Chapter 11 DNA, RNA and Proteins Section 11.1 Summary – pages 281 - 287 Deoxyribonucleic Acid- type of nucleic acid DNA is the code for manufacturing.

Chapter 11

DNA, RNA and Proteins

• Deoxyribonucleic Acid- type of nucleic acid

• DNA is the code for manufacturing all the proteins for an organism.

• DNA is made of nucleotides

What is DNA?What is DNA?

• Nucleotides have three parts: a simple sugar, a phosphate group, and a nitrogenous base.

Phosphate group

Sugar (deoxyribose)

Nitrogenous base

The structure of nucleotidesThe structure of nucleotides

NitrogenNitrogen BasesBases: adenine (A), guanine (G) cytosine (C), and thymine (T).

Adenine (A) Guanine (G) Thymine (T)Cytosine (C)

•Pyrimidines•Purines

SugarSugar - deoxyribose .

Nucleotide Structure

Base PairingBase Pairing

Adenine – Thymine

Cytosine - Guanine

A - T

C-G

A-T

C-G

A - T

C-G

A - T

A-T

•C-G

• In DNA, the amount of adenine is always equal to the amount of thymine, and the amount of guanine is always equal to the amount of cytosine.

The structure of nucleotidesThe structure of nucleotides

• Nucleotides join together to form long chains

• Phosphate groups and deoxyribose molecules- form the backbone of the chain

The structure of DNAThe structure of DNA

It is a double helix and is twisted

Chromosome The sequence of nucleotides forms the unique genetic information of an organism.

REPLICATION

ReplicationReplication

Before mitosis or meiosis, the chromosomes are copied – this is called DNA replication.

Happens during Interphase

The new DNA is identical to original DNA

Replication of DNA

Replication of DNA

DNA

Replication

Replication

Copying DNACopying DNA

Original DNA

Original DNA

Strand

Original DNA

Strand

Free Nucleotides New DNA

moleculeNew DNA

Strand

New DNA molecule

Replication of DNA

Replication of DNA

Click this image to view movie

type of nucleic acid

single stranded

RNARibonucleic acid

RNARibonucleic acid

sugar is ribose Ribose

RNARNA

Nitrogen bases:

adenine – uracil

cytosine - guanine

Uracil

Hydrogen bonds Adenine

RNARNA

•NO thymine

Comparing DNA and RNAComparing DNA and RNA

DNA

1. double stranded

2. sugar – deoxyribose

3. nitrogen bases

- adenine-thymine

- cytosine-guanine

RNA

1. Single stranded

2. Sugar – ribose

3. Nitrogen bases:

- adenine- uracil

- cytosine- guanine

Proteins are made of amino acids.

The sequence of nucleotides in each gene contains the code for making the string of amino acids that make up a protein.

Genes and ProteinsGenes and Proteins

TranscriptionTranscription

1. DNA - instructions for making proteins (proteins are made of amino acids)

2. RNA transcribes the instructions from the DNA- mRNA

• Messenger RNA (mRNA), brings instructions from DNA in the nucleus to the ribosomes. (in the cytoplasm)

mRNA

Difference in Replication and TranscriptionDifference in Replication and Transcription

• Replication – forms a double stranded DNA molecule from the DNA in the nucleus and it is identical to the original DNA

• Transcription – forms a single stranded RNA molecule called mRNA from the DNA that is in the nucleus

DNA separates – mRNA is assembled A A TC C GG G CG G CC C GT U AT U AC C G

DNA DNA

TranscriptionTranscription

Translation: From mRNA to ProteinTranslation: From mRNA to Protein

1. mRNA is made in the nucleus and travels to the ribosomes in the cytoplasm.

- ribosomes are made of rRNA (ribosomal RNA)

2. ribosome attaches to the mRNA

tRNA –( transfer RNA) – brings the correct

amino acid to the ribosome to make the protein

• Transfer RNA (tRNA) is the supplier. Transfer RNA delivers amino acids to the ribosome to be assembled into a protein.

RNARNA

Click image to view movie

TranslationTranslation

• Strand of mRNA

AUG UAA CGA CGA GAU GUG UGA

• Codon – set of three nitrogenous bases that represent an amino acid (the order of the nitrogen bases is the recipe for the protein)

AUG UAC CGA CGA GAU GUG UGA

Methionine, Tyrosine, Arginine, Arginine, Aspartic Acid, Valine, Stop

Each codon represents an amino acid

mRNA strand

Try one!!!! Write the amino acids that correspond to the codon!!!!

AUG UUU ACA AAA GGG GAG GUC UAA

• methionene, phenylalanine, threonine, lysine, glycine, glutamic acid,valine,stop

Now try something different- here is the mRNA – write what the DNA code was for this mRNA.

AUG UUU ACA AAA GGG GAG GUC UAA

TAC AAA TGT TTT CCC CTC CAG ATT

Review of Translation

1. mRNA leaves the nucleus and goes to the ribosome

2. mRNA has the code for making the protein

3. tRNA brings the correct amino acid to the ribosome to make the protein

Mutation

Any change in the DNA sequence

Mutations

Body cell – damage to a gene may impair the function of the cell

- ex: cancer

Reproductive Cell – mutation could become a part of the genetic makeup of the offspring

-ex:genetic disorder, death

Types of mutations

Point mutation – a change in a single base pair in DNA – wrong amino acid

- ex: CCC – codon for proline CGC(mutation) – codon for arginine Insertion – an extra base pair inserted – changes

the codon

Deletion – a base pair is missing – again changes the codon

Results in a frameshift mutation- it shifts the reading of codons so has the wrong amino acids

for the protein

PracticeDNA strand:

TAC AAA TGT TTT CCC CTC CAG ATT

RNA strand:AUG UUU ACA AAA GGG GAG GUC UAA

Amino Acids making up the protein: •methionene, phenylalanine, threonine, lysine, glycine, glutamate,valine,stop

Point mutationDNA strand:

TAC AAA TGT TAT CCC CTC CAG ATT

RNA strand:

AUG UUU ACA AUA GGG GAG GUC UAA

Amino Acids making up the protein: • methionene, phenylalanine, threonine,

isoleucine, glycine, glutamate,valine,stop

Frameshift Mutation

DNA strand: (deletion)

TAC AAA TGT TT CCC CTC CAG ATT

RNA strand:

AUG UUU ACA AA GGG GAG GUC UAA

AUG UUU ACA AAG GGG AGG UCU AAG

Amino Acids making up the protein: • methionene, phenylalanine, threonine,

lysine,glycine,arginine, serine, lysine

Chromosomal mutations

• Deletion-part of the chromosome is left out

• Insertion- part of chromatid breaks off and attaches to its sister chromatid (duplication of genes on one chromosome)

• Inversion – when a chromsome breaks off and reattaches backwards

• Translocation- part of one chromosome breaks off and is added to a different chromosome

Causes of mutations• Mutagen- any thing that causes a change

in the DNA

- radiation, chemical , UV light, nuclear

radiation, asbestos,