Dna and protein synthesis
This presentation is the property of its rightful owner.
Sponsored Links
1 / 45

DNA AND PROTEIN SYNTHESIS PowerPoint PPT Presentation


  • 29 Views
  • Uploaded on
  • Presentation posted in: General

DNA AND PROTEIN SYNTHESIS. 2008. DNA (DEOXYRIBONUCLEIC ACID) Nucleic acid that composes chromosomes and carries genetic information. CHROMOSOME ORGANIZATION 1. A chromosome is an enormous strand of super coiled DNA.

Download Presentation

DNA AND PROTEIN SYNTHESIS

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Dna and protein synthesis

DNA AND PROTEIN SYNTHESIS

2008


Dna and protein synthesis

DNA (DEOXYRIBONUCLEIC ACID)

  • Nucleic acid that composes chromosomes and carries genetic information.


Dna and protein synthesis

CHROMOSOME ORGANIZATION

1. A chromosome is an enormous strand of super coiled DNA.

2. Sections of DNA on the chromosome that code for proteins are called genes.

3. Noncoding sections of DNA are called “junk DNA” (regulatory or unknown function)


Dna and protein synthesis

BUILDING BLOCKS OF DNA

Composed of nucleotides

  • Nucleotides contain three parts:

    1. 5-Carbon Sugar (deoxyribose)

    2. Phosphate Group

    3. Nitrogen Base (four types, adenine, guanine, thymine and cytosine)


Dna and protein synthesis

  • Adenine and Guanine are purines (composed of two rings of nitrogen atoms)


Dna and protein synthesis

  • Thymine and Cytosine are pyrimidines (composed of one ring of nitrogen atoms)


Dna and protein synthesis

STRUCTURE OF DNA

  • Consists of two strands of nucleotides that form a twisted ladder (double helix)

  • Sugar and phosphate alternate along the sides of the ladder (linked by strong covalent bonds)

  • Pairs of nitrogen bases form the rungs of the ladder (linked by weak hydrogen bonds).


Dna and protein synthesis

  • Specific base pairing arrangement (Chargaff’s Rule)

    A-T : 2 hydrogen bonds

    C-G : 3 hydrogen bonds

  • Nitrogen bases attach to the sugar portion of the side (NOT the phosphate)

  • Strands run in opposite directions


Dna and protein synthesis

FUNCTION OF DNA

  • DNA codes for proteins (structural proteins, enzymes, and hormones)

  • information for building proteins is carried in the sequence of nitrogen bases

  • proteins determine physical and metabolic traits and regulate growth and development.


Dna and protein synthesis

DNA REPLICATION

Process in which DNA is copied


Dna and protein synthesis

PURPOSE OF DNA REPLICATION

Gives daughter cells produced by cell division a complete set of genetic information identical to the parent cell.


Dna and protein synthesis

WHERE REPLICATION OCCURS

Nucleus


Dna and protein synthesis

WHEN DURING THE CELL CYCLE REPLICATION OCCURS

Interphase (S)


Dna and protein synthesis

HOW REPLICATION OCCURS

1. Helicase enzymes unzip the parent strand by separating the nitrogen base pairs.

2. DNA polymerase pairs free DNA nucleotides with the exposed bases on both strands following the base pair rules.

  • each strand from the parent molecule serve as a template


Dna and protein synthesis

3. Hydrogen bonds reform spontaneously sealing the two strands of each DNA molecule together.


Dna and protein synthesis

RESULTS OF REPLICATION

  • Two molecules of DNA that are identical

  • Each is half old (strand from parent) and half new (strand synthesized by DNA polymerase)


Dna and protein synthesis

RNA (RIBONUCLEIC ACID)

Nucleic acid involved in the synthesis of proteins


Dna and protein synthesis

RNA STRUCTURE

Composed of nucleotides, but differs from DNA in three ways.

  • Single strand of nucleotides instead of double stranded

  • Has uracil instead of thymine

  • Contains ribose instead of deoxyribose


Dna and protein synthesis

RNA FUNCTION

Three forms of RNA involved in protein synthesis

1. mRNA (messenger): copies instructions in DNA and carries these to the ribosome.

2. tRNA (transfer): carries amino acids to the ribosome.

3. rRNA (ribosomal): composes the ribosome.


Dna and protein synthesis

PROTEIN SYNTHESIS

Cells build proteins following instructions coded in genes (DNA).

  • Consists of two parts, transcription and translation


Dna and protein synthesis

TRANSCRIPTION

DNA is copied into a complementary strand of mRNA.

WHY?

  • DNA cannot leave the nucleus. Proteins are made in the cytoplasm. mRNA serves as a “messenger” and carries the protein building instructions to the ribosomes in the cytoplasm.


Dna and protein synthesis

LOCATION OF TRANSCRIPTION

Nucleus


Dna and protein synthesis

HOW TRANSCRIPTION OCCURS

1. RNA polymerase untwists and unzips a section of DNA (usually a single gene) from a chromosome.


Dna and protein synthesis

2. RNA polymerase pairs free RNA nucleotides to the exposed bases of one of the DNA strands following base pair rules.

  • Uracil replaces thymine

  • Only 1 strand of DNA serves as a template, the other “hangs out”


Dna and protein synthesis

3. Newly synthesized mRNA separates from template DNA and DNA zips back up.


Dna and protein synthesis

RESULT OF TRANSCRIPTION

mRNA strand with instructions for building a protein that leaves the nucleus and goes to the cytoplasm.


Dna and protein synthesis

TRANSCRIPTION EXAMPLE

  • Transcribe the following DNA Sequence in mRNA

    TAC CGG ATC CTA GGA TCA

    AUG GCC UAG GAU CCU AGU


Dna and protein synthesis

PROTEINS

Structural and functional components of organisms.

  • Composed of amino acids

  • order of nucleotides in DNA determines order of amino acids in a protein

  • One gene codes for one protein


Dna and protein synthesis

GENETIC CODE

The “language” that translates the sequence of nitrogen bases in DNA (mRNA) into the amino acids of a protein.

  • Codon = three nucleotides on DNA or mRNA

  • One codon specifies one amino acid

  • Some codons are redundant (code for the same amino acid)

  • The genetic code is universal to all organisms


Dna and protein synthesis

DNA: TAC CTT GTG CAT GGG ATC

mRNA AUG GAA CAC GUA CCC UAG

A.A MET G.A HIS VAL PRO STOP


Dna and protein synthesis

IMPORTANT CODONS

  • AUG = start translation (Met)

  • UAA, UAG, UGA= stop translation


Dna and protein synthesis

TRANSLATION

Instructions in mRNA are used to build a protein


Dna and protein synthesis

LOCATION OF TRANSLATION

ribosome (in the cytoplasm)


Dna and protein synthesis

PROCESS OF TRANSLATION

1. mRNA binds to the ribosome.

2. Ribosome searches for start codon (AUG)

3. tRNA brings correct amino acid (methionine) to the ribosome.

  • Each tRNA carries one type of amino acid.

  • The anticodon (three nitrogen bases on tRNA) must complement codon for amino acid to be added to protein chain


Dna and protein synthesis

4. ribosome reads next codon

5. tRNA’s continue lining up amino acids according to codons

6. peptide bonds link amino acids together

7. ribosome reaches STOP codon

  • Amino acid chain is released


Dna and protein synthesis

RESULT OF TRANSLATION

A Protein


  • Login