unit4 – lecture3. dna dna = de-oxy-ribo-nucleic acid “blueprint” for traits double helix shape...
TRANSCRIPT
Unit4 – Lecture3
DNADNA = De-oxy-ribo-nucleic Acid
“blueprint” for traitsdouble helix shapecomposition:
polymer of nucleotide monomersnucleotide [3 parts]:
sugar [deoxyribose]phosphatenitrogen base
Nitrogen BasesNitrogen Bases:
are complementary:adenine [A] bonds with thymine [T]cytosine [C] bonds with guanine [G]
Nitrogen Bases – cont’dNitrogen Bases:
amount of A = amount of Tamount of C = amount of G
purines: A & Gpyrimidines: C & T
Discuss
With what you just learned, find the answer to the following math problem:
If your cells contained 12% adenine, how much of each of the other
nitrogen bases do your cells contain?
Discuss If your cells contained 12% adenine, how much
of each of the other nitrogen bases do your cells contain?
if A = 12% then T = 12% total = 24% A&T
100% - 24% = amount of C&G76% = amount of C&G
76 / 2 = amount of C or amount of GC = 38%, G = 38%
DNA – cont’dWatson & Crick [1953]
proposed the structure of DNAstole the work of Rosalind Franklin
X-Ray Crystallography
DNA Replication happens in the cell nucleusoccurs during interphase
DNA Replication – cont’denzyme unzips DNA double strand by
breaking the hydrogen bonds between basesfree-floating bases bond to open DNA
DNA Replication – cont’dcontinues…end result = 2 strands, ½ new & ½ old DNArepeat.
RNARNA – Ribo-nucleic Acid
sugar = ribose [instead of deoxyribose]single strandedhas nitrogen base Uracil instead of
ThymineA bonds with UC bonds with G
Discuss
Restate to your partner what the three differences are between RNA and DNA.
RNA – cont’d
Codon Chart
RNA – cont’d[RNA]
[three types:]tRNA – transfer
ferries amino acids to ribosomecontains “anticodons”
complementary to mRNArRNA – ribosomal
makes up the ribosomes
RNA – cont’d[RNA]
[three types:]rRNA – ribosomal
makes up the ribosomes
Discuss
Name and explain the three types of rna to your partner.
Protein SynthesistransCription
DNA mRNAoccurs in the
nucleusprocess begins at
“promoter”promoter tells
where to start copying DNA sequence
Protein SynthesistransCription
enzyme unzips DNA but RNA bases pair instead of DNA basescomplementary
bases are added
Protein SynthesistransCription
continue adding bases until a “termination sequence” is located.
mRNA carries message outside of the nucleus through nuclear pores into the cytoplasm
Protein SynthesistransLation
mRNA proteinribosomes read
mRNA and use tRNA to make proteins
steps:
Protein SynthesistransLation
ribosomes clamp onto mRNA strand
finds “start” codon [AUG]
tRNA molecule containing matching anti-codon moves to ribosome
tRNA enters ribosome; attaches to strand
Protein SynthesistransLation
another tRNA enters ribosome
ribosome bonds amino acids [peptide bond]
first tRNA leaves, another enters
repeat until “stop” codon is reached
Write this down!
Any nitrogen bases that are BEFORE the “start”
or AFTER the “stop”
are NOT translated into amino acids.
Protein SynthesistransLation
result – chain of amino acids linked by peptide bonds= polypeptide= proteinpolypeptide
processed and shipped using ER & Golgi.
Let’s Try ItC C A T A C G G T G T C T C C G A T A T T
T T Ais this DNA or RNA? how do you know?transcribe the DNA into mRNA
C C A T A C G G T G T C T C C G A T A T T T T A
G G U A U G C C A C A G A G G C U A U A A A A Ufind the start codon [AUG]
G G U A U G C C A C A G A G G C U A U A A A A U
Let’s Try ItG G U A U G C C A C A G A G G C U A U A
A A A Ubeginning with AUG, separate your
mRNA into codons.A U G / / C C A / / C A G / / A G G / / C U A / / U A
A / / A A Ubeginning with your AUG, translate
your mRNA into amino acidskeep translating until “stop” codon is
reached
Codon Chart
Let’s Try ItA U G / / C C A / / C A G / / A G G / / C U A / / U A
A / / A A U MET / / PRO / / GLN / / ARG / / LEU / /
(stop)