TOPIC: PROTEIN SYNTHESIS (8.4-8.5)

• OBJECTIVE: LEARN THE STEPS OF

HOW TO MAKE A PROTEIN

BIG PICTURE:MAKING PROTEINS

• DNA RNA PROTEIN • Nucleus Cytoplasm Ribosomes

WHY PROTEINS??

• Proteins are polymers = CHON– Proteins make up ENZYMES, muscles, hair, nails, and code for

traits

• Amino acids held together by peptide bonds

– There are 20 amino acids in nature

• Function of the protein depend on the twists and folds

8.4: Transfer of Genetic Information

• DNA RNA

• RNA:– Is Ribonucleic acid (isn’t missing the oxygen)

– Has RIBOSE as the sugar

– Can leave the nucleus to go to ribosomes

– Is single stranded

– No “T”s…has Uracil (U) bonding to A

3 Different Types of RNA• Messenger RNA

– mRNA

– Carries MESSAGE coded from the DNA to the cytoplasm

3 Different Types of RNA

• Transfer RNA

– tRNA

– Each tRNA binds to specific amino acids and TRANSFERS to ribosomes

3 Different Types of RNA

• Ribosomal RNA– rRNA

– Makes up RIBOSOMES

Transcription

• The process by which the genetic information in DNA is copied to RNA– The code is TRANSCRIBED…DNA to RNA

– In NUCLEUS

The Genetic Code

• DNA codes for mRNA– 3 mRNA nucleotides make up

a codon

– A codon codes for a specific amino acid

– All organisms use the same genetic code

f

The Genetic Code

The Genetic Code

• Start codon (AUG) called methioninetells where to start translating the mRNA

• Stop codon (UAA, UAG, UGA) tells where to stop translating the mRNA

8.5: Translation

• The process of assembling proteins

– RNA PROTEIN

– Have to code for tRNA too which has an anticodon so the AA can be TRANSFERRED to ribosomes

TOPIC: GENE EXPRESSION and GENETIC ENGINEERING

• OBJECTIVE: LOOK AT BIOTECHNOLOGY (Ch 8.7-9.6)

GENE EXPRESSION

• Promoter– DNA segment that promotes

transcription and recognizes mRNA (where transcription begins)

• Structural Genes– Genes that code for particular proteins

Controlling Gene Expression

• Conserve resources

• Only make proteins when needed***

Structure of Eukaryotic Gene

• Promotor– Where transcription begins

• Beyond the promotor– Introns

• Sections of genes that do not code for amino acids; no proteins are made

– Exons• Sections of genes that do code for amino

acids, so proteins are made

• Less than 10% of a human gene

Structure of Eukaryotic Gene

• Promotor – Where transcription begins

• Beyond the promotor– Introns

• Sections of structural genes that do not code for amino acids; no proteins are made

– Exons• Sections of structural genes that do code for

amino acids, so proteins are made

• Less than 10% of a human gene

……Genetic Engineering Techniques

• Recombinant DNA– Directly changes DNA

– Can remove DNA from cells

– Join DNA fragments together• Is recombined

– Cut DNA into fragments• Use restriction enzymes

– Analogy: Are “scissors” for cutting long chains of DNA into smaller parts

Gene Therapy

• Using recombinant DNA to replace or modify defective genes in humans

• Trying to cure disease instead of treat them:– Cystic fibrosis

– Cancer

– SCID (no immune system)

Mutations

• Any mistake or change in the DNA sequence– Accuracy of DNA is important to

ensure genetic continuity of new cells and offspring

3 types of mutations:• 1. Point mutations: change in ONE DNA base

– This would change the meaning of the codon on the mRNA

– Example:

• THE DOG BIT THE CAT

• THE DOG BIT THE CAR = mutation

mutatedbase

3 types of mutations:• 2. Frameshift mutations: a single base is added or deleted

from DNA

– This would cause every codon to be wrong from that point on in protein coding

– Example:

• THE CAT ATE THE FAT RAT

• THE ATA TET HEF ATR ATT

3 types of mutations:

• 3. Chromosomal mutations:– Affects the entire chromosome– If a chromosome is missing= monosomy

• Monosomy on Sex Chromsomes = Turner Syndrome

– 45 chromosomes in humans

– May involve an extra chromosome = trisomy• Trisomy on Chromosome 21 is Down Syndrome

– 47 chromosomes in humans

CAUSES OF MUTATIONS

• Mutations can be good, bad or nothing– They are usually random events but….

• Errors in DNA provide the variation that must be present for the evolution of species