bio
DNA location
the nuclear membrane of the cell (nucleus)
histones
a type of protein found in chromatin (knot-like)
chromosome
a structure made up of DNA and proteins that carries genetic information (genes) - only visible during mitosis
first step of DNA extraction
Break through the cell membrane of the cell (use 20% detergent)
second step of DNA extraction
Break through nuclear membrane of the cell (use detergent)
third step of DNA extraction
separate the DNA from the proteins and extract DNA (use salt solution and ethanol)
DNA definition
Deoxyribonucleic acid - a molecule that contains hereditary information and codes for proteins to give organisms their traits
difference between DNA and Chromosomes
DNA - loosely stored in the nucleus
Chromosomes - tight and only visible during mitosis
two kinds of nucleic acids
DNA - deoxyribonucleic acid
RNA - ribonucleic acid
what are nucleic acids?
large polymers that are made up of monomers
monomers that make up nucleic acids:
nucleotides
3 parts of nucleotides:
sugar, nitrogen base, phosphate group
what do the phosphate group and sugar do?
make up the backbone of the DNA (like the legs of a ladder, NOT THE RUNGS)
4 different nitrogen bases:
adenine, guanine, cytosine, thymine (uracil is only in RNA)
adenine
double ring purine
guanine
double ring purine
cytosine
single ring pyrimidine
thymine
single ring pyrimidine
adenine pairs with:
thymine in DNA and uracil in RNA
guanine pairs with:
cytosine
cytosine pairs with:
guanine
thymine pairs with:
adenine
DNA is a ___ molecule:
double-stranded
how many nucleotides does DNA have?
two strands of nucleotides
how are the two strands of nucleotides held together?
through hydrogen bonds
why is DNA stable even if the hydrogen bonds are weak?
DNA has SO MANY hydrogen bonds
in a single strand of nucleotides, how are each nucleotide connected to the next?
through covalent bonds
why are the 2 strands of nucleotides oriented in opposite directions?
the nucleotides are antiparallel
what is the ladder structure of DNA called?
a double helix
complementary base pairing
certain bases bind with certain bases - dependent on the three-dimensional structure of the bases
Johann Miescher
famous scientist that isolated DNA from cell nuclei. thought it was involved with heredity but doubted that idea
James Watson (american) and Francis Crick (british)
scientists of the 1950s who used molecular models and information from Rosalind Franklin’s x-ray to find the 3D structure of DNA - won nobel peace prize
Maurice Wilkins (British)
an x-ray crystallographer who worked with Rosalind Franklin - received nobel peace prize, despite it being Franklin’s work
Rosalind Franklin (British(
female scientist of the 1950s who took X-ray pictures of crystallized DNA - helped figure out the two stranded helical shape of the molecule - did not get credit for her work or win nobel peace prize
Erwin Chargaff
scientist of the 1950s that found that in any sample of DNA, adenine binded to thymine and guanine binded to cytosine
2 categories for cells:
prokaryotic and eukaryotic
Prokaryotic cells include:
Bacteria, archae
Eukaryotic cells include:
protists, fungi, plants, anmials
Structural differences of a prokaryotic cell:
no nucleus
no membrane bound organelles
unicellular
small, simple (1-10 microns)
1 circular chromosomes - maybe plasmid
Structural differences of Eukaryotic cell:
has a nucleus
has membrane bound organelles
uni/multicellular
larger, more complex (10+ microns)
Many linear chromosomes
structural similarities:
plasma membrane - cell membrane
have ribosomes (prokaryotes have smaller ribosomes)
Cytosol (cytiplasm) - gel fluid with solutes
have DNA and RNA
may have Flagella (slight difference between prok/euk structure)
both can have cell walls
gene:
a segment of DNA that codes for a specific protein
genome:
the complete set of genetic material present in a cell
relationship between DNA, genes and genome
DNA makes up genes, genes and DNA make up genome, not all DNA codes for a trait
DNA contains the messages/codes to make __
proteins
The order of the ___ is what determines the protein created from the message
nitrogenous bases
order of DNA analysis:
dna extraction, gel electrophoresis, PCR, sanger method, shotgun sequencing, compare DNA
gel electrophoresis
after samples are loaded into the well, DNA fragments move down from negative to positive. we can find differences between the fragments and isolate the DNA segments with the differences
what direction do the DNA fragments move in?
negative to positve
light fragments
move down fastest
heavy fragments
move down slowest
5’ =
phosphate group
3’ =
sugar
polymerase chain reaction
3rd step in dna analysis - makes repeated clones of the isolated DNA from gel electrophoresis
Sanger method
to determine the order of the bases in the DNA, fluorescent tags are placed on different bases and run through a DNA sequencing machnie
Shotgun sequencing
after the Sanger method, we take all the small fragments and use a computer to find overlaps, and puts them together
Gene (genome) comparison
After all the previous steps, the last step is gene comparison, where you compare each base with each other and find the differences