If all of your cells had a mutationin an important gene, whycould that be bad?

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Chromosomes-• Each chromosome is made of many genes.

Genes-• Each gene holds a sequence to be transcribed and translated into a protein.

• A gene is an instruction for a protein to be made by your body.

• All cells in you have the SAME genetic code.• only read certain genes to tell them what that cell should do

• When a new cell is made…• these cells differentiate, turning on/off different parts of DNA to make them a specific type of cell

• DNA is the code of life

• BUT- it cannot leave the nucleus, AND it is written in the wrong language

• You need something to COPY and TRANSLATE it!

RNA (the copier)-• Single-stranded ribonucleic acid acts to bring the DNA’s message to the ribosome, telling it what protein to make.

Only two difference-• In RNA, no T. Instead, has U • Single-, not double-stranded

3 types• rRNA (ribosomal RNA)• makes up ribosomes

• *mRNA (messenger RNA)• brings DNA’s code to ribosome

• *tRNA (transfer RNA)• brings amino acids to ribosome for protein construction

• DNA used as a template• DNA opens in part, and each “gene” is used as a template for an mRNA strand to be constructed

• mRNA read in 3-letter sequences by the ribosome

Animation of Transcription

RNA goes to the Ribosome (the translatorRNA is “translated” into a protein

• each coded tRNA brings with it an amino acid to add to the protein

Animation of Translation

A change in a genetic sequence.

This can result in a change in the three-letter sequence, which results in differentamino acids being added, and the wrongprotein made

Point mutations-• A single DNA nucleotide is changed, resulting in one wrong codon being produced.

AAT AAG would add L instead of A to the amino acid chain.

Frame-shift mutations• Insertion or deletion• One nucleotide is either added or removed from the sequence, resulting in a change in all of the codons that result in the chain.

ATT GCC CTG GAT TAC

ATT CGC CCT GGA TTA C

Lac gene:• When glucose present, lac (lactose) gene is off (use glucose instead of lactose for energy

• When no glucose, lac gene turns back on to use other sugars (lactose) to | make energy

In many cases, the environment anorganism is in will change its geneticexpression.• Some will turn genes on, some will turn genes off

• **Your DNA doesn’t change, what does change is what genes are turned on and which are turned off

If a rabbit moves to a new locationand its fur color changes, has its DNA changed? Explain?