ANTIBIOTICS

•Antibiotics – drugs that disable or kill infectious

bacteria.

•Most antibiotics are naturally occurring chemicals

derived from microorganisms.

•The goal of antibiotic treatment is to harm invading

bacteria while doing no damage to the human host.

•Most antibiotics achieve such precision by binding to

structures found only in bacterial cells.

Microscope as Windows on the World of Cells

•Light microscope – visible light is projected through the specimens.

•Electron microscope – uses a beam of electrons toresolve objects.

a. Scanning EM – used to study the detailedarchitecture of the cell surface.

b. Transmission EM – used to study the internalstructure of a cell.

• Magnification is an increase in theobject’s image size.

• Resolving power – the ability of anoptical instrument to show two objectsas separate.

• Cells were first described in 1665 byRobert Hooke.

• Cell theory – all living things arecomposed of cells and that all cellscome from other cells.

THE SIZE RANGE OF

CELLS

Prokaryotic cells• Found in organisms of

the domains Bacteriaand Archaea

• Bounded by a barriercalled plasmamembrane thatregulates the traffic ofmolecules between thecell and itssurroundings.

Eukaryotic cells• Found in organisms of

the domain Eukarya

• Bounded by a barriercalled plasmamembrane thatregulates the traffic ofmolecules between thecell and itssurroundings.

Prokaryotic cells Eukaryotic cells

Inside all cells is a thick jellylike fluid called the cytosol, in which cellular components are suspended.

All cells have one or more chromosomes carrying genes made of DNA.

All cells have ribosomes that build proteins according to instructions from the genes.

Surrounding the plasma membrane of most prokaryotic cells is a rigid cell wall, which protects the cell and helps maintain its shape.

In some prokaryotes, a sticky outer coat called a capsule surrounds the cell wall.

Capsules provide protection and help prokaryotes stick to surface.

Capsules enable some infectious bacteria to evade engulfment by the immune system cells.

Some prokaryotes have short projections called pili, which can also attach to surface.

Many prokaryotic cells have flagella, long projections that propel them through their liquid environment.

THE EUKARYOTIC CELLS

•All eukaryotic cells are

fundamentally similar to one

another and quite different from

prokaryotic cells.

•The entire region of the cell

between the nucleus and plasma

membrane is called the cytoplasm.

•The cytoplasm of a eukaryotic cell

consists of various organelles

suspended in the liquid cytosol.

•Most organelles are found in both

animal and plant cells.

•Only plant cells have chloroplast

and only animal cells have

lysosomes.

* The plasma membrane and other membranes of the cell

are composed of mostly of lipids and proteins.

•Most of the lipids belong to a special category called

phospholipids.

•* The phosphate group is electrically charged, making it

hydrophilic but the two fatty acids tails are hydrophobic.

•The hydrophobic fatty acid tails of the molecules stay in

the membrane interior away from water, while the

hydrophilic phospholipid heads remain surrounded by

water on the inside or outside of the cell.

•Embedded in the phospholipid bilayer of

most membranes are proteins that help

regulate traffic across the membrane and

perform other functions.

•The phospholipid and most of the proteins

are free to drift about in the plane of the

membrane. Thus, a membrane is a fluid

mosaic – fluid because the molecules can

move freely past one another and a mosaic

because of the diversity of proteins.

CELL SURFACES

Plant cells have a cell wall made from

cellulose fibers embedded in other

molecules.

The walls protect the cells, maintain cell

shape, and keep cells from absorbing so

much water that they burst.

Plant cells are connected via channels

that pass through the cell walls, joining

the cytoplasm of each cell to that of its

neighbors.

CELL SURFACES

Most of animal cells secrete a sticky

coat called the extracellular matrix.

This layer holds cells together in

tissues, and it can also have protective

and supportive functions.

The surfaces of most animal cells

contain cell junctions, structure that

connect cells together into tissues,

allowing them to function in a

coordinated way.

GENETIC CONTROL OF THE CELL

The nucleus is separated

from the cytoplasm by a

double membrane called

the nuclear envelope.

Within the nucleus, long

DNA molecules and

associated proteins form

fibers called chromatin.

Each long chromatin fiber

constitutes one

chromosomes.

Ribosomes are

responsible for protein

synthesis.

In eukaryotic cells, the

components of ribosomes

are made in the nucleus.

Other ribosomes are

attached to the outside of

the nucleus or an

organelle called ER.

Nucleus Ribosomes

DNA programs protein production in thecytoplasm by transferring its codedinformation to a molecule called mRNA. ThemRNA molecule then carries the order to“build this type of protein” from the nucleusto the cytoplasm.

The mRNA exits through pores in the nuclearenvelope and travels to the cytoplasm, whereit then bends to ribosomes.

The ribosome moves along the mRNA,translating the genetic message into a proteinwith a specific amino acid sequence.

EndomembraneSystem

Nuclear envelope

Endoplasmic reticulum

Golgi apparatus

Lysosomes

Vacoules

ROUGH ER SMOOTH ER

Make more membrane

Phospholipids made by enzymes of

the rough ER are inserted into the

ER membrane.

In this way, the ER membrane

grows, and portions of it are

transferred to other parts of the

cell.

Some products manufactured by

rough ER are dispatched to other

locations in the cell by means of

transport vesicles, sacs made of

membrane that bud off from the

rough ER.

Lacks the ribosomes that

populate the surface of

rough ER.

It synthesize lipids,

including steroid.

For example, the cells in

ovaries or testes that

produce the steroid sex

hormones are enriched

with smooth ER.

THE GOLGI APPARATUS•IT WORKS WITH THE ER AS IT RECEIVES, REFINES, STORES, AND

DISTRIBUTES CHEMICAL PRODUCTS OF THE CELL.

•PRODUCTS MADE IN THE ER REACH GOLGI APPARATUS IN TRANSPORT

VESICLES.

•THE GOLGI APPARATUS CONSISTS OF A STACK OF MEMBRANE PLANES.

LYSOSOMES

•A LYSOSOME IS A

MEMBRANE ENCLOSED

SAC OF DIGESTIVE

ENZYMES FOUND IN

ANIMAL CELLS.

•LYSOSOMES DEVELOP

FROM VESICLES THAT

BUD OFF FROM THE

GOLGI APPARATUS.

•LYSOSOMES FUSE

WITH THE FOOD

VACUOLES, EXPOSING

THE FOOD ENZYMES

THAT DIGEST IT.

•Lysosomes develop from vesicles

that bud off from the Golgi apparatus.

•LYSOSOMES BREAK DOWN THE LARGE MOLECULES OF DAMAGED ORGANELLES. WITHOUT HARMING THE CELL.

•A LYSOSOME CAN ENGULF AND DIGEST PARTS OF ANOTHER

ORGANELLE, ESSENTIALLY

RECYCLING IT BY MAKING ITS

MOLECULES AVAILABLE FOR THE CONSTRUCTION OF NEW ORGANELLES.

VACUOLE

VACUOLES

•VACUOLES ARE LARGE SACS OF MEMBRANE THAT BUD FROM THE ER, GOLGI APPARATUS, OR PLASMA

MEMBRANE.

•VACUOLES HAVE A VARIETY OF FUNCTIONS; FOOD VACUOLE BUDDING FROM THE PLASMA MEMBRANE AND CONTRACTILE VACUOLES THAT PUMP OUT EXCESS WATER

THAT FLOWS INTO THE CELL FROM THE OUTSIDE ENVIRONMENT.

CENTRAL VACUOLE•IT ACCOUNTS FOR MORE THAN HALF THEVOLUME OF A MATURE PLANT CELL.

•IT STORES ORGANIC NUTRIENTS, SUCH ASPROTEINS STOCKPILED IN THE VACUOLES OFSEED CELLS.

•IT CONTRIBUTES ON THE GROWTH OF PLANTBY ABSORBING WATER AND CAUSING CELLSTO EXPAND.

•IN THE CELLS OF FLOWER PETALS, CENTRALVACUOLE CONTAIN PIGMENTS THAT ATTRACTPOLLINATING INSECTS.

•IT ALSO CONTAINS POISONS THAT PROTECTAGAINST PLANT-EATING ANIMALS.

Chloroplasts

Mitochondria

Energy Conversion

CHLOROPLASTS

•ARE THE ORGANELLES THAT PERFORMPHOTOSYNTHESIS

•IT IS PARTITIONED INTO THREE MAJORCOMPARTMENTS BY INTERNALMEMBRANES.

•ONE COMPARTMENT IS THE SPACEBETWEEN THE TWO MEMBRANES THATSURROUND THE CHLOROPLAST.

•THE SECOND COMPARTMENT IS THESTROMA, A THICK FLUID WITHIN THECHLOROPLAST.

•THE THIRD IS THE GRANA, SUSPENDED INTHE FLUID THAT FORMS A NETWORK OFMEMBRANE-ENCLOSED DISKS AND TUBES.

MITOCHONDRIA•ARE THE ORGANELLES OF CELLULAR RESPIRATION IN NEARLY ALL CELLS, HARVESTING ENERGY FROM SUGARS AND OTHER

FOOD MOLECULES AND USING IT TO PRODUCE ANOTHER FORM OF CHEMICAL ENERGY CALLED ATP.

•AN ENVELOPE OF TWO MEMBRANES ENCLOSES THE MITOCHONDRION, WHICH CONTAINS A THICK FLUID CALLED

THE MATRIX.

•THE INNER MENBRANE OF THE ENVELOPE HAS NUMEROUS INFOLDINGS CALLED CRISTAE.

•BY INCREASING THE SURFACE AREA OF THE MEMBRANE, THE CRISTAE MAXIMIZE ATP OUTPUT.

Cell ShapeCell

Movement CYTOSKELETON

CYSTOSKELETON•IT GIVES MECHANICAL SUPPORT TO THE CELL AND

MAINTAIN ITS SHAPE.

•IT CONTAINS SEVERAL TYPES OF FIBERS MADE FROM DIFFERENT TYPES OF PROTEINS.

•MICROTUBULES ARE STRAIGHT, HOLLOW TUBES COMPOSED OF PROTEINS.

•INTERMEDIATE FILAMENTS AND MICROFILAMENTS WHICH ARE THINNER AND SOLID

•THE CYTOSKELETON PROVIDES ANCHORAGE AND REINFORCEMENT FOR MANY ORGANELLES IN A CELL.

•IT CAN QUICKLY DISMANTLE IN ONE PART OF THE CELL BY REMOVING PROTEIN SUBUNITS AND REFORM IN A

NEW LOCATION BY REATTACHING THE SUBUNITS.

CILIA AND FLAGELLA•IN SOME EUKARYOTIC CELLS, MICROTUBULES ARE

ARRANGED INTO STRUCTURES CALLED FLAGELLA AND CILIA.

•FLAGELLA AND CILIA ARE MOTILE APPENDAGES –EXTENSIONS FROM A CELL THAT AID IN MOVEMENT.

•.

•Cilia are generally shorter and more numerous than flagella and promote

movement by a coordinated back-and-forth motion.

•Eukaryotic flagella propel cells through their undulating,

whiplike motion.

THE BASICS OF PHOTOSYNTHESIS

PHOTOSYNTHESIS- is a process whereby PLANTS, ALGAE and certain BACTERIA transform light energy to chemical energy.

Using carbon dioxide and water as starting materials.

THE CHEMICAL ENERGY

Produced via photosynthesis is stored in the bonds of sugar molecules.

AUTOTROPHS- Organisms that generate their own organic matter from inorganic ingredients.

CHLOROPLASTS: SITES OF

PHOTOSYNTHESIS

• CHLOROPLAST-Photosynthesis in plants and algae occurs within light-absorbing organelles.

• It is also concentrated in the interior cells of leaves, with a typical cell containing 30-40 chloroplasts

• All green parts of plant have chloroplasts and can carry out PHOTOSYNTHESIS.

CHLOROPHYLL

• Source of green color, a light absorbing molecule(a pigment) in the chloroplasts that plays a central role in covering solar energy to chemical energy.

STOMATA

• Carbon dioxide enters a leaf and oxygen exits by way of tiny pores.

THE SIMPLIFIED EQUATION FOR PHOTOSYNTHESIS

• Explanation

This equation basically is a chemical representation of photosynthesis in a reaction form, which takes place in the chloroplasts. If you have a brief idea about the required raw materials and the products of this process, you will easily understand the chemical reactions.

In photosynthesis, carbon dioxide is used as a substrate base for producing glucose and oxygen with the help of light energy and water. Also, energy from the plants is utilized in fixing carbon dioxide and converting it to sugar. It is a complex process, but can be represented in a simplified reaction form. The following is the balanced photosynthesis equation, which will help you to understand this process:

6 CO2 + 6 H2O + Light energy → C6H12O6 + 6 O2

Carbon dioxide + Water + Light energy → Glucose + Oxygen

• The reactants are carbon dioxide, water, and sunlight, which after completion of the reaction give rise to glucose and oxygen. The numerical value placed before the compounds indicates the number of molecules required for the process. For example; 6 CO2 stands for six molecules of carbon dioxide and 6 O2 means six molecules of oxygen. Thus, in this process, six molecules of carbon dioxide and six molecules of water react in presence of sunlight to produce one molecule of glucose and six molecules of oxygen.

• The final product of this process, i.e., glucose is stored in the complex molecular structure of the plant cells. Oxygen produced as a byproduct is released to the surrounding for use in respiration by living organisms including humans and animals. Apart from oxygen supply, glucose synthesized by means of photosynthesis is source of energy for living organisms, and is circulated in the food chain. Thus, plants are crucial for balancing the atmospheric air composition, and supporting life in every step.

• Read more at Buzzle: http://www.buzzle.com/articles/photosynthesis-equation-for-photosynthesis.html