unit 6 Flashcards
makeup of nucleotide monomers
phosphate group
sugar(deoxyribose)
nitrogenous base(A,G,C,T)
purines
A and G
pyrimidines
C
T(DNA), U(RNA)
DNA structure + antiparallel
5’ (phosphate end) and 3’ end run antiparallel
double helix
Chargroff’s rule + DNA structure
equal ratios of A+T, G+C
future models had to follow this rule
DNA packing into eukaryotic chromosome
DNA coils up around histone proteins to make chromosomes made of 2 sister chromatids held by the centromere
- these separate to become own chromasome eventually
semi-conservative DNA replication
-each new double strand of DNA consists of an original strand and a newly synthesized strand
-old strand acts as template for old strand
What does the enzyme helicase do
unzips the two strands of DNA into seperate strands
What does the enzyme topoisomerase
untwists the double helix shape of DNA
what does the enzyme DNA polymerase do
builder of new DNA strands off of temporary RNA primers
What does the enzyme ligase do
stitcher of DNA strands together after RNA primer is removed
5’ and 3’ end of DNA and their affect of DNA replication
DNA polymerase can only start from the 3’ end working toward the 5’ end
leading strand starts from 3’ end and goes in 1 go
lagging strand starts in middle and keeps going back with RNA primers
Okazaki fragments
- short sections of DNA formed in the lagging strand
- necessary because allows for replication of both strands so that DNA replication can happen
-linked by RNA primers which are replaced by DNA fragments
Chromosomes vs Chromatin
- Chromatin: loose form of DNA
- chromosomes: tightly condensed forms from Chromatin in cell division that are visible; seperate pieces of DNA in a cell
- chromatids: seperate pieces of DNA in a cell
somatic cells vs gametes
- somatic cells: body cells in an organism: 2 sets of chromasomes
- gametes: reproductive cells, sperm and egg: 1 chromasome set
