Chapter 11 DNA, RNA and Proteins

Section 11.1 Summary – pages 281 - 287 What is DNA? Deoxyribonucleic Acid- type of nucleic acid DNA is the code for manufacturing all the proteins for an organism. DNA is made of nucleotides Section 11.1 Summary – pages 281 - 287

The structure of nucleotides Nitrogenous base Phosphate group Sugar (deoxyribose) Nucleotides have three parts: a simple sugar, a phosphate group, and a nitrogenous base.

Nucleotide Structure Sugar - deoxyribose . Nitrogen Bases: adenine (A), guanine (G) cytosine (C), and thymine (T). Cytosine (C) Thymine (T) Adenine (A) Guanine (G) Purines Pyrimidines

Base Pairing Adenine – Thymine Cytosine - Guanine A - T A - T C-G A-T

The structure of nucleotides 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 DNA Nucleotides join together to form long chains Phosphate groups and deoxyribose molecules- form the backbone of the chain It is a double helix and is twisted

Section 11.1 Summary – pages 281 - 287 The sequence of nucleotides forms the unique genetic information of an organism. Chromosome Section 11.1 Summary – pages 281 - 287

REPLICATION

Section 11.1 Summary – pages 281 - 287 Replication Before mitosis or meiosis, the chromosomes are copied – this is called DNA replication. Happens during Interphase The new DNA is identical to original DNA Section 11.1 Summary – pages 281 - 287

Section 11.1 Summary – pages 281 - 287 DNA Replication Replication of DNA Replication Section 11.1 Summary – pages 281 - 287

Copying DNA New DNA molecule Original DNA Strand Free Nucleotides New DNA Strand Original DNA Strand Original DNA

Section 11.1 Summary – pages 281 - 287 Replication of DNA Click this image to view movie Section 11.1 Summary – pages 281 - 287

RNA Ribonucleic acid type of nucleic acid single stranded

Section 11.2 Summary – pages 288 - 295 RNA Ribose sugar is ribose Section 11.2 Summary – pages 288 - 295

RNA Nitrogen bases: adenine – uracil cytosine - guanine NO thymine Hydrogen bonds Adenine

Comparing DNA and RNA DNA 1. double stranded 2. sugar – deoxyribose 3. nitrogen bases - adenine-thymine - cytosine-guanine RNA Single stranded Sugar – ribose Nitrogen bases: - adenine- uracil - cytosine- guanine

Genes and Proteins 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.

Section 11.2 Summary – pages 288 - 295 Transcription 1. DNA - instructions for making proteins (proteins are made of amino acids) RNA transcribes the instructions from the DNA- mRNA Section 11.2 Summary – pages 288 - 295

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

Difference 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 T C C G G G C T U A DNA DNA

Section 11.2 Summary – pages 288 - 295 Transcription Section 11.2 Summary – pages 288 - 295

Section 11.2 Summary – pages 288 - 295 Translation: From mRNA to Protein mRNA is made in the nucleus and travels to the ribosomes in the cytoplasm. - ribosomes are made of rRNA (ribosomal RNA) ribosome attaches to the mRNA tRNA –( transfer RNA) – brings the correct amino acid to the ribosome to make the protein Section 11.2 Summary – pages 288 - 295

Section 11.2 Summary – pages 288 - 295 RNA Transfer RNA (tRNA) is the supplier. Transfer RNA delivers amino acids to the ribosome to be assembled into a protein. Click image to view movie Section 11.2 Summary – pages 288 - 295

Section 11.2 Summary – pages 288 - 295 Translation Section 11.2 Summary – pages 288 - 295

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)

mRNA strand AUG UAC CGA CGA GAU GUG UGA Methionine, Tyrosine, Arginine, Arginine, Aspartic Acid, Valine, Stop Each codon represents an amino acid

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

AUG UUU ACA AAA GGG GAG GUC UAA 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 mRNA leaves the nucleus and goes to the ribosome mRNA has the code for making the protein tRNA brings the correct amino acid to the ribosome to make the protein

Any change in the DNA sequence 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

Practice DNA 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 mutation DNA 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,