D1 Flashcards
what is DNA replication
prodcution of two identical daugther cellls from one DNA strand
in multicellular organisms, what is DNA replication used for
- growth
- replacement
- reproduction; continuity of genetic sequence
what is semi conservative replication
one strand of the original DNA is kept in the two daughter ells and the other strand is new
where do hydrogen bonds from in DNA
Between complimentary base pairs
dna must replicate before
mitosis
what unwinds the dna in replication
helicase
helicase breaks _ bonds and _ DNA
breaks, unzips
what goes along the split strands of dna
DNA plymerase
process of DNA plymerase
uses the original DNA asa. template and catalyses the condensation of nucelotides to create the backbone of dna for the other part of the helix
where do nucleotides condense
phosphate and deoxyribose
polymerase attatches and reads in a 3’-5’ direction this means
the new strand will be built in a 5’-3’ direction
pcr and electrophoresis
used to analyse DNA,RNA,proteins
what happens during electrophoresis
molecules are separated using electrical current
what are the factors that allow/influence separation
- electrical charge
- size
- type of jel
positive molecules move to
cathode (negative electrode)
negative molecules move to
anode (positive electrode)
size influnces molecule movement beacause
different sizes move at different rates
jel influences
because the pore sizes
to do electrophoresis you must use
polumerase chain reaction PCR
Steps of electophosis
1) put an agrose gel plate with wells at one end
2)submerge gel in elctrolye solution
3)load DNA into wells
4)apply electrical current. put DNA closest to cathode beacuse the negative phosphate will attract to anode
5)smaller ones will move faster
6) when smll ones are nearly at anode dye them to reveal the dna
7) the same dna molecules travel the same distance
8)each well can have different trials for comparison
pcr is used to
copy DNA artifically, can produce thousands of exact replicas
pcr requires target
dna/rna. it doesnt require the whole geno,e just the specific sections that vary
pcr requires dna po
lymerase more specificially TAQ polymerase as it is heat stable taken from bacteria in hot springs
pcr requires free nucleptides
to construct new strand
pcr requires primers
used to bind to the dna and signal the start for TAQ
pcr requires buffer
solution to provide optimal ph
where does pcr take place
eppendorfs - a thermal cylider
stage one pcr
denaturation
heated to 95 degrees wich breaks the two strands apart
stage two pcr
annealing
decreased temps to 53 degrees so primers can anneal
stage three pcr
elongation/extention
temperatures increases to 73 degrees for one minute so taq plymerase can build the new strand
what are PCR and electrophresis used to do together
produce DNA profiles
process of making dna profiles
- dna taken from a person
- primers used to promote amplification of STR through pcr
- Amplified STRs are separated by jels
- patterns can be analysed
what are str
STRS short tandem repeats are reapted in dna bases that are used to identify similarity between peoples dna
what is genetic profiles used for in real life
forensic investigations
paternity investigations
transcription
DNA is transcribed and mRNA is produced
translation
mRNA is translated and proteins produced
anitsense strand
the strand used to make the mRNA runs 3-5
sense strand
the copied strand runs 5-3
what opens the DNA helix
RRRRRRRRRRRRna polymerase unwiding about one turn at a time
stage 2 transcription
RNA polymerase gets free nucleptides and matches them to base pairs. the sugar and phosphate bond to make mrna
stage 3
dna rewinds and mRNA leaves nucleus
what would be the mrna pairs for gga
ccu
what would be the mrna pairs for ctt
gaa
what would be the mrna pairs for tag
aug
what is gene expression
we have so many coding genes, the body turns them on and off when they are needed.
when they are swicthes on they transcript and translate. when they are off they dont.
first stage of gene expression
tarnscription
where does translateon happen
ribiosomes in the cytoplasm
after transcription mrna moves out of nucelar pore and diffuses into cytoplams
what does translation do
uses mRNA to sysnthesize a polypeptide
what is a ribosome
a complex structure with a large and a small subunit (made of proteins and rna)
what attacthes to the small part of ribosome
mRNA
What attatches to the large part of ribosome
tRNA
instead of free nucleotides in translation in transcription there are free
tRNA
triplet of trna is
antiocodon - with amino acid
triplet of mra is
codon
each triplet of trna codes for
one of the 64 amino acids
how is it signalled that the polypeptide has formed
stop codon
metaphor for transcription
converting the text from english to french. getting from e-è so t-u
metaphor for translation
converting it from french into japanses aca = tryposine (completely different)
DNA is chemically stable meaning what?
the covalent bonds make the backbones very strong. this meaning they have contunity rather than change. some genes are transcribed many times throughout a persons life
many polypetides are ?
enzymes that catalyse a reaction
trna carries
the anitcodons
in the ribosome how many TRNs can be binding at once
two
0triplet (genetic code
- a codon (on the mRNA) with three bases
- 3 is nesecary because there is 20 ammino acids
- this makes 64 combinantes 4 cubed
degenecary (genetic code)
beacuse there is 64 bases and 20 ammino acids normally more than 2 combinations can code for the same ammino acid
this can help minimise the effects of mutations
university
in most cases the same bases code for the same ammino acids across defferent species. this gives evidence for evolution from the same cells
some codes symbolise the start stop
what is elongation of a peptide chain
peptide bonds form between amino acids
this is an anabolic reaction cus they are adding on
this requires atp energy, provided from mitrochonria
happen until stop codon
a site
enterance site for new tRNA
P site
holds the peptide chain
step 1 enlongation
peptide bond forms between the amino acids in P AND A and then chain dagles from a
step 2 elongation
ribosome shifts up a spot so the trna is now in P holding the chain. the empty one leaves and A is open
step 3
trna goes into a site till the correct one matches
aug
start codon
step 4
a has the match. pe has chain. e is open - cycle continues
coding strand
the one thats esentially being made in the form of RNA
template strand
the one rna polymerase is moving along.
a mutation
a change in the sequence of bases in dna, wich may result in a new allel
mutations occur..
all the time and are random. during the S phase of interphse
mutations can be
- harmul
- neutral
- benefitial
mutations in body cells
not inheritab;r and they are eliminated when this cell dies
mutations in gamete cells
inheritable
a point mutation
is a single base change but this can lead to changed mRNA and then edit ammino acid in translation
sickle cell is a mutuation in one base
DNA changes to GAG-GTG
template is CAC
mrna is GUG instead of GAG
it occurs in the sixth postion of the ammino acid chain
base supstututions 3 categories
- neutral
- deterious (harmful)
- benefitial
same sense mutations
when the switch in base still codes for the same amino acid due to the redundancy of the genetic code
nonsense mutations
when the amino acid becomes a stop codon (ATT,ATC,ACT) causing terminaton
the impact varies on the function of the protein
mis sense mutations
when the change in base changes the coded amino acid
these can be both none harmful if the two ammino acids are similar but also lethal- like sickl cell
SNP
single nucelotide polymorphism
single nucleotide polymorphism
when a neutral or benefitial mtation occurs in more than 1% of the population has it.
insertion/deletion
when bases are entirely added or removed
frameshift mutation
when an entire polypeptide reading is alterned due to an insertion or deltion
multiple of 3 insertions and deltions
if 3 bases are added or removed, only that amino acid in the polypeptide will be altered. the rest will be the same
if it not a multiple of 3 insertion and deletion
a frameshift mutation will occur and all the following triplets will code for different ammino acids
mutagens
increases mutation frequency above the background level; they are harmful
chemical mutagens + three examples
chemical changes later bases. can be found in substances such as
-nitrosamines; ciggaretts
-mustard gas; used as a chemical weapon
- benzene; used as a solvent in pharmesoutecals
high energy radtiation mutagens plus examples
breaks bonds in DNA alowing insertion deltion and substitutions
- x rats
- beta particles
- UVB AND UVC ultraviolet
-gamma
mutation randomness
- occurs randomly anywhere
- organisms cannot controll/do mutations intentionally but rate may be controlled
- impacted by sandwitch; gaa is more likley than acg
- purpose of dna may play a role; protein coding dna is more succesptible
sompatic cell mutations
- body cells not gamamtes
- not that damaging
- will only kill the one body cell
- a group of somatic mutations can be detrienal. eg mutations in cells that controll cell growth may cause cancer
germ cells are
cells that give rise to gamates; found in testes and ovaries
germ cell mutations
- gamates may carry mutation wich is then passed to offspring
- all cells are derved in an organism from the zygote so gets mutation
germ line
inheritation of genetic information across generations through the zygote egg and sperm
mutations for species
mutations increase gene pools and allow evolution and natural selection. they be harmful to one organism but beneficial to the species.
