nucelotides Flashcards
what is DNA and RNA
nucleic acids which are polymers
what are the monomers of DNA
nucleotides
What does DNA contain
deoxyribose
phosphate group
Bases: adenine guanine thymine and cytosine
what does RNA contain
nitrogenous bases adenine uracil cytosine guanine
ribose sugar
phosphate group
how do nucleotides join
phosphodiesther bond between phosphate group of one molecule and pentose sugar of other
what is the structure of RNA
contains bases uracil, adenine, cytosine and guanine
single stranded- made of one polynucleotide strand
smaller than DNA
less stable than DNA
what is the structure of DNA
double stranded
bases are complementary
hydrogen bonds between bases
forms ‘double helix’
how does DNA being a long molecule relate to its function
holds alot of information
how does DNA being double stranded relate to its function
both strands used as templates during DNA replication
how does helical structure relate to DNAs function
compact
how does sugar phosphate backbone relate to DNA function
provides chemical and physical protection of bases
how does complimentary base pairs relate to DNAS function
accurate DNA replication
how do weak hydrogen bonds (individual) relate to DNAs function
easily broken for replication
how do strong hydrogen bonds (collective) relate to DNAS function
stable molecule
how does base sequence relate to function of DNA
codes for primary structure of protein
compare structure of DNA vs RNA
DNA is longer whereas RNA is shorter
DNA is more stable (double stranded) whereas RNA less stable
DNA contains deoxyribose whereas RNA ribose only
DNA- ATCG whereas RNA- AUCG
what does ATP stand for
Adenosine triphosphate
what is the structure of atp
3 phosphate groups ribose and adenine
what happens when 3 phosphate groups are easily broken
release large amounts of energy
How is ATP made
ADP and Pi react to form atp. It’s a condensation reaction, energy is required and ATP synthase is the enzyme involved
how is ATP broken down
ATP is broken down into ADP and Pi. Its a hydrolysis reaction, energy is released and ATP hydrolase is the enzyme involved
what processes make ATP
oxidative phosphorylation
photophosphorylation
substrate-level phosphorylation
what is oxidative phosphorylation
addition of phosphate to ADP to make ATP
energy from electron transfer chain in aerobic respiration
what is photophosphorylation
energy from light in photosynthesis
what is substrate level phsophorylation
energy released from chemical reaction of phosphate ion donated by substrate
How is ATP used
provides energy for chemical reaction because phosphate ion added to substrate to make it more reactive
Addition of phosphate to protein because causes a shape change and can then carry out its function
why is ATP useful as a molecule
single bond broken therefore immediate energy release
small amount of energy released
easy/rapid synthesis because only 1 bond formed
soluble so diffuses around cell easily
when does DNA replication occur
during synthesis phase of cell cycle
What is the process of DNA replication
- DNA helicase unzips DNA by breaking hydrogen bonds and this seperates DNA molecule into 2 seperate strands
- Activated and free nucleotides join by complimentary base pairing to two template strands
hydrogen bonds form between free nucleotides and each template strand - DNA polymerase joins sugar phosphate backbone by forming phosphodiesther bonds between nucleotides
- semi-conservative replication: new DNA molecules made of 1 new and 1 original strand
- each molecule forms a double helix
how does DNAs structure allow replication
double stranded so each strand acts as a template
hydrogen bonds easily broken
complementary base pairing holds strands together
How was the meselson-stahl experiment carried out
Grew e coli on 15N (heavy nitrogen)
then transfered bacteria to 14N substrate0
Means that DNA replications now can only use 14N
using ultracentrifugation the DNA from each subsequent replication can be seperated
band reveals the mechanism
what is meant by DNA being universal
all cells have double helical DNA
what does DNA only code for
proteins
what is a code
sequence of DNA bases which are read as base triplets
what does each triplet code for
one amino acid which determines proteins primary structure
what is a gene
short length of DNA that codes for a polypeptide
what do proteins determine
characteristics of cells, tissues and organs, whole organisms
why is a genetic code universal
all organisms have DNA
why is a genetic code non-overlapping
each base is in only 1 base triplet
why is genetic code a triplet code
groups of 3 bases code for one amino acid
why is genetic code degenerate
each amino acid has at least one triplet code
what is mRNa
messenger RNA
what is tRNA
transfer RNA
what is the structure and function of mRNA
carries nucleotide message of a gene from DNA in nucleus out of nucleus to ribosome
simple linear strand
length of a gene (1000s nucleotides)
has codons (sequences of 3 bases)
what is the structure and function of tRNA
carries specific amino acids to mRNA and ribosome so that amino acids can be put together in order dictated by mRNA
clover leaf shape because forms H bonds with itself
80 nucleotides
contains anticodons (3 nucleotides)
what is the process of transcription
- DNA helicase unzips DNA- breaking H bonds
- RNA polymerase enables binding of complementary RNA complimentary nucleotides to template strand and forms bonds in sugar phosphate backbone
- mRNA synthesis finishes when stop triplet reached on DNA
4, mRNA splicing then occurs
what is splicing
Splicing removes introns and rejoins exons and exons can be rejoined in different orders to create different proteins
