DNA Stuff Flashcards
Genes
A unit of inheritance
All of our physical characteristics are a result of the genes we inherit from our parents
Genes are located on chromosomes in the nucleus of our cells
Made of proteins and DNA
Who performed experiments to show DNA was the genetic material
Hershey and chase
How did they show DNA is the genetic material
Bacteriophages (phages), viruses that infect bacterial cells
Phages labeled with radioactive sulfur to detect proteins or radioactive phosphorous to detect DNA
Results of DNA experiment
Sulfur-labeled protein stayed with the phages outside the bacterial cells, phosphorous labeled DNA detected inside cell
Cells with phosphorous labeled DNA produced new bacteriophages with radioactivity in DNA but not in protein
DNA
Deoxyribonucleic acid
An organism’s genetic material that is capable of replicating
Type of macromolecule called a nucleic acid (include DNA and RNA)
Nucleic acids are long polymers made up of many monomers called nucleotides
Shape of DNA
Double helix
Discovered by Watson and crick
Two polynucleotide strands, held together by hydrogen bonds
Two strands twist to form the double helix
Nucleotides
Small molecules that bind together to form nucleic acids
Made of one sugar (deoxyribose), one phosphate group, and one nitrogenous base
Four nitrogenous bases
Adenine, guanine, thymine, cytosine
Purines
Adenine and guanine (larger)
Pyrimidines
Thymine and cytosine (smaller)
Chargaff
Discovered A = T and G = C
Hydrogen bonds between the base pairs hold the two strands of DNA together
Strands
DNA’s sugar phosphate backbones run in opposite directions
Each strand has a 3’ end and a 5’ end
Primed numbers refer to the carbon atoms of the nucleotide sugars
Sequence of nucleotides is…
Different for every organism
Sequence variation = genetic variation
RNA
Single stranded nucleic acid
Functions in protein synthesis
DNA vs RNA
RNA contains ribose instead of deoxyribose
RNA contains uracil instead of thymine
DNA replication
When DNA makes a copy of itself
Replicates when a cell divides to make two new cells, each cell must have own copy of DNA
Base paring in rules provide copying mechanism for DNA
Semi conservative model
Each new copy of DNA contains one original strand and one new strand
How does DNA replicate
Requires enzymes
Helicase
Unzips a strand of DNA, exposing free bases
DNA polymerase
Adds nucleotides one at a time to the free bases
DNA ligase
Links fragments of nucleotide strands that occur on one side of the DNA molecule
Which side can nucleotides be added to
Nucleotides can only be added to the 3’ end of the parental strand of DNA
Daughter strand synthesized continuously
Goes in, starts at 3’ so it begins w 5’
Daughter strand synthesized in pieces
Okazaki fragments, goes out, starts at 3’ but goes out to 5’ so end is 3’
Why does DNA replicate
Cell replication and organism reproduction
Cell replication
Growth of the body and repair of wounds
DNA replication allows a body to grow larger because it is made of more cells
Organism reproduction
Asexual reproduction: single called organisms divide into two cells, each cell gets identical DNA
Sexual reproduction: half the DNA from two parents combine in a new cell, offspring has a mix of parents’ genes
Smallest to largest
nitrogenous base, nucleotide, gene, nucleic acid, nucleus, cell
strand synthesized continuously
leading strand
strand synthesized in pieces
lagging strand
central dogma of life
DNA becomes RNA becomes a protein
dna to rna
transcription
occurs in the nucleus
rna to protein
translation
occurs on ribosome
three types of rna
mRNA, tRNA, rRNA
mRNA
messenger
single-stranded
tRNA
transfer
amino acid, anti-codon
rRNA
ribosomal
rRNA makes up ribosomes
three stages of transcription
initiation, elongation, termination
initiation
RNA polymerase and transcription factors bind to promoter sequence (start of section to be copied)
coding strand and template strand
transcription factor and RNA polymerase
elongation
the DNA elongates and the pre-mRNA copies the DNA
termination
the pre-mRNA has copied, the RNA polymerase leaves, the pre-mRNA leaves
mRNA processing
introns and exons, exons spliced together
introns
do not code for proteins
going to be taken out
exons
kept
genetic information that is expressed as proteins
eons spliced together
G-cap
tells mRNA where to go once it leaves the nucleus (ribosome)
Poly Atail
allows mRNA to leave nucleus (helps resist enzyme degradation)
order of mRNA
g-cap, exons, Poly A tail
codon
sequence of 3 RNA nucleotides that correspond to specific amino acids
translation stages
initiation, elongation, termination
initiation translation
mRNA binds to bottom part of ribosome and tRNA binds to start codon
anti-codon on tRNA
elongation translation
polypeptide chain forms as tRNA brings more amino acids to ribosome
what are between amino acids
peptide bonds
termination translation
stop codon reached, no more tRNAs come, ribosomes and mRNAs fall apart
binding sites on top of ribosome
a, p, e
A binding site
amino acid dropped off
P binding site
polypeptide builds
E binding site
tRNA exits
why is DNA important
to make proteins
holds instructions for life
what does DNA become
proteins/codes for proteins
what catalyzes the elongation of the DNA strand
dna polymerase
which end is the 5’ end
the one with the thing sticking off of it (phosphate group)
how many origins/forks
two forks for every one origin
point mutations
change in base sequence in DNA or RNA
chromosomal mutations
problem with whole chromosome
outcomes of point mutations
single amino acid change (substitution), missense mutation, nonsense mutation, frameshift
single amino acid change (substitution)
one base change for another base
can occur during DNA replication/transcription
ex. sickle cell anemia
glutamic acid vs valine
glu has hydrophilic R-group on outside of protein
val has hydrophobic R-group on inside of protein
missense mutation
creates a slightly different shape
results: could have no big effect (wobble)
could function poorly (protein could function poorly)
protein could function better (evolution)
nonsense mutation
base changes produces a stop codon in the middle of the protein
frameshift
always produces non-functional proteins
sperm/egg results in baby not born
adult results in cancer
insertion or deletion of one base on DNA (replication) or mRNA (transcription)
insertions/deletions
a letter is added or removed
it is called mutated
all amino acids after the deletion or insertion are incorrect)
how do mutations occur
chemicals called mutagens
ex: uv rays in the sun, cigarette smoke, drugs, asbestos
parts of neuron
dendrites, cell body, axon, axon terminals
cerebrum
things you learn in school ex 2+2=4
large twisted part, curled
cerebellum
high five, motions, muscle activity
circle under cerebrum
brain stem
involuntary reactions, hiccups
large thing under cerebellum
hippocampus
memory
looks like a seahorse, next to cerebellum
amygdala
emotions
little circle off of hippocampus
prefrontal cortex
decisions
smaller curly twisted part next to cerebrum
