Unit 1.5 Flashcards
Polymer?
made of monomers
single units
nucleotide
What is nucleotide made of?
3 components
Phosphate
Pentose
Sugar
Nitrogenous base
DNA sugar?
Deoxyribose
RNA sugar?
ribose
ATP?
Heterotrophic organisms derive chemical energy from food
Autotrophic organisms derive chemical energy from light energy through photosynthesis
what does it stand for?
Adenosine Triphosphate
What does it mean by universal energy currency?
used in all chemical reactions in all cells
How much ATP do humans break down?
50 kg of ATP a day but the body only retains 5g because ATP is not a storage molecule
Equation?
ADP + Pi—- ATP
condensation / phosphorylation
ATP —- ADP +Pi
Hydrolysis
The structure of ATP?
when energy is needed in a living organism, the enzyme ATPase hydrolyses the termianl bond between the 2nd and third phosphate
if ATP = hydrolysed into adenine diphosphate
it releases 30.6kj of energy
Equation for this?
ADP+Pi — ATP
Photophosphoryation
condensation requires 30.6 KJ ( endergonic)
ATP transfers?
free energy from energy rich compounds (glucose) to cellular reactions it would produce a massive increase in temp which would destroy the cell
instead ATP releases small quantities of energy in a series of steps, minimising energy lost
Compare Glucose + ATP?
only 1 enzyme = needed to release energy from ATP but many are needed for glucose
ATP releases energy in small amounts when and where is needed whereas glucose releases energy all at once
ATP is a universal energy currency which can be used in all reactions in all cells but glucose cannot
ATP is easily hydrolysed in a single reaction, whereas glucose has many intermeidates
Role of ATP at cellular level?
metabolism
movement - muscle contraction
Active transport - to change the site of the carrier protein
nerve transmission - for use by Na+/K+ pump
secretion from vesicles
biolumniscence
Bioluminscence?
production + emission of light from a living organism
The structure of DNA?
pentose sugar in the nucleotide = deoxyribose
4 organic bases
Adenine
Thymine
Cytosine
Guanine
Sugar phosphate backbone protects genetic into 2 polynucleotide strands
in the shape of a double helix
bases face each other + joined by H bonds
between A+T - 2 H bonds
between C-G - 3 H bonds
A = complementary to T
G = complementary to C
DNA = very long, thin + tightly coiled into the chromosome
double helix diameter - 2nm
chromosome number = longest at 85nm
nucleotide in 1 strand = arranged in the opposite direction to those in the complementary strand
they are antiparallel - not going in the same direction
Functions of DNA?
single molecule which passes from generation to generation unchanged
a large molecule to accommodate the vast genetic information
the 2 strands are easily to separate as they’re held by weak hydrogen bonds
the bases of the inside of the double helix contain the genetic information whilst the backbone offers protection
Structure of RNA?
single stranded polynucleotide
contains pentose sugar ribose
2 purines (AG)
2 pyrimidines(CU)
3 types of RNA?
mRNA
tRNA
rRNA
mRNA?
messenger RNA
long, single stranded
synthesised in the nucleus
carries genetic information from the DNA to the ribosomes in the cytoplasm(function)
rRNA?
ribosomal RNA
cytoplasm
large + complex
component of a ribosome
function?
the site of translation of the genetic code into proteins
tRNA?
Transfer DNA
small single stranded
folded so the bases can form complementary pairs
clover leafed shape
Function of tRNA?
to carry a sequence of 3 bases called an anticodon + transport specific amino acids
Compare DNA and RNA?
DNA = double helix
RNA = single stranded
DNA = long
RNA = short
DNA = Deoxyribose
RNA = ribose
Purines = the same in both
DNA = Pyrimidines CT
RNA = Pyrimidines CU
Watson crick?
proposed the molecular structure of DNA
they used information on Franklin + Wilkins who used X Ray defraction to show the structure of DNA
Function of DNA?
small molecules of DNA occur in chloroplasts and some have RNA
2 main functions = replication + DNA have complementary strands. the base sequence of 1 determines the other
If the 2 strands of double helix separate what happens?
2 identical double helixes can be formed
each parent strand acts as a template
2nd function?
protein synthesis
sequence of bases determines the amino acid sequence + protein which can be made
DNA replication?
chromosomes may make copies of themselves, so when the cell divides each daughter cell receives an exact copy of the genetic information
this replication occurs during interphase in the nucleus
Conservative replication?
the parental double helix remains intact and whole new double helix is made
the 2 new double helixes contain pigments from both parent strands
Semi Conservative Replication?
parental double helix seperates into 2 strands
each strand acts as a template to produce a new strand
Meselson + Stahl?
cultured E.coli
the medium contained the heavy isotope N15
Process?
the medium contained heavy isotope N15
create 4 test tubes light or heavy
N15 were washed + transferred to a medium of N14 and were allowed to divide
DNA from the first generation were centrifuged
DNA from 2nd generation settled at a high point medium point and a lower point indicating
N15 N15 N15 N14 N14 N14
this rules out conservative replication
Genetic code?
DNA = a store of genetic information
Information = coded in the sequence of bases which make up genes
Base sequences determines which amino acids join together and which proteins are made
If 3 bases = removed from a polypeptide chain?
there will be 1 less amino acid
If one base coded for 1 amino acid how many could be made?
only 4 amino acids
If 2 bases codes for 1 amino acid?
would be 16combinations
If 3 bases coded for 1 amino acids?
there would be 64 combinations
3 bases encode?
each amino acids and is known as the triplet code
4 to the power of n, what is n?
number of bases
How many possible codes?
but only 20 amino acids are found in proteins
Degenerate?
not being used but still present
Codon?
triplet of bases in DNA that codes for an amino acid
Anticodon?
a triplet of bases found on tRNA
removal of introns
Intron?
non coding nucleotide sequence found in DNA and pre mRNA
must be removed before sequence is copied
Exon?
a nucleotide sequence in DNA and pre - mRNA that remained present after the introns have been removed as it is coding DNA
In eukaryotes?
introns = removed before code is translated into a protein
Introns?
cut out using restriction endonuclease
What are exons joined by?
using enzyme ligase
Transcription?
a segment of DNA which acts as a template for the synthesis of a complementary sequence of RNA
(using RNA polymerase)
Translation?
of codons on an mRNA strand on a ribosome in the cytoplasm which is used to produce a specific sequence of amino acids which can be made into a polypeptide chain using ribosome
Transcription?
DNA does not leave the nucleus as it is too big
DNA acts as a template
Enzyme DNA nuclease breaks the hydrogen bonds between the bases
the 2 strands seperate and unwind, exposing the bases
mRNA enters through the nuclear pore and aligns opposite the DNA strand
free nucleotides = present in the nuclear plasm
enzyme RNA polymerase binds to the template of DNA at the start codon
Free Nucleotides align opposite the template strand
RNA polymerase moves along the DNA strand, forming H bonds between the nucleotides
The DNA strand rewinds to form a double helix
RNA polymerase?
when the RNA polymerase separates from the template strand
a stop codon = signalled
a newly formed complementary copy of mRNA leaves the nucleus via the nuclear pore
Translation?
Ribosome has 2 subunits
large = 2 attachment sites
small = 1 attachment sites
the ribosome acts as a work bench to hold the codon and anti codon complex
when the 2 amino acids sufficiently close they form a peptide bond
the polypeptide chain = packaged and modified in the Golgi body
3 sites of translation
Initiation
elongation
Termination
Intiation?
tRNA with the anticodon complex attaches to the ribosome forming H bonds with the mRNA strand
second tRNA attaches to the ribosome, allowing peptide bonds to be formed
Elongation?
Ribosomal enzyme = required to create the peptide bond
the first tRNA leaves and returns to the cytoplasm to find specific amino acids
Ribosome moves by 1 codon along the mRNA strand
Another tRNA binds
Termination?
sequence repeats until a stop codon = reached
the ribosome, mRNA and polypeptide = separate