The cell cycle, DNA, Cell division and protein synthesis...
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1 The cell cycle, DNA, and protein synthesis • We will be covering bits and pieces of Ch. 19 (the cell cycle) and Ch. 21 (DNA and protein synthesis) Cell division • = the reproduction of cells • 1. Mitosis produces somatic cells (= all body cells except sex cells • 2. Meiosis produces sex cells (= ♂ sperm and ♀ eggs) – We’ll cover meiosis with the reproductive system chapter The cell cycle 2 main parts : • 1. Interphase – normal cell functions; prep for cell division (e.g. DNA replication) – Most somatic cells spend majority of lives in interphase (duration varies by cell type) • 2. Cell division/ mitosis Changes in chromosome structure during the cell cycle
Transcript of The cell cycle, DNA, Cell division and protein synthesis...
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The cell cycle, DNA,and protein synthesis
• We will becovering bitsand pieces ofCh. 19 (the cellcycle) and Ch.21 (DNA andproteinsynthesis)
Cell division• = the reproduction of cells• 1. Mitosis produces somatic cells (= all body cells except sex cells• 2. Meiosis produces sex cells (= ♂ sperm and ♀ eggs)
– We’ll cover meiosis with the reproductive system chapter
The cell cycle2 main parts:• 1. Interphase –
normal cellfunctions; prepfor cell division(e.g. DNAreplication)– Most somatic
cells spendmajority of livesin interphase(durationvaries bycell type)
• 2. Cell division/mitosis
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Overview of mitosis
Stages of cell division(mitosis) – continued on next slide
Stages of cell division (mitosis), continued
Cytokinesis• = division of cytoplasm after mitosis; last stage of cell division
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Review ofDNA
structure…
• …so that we can betterunderstand DNA replicationand protein synthesis
• Remember, for DNA:– A is complementary to T– C is complementary to G
DNA replication
• Occurs during the “S”(middle) part ofinterphase of the cellcycle
• DNA polymerases =enzymes that link theadjacent nucleotidesof each new(complementary)strand
Gene expression is protein synthesis
• Gene = a segment of DNA that contains a sequence ofnucleotide bases that codes for a specific polypeptide orprotein
• Transcription: information stays in the same language(nucleotide base sequence)– Takes place in nucleus
• Translation: information is translated from nucleotide basesequence to amino acid sequence– This is the actual “protein synthesis” part this whole process– Takes place in cytoplasm
transcription translationDNA mRNA protein(gene)
Needs for protein synthesis• 1. Instructions:
– Genes on DNA in nucleus
• 2. An assembly site:– Ribosomes (which are made up of rRNA + proteins) in cytoplasm
• 3. A courier:– mRNA (messenger RNA) takes instructions from nucleus to assembly
site in cytoplasm
• 4. Raw materials:– Amino acids in cytoplasm
• 5. Transport of raw materials to assembly site:– tRNA (transfer RNA) carries amino acids to ribosome
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The genetic code• Codon = three (3) nucleotide bases in a specific sequence that code for
one amino acid• So a gene contains all the codons needed to code for a specific
polypeptide– May be hundreds or thousands of bases long
(mRNA codons)
Transcription• = making an mRNA copy of a DNA gene in the nucleus• RNA polymerase = the enzyme that makes it happen• The finished mRNA transcript will leave the nucleus and
travel to a ribosome in the cytoplasm
Translation• = assembling amino acids into
a polypeptide at the ribosomeaccording to the mRNAsequence
• Anticodon = 3 base sequenceof tRNA that is complementaryto a mRNA codon– Determines which amino acid
the tRNA can carry
• Remember, for RNA:– A is complementary to U– C is complementary to G
Ribosomes: the workbenches onwhich proteins are built (translation)
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Translation
Translation
Translation
Review: DNA vs. RNA
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Review: the 3 types of RNA
