Ch 7 Molecular Genetics Flashcards
Griffith (1927)
discovered bacterial transformation
bacterial transformation
ability of bacteria to alter their genetic makeup by absorbing foreign DNA milecules from other bacterial cells and incorporating the foreign DNA in their own
Avery Macleod and Mcarty
published that Griffith’s bacteria were transferring DNA
Hershey and Chase
proved DNA not proteins is the molecule of inheritance.
Rosalind franklin
critical to Watson and crick’s model of dna
watson and crick
won nobel prize for correctly describing structure of DNA as double helix
Hershey and chase experiment
tagged bacteriophages with radioactive isotopes 32P and 35S. FOund stuff
Role of hydrogen bonds in DNA
pair together nucleotides of opposite chains. also site of unzipping during replication
semiconservative replication
proved by meselson and stahl. where DNA replication makes two new molecules from one old strand and one new.
when does dna replication occur during cell cycle
interphase
what catalyzes new DNA replication
DNA polymerase. it also proofreads each DNA strand
how do eaukaryotic cells cope with possible loss of genes at end of chromosomes>?
have special repeating nonsense nucleotide sequences at ends of each chromosome, called telomeres
Messenger RNA
carries messages directly from DNA in the nucleus to the cytoplasm during the making of a protein. carries triplet nucleotides called codons
transfer rna
cloverleaf shape. carries amino acids to mRNA at ribosome to form polypeptide. triplet nucleotides are anticodons.
ribosomal rna
structural makes up the ribosome
transcription
DNA makes RNA. Facilitated by RNA polymerase, occurs in nucleus. Triplet code of DNA transcribed to codon sequence in mRNA
RNA polymerase
facilitates transcription
introns
RNA regions that dont code for proteins and are removed by enzymes. (intervening sequences)
exons
coding regions, non-introns. after RNA is cut and leaves the nucleus, it is much shorter becuase exons are left
Translation; what? where? how?
mRNA is converted into amino acid. Occurs in the ribosome. Amino acids (in cytoplasm) are carried by tRNA to the codons of mRNA at ribosome, use base pair rules.
can tRNA bind to two different codons?
yes
do cells make every protein all the time?
no, pancreas cells dont always need to make insulin. sometimes they are turned off.
operons
cluster of functional genes and the switches that turn them on/off
Lac operon
inducible operon, turned off usually unless actively triggered to turn on (by enviro)
represible operon
always turned on unless actively turned off because its not needed
two parts to an operon
promoter and operator
promoter (operon)
the on switch. binding site of RNA polymerase, which must always bind to DNA before transcription.
Operator (operon)
binding site for the repressor that turns of the lac operon.
TATA box
part of operon with sequences of alternating thymine and adenine, helps RNA polymerase bind to promoter.
point mutation
simplest mutation; base pair substitution where one nucleotide converts to another.
insertion and deletion
gene mutations that aer caused by one nucleotide. insertion is addition of letter, deletion is removal of letter. both cause frameshifts!
aneuploidy
chromosome mutation where there is any abnormality in the number of chromosomes
polyploidy
chromosome mutation, having extra ets.
nondisjunction
causes aneuploidy and polyploidy, failure of homologous pairs to separate in meiosis
genetic mutation that causes trisomy-21
aneuploidy - extra chromosome 21
genetic mutation that causes large and brilliantly colored flowers
polyploidy
genetic mutation that causes sickle cell anemia
base pair substitution
humane genome
our genetic material. consists of 3 billion base pairs and 30000 genes.
junk DNA
97% of DNA and does not code for proteins. some are regulatory sequences that control gene expression
recombinant DNA
taking DNA from two sources and combining them in one cell. used for genetic engineering or biotechnology
restriction enzymes
cut DNA at recognit9ion sites, they are molecular scissors. they cut DNA into restriction fragments.
gel electrophoresis
separates large molecules of DNA based on their rate of movement across agarose gel in an electric field. small molecules move faster.
preparation of gel electrophoresis
DNA is cut by restriction enzymes into small enough pieces to be run across the gel.
polymerase chain reaction
cell-free automated technique where a piece of DNA can be rapidly copied. this DNA can then be used to study or compare with other samples
