dna protein synthesis
Download
Skip this Video
Download Presentation
DNA / Protein Synthesis

Loading in 2 Seconds...

play fullscreen
1 / 73

DNA / Protein Synthesis - PowerPoint PPT Presentation


  • 105 Views
  • Uploaded on

DNA / Protein Synthesis. History of DNA Research. DNA – Deoxyribonucleic acid 1) Frederick Griffith (1928)- discovered that a factor in heat-killed, disease-causing bacteria can “transform” harmless bacteria into ones that can cause disease. Griffith's Experiments

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 'DNA / Protein Synthesis' - bruno-osborn


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
history of dna research
History of DNA Research

DNA – Deoxyribonucleic acid

1) Frederick Griffith (1928)- discovered that a factor in heat-killed, disease-causing bacteria can “transform” harmless bacteria into ones that can cause disease.

slide4
Griffith's Experiments
    • Griffith set up four individual experiments.
    • Experiment 1: Mice were injected with the disease-causing strain of bacteria. The mice developed pneumonia and died.
slide5
Harmless bacteria (rough colonies)
  • Experiment 2: Mice were injected with the harmless strain of bacteria. These mice didn’t get sick.

Lives

slide6
Experiment 3: Griffith heated the disease-causing bacteria. He then injected the heat-killed bacteria into the mice. The mice survived.

Heat-killed disease-causing bacteria (smooth colonies)

Lives

slide7
Heat-killed disease-causing bacteria (smooth colonies)
  • Experiment 4: Griffith mixed his heat-killed, disease-causing bacteria with live, harmless bacteria and injected the mixture into the mice. The mice developed pneumonia and died.

Harmless bacteria (rough colonies)

Live disease-causing bacteria(smooth colonies)

Dies of pneumonia

slide8
Heat-killed disease-causing bacteria (smooth colonies)
  • Griffith concluded that the heat-killed bacteria passed their disease-causing ability to the harmless strain.

Harmless bacteria (rough colonies)

Live disease-causing bacteria(smooth colonies)

Dies of pneumonia

slide9
Transformation 
    • Griffith called this process transformation because one strain of bacteria (the harmless strain) had changed permanently into another (the disease-causing strain).
    • Griffith hypothesized that a factor must contain information that could change harmless bacteria into disease-causing ones.
history of dna research1
History of DNA Research

2) Oswald Avery (1944)- discovered DNA was responsible for transformation

history of dna research2
History of DNA Research

3) Hershey and Chase (1952)- their studies supported Avery’s work by studying bacteriophage (a virus that infects bacteria)

history of dna research3
History of DNA Research

4) Watson and Crick (1953)- first to develop a double-helix model of DNA

slide14
DNA
  • DNA is found inside the nucleus of every cell in your body
dna structure
DNA Structure
  • DNA is made up of nucleotides.

Nitrogenous

Base

Phosphate

Sugar

parts of a nucleotide
Parts of a nucleotide
  • A nucleotide contains three parts:

1) Phosphate group

2) 5-carbon sugar group (deoxyribose)

3) Nitrogenous bases (4 types)

      • Adenine (A)
      • Guanine (G) Purines (double rings)
      • Cytosine (C)
      • Thymine (T) Pyrimidines (single ring)

To help you remember:

CUT = PY

chargaff s rule
Chargaff’s Rule
  • Erwin Chargaff (1949) discovered the base-pairing rules for nitrogenous bases:

1) A always pairs with T

C always pairs with G

2) % A in DNA = % T in DNA

% C in DNA = % G in DNA

slide19
Guanine

Cytosine

Adenine

Thymine

slide20
Double Helix
    • DNA molecule is composed of two long chains of nucleotides twisted and held together by hydrogen bonds in the center between the nitrogen bases
slide22
In even in your smallest chromosome there are 30 million base pairs. How does so much DNA fit in every tiny cell in your body?
slide23
DNA
  • You fold it!
  • Think about how much easier it is to pack your suitcase when everything is nicely folded.

Can’t fit

Much more fits when you organize and fold it.

slide24
DNA must condense (make itself smaller) by folding itself around proteins called Histones.
  • When DNA wraps around Histones it forms tight coils and is called chromatin.
slide25
What are histones?
  • Histones are proteins that DNA wraps around.
  • What is Chromatin?
  • Chromatin is what you call DNA when it is wrapped around the Histones.
example
Example:

Histone

DNA

Double Helix

Chromatin

DNA around histones

chromosomes
Chromosomes
  • When the chromatin forms coils and condenses it forms a chromosome.
  • See Fig. 12-10 in your book.
slide28
DNA

Double Helix

Chromosomes

Made up of chromatin

Chromatin

DNA around histones

Histone =

slide29
DNA Double Helix  Chromatin  Chromosome

DNA Double Helix

DNA Chromatin

DNA Chromosome

http://www.biostudio.com/demo_freeman_dna_coiling.htm (dna coiling)

dna replication
DNA Replication
  • Occurs when cells divide.

(Cell division)

dna replication1
DNA Replication
  • DNA makes an exact copy of itself
  • takes place inside the nucleus during S phase before cell division
replication
Replication
  • Each strand of the double helix of DNA serves as a template against which the new strand is made.
slide33
phosphate

Sugar-phosphate

Sugar-phosph

DNA Base Pairing Rules

  • A compliments T
  • T compliments A
  • G compliments C
  • C compliments G

G

A

C

T

T

C

A

A

G

T

replication1
Replication

Step 1: The hydrogen bonds between the double helix break and two strands separate. Each strand is called a template strand.

Step 2: Two new complementary strands are formed following the rules of base pairing. The new strands are called complimentary strands.

Template strand

Compliment strand

how dna replication works
DNA Polymerase

A

T

How DNA Replication Works!

DNA polymerase is an enzyme that adds the complimentary bases to the DNA template strand and also “proofreads” or checks that it is correct.

replication2
Replication
  • Template Strand (original)
  • CGTATCCGGAATTT
  • The complimentary strand..
  • GCATAGGCCTTAAA
slide38
Template strand

Complimentary Strand

ACGGCAT

TACGGCAT

TGCCGTA

ATGCCGTA

complimentary
Complimentary
  • If I have a strand that DNA sequence of CAT what would be on the complimentary strand?
  • CAT

GTA

slide40
RNA
  • Ribonucleic acid
  • Single strand
  • made up of nucleotides
  • contains three parts:
    • 1) Phosphate group
    • 2) 5-carbon sugar group (ribose)
    • 3) Nitrogenous bases (4 types)
      • Adenine (A)
      • Guanine (G) Purines (double rings)
      • Cytosine (C)
      • Uracil (U) Pyrimidines (single ring)
slide41
Base-pairing in RNA

1) A always pairs with U

2) C always pairs with G

compare dna and rna
Compare DNA and RNA

1) Sugars are different:

DeoxyriboseRibose

H OH OH OH

H OH OH OH

compare dna and rna1
Compare DNA and RNA

DNA RNA

2) A, G, C,T A, G, C, U

(A–T, C-G) (A-U, C-G)

3) Double stranded Single stranded

4) only 1 type 3 types

protein
Protein
  • Proteins are made of building blocks called amino acids.
  • Proteins are different from one another by the sequence, or order, of their amino acids.
protein1
Protein
  • There are 20 different amino acids.
  • Thousands of proteins can be made from these amino acids because there are many different orders that they can be in.
slide47
Proteins are made in two steps:
    • Transcription
    • Translation
slide48
What is transcription?
    • The process where mRNA is made from a DNA template
    • Transcription happens in the nucleus
slide49
What is translation?
    • Translation is the decoding of an mRNA message into a protein.
    • Translation takes place on ribosomes in the cytoplasm
transcription
Transcription
  • Protein synthesis begins when a strand of (A) DNA unravels.
  • The code for producing a protein is carried in the sequence of the (B) bases in the DNA.
  • Each group of three bases forms a codon, which represents a particular amino acid.
transcription1
Transcription
  • One of the unwound strands of DNA forms a complementary strand called (C) mRNA.
  • This process is called transcription.
  • It takes place in the nucleus of the cells.
slide54
Bases

DNA

mRNA

post transcriptional modification
Post-transcriptional modification
  • DNA is composed of coding and noncoding sequences
  • Noncoding region = Introns
  • Coding region = Exons (code for proteins)
  • During transcription, introns are cleaved and removed, while exons combine to form useful mRNA
post transcriptional modification1
Post-transcriptional modification

E I E I E

initial DNA

 introns cleaved

pre-mRNA

 exons combine

final mRNA

slide57
Now look at the right side of the picture.
  • The mRNA has moved into the cytoplasm, where it attaches to a (D) ribosome.
  • A phase of protein synthesis called translation then begins.

Ribosome

mRNA

slide58
A (E) tRNA approaches the ribosome.
  • At one end of this molecule are three bases known as an (F) anticodon.
  • At the ribosome, each anticodon lines up with its complementary codon on the mRNA.

tRNA

Anticodon

Codon

Anticodon

slide59
This occurs according to base pairing.
  • At the other end of tRNA, an (G) amino acid is attached.
  • As the ribosome moves along the strand of mRNA, new tRNAs are attached.
  • This brings the amino acids close to each other.
codon chart
Codon Chart
  • To determine which amino acid we choose we use this chart:

CODONAMINO ACID

AGU

AGC

GGU

slide62
What are mutations?
    • Mutations are changes in the DNA sequence that affects the genetic information
slide63
Types of mutations:
  • Gene mutations result from changes in a single gene
  • Chromosomal mutations involve changes in whole chromosomes
slide64
Gene mutations:
    • Point mutations – affect only one nucleotide because they occur at a single point
      • Include substitutions, additions, and deletions
    • Frameshift mutations – when a nucleotide is added or deleted and bases are all shifted over, leaving all new codons.
      • Include additions and deletions
      • Substitutions don’t usually cause a frameshift
substitutions
Substitutions

One base change

insertions
Insertions

Many base changes

slide68
Chromosomal mutations:
    • Include deletions, duplications, inversions, and translocations.
slide73
Significance of Mutations
      • Many mutations have little or no effect on gene expression.
      • Some mutations are the cause of genetic disorders.
ad