1.4 DNA + Protein Synthesis Flashcards
what are the 3 types of nucleic acids
deoxyribonucleic acid
ribonucleic acid
atp
what are nucleic acids made of
nomers called nucleotides
describe the structure of a nucleotide
a phosphate group, pentose sugar and nitrogenous base
the phosphate and pentose sugar are linked by an ester bond
pentose sugar and base are linked by glycosidic bond
what are the four nitrogenous bases
adenine
thymine
cytosine
guanine
what is the difference between a purine and pyrimidine
purine
double ringed structure - A + G
pyrimidine
single ringed structure - C + T
what bond links the pentose sugar and phosphate group on separate nucleotides together
phosphodiester bond
how many hydrogen bonds between complementary base pairs
A-T has 2 hydrogen bonds
G-C has 3 hydrogen bonds
describe the structure of ATP
an adenine base
ribose sugar
three inorganic phosphate groups
how does ATP release energy
when energy is needed in the cell, the third phosphate bond is broken during hydrolysis
this is catalysed by ATPase and products are ADP
why is ATP used as a source of energy
it is a universal energy source
it is an immediate energy source
how does DNA replicate
using semi-conservative DNA replication
describe the process of semi-conservative DNA replication
the parental strand is unzipped
- hydrogen bonds broken
-complementary bases are unpaired
-catalysed by DNA helicase
DNA polymerase lines up free nucleotides to their complementary bases
DNA ligase catalyses the formation of hydrogen bonds and phosphodiester bonds
two new daughter strands are formed
describe Meselsohn and Stahl’s experiment
- They transferred their heavy DNA to a medium with a lighter isotope.
- They took samples after the DNA replicated for the first time and the second time.
- They extracted the DNA and centrifuged it.
- First replication made hybrid DNA=Destroyed conservative model.
- Second replication made light & hybrid DNA=Destroyed dispersive model.
- Concluded that DNA replication is semiconservative
give three features of the DNA code
triplet code
degenerate (64 permutations)
non-overlapping
describe the structure of RNA
phosphate group
ribose sugar
nitrogenous bases (adenine, guanine, cytosine, uracil)
what are the three types of RNA
mRNA-messenger
tRNA-transfer
rRNA-ribosomal
describe differences between ribonucleic acid and deoxyribonucleic acid
RIBONUCLEIC ACID -pentose sugar is ribose -3 types -A,U,C,G -single stranded DEOXYRIBONUCLEIC ACID -pentose sugar is deoxyribose -only one type -A,T,C,G -double-stranded
describe the process of transcription
- DNA dependent RNA polymerase binds onto DNA strand
complementary base pairs break
H-bonds break
helix unwinds - enzyme moves along the DNA strand inserting complementary mRNA nucleotides to produce a single strand of mRNA
- at the end of the gene, the enzyme moves away from the DNA and DNA helix reforms
describe the process of translation
- ribosome binds onto the start codon
- tRNA molecule with an anti-codon that is complementary to the codon of mRNA fits onto the binding site, carrying a specific amino acid
- another tRNA binds at the second binding site
- the amino acids are joined in a condensation reaction to form a dipeptide
- ribosome moves along the mRNA until a stop codon is reached and a polypeptide is formed
define a mutation
change in the arrangement of bases in an individual gene or structure of chromosome
name the three types of mutation
point mutation
chromosomal mutation
whole-chromosomal mutation
name the three types of point mutations
deletion
insertion
substitution
name the four types of chromosomal mutations
gene deletion
gene duplication
inversion
translocation
describe the different effects of mutations
- production of a new superior protein - leads to reproductive advantage
- neutral mutations-no change
- production of inferior or no protein- can be fatal or disease-causing
what are the causes of mutations
x-rays
ionising radiation
chemicals
