sohan - DNA

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