Cells•Smallest unit of life. •Able to carry out all functions of life.

Cell Theory• All living organisms are made of one or more

cells.• All cells come from other cells.

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The Cell Cycle

•series of changes a cell undergoes from the time it forms until the time it divides• stages • interphase• mitosis• cytoplasmic division

Stages of Interphase

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• Cell grows, maintains routine functions• Cell replicates genetic material and synthesizes new organelles to prepare for division

• G1: 1st growth stage. Cell matures and carries out it’s assigned function. May last indefinitely.• S: Genes are copied• G2: 2nd growth stage. Membranes, cytosol, and organelle numbers increase.

Mitosis

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2 identical daughter cellsExact replicas of the parent cellGrowth, Repair, Replacement

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Genes• DNA- molecule that carries

genetic information• Chromosome- DNA plus

associated proteins• Gene – segment of DNA

that codes for one protein• Genome – complete set of

genes

1 gene = 1 protein

DNA and the Cell Cycle

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Genes

Gene – segment of DNA that codes for one protein1 gene = 1 protein

Genome – complete set of genesGenetic Code – method used to translate a sequence of nucleotides of DNA into a sequence of amino acids

What is the difference between a gene, DNA, and a chromosome?

Protein Synthesis

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1) Transcription: DNA copied to mRNA in nucleus

2) Translation: mRNA copied to protein at ribosomes• Codon: mRNA triplet• Anticodon: tRNA triplet

DNA mRNA protein

DNA vs RNA DNA RNAdouble stranded single stranded Deoxyribose RiboseA,C,T,G A,C,U,GMust stay in nucleus Can leave nucleus1 type 3 types

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RNA MoleculesMessenger RNA (mRNA) -

• delivers genetic information from nucleus to the cytoplasm• single polynucleotide chain• formed beside a strand of DNA• RNA nucleotides are complementary to DNA nucleotides

(exception – no thymine in RNA; replaced with uracil) • making of mRNA (copying of DNA) is transcription

Transfer RNA (tRNA) -• carries amino acids to mRNA• carries anticodon to mRNA• translates a codon of mRNA into an amino acid

Ribosomal RNA (rRNA) –• provides structure and enzyme activity for ribosomes

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TranscriptionRNA polymerase copies DNA mRNAActive strandComplementary strand

Transcription

TranscriptionmRNA is a mirror image of the active strand, except T is now U

mRNA Leaves Nucleus

Translation•On the ribosome•mRNA codon matches to tRNA anticodon•tRNA carries amino acid

TranslationmRNA Protein

Protein Chain•Where did the original DNA go?•Where did the mRNA go?•Where did the tRNA go?•Where did the ribosome go?•Where did the amino acids go?•Where does the protein go?

Genetic Code64 codons20 amino acidsRedundancy