DNA, CHROMOSOMES, GENEDNA, CHROMOSOMES, GENESEL TIDAK AKTIF MEMBELAHSEL TIDAK AKTIF MEMBELAH nukleus mengandung nukleus mengandung kromatinkromatin (a tangle of fibers (a tangle of fibers composed of protein and DNA). composed of protein and DNA). SEL AKTIF MEMBELAHSEL AKTIF MEMBELAH-DNA mengalami duplikasi via -DNA mengalami duplikasi via mitosis sel baru sel baru mendapat kopi semua materi genetik sel "parent". mendapat kopi semua materi genetik sel "parent". -Kromatin menata diri menjadi -Kromatin menata diri menjadi kromosomkromosom

molekul DNA molekul DNA

Gen-genGen-genGenes=individual segments of DNA contain the =individual segments of DNA contain the instructions needed to direct the synthesis of a protein instructions needed to direct the synthesis of a protein with a specific function with a specific function

Different organisms differ in their complexity Different organisms differ in their complexity have have different numbers of chromosomes and genes:different numbers of chromosomes and genes:

- the more complex an organism the more - the more complex an organism the more

chromosomes it has chromosomes it has

- - frog: 26 chromosomes (13 pairs) frog: 26 chromosomes (13 pairs)

- human: 46 chromosomes (23 pairs)- human: 46 chromosomes (23 pairs) Tiap kromosom mengandung 1 molekul DNA, pada Tiap kromosom mengandung 1 molekul DNA, pada

manusia berukuran panjang 12 cmmanusia berukuran panjang 12 cm Semua DNA dalam sel manusia (46 kromosom) Semua DNA dalam sel manusia (46 kromosom)

panjangnya 2 m panjangnya 2 m dikemas dalam inti sel (ukuran: 2-3 dikemas dalam inti sel (ukuran: 2-3 mikrometer).mikrometer).

NUCLEIC ACIDNUCLEIC ACID- - NANA is one of several is one of several macromoleculesmacromolecules in the body in the body

(in addition to (in addition to fatsfats, , proteins,proteins, carbohydratescarbohydrates))

- Like the other mm, NA are polymers made up of - Like the other mm, NA are polymers made up of

individual monomers linked together in long chains. individual monomers linked together in long chains.

- NA = - NA = polynucleotides polynucleotides made up of individual made up of individual nucleotides linked together. nucleotides linked together.

- Nucleotide can be broken down to yield 3 components: - Nucleotide can be broken down to yield 3 components: a sugar, a nitrogen base, and phosphoric acid. a sugar, a nitrogen base, and phosphoric acid.

There are two types of nucleic acids: There are two types of nucleic acids: DNADNA & & RNARNA..

- - DNADNA stores genetic information stores genetic information, and , and RNA RNA allows allows that information to be made use of in the cellthat information to be made use of in the cell ..

- Both DNA & RNA contain nucleotides with similar - Both DNA & RNA contain nucleotides with similar components.components.

- - RNA (ribonucleic acid):RNA (ribonucleic acid): the sugar the sugar component is component is riboseribose indicated by the name indicated by the name ""riboribonucleic acid". nucleic acid".

- - DNA (DNA (deoxyribodeoxyribonucleic acid) nucleic acid) the sugar component is the sugar component is deoxyribosedeoxyribose. the prefix . the prefix deoxydeoxy means that an oxygen atom is means that an oxygen atom is missing from one of from one of the ribose Carbon atomsthe ribose Carbon atoms

NucleosideNucleoside- Nucleoside is - Nucleoside is sugarsugar bonds to a bonds to a nitrogen base nitrogen base - There are FIVE nitrogen bases that are found in DNA - There are FIVE nitrogen bases that are found in DNA

& RNA (Uracil is found ONLY in RNA!). & RNA (Uracil is found ONLY in RNA!). - These 5 bases are divided into 2 categories based on - These 5 bases are divided into 2 categories based on

their molecular structure, those are: their molecular structure, those are: 1. purines (Adenine and Guanine)1. purines (Adenine and Guanine)2. pyrimidines (Thymine, Cytosine, and Uracil) 2. pyrimidines (Thymine, Cytosine, and Uracil)

•Bagaimanakah informasi genetik diturunkan dari generasi ke generasi, or dari sel ke sel? •Bagaimanakah “serangkaian huruf” (sequence) menentukan protein apa yang dibuat dalam sel dan mengarahkan aktivitas sel-sel?? •Jawaban: harus ada mekanisme pengkopian DNA.

Aliran informasi genetikAliran informasi genetikDogma sentral pada genetika molekul:Dogma sentral pada genetika molekul: Fungsi DNA: menyimpan informasiFungsi DNA: menyimpan informasi Fungsi RNA: membaca, menterjemahkan dan Fungsi RNA: membaca, menterjemahkan dan

menggunakan informasi dari DNA untuk pembuatan menggunakan informasi dari DNA untuk pembuatan protein protein

  

Three fundamental processes take place in Three fundamental processes take place in the transfer and use of genetic informationthe transfer and use of genetic information

1.1. Replication is the process by which a replica, or Replication is the process by which a replica, or identical copy, of DNA is made. Replication occurs identical copy, of DNA is made. Replication occurs every time every time a cell dividesa cell divides so that information can be so that information can be preserved and handed down to offspring. This is preserved and handed down to offspring. This is similar to making a copy of a file onto a disk so you similar to making a copy of a file onto a disk so you can take that file to a different computer. can take that file to a different computer.

2.2. Transcription is the process by which the genetic Transcription is the process by which the genetic messages contained in DNA messages contained in DNA are "read" or are "read" or transcribedtranscribed. The product of transcription, known as . The product of transcription, known as messenger RNAmessenger RNA (mRNA), leaves the cell nucleus (mRNA), leaves the cell nucleus and carries the message to the sites of protein and carries the message to the sites of protein synthesis. synthesis.

3.3. Translation is the process by which the genetic Translation is the process by which the genetic messages carried by mRNA are decoded and used messages carried by mRNA are decoded and used to build proteins. to build proteins.

Experiments: DNA from different cells of the same sp Experiments: DNA from different cells of the same sp have the same proportions of the four bases. have the same proportions of the four bases.

For example: For example:

- human DNA contains about 30% each of A and T, and - human DNA contains about 30% each of A and T, and 20% each of G and C. 20% each of G and C.

- other organisms: the figures are different but the - other organisms: the figures are different but the amounts of A and T are always the same, as are the amounts of A and T are always the same, as are the amounts of C and G! amounts of C and G! Why is this the case? Why is this the case?

In 1953, James Watson and Francis Crick proposed a In 1953, James Watson and Francis Crick proposed a structure for DNA that not only accounts for this pairing structure for DNA that not only accounts for this pairing of bases but also explains how relatively simply the of bases but also explains how relatively simply the system of storing and transferring genetic information is.system of storing and transferring genetic information is.

THE WATSON-CRICK MODEL BASE-PAIRING

DNA’s Double HelixDNA’s Double Helix

DNA Base PairingDNA Base Pairing

Adenine:ThymineAdenine:Thymine

Cytosine:GuanineCytosine:Guanine