GENETICS - FINALS Flashcards
definition and terms
who proposed that the genes are partially linked or there is a linkage between them
-bateson
-saunders
-punnett
the association of genes within the some chromosome but which can be separated by recombination
linkage
a result of crossing-over wherein there is an exchange of segments between homologous chromosomes
recombination
linkage is not complete and gene pairs assort at least partially independent of each other
incomplete linkage
“the closer the genes are located on the chromosome, the greater the probability that they would be inherited together”
thomas hunt morgan
genes are closely associated that they are always inherited together
complete linkage
AB/ab or cis form also indicated the _
coupling phase
ab/AB or trans form also indicated the _
repulsion phase
the strength of linkage is expressed as linkage value
determination of linkage
the use of three genes to produce a linkage map
three-point test cross
phenomenon of inhibition of cross-over of by another cross-over nearby
interference
designed by H.J. Muller in 1916 and used by measuring
coefficient of coincidence
carriers of genes
chromosomes
fragments of DNA
genes
basic unit of chromatin
nucleosome
consists of a phosphate group, pentose sugar, and nitrogen base
nucleotides
3 parts of nucleotide
-sugar (fructose)
-nitrogenous base
-phosphate group
characteristic of DNA
-strands are anti-parallel
-it follows the chargaff’s rule
-adenine=thymine
-guanine=cytosine
factors contributing to the stability of the DNA
- covalent bonds present
- many hydrogen bonds between base pairs
- hydrophobic interactions between the stacked nitrogen base pairs
4 scientist who discovered DNA
-james watson
-rosalind franklin
-francis crick
-maurice wilkins
types of RNA
-mrna
-trna
-rrna
made when DNA is transcribed into RNA
messenger RNA (mRNA)
reads the mRNA during transcription and translates it into amino acids
tranfer RNA (tRNA)
RNA found in ribosomes
ribosomal RNA (rRNA)
large complex molecules, made up of amino acids, that many important roles in the body
proteins
required for the structure, function and regulation of the body’s tissues and organs
proteins
comes from the greek word protcos, meaning “primary” or “first place”
proteins
DNA replication is semiconservative is proved by
-matthew maselson
-franklin stahl
the two parental stands reassociate after acting as templates for new strands, thus restoring the parental double helix
conservative models
the two strands of the parental molecule separate, and each functions as a template for synthesis of a new, complementary strand
semiconservative model
each strand of both daughter molecules contains a mixture of old and newly synthesized DNA
dispersive model
DNA unwinds at the __
origin of replication
opens up the DNA-forming replications and they are extended bidirectionally
helicase
coat the DNA around the replication fork to prevent rewinding of the DNA
single-strand binding proteins
binds at the region ahead of the replication fork to prevent supercoiling
topolsomerase
synthesizes RNA primers complementary to the DNA strand
primase
starts adding nucleotides to the 3’ - OH end of the primer
DNA polymerase
___ are removed by exonuclease activity
RNA primers
exonuclease activity removes RNA primer and replaces with newly synthesized DNA
DNA polymerase I
has the repair function and fix an error in the newly synthesized sequence
DNA polymerase II
main enzyme that adds nucleotides in the 5’-3’ direction
DNA polymerase III
unwinds the DNA helix by breaking hydrogen bonds between the nitrogenous bases
helicase
seals the gaps between the okazaki fragments to create one continuous DNA strand
ligase
synthesizes RNA primers needed to start replication
primase
helps to hold the DNA polymerase in place when nucleotides are being added
sliding camp
help relieve stress on DNA when unwinding by causing breaks and then resealing the DNA
topolsomerase
binds to single-stranded DNA to avoid DNA rewinding back
single-strand binding proteins
who formulated one gene - one enzyme hypothesis
-george w. beate
-edward tatum
every gene controls a particular enzyme and the ultimate products of a metabolic process was affected by a stepwise succession of enzymes, each produced by a particular gene
one gene - one enzyme hypothesis
also known as RNA synthesis
transcription
it is the process where the transfer of information is from a double-stranded DNA molecule to a single-stranded RNA molecule
transcription
rich in AT
prinbnow box
facilitates localized unwinding of the DNA
pribnow box
contains a G:C rich region followed by six or more A:T base pairs with the A’s present in the template strand
rho - independent terminator
the G:C rich region can base pair and form a hairpin-like structure which retards the movement of RNA polymerase along the DNA
rho - independent terminator
requires a protein rho
rho - dependent terminator
it has high C and low G content upstream of the terminator and this signals rho to bind to mRNA
rho - dependent terminator
the addition of about 100-200 adenine nucleotides to the 3’ end of the primary transcript m
3’ poly-a-tail
a modified guanine added to the 5’ end of the transcript that protects the transcript from being broken down
5’ cap
the noncoding introns are cut off by enzyme spliceosome
splicing
