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Environmental Biotechnology

ENV- 608

Lecture # 2

Prepared by: Noor Fatima

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Eukaryotic Cell

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Prokaryotic Cell

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Structural difference

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1. What organelle is known as thecontrol center of the cell?

2. What structures are found in the nucleus?

3. What are short segments of chromosomes?

4. What are genes/chromosomes composed of?

5. How do genes/chromosomes control the

activity of the cell?

Review

Nucleus

Chromosomes

Genes

DNA

Produce proteins that regulate cell functions & structures

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ReviewReview

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Why Study DNA?

To discover the chemical structure of the gene

Understand how genes control the inherited

characteristics of living things.

To study gene expression to produce different

cell functions, shape and size.

Every cell in an individual contains the same

DNA.

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History

1869 - Friedrich Miescherdiscovered DNA in

nucleus1928 - Frederick GriffithIdentified DNA as source of

genetic material using bacteria

1930 - Oswald Avery, Colin MacLeod and Maclyn

McCarty - Confirmed that genes made of DNA1950 - Alfred Hershey and Martha Chase confirmed

DNA is the biochemical of heredity using

radioactive markers bacteriophages

1952- Maurice Wilkins and Rosalind Franklin X-rayed

DNA to show repeating nucleotide structure1953- James Watson and Francis Crick combined data

to create a 3-D model of structure called the

double helix

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History

1869 - Friedrich Miescherdiscovered DNA in

nucleus1928 - Frederick GriffithIdentified DNA as source of

genetic material using bacteria

1930 - Oswald Avery, Colin MacLeod and Maclyn

McCarty - Confirmed that genes made of DNA1950 - Alfred Hershey and Martha Chase confirmed

DNA is the biochemical of heredity using

radioactive markers bacteriophages

1952- Maurice Wilkins and Rosalind Franklin X-rayed

DNA to show repeating nucleotide structure1953- James Watson and Francis Crick combined data

to create a 3-D model of structure called the

double helixJames Watson Francis Crick

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Double Helix: 2 spirals wound around each other

DNA Shape

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Is a polymer of 1000s ofnucleotide monomers

Is a double strand of covalently bonded nucleotides

in twisted ladder shape

twisted ladder shape = double helix

Rungs of ladder = nitrogenbases

Sides of ladder = sugar & phosphate

groups (also called the DNA backbone)

DNA Structure

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Is a polymer of 1000s ofnucleotide monomers

Is a double strand of covalently bonded nucleotides

in twisted ladder shape

twisted ladder shape = double helix

Rungs of ladder = nitrogenbases

Sides of ladder = sugar & phosphate

groups (also called the DNA backbone)

DNA Structure

SugarPhosphateBackbone

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o Nucleotide- Individual unit of DNA.

o Made of three parts:

i. Deoxyribose (5-carbon sugar)

ii. Phosphate group

iii. A nitrogen-containing base

Nucleotide

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o Nucleotide- Individual unit of DNA.

o Made of three parts:

i. Deoxyribose (5-carbon sugar)

ii. Phosphate group

iii. A nitrogen-containing base

Nucleotide

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Four nitrogen-containingbaseso Adenine

o Guanine

o Cytosine

o Thymine

Bases

sugar

(deoxyribose)

adenine

Abase with a

double-ring

structure

guanine

(G)

base with adouble-ring

structure

cytosine

(C)base with a

single-ring

structure

thymine

(T)base with a

single-ring

structure

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Adenine

double ringed =

Guanine

Thymine

single ringed = Cytosine

Bases

purines

pyrimidines

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Deoxyribose (like ribose)is a sugar with 5 carbon

atoms in a ring

Oxygen is one of the ring

membersIn Deoxyribose, one of the OH groups is missing

and replaced with hydrogen

Thus deoxy =

- 1 oxygen

Nucleotide

sugar

baseP

OHH

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P - the Phosphate groupIs important because it

links the sugar on one

nucleotide with the phosphate

of the next nucleotide to make

a polynucleotide

Nucleotides are connected to each other

via a covalent bond

Nucleotide

sugar

baseP

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Bases are paired together in specificmanner

Because of chemical structure and shape

Adenine only pairs with ThymineGuanine only pairs with Cytosine

Exactly enough room for only one purine

and one pyramide base between thetwo strands of DNA

Base Pairing Rule

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Bases held together in rungs byweak hydrogenbonds

2 hydrogen bonds between A & T

3 hydrogen bonds between C & G

Base Pairing Rule

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Structure of DNA Review

Hydrogen

bonds

Nucleotide

Sugar-phosphate

backbone

Key

Adenine (A)

Thymine (T)

Cytosine (C)

Guanine (G)

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Structure of DNA-Review

Adenine Guanine Cytosine Thymine

Phosphate group Deoxyribose

Purines Pyrimidines

Bases

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Carry information from one generation to

another

Put information to work to determine anorganisms characteristics

Can be easily copied

Store and transmit genetic information

needed for all cell functions.

DNA Function