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DNA and RNA. Ch. 12. They were done to determine whether genes are made up of DNA or protein. He injected bacteria into mice in four separate experiments. Griffith’s Experiments. S bacteria caused pneumonia and death when injected. R bacteria had no visible effect.

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Dna and rna l.jpg

DNA and RNA

Ch. 12


Griffith s experiments l.jpg

They were done to determine whether genes are made up of DNA or protein.

He injected bacteria into mice in four separate experiments.

Griffith’s Experiments


His results l.jpg

S bacteria caused pneumonia and death when injected. or protein.

R bacteria had no visible effect.

Heat killed S bacteria did no harm.

Heat killed S and live R were injected and the mouse died of pneumonia.

Streptococcus pneumonia bacteria were used.

S strain was smooth and caused pneumonia.

R strain was rough and did no harm.

His results..


What can we conclude l.jpg

If the mice died with S and heat-killed S and R, but not when S was heat-killed or R by itself, then there had to be some transforming material that was transformed from the heat-killed S to living R changing it into S bacteria.

What was this transforming material?

DNA

What can we conclude?


Oswald avery l.jpg

Repeated Griffith’s experiment. when S was heat-killed or R by itself, then there had to be some transforming material that was transformed from the heat-killed S to living R changing it into S bacteria.

Discovered that it is the nucleic acid DNA stores and transmits the genetic information from one generation of an organism to the next.

Oswald Avery


Hershey and chase s experiment l.jpg

2 experiments. when S was heat-killed or R by itself, then there had to be some transforming material that was transformed from the heat-killed S to living R changing it into S bacteria.

Used bacteriophages (viruses) that injected radioactive material into bacteria. They they looked to see if the bacteria became radioactive.

Phages with green radioactive DNA 32-P injected it into bacteria and the bacteria became radioactive.

Phages with green radioactive protein 35-S injected it into bacteria and it did not become radioactive.

Hershey and Chase’s Experiment

What can we conclude?


Dna structure l.jpg

Remember that the structure of a molecule is related to its function, so knowing what a molecule looks like gives researchers insight into how DNA works.

What do you know about DNA?

Deoxyribonucleic acid

Double Helix

5’C sugar, Deoxyribose

Phosphate Group

4 Nitrogen Bases

First double helix structure built by Watson and Crick

Published in 1953

DNA Structure

Nucleotide


Discovery of dna x ray evidence l.jpg

Rosalind Franklin used X-ray diffraction to reveal the shape of DNA.

Discovery of DNA: X-Ray evidence

  • The X-shaped pattern shows that the strands of DNA are twisted around each other.


Purines and pyrimidines make up the 4 n bases l.jpg

Purines of DNA.- larger

Adenine and Guanine

Pyrimindines- smaller

Cytosine and Thymine

Purines and Pyrimidines make up the 4 N bases

Pairing of the bases in the DNA structure: Chargaff’s Rule

(amount of A = amount of T and amount of C =amount of G

A—T

C—G


Double helix l.jpg

The shape of DNA is that of a “twisted ladder”. of DNA.

The P group is attached to the sugar and that forms the backbone.

The “rungs” of the DNA are the pairing of the bases.

Watson and Crick

Double Helix


Dna replication semi conservative l.jpg
DNA Replication of DNA.Semi-conservative

The DNA unzips. Enzymes split apart the base pairs and unwind the DNA.

Free nucleotides in the cell find bases to pair up with on each side along the “open” DNA via DNA polymerase.

The sugar-phosphate backbone completes the 2 new DNA strands.

Each strand has a new and old strand.

DNA Replication Simulation


Dna vs rna l.jpg

DNA of DNA.

Double Stranded

Base Pairs (A-T, G-C)

Deoxyribose sugar

RNA

Single Stranded

Base Pairs (A-U, G-C) Uracil is used instead of Tymine

Ribose Sugar

DNA vs. RNA


Protein synthesis l.jpg

Process when the organism’s genotype is translated into it’s phenotype.

Remember that proteins are made up of chains of Amino Acids.

How many a.a. are there?

2 Processes

Transcription- DNA to RNA

Translation- RNA Protein

Protein Synthesis

  • 1.26 The genetic material in DNA molecules provides the instructions for assembling proteins. This works the same in nearly all life forms.


Transcription l.jpg

RNA polymerase unwinds a section of DNA it’s phenotype.

RNA polymerase binds unattached RNA nucleotides to complementary DNA strand.

A new strand of mRNA (messenger RNA) is made.

DNA will signal RNA pol to leave and transcription stops.

It occurs in the nucleus.

Tutorial

Transcription


Rna splicing l.jpg

Before mRNA can leave the nucleus, RNA must be spliced. it’s phenotype.

It gets rid of introns and exons are spliced together.

mRNA now leaves the nucleus and into the cytoplasm where it finds a ribosome.

Introns- non-coding regions of DNA or RNA.

Exons-coding regions

RNA splicing


Things to know before we go on l.jpg

Codon- it’s phenotype. 3 base sequence of mRNA that codes for an amino acid.

Anti-codon: complementary 3 base sequence to mRNA on a tRNA.

rRNA- ribosome where amino acids are put together.

tRNA (transfer RNA)- matches up anticodons to codons to make amino acids that form proteins.

Things to Know before we go on.


Translation l.jpg

rRNA attaches to first codon on mRNA. it’s phenotype.

A tRNA brings an a.a. to the rRNA with the anti-codon and matches it up with the codon.

3. A 2nd tRNA brings in the next one and then a peptide bond bonds the 2 a.a. together. It moves over and the 1st one leaves so the next one can come in.

Translation

http://www.rothamsted.bbsrc.ac.uk/notebook/courses/guide/trad.htm


Starting and stopping translation l.jpg

AUG- Methionine is the Start Codon. it’s phenotype.

There are 3 Stop Codons: UAA, UAG, and UGA.

Starting and Stopping Translation


Slide25 l.jpg

Protein synthesis it’s phenotype.


1 23a inserting deleting or substituting dna sequences can alter a gene l.jpg

A random change in the sequence of nucleotides in DNA is a it’s phenotype.mutation.

Chromosomal mutations- involve whole chromosomes.

Gene mutations- result from changes in a single gene.

4 types of mutations:

Deletion

Duplication

Translocation

inversion

1.23a Inserting, deleting, or substituting DNA sequences can alter a gene.


Chromosomal deletion l.jpg

When a chromosome breaks and a piece of it is lost. it’s phenotype.

Chromosomal Deletion


Duplication l.jpg

When a part of the chromosome breaks off and is incorporated into its homologous chromosome.

Duplication

A B C o D E F

A B B C o D E F


Translocation l.jpg

Occurs when part of a chromosome breaks off and attaches to a different, nonhomologous chromosome.

Translocation


Inversion l.jpg

Occurs when part of a chromosome breaks off, turns around, and reattaches in the reverse order.

Inversion


Frameshift mutations gene mutation l.jpg

When nucleotides are deleted or added, it changes the order or code of the codons, results in different a.a.

Frameshift mutations (Gene mutation)


Point mutations gene mutation l.jpg

Occur when there is only one change in the nucleotide. It only changes one a.a. coded for.

Substitution

Point Mutations (Gene mutation)


Jumping genes l.jpg

Occurs when a large stretch of DNA is inserted into the gene.

1.28b Genetic variation occurs from crossing over, jumping genes and deletion and duplication of genes.

Jumping Genes


Polyploidy l.jpg

When nondisjuction occurs in all chromosome pairs. gene.

Occurs often in plants and can make them “robust”.

(Plants have too many chromosomes)

Polyploidy


Structure determines function l.jpg

When genes are changed, the proteins they code for may change and this can affect cell structure and function,which changes a phenotype.

The control of gene expression (protein synthesis), is different in prokaryotes and eukaryotes.

Structure Determines Function


Gene expression l.jpg

Prokaryotes change and this can affect cell structure and function,which changes a phenotype.

Genes turn on and off primarily in response to changes in environmental factors.

1.1b Different parts of the genetic instructions are used in the different kinds of cells and are influenced by the cell’s environment and past history.

Eukaryotes

Gene regulation involves several complex systems.

Most eukaryotic genes are controlled individually and have regulatory sequences that are much more complex.

TATA box

Gene Expression


Operons l.jpg
Operons change and this can affect cell structure and function,which changes a phenotype.

  • A group of genes that operate together are known as operons.

  • In E.coli there are 4288 protein encoding genes that are turned off and on together.

  • Because the genes must be expressed in order for the bacterium to be able to use the sugar lactose as food, they are called lac operon.


Gene regulation in prokaryotes l.jpg

The regulatory gene codes for production of the repressor that binds to DNA, preventing RNA pol from binding to the promoter. Protein synthesis can’t occur.

Gene Regulation in Prokaryotes

Lac genes (operon)- group of genes that operate together.


The repressor is inactivated l.jpg

2. Enzymes bind to the repressor and changes it’s shape so it can’t combine to DNA. Now, RNA pol can bind to promoter.

The repressor is inactivated.


The genes are on l.jpg

3. RNA pol moves along DNA where mRNA is translated to produce product. When there is enough “product” in the cell, the repressor takes back original shape and turns genes back off.

The Genes are On


Analogy of gene regulation in prokaryotes l.jpg

An analogy to gene control would be when a house gets below a certain temp. the furnace kicks on and when it is hot enough it turns back off.

What would the promoter be?

Analogy of Gene Regulation in Prokaryotes


Gene expression in eukaryotes l.jpg
Gene Expression in Eukaryotes a certain temp. the furnace kicks on and when it is hot enough it turns back off.

  • TATA box is about 30 bp long and helps RNA polymerase to find position by marking a point just before the point for transcription to begin.


Development and differentiation l.jpg
Development and Differentiation a certain temp. the furnace kicks on and when it is hot enough it turns back off.

  • Differentiation- cells become specialized in structure and function.

  • Hox genes- control the differentiation of cells and tissue in the embryo. A mutation can completely change the organs that develop in specific body parts. Legs instead of antennae on fruit fly can grow on head.


Hox gene clusters l.jpg
Hox gene clusters a certain temp. the furnace kicks on and when it is hot enough it turns back off.

What do you recognize about where each gene controls in each organism?


Dna and rna review l.jpg
DNA and RNA review a certain temp. the furnace kicks on and when it is hot enough it turns back off.

  • Go to the following link and click on your book. Go to Ch. 12. Take the self-test and do the Active Arts.

  • Ch. 12 Review


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