Zhihong Li（李志红）

Department of Biochemistry

Lecture 1

Introduction to Biochemistry

（生物化学）

Introduction

What is the Biochemistry?

History and development

How to study Biochemistry?

1. Biochemistry Definition: The chemistry of life

The science concerned with the chemical basis of life.

The science concerned with the various molecules that occur in living cells and organisms and with their chemical reaction.

Anything more than a superficial comprehension of life – in all its diverse manifestation - demands a knowledge of biochemistry.

Biochemistry Aim: to describe and explain, in m

olecular terms, all chemical processes of living cells Structure-function Metabolism and Regulation How life began ？

Biochemistry Significance: be essential to all

life sciences as the common knowledge Genetics; Cell biology; Molecular

biology

Physiology and Immunology

Pharmacology and Pharmacy

Toxicology; Pathology; Microbiology

Zoology and Botany

Biochemistry Medical students who acquire a sound

knowledge of biochemistry will be in a strong position to deal with two central concerns of the health sciences:

(1) the understanding and maintenance of health

(2) the understanding and effective treatment of disease

Causes of cancers Molecular lesions causing various genetic

diseases Rational design of new drugs

2. History and development of Biochemistry

1903, Neuberg (German): “Biochemistry”

“Chemistry of Life”

Two notable breakthroughs

(1) Discovery of the role of enzymes as catalysts

(2) Identification of nucleic acids as information molecules

Flow of information: from nucleic acids to proteins

DNA RNA Protein

In 1937 ， Krebs for the discovery of the Citric Acid Cycle-won the Nobel Prize in Physiology or Medicine in 1953

In 1953 ， Watson & Crick for the discovery of the “DNA Double Helix” -won the Nobel Prize in Physiology or Medicine in 1962

Some historic events

In 1955 ， Sanger for the determination of insulin sequence- won the Nobel Prize in Physiology or Medicine in 1956

In 1980 ， Sanger & Gilbert for Sequencing of DNA-won the Nobel Prize in Chemistry in 1980

In 1993, Kary B. Mullis for invention of PCR method -won the Nobel Prize in Chemistry in 1993

Gene engineering

Clone

Transgenic animal

Green Fluorescence protein

HGP from 1990, completed in 2003

3.What dose the Biochemistry discuss? structure and function of cellular comp

onents proteins, carbohydrates, lipids, nucleic aci

ds and other biomolecules

Metabolism and Regulation Gene expression and modulation

DNA RNA Protein

Polymers and Monomers Each of these types of molecules

are polymers that are assembled from single units called monomers.

Each type of macromolecule is an assemblage of a different type of monomer.

Macromolecule

Carbohydrates

Lipids

Proteins

Nucleic acids

Monomer

Monosaccharide

Not always polymers; Hydrocarbon chains

Amino acids

Nucleotides

How do monomers form polymers?

In condensation reactions (also called dehydration synthesis), a molecule of water is removed from two monomers as they are connected together.

Building block Simple sugar Amino acid Nucleotide Fatty acid

Macromolecule Polysaccharide Protein (peptide) RNA or DNA Lipid

Anabolic

Catabolic

4. Cells

Basic building blocks of life Smallest living unit of an organism A cell may be an entire organism (unicellular) o

r it may be one of billions of cells that make up the organism (multicellular).

Grow, reproduce, use energy, adapt, respond to their environment

Many cannot be seen with the naked eye a typical cell size is 10µm; a typical cell mass is 1 na

nogram.)

Cells May be Prokaryotic or Eukaryotic

Prokaryotes (Greek: pro-before; karyon-nucleus) include various bacteria

lack a nucleus or membrane-bound structures called organelles

Eukaryotes (Greek: eu-true; karyon-nucleus) include most other cells (plants, fungi, & animals)

have a nucleus and membrane-bound organelles

•Cell membrane & cell wall•Nucleoid region contains the DNA •Contain ribosomes (no membrane)

• Cell Membrane• Nucleus• Cytoplasm with organelles

Characteristic Bio-membranes and Organelles

• Mitochondria- the power generatorsMitochondria (Greek: mitos-thread; chondros-granule): Surrounded by a double membrane with a series of folds called cristae. Functions in energy production through metabolism. Contains its own DNA.

•Plasma Membrane-Cell’s defining boundary Providing a barrier and containing transport and signaling systems.

•Nucleus – Cell’s information center Double membrane surrounding the chromosomes and the nucleolus. The place where almost all DNA replication and RNA synthesis occur. The nucleolus is a site for synthesis of RNA making up the ribosome

•Rough endoplasmic reticulum (RER) Covered with ribosomes (causing the "rough" appearance) which are in the process of synthesizing proteins for secretion or localization in membranes.

•RibosomesProtein and RNA complex responsible for protein synthesis

•Smooth endoplasmic reticulum (SER)A site for synthesis and metabolism of lipids.

Endoplasmic reticulum (ER) – The transport network for molecules

•Cytoplasmenclosed by the plasma membrane, liquid portion called cytosol and it houses the membranous organelles.

•Lysosomes-contain digestive enzymeA membrane bound organelle that is responsible for degrading proteins and membranes in the cell.

•Golgi apparatus -process and package the macromolecules.A series of stacked membranes. Vesicles carry materials from the RER to the Golgi apparatus. Vesicles move between the stacks while the proteins are "processed" to a mature form.

5. Biomolecules Just like cells are building blocks of tissues, bi

omolecules are building blocks of cells. Animal and plant cells contain approximately

10,000 kinds of biomolecules. Water constitutes 50-95% of cells content by

weight. Ions like Na+, K+ and Ca2+ may account for anot

her 1%. Almost all other kinds of biomolecules are org

anic (C, H, N, O, P, S). Organic compounds are compounds compose

d primarily of a Carbon skeleton.

Carbon Carbon is more abundant in living

organisms than it is in the rest of the universe.

What makes Carbon Special? Why is Carbon so different from all the other elements on the periodic table?

The answer derives from the ability of Carbon atoms to bond together to form long chains and rings.

Carbon can form immensely diverse compounds, from simple to complex.

Methane with 1 Carbon atom

DNA with tens of Billions of Carbon atoms

Biomolecules

are compoun

ds of carbon

with a variety

of functional

groups

Types of biomolecules Small molecules:

Lipid, phospholipid, glycolipid, sterol, Vitamin Hormone, neurotransmitter Carbohydrate, sugar

Monomers: Amino acids Nucleotides Monosaccharides

Polymers: Peptides, oligopeptides, polypeptides, proteins Nucleic acids, i.e. DNA, RNA Oligosaccharides, polysaccharides (including cellulo

se)

Chemical composition of a normal man (weight 65 kg)

Constituent Percent (%) Weight (kg)

Water 61.6 40

Protein 17.0 11

Lipid 13.8 9

Carbohydrate

1.5 1

Minerals 6.1 4

Structural hierarchy in the molecular organization of cells

Similarities among all types of cells All cells use nucleic acids (DNA) to store

information Except RNA viruses, but not true cells

(incapable of autonomous replication)

All cells use nucleic acids (RNA) to access stored information

All cells use proteins as catalysts (enzymes) for chemical reactions A few examples of RNA based enzymes, which may

reflect primordial use of RNA

All cells use lipids for membrane components Different types of lipids in different types of cells

All cells use carbohydrates for cell walls (if present), recognition, and energy generation

Carbohydrates Lipids Proteins Nucleic Acids

1. You are expected to learn the structure and functions of these organic compounds:

How much biochemistry do you need to know for this course?

2. You will be expected to learn the basic biochemical processes of major cell functions, such as respiration, protein synthesis and so on.

Topics1 Introduction , amino acid and protein (8h)

2 Nucleic acid: Structure and properties (4h)

3 Carbohydrates: Structure and properties (2h)

4 Vitamins and coenzymes (4h)

5 Enzymes (6h)

6 Metabolism of carbohydrates (8h)

7 Assessment

8 Bioenergetics (4h)

9 Metabolism of lipids (8h)

10 Metabolism of amino acids (6h)

11 Integration of metabolism and review(2h)

• U Satyanarayana, Biochemistry• Murray RK, Harper’s Illustrated Bioc

hemistry, 26th ed.

• Nelson DL and Cox MM. Lehninger Principles of Biochemistry, 5th ed. 2008.

6. Text book and references

• Inspiring interest, confidence

• Previewing and reviewing freshly

• Taking studying notes

• Discussing in groups

• Practice, crosstalk with other subjects

• Making use of internet

7. Some tips for study of biochemistry

Just do as some proverbs say:

“I hear, and I forget, I see, and I remember,

I do, and I understand.”

“Practice makes

perfect”“No pains, no gains”

Final theory grade Final theory grade=

First Assessment: 30~35%

Final exam: 45~50%

Daily performance: 20%

Notice: 1/3 absent, can not take part in the final exam.