chp 12 Flashcards
griffith
- mice experiment
- concluded that dna can transfer from dead to alive things
avery
- identified what transformed the dna
- confirmed that when s strain died dna was released
hershey & chase
- used radioactive labeling to trace the dna and protein
- concluded that viral dna was injected into the cell
chargaff
said guanine goes with cytosine and adenine goes with thymine
nucleotide
- adenine
- guanine
- cytosine
- thymine
purines
adenine and guanine
pyrimidines
cytosine and thymine
watson & crick
- made double helix model
1. two outside strands of deoxyribose and phosphate
2. thymine and adenine and cytosine and guanine pair together
x-ray diffraction
helped discover that dna was actually double helix
dna orientation
top strand is 5’ to 3’, bottom strand is opposite direction so 3’ to 5’
chromosome structure
dna coils around histones to make chromatin
dna replication
- occurs in eukaryotic nucleus
- happens before mitosis/myosis
key enzymes in replication
- helicase “unzipper”
- primase “initializer”
- dna polymerase “builder”
- ligase “gluer”
helicase
unzips the double helix structure
primase
makes RNA primer for dna polymerase
dna polymerase
builds new strand in 5’ to 3’
ligase
glues everything together at the end of replication
semiconservative replication
one strand of parental dna serves as a template and one strand of new dna so that the cell can still function
unwinding
helicase is responsible for unwinding the double helix
- primase adds a short segment of RNA primer on each dna strand
base pairing
dna polymerase adds appropriate nucleotides by adding to the 3’ end of the new dna strand
leading strand
first strand that is stretched as the dna unwinds, other strand is lagging
lagging strand
elongates away from the replication fork and is synthesized into small fragments called okazaki fragments
joining
da polymerase removes the rna primer and fills in the place with dna nucleotides
- ligase links 2 sections
eukaryotic replication vs prokaryotic replication
e: dna unwinds as dna is replicated
p: circular dna strand is opened at one origin of replication
rna
single stranded
-contains sugar ribose and the base uracil instead of thymine
messenger rna (mRNA)
-long strands of rna nucloetides that are formed complementary to the strand DNA
ribosomal rna (rRNA)
-associates with proteins to form ribosomes in the cytoplasm
transfer rna (tRNA)
- smaller segments of rna nucleotides that transport amino acids to the ribosomes
transcription
dna code is transferred to rna in the nucleus
introns
intervening sequences in rna processing
exons
remaining pieces of dna that serve as the coding sequences
codon
3 base code in dna/rna
translation
tRNA molecules act as interpreters of the mRNA codon sequence
anticodon
3 base coding sequence in the middle of th folded strand
one gene one enzyme
one gene codes for one peptide
- genes are chemicals
prokaryote gene regulation
-ability of an organism to control which genes are transcribed in response to the environment
operon
a section of dna that contains the genes for the proteins needed for a specific metabolic pathway
4 things needed for prokaryotic gene regulation
- operator
- promoter
- regulatory gene
- genes coding for proteins
eukaryotic gene regulation
regulates transcription
gene mutation
-permanent change that occurs in a cells dna
types of mutation
- point mutation
- insertion
- deletion
causes of mutations
- spontaneous
- chemicals and radiation can damage dna
- high-energy forms of radiation (x-rays, gamma rays) are higly mutagenic
