Theme 1B Flashcards
What are the 3 components of DNA
Pentose sugar-ribose (RNA) or Deoxyribose (DNA)
Nitrogenous bases (purine or Pyrmidine
Phosphate
What is the difference between ribose and deoxyribose
Given the name deoxy, deoxyribose is missing an oxygen on 2 prime c.arbon. Ribose on the other hand has an OH on the 2 prime carbon
What is the difference between purine and pyridine ring
Purine has a double ring Adenine and guanine are purines that bind to N9 nitrogen
While Pyrmidine has a single ring cytosine, thymine and uracil are pyrimidine that bing to N1 nitrogen
What is a nucleoside
molecules of a sugar and a base together
What is deoxyribonuleoside
2-deoxyribose sugar+purine/ pyridine ring
What is a nucleotide
A molecule containing a nitrogenous base a phosphate group and a pentose sugar
Where is the phosphate group attached to the sugar
It is attached to the carbon 5 of ribose/deoxyribose sugar
What is DNA
a polymer of deoxyribonucleotide
What are the role of phosphodiester bonds in DNA
Nucleoyide monomers polymerize (attach to each other) using phosphodiester bond
What role do covalent bonds play in DNA
Covalent bonds form between phosphate and C-3 and C-5 of two sugars forming pentose-phosphate backbone
What makes a polynucleotide polar
because of 5 prime and 3 prime end
Are DNA molecules negatively charged
YES
What are the 3 characteristics of DNA
It is linear
Has a pentose phosphate backbone
Nitrogenous bases held the code since they are the only unique thing between individuals
What is chargaffs rule
the percentage of purines is equal to the percentages of pyrimidines.
There is the same amount of c and gs
there is the same amount of a and t
What was Rosalind franklins role in finding the structure of DNA(3)
she printed a photo of DNA and concludes that
Dna molecules are cyndrical and 2mm in diameter
0.34 periodicity suggest bases are stacked on top of each other
Helical structure of DNA
What keeps two dna strands bonded together
hydgrogen bonding
at has two bonds
cg has 3 bond
How can we denature DNA
under heat or alkali
What is chromatin
regions of dna with its associated proteins on a chromosome
What are plasmids
prokaryotes have one circular chromosome called plasmids
Describe eukaryotic chromosomes
they are linear and enclosed in a nucleus
What are the 3 components of eukaryotic chromosomes
- Orgin of replication
- Centromeres
- Telomeres
What is the origin of replication
DNA sequences along chromosome which initiate dna replication
Centromere
DNA sequences required for correct segregation of chromosomes by directing formation of the kintochiore in which the biotic spindle attaches
Telomeres
DNA sequences located at the end of the chromosome
Only needed for eukaryotes
In humans which cells are haploid
sexually reproductive cells
Why are some eukaryotes polyploid
They have huge cells and need lots of protein and genes +DNa are used to make atheist proteins
What are the 3 reasons that dna is organized in chromosomes
- Chromosomes compact dna so it can fit in nucleus
- Chromosomal structure protects dna from damage
- chromosomes can be easily separated and transmitted to each daughter cell during cell division
What are histones
basic positively
charges proteins that DNA winds around
What is the Role of histone 1
binds to dna and nucleosomes causing nucleosomes to form coiled chromatin
Nucleosome
ball of 4 different histones Dna wraps around nucleosomes
Dna packing is uniform true or false
False
What are euchromatin
regions have lower dna compaction and genes are actively expressed
What are heterchromotain
regions of high dna compaction where gene expression is silenced. Proteins can’t get in to turn genes on
Consistutive heterochromatin
area where Dna always highly compacted
centromemeres and subtelomeric regions
Facatve heterochromatic
can switch to euchromatin depending on cell type and during development
Which part of DNA have a negative charge
the phosphate group
