1 The Nucleic Acids An Introduction. 2 DNA 3 What does DNA stand for? Deoxy-riboseNucleic Acid Type of monosaccharide Found in the nucleus (eukaryote)

1

The Nucleic The Nucleic AcidsAcids

An IntroductionAn Introduction

2

DNADNA


3

What does DNA stand for?What does DNA stand for?

DeDe oxy-riboseoxy-ribose NucleicNucleic Acid Acid

Type of monosaccha

ride

Found in the nucleus (eukaryote) or nucleoid (prokaryote)

of cells

As in acids and bases

DNA can also be written as Deoxyribonucleic Acid

4

Where do you find DNA?Where do you find DNA?All mature cells contain DNA except the red blood cellsAll mature cells contain DNA except the red blood cells

DNA is found in the nucleus DNA is found in the nucleus Small amounts of DNA are also present in the Small amounts of DNA are also present in the

chloroplasts and mitochondriachloroplasts and mitochondria

Nucleus

Source: Source: http://www.tokyo-med.ac.jp/genet/picts/cell-e.jpghttp://www.tokyo-med.ac.jp/genet/picts/cell-e.jpg

Chloroplast

Mitochondrion

5

Building blocksBuilding blocks

A single unit of DNA is called a A single unit of DNA is called a nucleotide it is made up of:nucleotide it is made up of: A Sugar Molecule (Deoxy-ribose)A Sugar Molecule (Deoxy-ribose) A Phosphate molecule A Phosphate molecule A Nitrogenous BaseA Nitrogenous Base

P

6


P

P

P

P

P

The nucleotides are The nucleotides are bound together via bound together via covalent bonds covalent bonds between the between the phosphate groups, phosphate groups, forming a strand of forming a strand of DNADNA

These covalent These covalent bonds are very bonds are very strong and difficult strong and difficult to breakto break

7

DNADNA

DNA is made up of 2 strands.

The strands are held together by weak bonds between the nitrogen bases

The bonding between the strands is so weak that the two strands will easily separate at 100˚C

http://academy.d20.co.edu/kadets/lundberg/dnapic2.html

http://www.tokyo-med.ac.jp/genet/picts/dna.jpg

There are four types of nitrogen bases:

Cytosine (C), Guanine (G), Adenine (A) and Thymine (T)

What pairs with C?

What pairs with A?

8

DNADNA

Once the 2 strands of DNA are bound together, the strands coil to form a helical

shape

This is why DNA is often called a double helix

In this diagram, the 2 DNA strands have backbones that are shown in blue and red

The nitrogen bases are shown in yellow



9

10

The Gene CodeThe Gene Code The order of the nitrogenous bases A, The order of the nitrogenous bases A,

T, G & C is very important. T, G & C is very important. The sequence provides cells with The sequence provides cells with

templates for the production of every templates for the production of every protein in the bodyprotein in the body

These proteins play many different These proteins play many different roles in the body roles in the body

Each segment of DNA which Each segment of DNA which determines the structure of one protein determines the structure of one protein is called a is called a genegene

11

The DNA in the nucleus of your cells is tightly wound up to form chromosomeschromosomes so as to take up less space and avoid being tangled

12

ChromosomesChromosomes

Each chromosome Each chromosome carries carries approximately approximately 30,000 genes 30,000 genes

13

RNARNA


14

What does RNA stand for?What does RNA stand for?

RiboseRibose NucleicNucleic Acid Acid

Type of monosaccha

ride

Found in the nucleus or nucleoid

of cells

As in acids and bases

RNA can also be written as Ribonucleic Acid

15


Like DNA, a single unit of RNA is called Like DNA, a single unit of RNA is called a nucleotide. It is made up of:a nucleotide. It is made up of: A Sugar Molecule (Ribose)A Sugar Molecule (Ribose) A Phosphate molecule A Phosphate molecule A Nitrogenous BaseA Nitrogenous Base

Notice that the sugar molecule in RNA is Notice that the sugar molecule in RNA is different than in DNAdifferent than in DNA

16

RNARNA

There are 2 other major differences in the make up of RNA compared with DNA:

• RNA is made up of only 1 strand of nucleotides

• In RNA, the four types of nitrogenous bases are: Cytosine (C), Guanine (G), Adenine (A) and Uracil (U)

•Note that RNA does not contain the base thymine but contains uracil instead.



So in RNA:

• Cytosine pairs with Guanine

• Adenine pairs with Uracil

17

RNARNA There are 3 different types of RNA:There are 3 different types of RNA: Messenger RNA (mRNA)Messenger RNA (mRNA) – copies and carries – copies and carries

the genetic code from the DNA in the nucleus the genetic code from the DNA in the nucleus to the ribosomesto the ribosomes

Ribosomal RNA (rRNA)Ribosomal RNA (rRNA) – makes up – makes up ribosomes which are responsible for ribosomes which are responsible for assembling the proteins according to the assembling the proteins according to the instructions on mRNAinstructions on mRNA

Transfer RNA (tRNA)Transfer RNA (tRNA) – molecules which – molecules which carry the amino acids to the ribosomes carry the amino acids to the ribosomes where they are used to construct the proteinwhere they are used to construct the protein

18

Where do you find RNA?Where do you find RNA?All mature cells contain RNA All mature cells contain RNA

RNA is found in the nucleus as messenger RNARNA is found in the nucleus as messenger RNAIn the ribosomes as ribosomal RNAIn the ribosomes as ribosomal RNA

In the cytoplasm as transfer RNA and messenger RNAIn the cytoplasm as transfer RNA and messenger RNA

Nucleus

Source: Source: http://www.tokyo-med.ac.jp/genet/picts/cell-e.jpghttp://www.tokyo-med.ac.jp/genet/picts/cell-e.jpg

Ribosomes

Cytoplasm

19

Protein ProductionProtein Production1. 1. Transcription:Transcription: DNA code on DNA code on genes copied genes copied to mRNA to mRNA templatetemplate2. mRNA is 2. mRNA is able to pass able to pass through through nuclear pores nuclear pores and travel to and travel to ribosomesribosomes3. Translation:3. Translation: Amino acids Amino acids are carried to are carried to the ribosomes the ribosomes by tRNA where by tRNA where they are they are assembled into assembled into a polypeptide a polypeptide chain chain according to according to the mRNA the mRNA sequencesequence

20

Protein ModificationProtein Modification4. Bending and 4. Bending and folding: The folding: The polypeptide is polypeptide is then able to then able to enter the RER enter the RER where it is where it is folded, bended folded, bended and further and further modified. modified. Small parts of Small parts of RER RER containing the containing the protein then protein then pinch off, pinch off, forming forming vesicles which vesicles which then travel to then travel to the Golgi Body the Golgi Body

21

Protein ExportProtein Export5. Finishing 5. Finishing touches: In the touches: In the Golgi body, the Golgi body, the protein may be protein may be further modifiedfurther modified

6. Export: Part of 6. Export: Part of the Golgi body the Golgi body containing the containing the finished product finished product will then pinch will then pinch off, forming a off, forming a vesicle which is vesicle which is transported to transported to the cell the cell membrane where membrane where it fuses with the it fuses with the membrane and membrane and expels its expels its contents outside contents outside the cell. This is the cell. This is called exocytosis.called exocytosis.

22

SummarySummary

DNADNA RNARNA

Double Stranded, Double Stranded, helicalhelical

Single stranded, 3 Single stranded, 3 different forms – different forms – mRNA, rRNA, rRNAmRNA, rRNA, rRNA

Nucleotides: C, G, A, TNucleotides: C, G, A, T Nucleotides: C, G, A, UNucleotides: C, G, A, U

Sugar: DeoxyriboseSugar: Deoxyribose Sugar: RiboseSugar: Ribose

Function: Carries code Function: Carries code for protein productionfor protein production

Function: Assembles Function: Assembles proteins using DNA proteins using DNA codecode

Documents

1 The Nucleic Acids An Introduction. 2 DNA 3 What does DNA stand for? Deoxy-riboseNucleic Acid Type of monosaccharide Found in the nucleus (eukaryote)