Unit 2.10 DNA,RNA

What gives DNA it’s unique properties and what does this shape help it do?

A three dimensional arrangement gives DNA it’s unique properties to store genetic info and copy and pass it from generation to generation

What do DNA and RNA have in common?

Both are nucleic acids made of long chains (polymers) of nucleotides (monomers)

Parts of nucleotide

—Sugar- DNA: deoxyribose (missing an oxygen atom)

RNA: ribose

(Sugar has 5 carbon atoms four in rings and one above)

—-Phosphate- source of acid, negative charge

—-Nitrogenous bases(basic, high ph)

What does DNA stand for?

Deoxyribonucleic Acid

Thymaine and Cytosine

Single ring

Adenine and Guanine

Larger double ring

Watson Crick

Double helix

Discovered base pairings and replication

Complementary strands

Double helix

The thickness of it is due to the two polynucleotide strands

Rosalind Frank

Photo 51 and x ray distraction data were critical in figuring out DNA structure but Wilkins stole a pic

What Replication results in?

Two daughter DNA molecules, one strand, one new (semi-conservative)

DNA polymerases

Enzymes that make covalent bonds between nucleotides of a new DNA strand and adds new nucleotide base parings to end of growing daughter strand

How does DNA polymerases repair DNA?

Some associated proteins can repair DNA that has been damaged by toxic chemicals,high energy, radiation

What happens during DNA replication at the origins of replication?

1) Origins of replication are specific DNA sites where replication begins

2) Replication proceeds in both directions forming a replication bubble

3) When a replication bubbles merge, they produce two completed double-stranded DNA molecules.

Genotype in DNA

Heritable info contained in sequence of nucleotide bases in its DNA,

Phenotype in DNA

Organisms physical traits arising from actions of a wide variety of a protein

What does DNA specify?

Synthesis of proteins

Transcription

Transfer of genetic info from DNA into an RNA molecule

Translation

Transfer of info from RNA into a polypeptide (protein strand)

DNA Genes….

Dictates the produce of polypeptide

One linear flow

The result of Translation?

polypeptides

Chain of amino acids=proteins

Transcription produces?

nucleic acids

(mRNA)

RNA molecule

—NUCLEUS

What are polypeptides made of, and how are they similar to nucleic acid?

Straight polymers made of 20 amino acid monomers (same in all organisms). Like nucleic acids, they are long chains built by linking repeating monomers together.

Main role of RNA in protein synthesis?

Acts mainly as a messenger,carrying genetic info that dictates the amino acid sequence of a polypeptide

How many possible codons (code words) exist in the genetic code?

There are 64 possible codons,each made from 3 nucleotides

How is genetic info converted from gene to protein?

The flow of info from gene to protein is based on a triplet code.

Genetic instructions in DNA and RNA are written as three-base words called codons,each specify an amino acid.

Genetic code

Set of rules that convert a nucleotide sequence in RNA to an amino acid sequence

AUG

Codes for methionine and provides signal to start polypeptide chain

UAA,UAG,UGA

STOP codons instruct ribosomes to end polypeptides

RNA splicing?

-Process where introns (non coding regions) are removed from pre-mRNA and the exons (coding regions) are

-joined together to form a finished mRNA molecule ready for translation

-Happens in transcription

mRNA in translation?

• Produced by transcription

• needs enzymes and chemical energy like ATP

• Carries genetic code from DNA to RNA

• Occurs in Cytoplasm ON ribosomes

tRNA in translation?

Interpreter

Translations of genetic message carried in mRNA into the amino acid requires an interpreter. Converts 3 letter codons of nucleic acids to amino acid

Match amino acids to appropriate codons to form new polypeptide

Structure of tRNA?

Single RNA strand (80 nucleotides) that folds onto itself,forming double stranded regions where bases pair with other bases in the same strand

Anticodon in tRNA?

The anticodon is a three base sequence of tRNA that is complementary to an mRNA codon, allowing the tRNA to match the correct amino acid to follow mRNA during translation.

Function of tRNA in translation?

Picks up appropriate amino acid that matches its anticodon

tRNa recognizes appropriate codon on the mRNA using its complementary anticodon.

What does all life share?

Genetic Code, so DNA can be used to modify bacteria

How DNA replication and transcription begin?

— In DNA replication, the two DNA strands seperate at an origin of replication,where the process starts

—In transcription,one DNA strands separate at an origin of replication,where the process starts

—Transcription,one DNA strand serves as the template for building the RNA molecule

—The other DNA strand is unused during transcription

Initiation of Transcription

START SIGNAL (PROMOTOR) beginning of gene. RNA POLYMERASE ATTACHES TO START transcription. Binds to promotor and begins making RNA.

—PROMOTOR tells which strand to use as a template different for each gene.

Elongation of Transcription

RNA GROWS LONGER as DNA polymerase moves along DNA. The new RNA molecule PEELS AWAY from DNA, and the DNA strands REJOIN behind it.

Termination of Trasncription

RNA polymerase reaches a SPECIAL DNA sequence called FERMENTATION, this signals END of gene. The Polymerase DETACHES, RNA is released and DNA comes back together.

How does RNA processing differ between prokaryotes and eukaryotes?

—Prokaryotes-RNA transcribed from a gene immediately functions as mRNA with no processing

—-Eukaryotes-transcriptions occurs in the nucleus and RNA is modified (splicing,5’ cap, poly-A tails) BEFORE it leaves the nucleus and enters the cytoplasm for translation by ribosomes.

5’ and 3’ meaning in DNA and RNA?

5’ and 3’ refer to carbon numbers on the sugar in nucleotide

-5’=phosphate group

-3’=hydroxl (-OH) group

—-Direction of nucleic acid strand

—Always synthesized 5’—> 3’

In what direction is the template strand read?

During replication and transcription,the template DNA strand is read 3’—>5 so the new strand can be built 5’ to 3’

Purpose of the 5’ cap and Poly-A tail on mRNA?

The cap and tail mark mRNA for export from the nucleus and help ribosomes recognize it as mRNA. They are extra nucleotides added to the ends of the RNA transcript.

Introns?

Noncoding regions of a gene. Removed from the RNA during processing before the mRNA leaves the nucleus.

What are exons?

Exons are the coding regions of a gene that contain info used to make protein. They stay in the final mRNA after processing.

Ribosomes?

Organelles in cytoplasm that coordinate the functioning of mRNA and tRNA and actually make polypeptides.

rRNA

—makes up part of ribosomes (cells protein making machine)

—combines with proteins to form large and small subunits of ribosome

— give ribosome shape and structure

—aligns mRNA and tRNA correctly

NOT translated DOES not code for proteins

—speeds up chemical reaction without being used itself

Initiation-Translation

Ribosomes assembles at start codon (AUG) on the mRNA acid (methionine) binds to start codon

—Ribosome holds mRNA and tRNA in place to start making the protein

Elongation-Translation

-tRNA brings another another amino acid matching the next mRNA codon

-RrNA in ribosome helps form peptide between amino acid

Ribosome moves along mRNA and protein chain grows larger

Termination-Translation

Ribosome- STOP codon (UAA,UAG, UGA)

-No tRNA matches stop codon,ribosome releases complete protein

-Ribosomes detach from mRNA

What does Transcription and Translation Overall let us do?

Allows genes to control the structure and function of cells.

-How genotype produces phenotype

What happens during S-Phase of Mitosis?

DNA replication

-G1:Growth

-S:DNA synthesis

G2-Growth AND preparation

M-Mitosis (cell division)