All organisms are made of cells

–          The cell is the simplest collection of matter that can live (reproduce)

–          Cell structure is correlated to cellular function.

–          All cells are related by their descent from earlier cells

 

Viruses are considered not to live because there reproduction depends on other organisms

How do we study cells?

Normally cells are too small to be seen by eye so we must use micros copes and other techniques like biochemistry to study them

         Light microscope :  the best magnification 1/1000

 

The quality of the image depends on 3 things

1)      Magnification : rates of object’s image size to its real size

2)      Resolution : basically it means the clarity of the image (the minimum size visible)

3)      Contrast

 

Electron microscopy

–          Two basic types of electron microscopes are used to study subcellular structures

1)      Scanning electron microscopes focus a beam of electrons outs the surface of a specimen, providing images that look there dimensional.

2)      Transmission electron microscopes :

Focus a beam of electrons through a specimen (TEMS), there kind of electron microscope is used to study the internal structure of cells.

 

Example of scanning and transmission electron microscopy

The other technique is Biochemistry

Cell fractionation

–          Cell fractionation on takes cells apart and separation the major organelles from one anther

–          Ultra centrifuges fractional cells into their component parts.

–          Cell fractionation enables scientists to determine the functions of organs

–          Biochemistry and cytology help correlate cell function with structure.

 

Biochemistry

–          Cell fractionation takes cells apart and separates the major organelles from the another

–          Ultra centrifuges : fractional cells into their component parts

–          Cell fractionation enables scientists to determine the functions of organelles

–          Biochemistry and cytology helps correlate cell function with structure

 

Comparing prokaryotic and eukaryotic

–          Basic features of all cells

.) Plasma membrane

.) Semifluid substance cells cytosol

.) Chromosomes (carry genes)

.) Ribosomes (make proteins)

–          The structural and functional unit of every organism is one of two types of cells : prokaryotic or eukaryotic

–          Only organisms of the domains bacteria and arches

–           consist of prokaryotic cells

–          Protests fungi, animals and plants all consist t of eukaryotic cells.

 

Prokaryotic cells

–          No nucleus

–          DNA is an unbound region called the nucleoid

–          No membrane bound organ cells

–          Cytoplasm bound by the plasma membrane

 

Eukaryotic cells

–          DNA is a nucleus that is bounded by a membranous nuclear envelope

–          Cytoplasm in the region between the plasma membrane and nucleus

–          Eukaryotic cells are generally much large than prokaryotic cells

In the center of nucleus there is a concentrated region called the nucleolus and this is where ribosomal RNA is made and processed it’s also the site where there’s a lot of organization of other RNA protein complexes that have to be assembled in the nucleus.

And we see the endoplasm reticulum and outside of that is the Golgi and mitochondria and centrosome.

Centrosome is the region where doing cell division the chromosomal DNA comes together and we have also lysosomes, peroxisomes and in the outside of the cell we see microvilli protruding from the cell.

The nucleus :information central

–          The nucleus contains most of the cell’s genes and is usually the most consequence…. organelle.

–          The nuclear envelope encloses the nucleus, separating it from the cytoplasm

–          The nuclear membrane is a double membrane each membrane consists of a lipid bilayer.

–          Pores regulate the entry and exit of molecules from the nucleus.

–          The shape of the nucleus is maintained by the nuclear lamina which is composed of protein.

 

Ribosomes: protein factories

 –          Ribosome are particles made of ribosomal RNA and proteins.

–          Ribosomes carry out protein synthesis in two locations:

–          In the cytosol (free ribosomes)

–          On the outside of the endoplasmic reticulum on the nuclear envelope (band ribosomes)

 

The endomembrane system regulates protein traffic and performs metabolic functions in the cell.

Ribosome is composed of large submit and small submit and between the 2 submits RNA in the middle and proteins going out in the middle part

The endomembrane system regulates protein traffic and performs metabolic function in the cell.

–          Components of the endomembrane system :

–          Nuclear envelop

–          Endoplasmic reticulum

–          Golgi apparatus

–          Lysosomes

–          Vacuoles

–          Plasma membrane

These components are either continuous or connected via transfer by vesicles.

The endoplasmic reticulum: biosynthetic factory

–          The endoplasmic reticulum (ER) accounts for more than half of the total membrane in many eukaryotic cells.

–          The ER membrane is continuous with the nuclear envelope.

–          There are two destinct regions of ER.

.) Smooth ER which lacks ribosomes

.) Rough ER with ribosomes studding its surface.

Functions of smooth ER and rough ER :

The smooth ER:

–          Synthesize lipids.

–          Metabolizes carbohydrates

–          Detoxifies poison

–          Stores calcium

The rough ER:

–          Has bound ribosomes, which secret glycoproteins (protein covalently bonded to carbohydrates )

–          Distributes transport vesicles proteins surrounded by membrane

–          Is a membrane factory for the cell

The Golgi apparatus: shipping and receiving center

–          The Golgi apparatus consists of flattened membranous sacs called cisternae

–          Functions of Golgi apparatus:

.) Modifies products of the ER

.) Manufactures certain macromolecules

.) Sorts and packages molecules into transport vesicles

Lysosomes: digestive compartments

–          Some types of cells can engulf other cells by phagocytosis this forms  a food vacuole

–          A  lysosome fuses with the food vacuole and digests the molecules.

–          Lysosomes also use enzymes to recycle the cell’ s over organelles and macromolecules a process called autophagy.

Mitochondria and chloroplasts change energy from one form to another.

–          Mitochondria are the sites of cellular respiration a metabolic process that generates ATP.

–          Chloroplasts, found in plants and algae are the sites of photosynthesis.

–          Peroxisomes are oxidative organelles.

–          Mitochondria and chloroplasts:

.) are not part of the endomembrane system

.) have a double membrane

.) have proteins made by free ribosomes.

.) contain their own DAN

Mitochondria: chemical energy conversion

–          Mitochondria are in nearly all eukaryotic cells

–          They have a smooth outer membrane and an inner membrane folded into cristae.

–          The inner membrane creates two compartments: inter membrane space and mitochondrial matrix.

–          Some metabolic steps of cellular respiration are catalyzed in the mitochondrial matrix

–          Cristae present a large surface area for enzymes that synthesize ATP

 

Chloroplasts: capture of light energy

–          The chloroplast is a member of a family of plant organelles called plastids

–          Chloroplasts contain the green pigment chlorophyll, as well as enzymes and other molecules that function in photosynthesis

–          Chloroplasts are found in leaves and there green organs of plants and in algae.

 

 

Peroxisomes: oxidation

–          Peroxisomes are specialized metabolic compartments bonded by a single membrane

–          Peroxisomes produce hydrogen peroxide and convert it to water.

–          Oxygen is used to break down different types of molecules