Chapter 11Chapter 11

DNA Structure, Protein DNA Structure, Protein Production, And MutationsProduction, And Mutations

DNA VS RNA- DNA VS RNA- Nucleic acidsNucleic acids

DNADNA RNARNA

StructureStructure Double HelixDouble Helix Single StrandSingle Strand

SugarSugar DeoxyriboseDeoxyribose RiboseRibose

Nitrogen Nitrogen BasesBases

Adenine Adenine thymine thymine Cytosine Cytosine GuanineGuanine

Adenine Adenine Uracil Uracil Cytosine Cytosine GuanineGuanine

FunctionFunction Stores and Stores and transmits transmits genetic genetic informationinformation

Messenger: Messenger: takes info takes info from nucleus from nucleus to ribosometo ribosome

DNA is a polymer made of repeating DNA is a polymer made of repeating subunits called nucleotides.subunits called nucleotides.

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

Phosphate group

Sugar (deoxyribose)

Nitrogenous base

The structure of nucleotidesThe structure of nucleotides

In DNA, there are four possible In DNA, there are four possible nitrogenous bases: adenine (A), guanine nitrogenous bases: adenine (A), guanine (G), cytosine (C), and thymine (T).(G), cytosine (C), and thymine (T).

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

Base Pairing Rule

Always TogetherAdenine always pairs with Thymine

Cytosine always pairs with Guanine

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

The structure of nucleotidesThe structure of nucleotides

DNA ReplicationDNA Replication

The process in which DNA makes an The process in which DNA makes an identical copy of itself.identical copy of itself.

An enzyme unzips the DNA An enzyme unzips the DNA molecule, complementary base pairs molecule, complementary base pairs are added to each side of the are added to each side of the separated strands producing two separated strands producing two identical DNA molecules.identical DNA molecules.

Replication of DNA

Replication of DNA

DNA

Replication

Replication

Protein productionProtein production

DNA contains the information used DNA contains the information used to produce proteins.to produce proteins.

Proteins are long chains of amino Proteins are long chains of amino acidsacids

• The sequence of nucleotides in each gene contains information for assembling the string of amino acids that make up a single protein.

3-Types of RNA3-Types of RNA

Messenger RNA (mRNA)Messenger RNA (mRNA) Takes Takes info from nucleus to the ribosome. info from nucleus to the ribosome. Contains the Contains the codoncodon..

Transfer RNA (tRNA) Transfer RNA (tRNA) Brings Brings amino acids with complementary amino acids with complementary base pairs to the mRna at the base pairs to the mRna at the ribosome. Contains the ribosome. Contains the anticodonanticodon..

Ribosomal RNA (rRNA)Ribosomal RNA (rRNA) Makes up Makes up one of the subunits of the ribosomesone of the subunits of the ribosomes

Protein Synthesis-Protein Synthesis-2

Processes 1. 1. Transcription:Transcription: A mRNA strand A mRNA strand

is made using the DNA for a pattern is made using the DNA for a pattern and transfers that information to the and transfers that information to the ribosome for assemblyribosome for assembly

2.2.Translation:Translation: tRNA molecules tRNA molecules bring the amino acids that have the bring the amino acids that have the complementary bases to the complementary bases to the ribosome and a chain of amino acids ribosome and a chain of amino acids is assembledis assembled

RNA ProcessingRNA Processing

Before the mRNA strand can leave Before the mRNA strand can leave the nucleus following transcription, the nucleus following transcription, the introns (parts that do not code) the introns (parts that do not code) are cut out leaving only the exons are cut out leaving only the exons (parts that code for proteins)(parts that code for proteins)

Each tRNA Each tRNA molecule molecule attaches to attaches to only one only one type of type of amino acid.amino acid.

Amino acid

Chain of RNA nucleotides

Transfer RNA molecule

Anticondon

The role of transfer RNAThe role of transfer RNA

The role of transfer RNAThe role of transfer RNA

Ribosome

mRNA codon

The amino acids are joined when a The amino acids are joined when a peptide bond is formed between them.peptide bond is formed between them.

AlanineMethionine

Peptide bond

The role of transfer RNAThe role of transfer RNA

A chain of amino acids is formed until A chain of amino acids is formed until the stop codon is reached on the the stop codon is reached on the mRNA strand.mRNA strand.

Stop codon

The role of transfer RNAThe role of transfer RNA

MutationMutation

A change in the number or structure A change in the number or structure of a chromosome.of a chromosome.

2-Types2-Types 1. gene mutations1. gene mutations 2.Chromosomal mutations2.Chromosomal mutations

Point Mutation- (Gene Point Mutation- (Gene mutation)mutation)

A change in a single base pair in A change in a single base pair in DNA.DNA.

Changes the amino acid in the Changes the amino acid in the proteinprotein

Does not always cause a problem.Does not always cause a problem.

THE DOG BIT THE CATTHE DOG BIT THE CAT THE DOG BIT THE CARTHE DOG BIT THE CAR

Frameshift MutationFrameshift Mutation

A single base is added or deleted A single base is added or deleted from the DNA causing all the other from the DNA causing all the other bases to be out of position.bases to be out of position.

More harmful than a regular point More harmful than a regular point mutation.mutation.

THE DOG BIT THE CATTHE DOG BIT THE CAT THE DOB ITT HEC ATTHE DOB ITT HEC AT

DeletionDeletionPart of a chromosome is Part of a chromosome is

lost.lost.

A B C D E F G H

A B C E F G H

Duplication/InsertionDuplication/InsertionA part of the chromosome A part of the chromosome

repeatsrepeats

A B C D E F G H

A B C B C D E F G H

InversionInversionPart of a chromosome Part of a chromosome

breaks off and reattaches breaks off and reattaches backwardbackward

A B C D E F G H

H A D C B E F G

TranslocationTranslocationPart of a chromosome Part of a chromosome

breaks off and attaches to a breaks off and attaches to a different chromosomedifferent chromosome

W X Y Z Y ZTranslocation

A B E FDCBX AWC HGGE HD F

W X Y Z Y ZTranslocation

Any agent that can cause a change in Any agent that can cause a change in DNA is called a DNA is called a mutagenmutagen..

Mutagens include radiation, chemicals, Mutagens include radiation, chemicals, and even high temperatures.and even high temperatures.

Forms of radiation, such as X rays, Forms of radiation, such as X rays, cosmic rays, ultraviolet light, and cosmic rays, ultraviolet light, and nuclear radiation, are dangerous nuclear radiation, are dangerous mutagens because the energy they mutagens because the energy they contain can damage or break apart contain can damage or break apart DNA.DNA.

Causes of Causes of MutationsMutations