BIOL10005 Lecture Notes - Lecture 2: Okazaki Fragments, Telomerase, Helicase
29 Jun 2018
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Lecture 2: The gene and replication of DNA
Structure of DNA
Gene: physical + functional unit of heredity --> carries info
oGene = segment of DNA
oMost located in chromosomes but also: mitochondria, plasmids, chloroplasts
DNA: Double stranded, polynucleotide
oNucleotide: deoxyribose, phosphate group, nitrogenous base
oStrands are complementary, antiparallel
oBases joined by hydrogen bonds --> broken via heat
oDNA wants to be double stranded:
Can use single strand DNA as a probe to find the desired (complementary)
strand
Chromosomes:
oProkaryote: cytosol
Hence, gene expression faster
oEukaryote: nucleus
Gene expression slower b/c have to be carried out of nucleus
oConsists of DNA + protein
oONLY VISIBLE DURING CELL DIVISION (not interphase)
oDNA & histones loosely wound = chromatin
oNucleosomes: pack genes so tightly so that the enzyme for gene expression can't get
to DNA
o1 of 2 molecule of DNA
Each strand = chromatid
oTHREE ELEMENTS TO FUNCTION:
Telomeres: structural stability
Centromeres: essential for segregation at cell division
Origins of replication: DNA replication start point'
DNA REPLICATION - synthesis stage of cell cycle
Semi-conservative
oOld DNA = template
oNew DNA: half old, half new
find more resources at oneclass.com
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Document Summary
Lecture 2: the gene and replication of dna. Gene: physical + functional unit of heredity --> carries info: gene = segment of dna, most located in chromosomes but also: mitochondria, plasmids, chloroplasts. Dna: double stranded, polynucleotide: nucleotide: deoxyribose, phosphate group, nitrogenous base o o. Bases joined by hydrogen bonds --> broken via heat: dna wants to be double stranded: Can use single strand dna as a probe to find the desired (complementary) strand. Gene expression slower b/c have to be carried out of nucleus. Consists of dna + protein: only visible during cell division (not interphase, dna & histones loosely wound = chromatin, nucleosomes: pack genes so tightly so that the enzyme for gene expression can"t get to dna o o. Dna replication - synthesis stage of cell cycle. Semi-conservative: old dna = template, new dna: half old, half new.
