Protein synthesis
Download
1 / 33

Protein Synthesis - PowerPoint PPT Presentation


  • 82 Views
  • Uploaded on

Protein Synthesis. A gene is the basic unit of heredity in a living organism All living things depend on genes Genes hold the information to build and maintain their cells and pass genetic traits to offspring the term gene often refers to the scientific concept of an allele .

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Protein Synthesis' - rob


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

  • A gene is the basic unit of heredity in a living organism

  • All living things depend on genes

  • Genes hold the information to build and maintain their cells and pass genetic traits to offspring

  • the term gene often refers to the scientific concept of an allele.

  • A sequence of nucelotides in DNA that performs a specific function such as coding for a particular protein


  • Complex molecules (macromolecules) composed of one or more polypeptide chains

  • Polypeptide chains are made of amino acids and folded into specific 3D shapes

  • The 3D shape determines protein function

  • DNA is a polymer made up of nucleotides

  • Protein is a polymer made up of amino acids



  • 1909- Archibald Garrod, a British physician

  • Proposed the relationship between genes and proteins

  • One gene directs the production of one enzyme

  • He observed that inherited diseases reflect a patient's inability to make a particular enzyme


  • Worked with patients having Alkaptonuria

  • Alkaptonuria- a genetic disorder in which urine appears black because it contains the chemical alkapton

  • When exposed to air, alkapton darkens in color

  • His analysis showed that alkapton was present in high concentration in people who had the disorder

  • He hypothesized that a defective enzyme causes an “inborn error of metabolism”


Intermediary Metabolites

Initial Reactant

Final Product

A

B

C

D

Enzyme 1

Enzyme 2

Enzyme 3

Biochemical reactions are controlled by enzymes

Enzymes are often are organized into chains of reactions known as metabolic pathways. Loss of activity in a single enzyme can inactivate an entire pathway.

He hypothesized that a defective enzyme causes an "inborn error of metabolism“

If there is an accumulation of substance B, then enzyme 2 must be defective

If there is an accumulation of substance C, then enzyme 3 must be defective


  • 1941- Beadle and Tatum

  • Prior work done:one-gene-one enzyme hypothesis suspected but not stated

  • Able to show the relationship between genes and enzymes

  • Purpose: "to determine if and how genes control known biochemical reaction"

  • Work with bread mold Neurosporacrassa



Complete Medium

Minimum

Medium

Minimum Medium

+ Amino Acid

Histidine

Proline

Leucine

Lysine

Arginine

Valine

Tryptophan


argF (gene)

argH (gene)

Precursor

Citrulline

arginine

Enzyme B

Enzyme D

Enzyme A

Enzyme C

Ornithine

Arginino-succinate

argE (gene)

argG (gene)

If the precursor accumulated, the defect was in enzyme A

If ornithine accumulated, enzyme B was defective




Protein synthesis1

Protein Synthesis while studying the amino acid sequence of hemoglobin from individuals with sickle cell anemia


The while studying the amino acid sequence of hemoglobin from individuals with sickle cell anemiacentral dogma of molecular biology is the

proposition put forward by Francis Crick

The information flow in the cell goes from the

deoxynucleicacid DNA, to the ribonucleic acid

messenger RNA, to protein

Never from protein to nucleic acids.


Translation while studying the amino acid sequence of hemoglobin from individuals with sickle cell anemia

Transcription


  • A while studying the amino acid sequence of hemoglobin from individuals with sickle cell anemiatype of molecule that consists of a long chain of nucleotide units.

  • Each nucleotide consists of a nitrogenous base, a ribose sugar, and a phosphate.


  • RNA is very similar to while studying the amino acid sequence of hemoglobin from individuals with sickle cell anemiaDNA, but differs in a few important structural details:

  • In the cell, RNA is usually single-stranded, while DNA is usually double-stranded

  • RNA nucleotides contain ribose while DNA contains deoxyribose

  • RNA has the base uracil rather than thymine that is present in DNA.


Transcription and translation

Transcription and Translation while studying the amino acid sequence of hemoglobin from individuals with sickle cell anemia

An Overview


Transcription
Transcription while studying the amino acid sequence of hemoglobin from individuals with sickle cell anemia





Translation
Translation recognizes a signal to stop transcribing



  • A sequence on the mRNA and binds to that sitetRNA delivers the appropriate amino acid and the polypeptide chain is elongated

  • Elongation continues until it reaches a “stop” signal



  • There are 20 amino acids found in sequence on the mRNA and binds to that siteproteins but only four different basesin mRNA

  • A sequence of three nucleotides mustbe used for each amino acid

  • Each triplet of nucleotides is called a codon

  • If only one nucleotide coded for one amino acid, we would be limited to four amino acids

  • If two nucleotides coded for one amino acid, the possibilities would be 16 (42=16)


  • The use of three nucleotides results sequence on the mRNA and binds to that sitein 64 (43=64)

  • 64 different possible combinations easily code for the existing 20amino acids

  • Each triplet of nucleotides codes for a specific amino acid


  • More than one sequence on the mRNA and binds to that sitecodon can code for a single amino acid, indicating a redundancy in the genetic code

  • Example:UUU, UUC, UCU, UCC all code for the amino acid Phenylalanine


  • Codon sequence on the mRNA and binds to that site: Sequence of three bases in DNA or complementary mRNA that serves as a code for a particular amino acid

  • Start Codon: Specific codon (AUG) that signals to the ribosomes that the translation starts at that point

  • Stop Codon: Specific codons that signal the end of translation to a ribosome


ad