Introduction

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CYL414: An Introduction to Biochemistry

Cell as structural and functional units of life

Instructor: Yashveer Singh, Chemistry

29 July 2015

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High degree of chemical complexity and microscopic organization

System for extracting, transforming and using energy from the

environment

Defined functions for organism’s components and regulated

interactions among them

Mechanism for sensing and responding to alterations in their

surroundings

Capacity for precise replication and self assembly

Capability to survive over time by gradual evolution

Distinguishing features of living organisms

Lehninger Principles of Biochemistry

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What is common to all life forms?

Whole bacteria comprises just one cell

(unicellular organisms)

An adult human body comprises

30 trillion cells

(multicellular organisms)

All living organisms, whether big or small, contain cells

Even a single cell is able to carry out essential life processes

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What is common to all life forms?


Diverse organisms, with nothing in common, are shown in the

painting, except the fact that all contain one or more cells

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All molecules, whether big or small, contain atoms

Atoms are units of molecule

What is common to all molecules?

Stoker’s Chemistry

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All buildings, whether big or small, will contain bricks

What is common to all buildings?

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Male reproductive organ produces several hundred million sperms

every day, which undergo division to form spermatozoa

Female reproductive organs produces (~2 million) eggs, which

undergo division to produce ovum

How does life begins in multicellular organisms?

http://www.biology.iupui.edu/biocourses/N100H/ch9meiosis.html

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The spermatozoa and ovum (called gametes) fuses during the

fertilization to form a zygote

Zygote, which is a single cell, undergo division and differentiation

to form a multicellular organism in less than a year after fertilization

Ever for multicellular organisms, life begins as a single cell


http://www.biology.iupui.edu/biocourses/N100H/ch9meiosis.html

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The zygote undergoes mitotic division to form blastula, which is a

hollow ball of cells

Ultimately, three germ layers are produced: ectoderm, mesoderm,

and endoderm


https://smartsite.ucdavis.edu/access/content/user/00002950/bis10v/week10/13z

ygoteembroyo.html

csls-text2.c.u-tokyo.ac.jp

http://csls-text2.c.u-tokyo.ac.jp/inactive/05_01.html





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The three layer differentiate and arrange into tissue, organs, and

organ systems. Ectoderm gives rise to skin and nervous system;

endoderm to the lining of digestive and respiratory tracts, parts of the

liver and pancreas, and bladder lining; and mesoderm to muscles,

skeleton, circulatory system, excretory system, gonads, and inner

layer of skin (dermis)

All the structure of a multicellular organism arises from division

and differentiation of a single cell

All functions carried out by a multicellular organism is due to the

arrangement of cells into tissue, organs, and organ system


https://smartsite.ucdavis.edu/access/content/user/00002950/bis10v/week10/13z

ygoteembroyo.html

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Therefore, the structural and functional unit of life is cell

No matter which organism it is, it must posses at least a cell

To understand life, one must go to cellular level

What is the unit of life?


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Living organism unlike nonliving materials, are rich in carbon,

hydrogen, and oxygen

It suggest possibility of carbon (organic) compounds

Chemical composition of living organisms

Biochemistry by Garrett and Grisham

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Carbon can form single, double, and triple bonds

A single carbon can form multiple bonds with variety of atoms

Carbon compounds also contain diverse set of functional groups



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Therefore, carbons have the unique ability to form complex

structures with long chain along with variety of rings and functional

groups



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Cells have universal set of small molecules: amino acids,

nucleotides, sugars and their phosphorylated derivatives, and mono-,

di-, and tricarboxylic acids

These molecules are used to assemble macromolecules:

polysaccharides, proteins, nucleic acids, and lipids (not a true

polymer)

Chemical composition of cells


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Stereochemistry also plays an

important role

A macromolecule may have cis-

an/or trans center

As a results the two isomers may

have very different structures



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If molecular asymmetry is present, macromolecules may also

exhibit optical isomerism

As a result interactions between macromolecules are stereospecific



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Cells in true sense a hierarchical organization of biomolecules or

macromolecules (continued on next slide)



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In the first step, macromolecules or biomecules are assembled.

Amino acids are used for protein synthesis, nucleotides for nucleic

acids, sugars for polysaccharide, and so on. These macromolecules

are formed using mainly covalent bonds

The macromolecules are then assembled into supramoleculer

assemblies (cell organelles) using noncovalent interactions. For

example, plasma membrane is assembled using lipid and proteins and

chromosomes are assembled using protein and nucleic acids

Finally, supramolecular assemblies (organelles) are arranged into a

cell structure



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Therefore, biochemistry is understanding the molecular basis of life

processes occurring at the level of cells

Then, what is biochemistry?


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Different classes of organisms


All living organisms are grouped into three categories: bacteria,

archaea, and eukarya

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Aerobic

Needs oxygen Anaerobic

Do not need oxygen

Obligate

Will not survive in the

presence of oxygen

Facultative

Will survive with or

without oxygen

Bacteria and archaea

Bacteria and archaea are unicellular organisms and can be either

aerobic or anerobic



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Living organisms are also categorized based on their source of

energy as shown above


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Viruses are considered non-living

because they need host cells to

grow and reproduce

What about viruses?

Timberlake’s Chemistry

Introduction

Documents

Transcript of Introduction