Presentation on theme: "SC STANDARD B-4 STUDENTS WILL DEMONSTRATE AN UNDERSTANDING OF THE MOLECULAR BASIS OF HEREDITY."— Presentation transcript:
SC STANDARD B-4 STUDENTS WILL DEMONSTRATE AN UNDERSTANDING OF THE MOLECULAR BASIS OF HEREDITY
EQ: HOW WOULD YOU COMPARE TRANSCRIPTION &TRANSLATION? Notebook: page 98
are coded DNA instructions that control the production of proteins within a cell.
single stranded nucleic acid 5-carbon sugar is ribose 1 phosphate group 1 of 4 nitrogenous bases: 1. adenine 2. guanine 3. cytosine 4. uracil
1. Messenger RNA (mRNA) carries copies of instructions for assembling proteins from the gene (in nucleus) ribosomes
single strand of nucleotides read in groups of 3 called codons look at the 2 codons on this slide: What sequence of nucleotides on DNA did this segment of mRNA come from?
with proteins make up ribosomes ribosomes made of 2 subunits: 30S and 50S
transfers each of the amino acids to the ribosome as is specified by the code in mRNA one end has the anticodon other end the a.a.
anticodon: group of 3 bases that are complimentary to the codon on mRNA
TRANSCRIPTION INVOLVES TRANSCRIBING (copying) THE CODE IN DNA MAKING mRNA INVOLVES TRANSLATING the CODE into AMINO ACIDS POLYPEPTIDE CHAINS PROTEINS mRNA, tRNA, rRNA TRANSLATION
mRNA molecules are made by copying part of a nucleotide sequence of DNA into a complimentary (C’) sequence in mRNA Steps: 1. RNA Polymerase opens DNA 2.RNA Polymerase uses 1 of the DNA strands as template uses C’ base pair rules
RNA Polymerase binds to DNA at certain points called “promoters”
after unwinding a short portion of the double helix, RNA Polymerase moves along 1 of the DNA strands making a strand of RNA using base-pair rules except there is no T in RNA: A is paired with U (Uracil)
RNA Polymerase moves along the DNA until it hits a signal to stop. this strand of RNA is called pre-mRNA
portions of DNA called introns do not code for proteins DNA portions that code for proteins called exons. introns get cut out of pre-mRNA and the exons get spliced together http://www.dnalc.org/view/16938-3D- Animation-of-RNA-Splicing.html http://www.dnalc.org/view/16938-3D- Animation-of-RNA-Splicing.html
is the “language” of the mRNA instructions written in a language that only has 4 “letters”: G, C, A, & U must code for 20 amino acids is read 3 letters at a time every 3 consecutive letters codes for 1 of the 20 a.a., a start signal, or a stop
codon: is a “word” in the code consists of 3 consecutive nucleotides that specify an a.a., a stop, or a start
Page of Notebook: page 105 “Crack the Code” Quick Lab from page 303 of textbook
cell uses information from mRNA to produce proteins
Step 1 mRNA attaches to ribosome 1 st codon codes for methionine tRNA with anticodon complimentary to codon in mRNA attaches to ribosome, delivering correct a.a. Step 2
Step 3 peptide bond forms between a.a brought to ribosome by 1 st & 2 nd tRNA ribosome only holds 2 tRNA so 1 st one leaves ribosome as 3 rd one “docks” Process repeated until “stop” codon Step 4
Step 5 polypeptide chain falls off ribosome Ribosome free to start another peptide chain http://www.wisc- online.com/Objects/Vie wObject.aspx?ID=AP130 2 https://www.youtube.co m/watch?v=Ikq9AcBcoh A http://www.wisc- online.com/Objects/Vie wObject.aspx?ID=AP130 2 https://www.youtube.co m/watch?v=Ikq9AcBcoh A http://www.dnalc.org/re sources/3d/TranslationB asic_withFX0.html http://www.dnalc.org/re sources/3d/TranslationB asic_withFX0.html Animations
TRANSCRIPTION DNA mRNA nucleus mRNA cytoplasm or RER mRNA + ribosome + tRNA protein TRANSLATION