01. cell structure and function

8/14/2019 01. Cell Structure and Function

1/24

Introduction


2/24


3/24

What is biochemistry?

Biochemistry can be defined as the scienceconcerned with the chemical basis of life (Gkbios life).

The cell is the structural unit of living systems.Thus, biochemistry can also be described asthe science concerned with the chemicalconstituents of living cells and with thereactions and processes they undergo.


4/24

Biochemistry is a hybrid science: Biology is the science of living organisms and

chemistry is the science of atoms and

molecules, so biochemistry is the science of the atoms and molecules in living organisms.

Its domain encompasses all the living worldwith the unifying interest in the chemicalstructures and reactions that occur in livingsystems.

What is biochemistry?


5/24

Biochemistry underlies ordinary life in unseen ways

For example, take a middle-aged man Takes a drug to lower his serum cholesterol. That drug

was developed by a pharmaceutical companysbiochemists to inhibit a key enzyme involved incholesterol biosynthesis

Shaves with a cream containing compounds thatsoften his beard. These active agents were developedafter studies of the physical properties of keratin, theprotein in hair.

Wears a shirt made from pest-resistant cotton. Thecotton plants were bioengineered by biochemists

through the transfer of genes from a bacterium intoplants.

All these everyday events depend on an understanding of thechemistry of living systems


6/24

Aim of Biochemistry

The major objective of biochemistry is thecomplete understanding, at the molecularlevel, of all of the chemical processes

associated with living cells. To achieve this objective, biochemists have

sought to isolate the numerous moleculesfound in cells, determine their structures, andanalyze how they function.


7/24

Most if not all diseases are manifestationsof abnormalities of molecules, chemical reactions,

or biochemical processes


8/24

The major causes of diseases. All of the causes listed act by influencing thevarious biochemical mechanisms in the cell or in the body


9/24

Some uses of biochemical investigations andlaboratory tests in relation to diseases.


10/24


11/24

Distinguishing features of living organisms

A high degree of chemical complexity andmicroscopic organization.

Thousands of different molecules make up a cells

intricate internal structures Systems for extracting, transforming, and

using energy from the environment enabling organisms to build and maintain their

intricate structures and to do mechanical,chemical, osmotic, and electrical work


12/24


13/24

Defined functions for each of their

components and regulated interactionsamong them The interplay among the chemical components of

a living organism is dynamic; changes in onecomponent cause coordinating or compensatingchanges in another, with the whole ensembledisplaying a character beyond that of its individualparts.

A history of evolutionary change.

Organisms change their inherited life strategies tosurvive in new circumstances


14/24

Cellular Foundations

The smallest organisms consist of single cellsand are microscopic.

Larger, multicellular organisms contain many

different types of cells, which vary in size,shape, and specialized function. Despite these obvious differences, all cells of

the simplest and most complex organisms

share certain fundamental properties, whichcan be seen at the biochemical level.


15/24

On the basis of their biochemicalcharacteristics, the diverse organisms of themodern world can be divided into three

fundamental groups called domains:1) Eukarya (eukaryotes),

2) Bacteria (formerly Eubacteria), and

3) Archaea (formerly Archaebacteria).prokaryotes


16/24

Tree of life


17/24

Eubacteria inhabit soils, surface waters, andthe tissues of other living or decayingorganisms.

Most of the well studied bacteria, includingEscherichia coli, are eubacteria.

The archaebacteria, more recently discovered,are less well characterized biochemically; most

inhabit extreme environmentssalt lakes, hotsprings, highly acidic bogs, and the oceandepths.


18/24

Cells are the Structural and Functional Units of allLiving Organisms

Cells of all kinds share certain structural features The plasma membrane defines the periphery of the

cell, separating its contents from the surroundings. The internal volume bounded by the plasma

membrane, the cytoplasm , is composed of anaqueous solution, the cytosol, and a variety of suspended particles with specific functions

All cells have, for at least some part of their life, eithera nucleus or a nucleoid, in which the genome the

complete set of genes, composed of DNAis storedand replicated


19/24

The nucleoid , in bacteria, is not separated from thecytoplasm by a membrane; the nucleus , in higherorganisms, consists of nuclear material enclosed withina double membrane, the nuclear envelope.

Cells with nuclear envelopes are called eukaryotes(Greek eu, true, and karyon, nucleus); thosewithout nuclear envelopesbacterial cellsareprokaryotes (Greek pro, before).

In comparison with the prokaryotes, eukaryotic cellshave greater specialization and complexity in theirstructure and functioning.

Eukaryotic cells are structured into compartments


20/24

Structure of an animal cell The eukaryotic cell is subdivided by

membranes. On the outside, it is enclosed by a plasma

membrane. Inside the cell, there is a large space containing

numerous components in solutionthecytoplasm.

Additional membranes divide the internal spaceinto compartments (confined reaction spaces).

Well defined compartments of this type areknown as organelles.


21/24


22/24


23/24

Organelles

Ribosomes are protein synthesizing machines Peroxisome destroys peroxides Cytoskeleton supports cell, aids in movement of

organelles Lysosome degrades intracellular debris Transport vesicle shuttles lipids and proteins

between ER, Golgi, and plasma membrane Golgi complex processes, packages, and targets

proteins to other organelles or for export Nucleus contains the genes (chromatin)


24/24

Smooth endoplasmic reticulum (SER) is site of lipid synthesis and drug metabolism

Rough endoplasmic reticulum (RER) is site of much protein synthesis

Nucleolus is site of ribosomal RNA synthesis Nuclear envelope segregates chromatin (DNA

+ protein) from cytoplasm Plasma membrane separates cell from

environment, regulates movement of materials into and out of cell

Mitochondrion oxidizes fuels to produce ATP

01. cell structure and function

Documents