEIN

SOLUTESOLUTE

Two Processes under Active TransportTwo Processes under Active Transport

1. Endocytosis 1. Endocytosis – entry of materials into the cell– entry of materials into the cell

a.a. PhagocytosisPhagocytosis - engulfing or taking in of - engulfing or taking in of solid particles – aka solid particles – aka “cell eating”“cell eating” e.g. e.g. Amoeba and Leucocytes through the Amoeba and Leucocytes through the use of their use of their pseudopodiapseudopodia after which a after which a phagosomephagosome (large vacuole that encloses (large vacuole that encloses the particle) is produced.the particle) is produced.

b. Pinocytosisb. Pinocytosis – taking in fluids – aka – taking in fluids – aka “cell drinking” ~ “cell drinking” ~ through the use of through the use of theirtheir pinocytic vesiclepinocytic vesicle (cavity or pouch)(cavity or pouch) after which aafter which a pinosomepinosome (vacuole that (vacuole that encloses the newly absorbed fluid) is encloses the newly absorbed fluid) is producedproduced. .

2. Exocytosis 2. Exocytosis – exit of materials from the cell; – exit of materials from the cell; process of expelling a macromolecule process of expelling a macromolecule through the help of the Golgi apparatus e.g. through the help of the Golgi apparatus e.g. release of release of InsulinInsulin in the blood stream among in the blood stream among animals and formation of animals and formation of cellulosecellulose among among plants. plants.

PASSIVE TRANSPORTPASSIVE TRANSPORT

A process that does not require energy nor A process that does not require energy nor protein carriers.protein carriers.

Two Processes under Passive TransportTwo Processes under Passive Transport

1. Diffusion 1. Diffusion – spontaneous and random – spontaneous and random movement of molecules from one place to movement of molecules from one place to another ~ direction of its motion is from a another ~ direction of its motion is from a region of high concentration to a region of low region of high concentration to a region of low concentration.concentration.

Concentration gradientConcentration gradient – the difference between – the difference between the concentration of two regionsthe concentration of two regions

Net diffusionNet diffusion – the direction of greater movement – the direction of greater movement of moleculesof molecules

Some facts regarding diffusion:Some facts regarding diffusion:

• Best exhibited by fluidsBest exhibited by fluids• Motion of diffusing particles are always random Motion of diffusing particles are always random • Net diffusion stops once equilibrium is attainedNet diffusion stops once equilibrium is attained• Even though net diffusion has already ceased, Even though net diffusion has already ceased, diffusion does not stopdiffusion does not stop• It may take place through membranesIt may take place through membranes

2. Osmosis 2. Osmosis – diffusion of materials through a – diffusion of materials through a semipermeable membrane.semipermeable membrane.

Semipermeable membraneSemipermeable membrane – permeable only to – permeable only to certain substances, especially allowing the certain substances, especially allowing the passage of a solvent but not of the solute.passage of a solvent but not of the solute.

Osmosis in Living CellsOsmosis in Living Cells

a. Hypotonic solution a. Hypotonic solution – contains lower – contains lower concentration of dissolved materials (solutes) concentration of dissolved materials (solutes) than the cell ~ aqueous solutions.than the cell ~ aqueous solutions.

b. Hypertonic solution b. Hypertonic solution – contains higher – contains higher concentration of dissolved materials (solutes) concentration of dissolved materials (solutes) than the cell ~ saline/ brine, sugary solutions than the cell ~ saline/ brine, sugary solutions etc.etc.

c. Isotonic solutionc. Isotonic solution– contains the same – contains the same concentration of dissolved materials (solutes) concentration of dissolved materials (solutes) as that of the cell (neutral).as that of the cell (neutral).

AQUEOUS SOLUTION IN PETRI DISH

WATER RUSHES INSIDE THE CELL

AQUEOUS SOLUTION IN PETRI DISH

CELL SWELLS

REACTION OF A CELL TO A REACTION OF A CELL TO A HYPOTONIC SOLUTIONHYPOTONIC SOLUTION

The pressure caused by the entry of water into the cell is called, “turgor pressure”

The pressure caused by the entry of water into the cell is called, “turgor pressure”

BRINE SOLUTION IN PETRI DISH

WATER RUSHES OUTSIDE THE CELL

BRINE SOLUTION IN PETRI DISH

CELL SHRINKS

REACTION OF A CELL TO A REACTION OF A CELL TO A HYPERTONIC SOLUTIONHYPERTONIC SOLUTION

The shrinking caused by the exit of water from the cell is called, “plasmolysis”

The shrinking caused by the exit of water from the cell is called, “plasmolysis”

SOLUTION WITH THE SAME CONCENTRATION

AS THE THE CELL

WATER RUSHES OUTSIDE THE CELL

REACTION OF A CELL TO AN REACTION OF A CELL TO AN ISOTONIC SOLUTIONISOTONIC SOLUTION

Since the cell loses and gains equal amounts of water, it neither swells nor shrinks.

Since the cell loses and gains equal amounts of water, it neither swells nor shrinks.

WATER RUSHES INSIDE THE CELL

SOLUTION WITH THE SAME CONCENTRATION

AS THE THE CELL

3. Facilitated diffusion 3. Facilitated diffusion – (aka – (aka “carrier-assisted “carrier-assisted transporttransport) similar to osmosis but the passage ) similar to osmosis but the passage of particles is aided by “carrier proteins”of particles is aided by “carrier proteins”

SOLUTESOLUTE

SOLUTESOLUTE

SOLUTESOLUTE

SOLUTESOLUTE

SOLUTESOLUTE

SOLUTESOLUTE

SOLUTESOLUTE

SOLUTESOLUTE

SOLUTESOLUTE

SOLUTESOLUTE

SOLUTESOLUTE

SOLUTESOLUTE

SOLUTESOLUTE

SOLUTESOLUTE

SOLUTESOLUTE