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Published byLinda King Modified over 9 years ago
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If all of your cells had a mutation in an important gene, why could 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.
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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
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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!
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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
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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
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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
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RNA goes to the Ribosome (the translator RNA is “translated” into a protein each coded tRNA brings with it an amino acid to add to the protein Animation of Translation
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A change in a genetic sequence. This can result in a change in the three- letter sequence, which results in different amino acids being added, and the wrong protein made
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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.
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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
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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
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In many cases, the environment an organism is in will change its genetic expression. 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
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If a rabbit moves to a new location and its fur color changes, has its DNA changed? Explain?
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