protein synthesis Flashcards
mRNA
messenger rna
formed in transcription
transfer rna
inolved in translation
ribosomal rna rRNA
SITE OF TRANSLATION
2 subunits
interfering rna RNAi
inhibits translation
contrast the structure of DNA with mRNS
DNA ds vs RNA ss
DNA LONGER
Thymine in DNA
deoxyribose sugar in DNA
hydrogen bonds
introns
define the term exon
base sequence coding for polypeptide
describe translation
mRNA binds to ribosomes
- ribosome finds START codon
- tRNA carrying a specific amino acids binds to mRNA codon
- tRNA anticodon specifically complementary to mRNA codon
- second tRNA molecule bringing amino acid binds to the codon site
- ribosome joins amino acids by peptide bonds
- using the energy from ATP
- tRNA released as ribosomes move along
- ribosome moves alomg the mRNA to form the polypeptide
- ribosome releases polypeptide into RER when stop codon reached
describe transcription
DNA helicase breaks the hydrogen bonds between the strands and unwinds DNA double helix
- only one strand acts as a template
- free RNA nucleotides are attracted to the DNA bases via complementary base pairing
- A-U, C-G
- RNA polymerase joins adjacent nucleotides together to form phosphodiester bonds
- condensation reaction
pre-mRNA spliced to remove introns
give 2 structural differences between trna and mrna
trna has hydrogen bonds
tRna has amino acid binding site
mRna linear vs tRNA cloverleaf
mRNA more nucleotides
mRNA codon vs tRNA anticodon
what is an allele
an allele is the different version of a gene
universal code
the same 3 bases on codon/triplet code for the same amino acids in all organisms
non-overlapping
each base is only part of one triplet/codon
degenerate
more than one triplet codes for an amino acid
3 bases =
DNA = triplet
mRNA = codon
tRNA = anticodon
define gene mutation
change to a single base in the DNA base sequence of a gene. happen randomly.
- changes 1 structure
-n changes position of weak hydrogenbonds
- alters 3 structure hanging H/IONIC AND DISULFIDE BONDS, altering active site and making protein non-functional
substitution mutations
- silent mutation if at end of the triplet
- code is degenerate
addition/deletion mutations
frame shift, reading frame moves to either left or right
- early then all triplets altered, changing AA
NAME some mutagenic agents
- increase the rate of spontaneous mutation
- high energy ionising radition: x rays/ gamma rays - damage the DNA bases and alter structure or interfere with replication
- DNA reactive chemicals (benzene)
- biological agents (viruses, bacteria)
chromosomal mutations
in meiosis, the homologous chromosomes may fail to separate during metaphase 1 or 2
- chromosome non-disjunction
- down syndrome = chromosome 21 (3 copies not 2)
inversion mutation
when a segment of bases is reversed from end to end
duplication mutations
doubling of chromosome or genome
translocation
base pairs relocate from one area of a genome to antoher, between non-homologous chromosomes
biotic factors
predators
disease
competition
lack of prey
lack of food availability
presence of mates
abiotic factors
weather
water levels
temperature
pH levels of soil
humidity
salinity
assumption of serial dilution
each colony has arisen from a single cell
number of bacteria in original sample
if 159 colonies on 1/1000 dilution agar plate
159 x 1000 = 1.59 x10^5 bacteria in original sample
counting bacteria after a given number of replication
2^n times X
n - divisions of bacteria
x = number started with
no of divisions in bacteria
log2n
n = bacteria present
loge = e^x
if exponential in graph, then shift log (log2)
a mutation in the gene coding for an enzyme could lead to the production of a non-functional enzyme. explan how.
- change in DNA base sequence of gene
- change in amino acids/ 1 structure
- change in 2 structyure
- change in ionic/disluphide and hydrogen bond
- change in 3 structure/ active site of enxyme
no ESC form, no longer complementary
not all mutations in the nucleotide sequence of a gene causes a change in the structure of a polypeptide. give 2 reasons why.
- degenerate code, more than one triplet codes for an amino acid
- mutation occurs in intron
define intron
non-coding sequencees within a gene of DNA
define non coding base sequences and describe where the non coding multiple repeats are positioned in the genome
- DNA that doesnt code for a protein/amino acid
- positioned between genes
