lecture 5&6 Flashcards
what is the purpose of nucleic acids
store and transmit genes
program amino acid sequence of polypeptide (proteins)
structure of nucleic acids
made of nucleotides
what are the two types of nucleic acids
deoxyribonucleic acid (dna)
ribonucleic acid (rna)
what does the dna do
stores information for protein synthesis
acts as a blueprint to make the proteins
what does the rna do
directs protein synthesis
acts as messenger to relay information from dna
what replaces thymine in rna
uracil
what is the structure of nucleic acids
a phosphate molecule
a 5 carbon sugar
a nitrogenous base
what sugars do dna and rna have
dna has deoxyribose
rna has ribose
what kind of formation do the dna strands have
antiparallel formation
3 prime to 5 prime
what are the functions of histones
wind the dna to fit 2m into 10 nanometers of space
control gene activation and deactivation
what do gene have to do with proteins
genes have the information needed to make the specific protein and the primary sequence of the protein
what are the two major steps in protein synthesis
transcription
translation
what are the steps of transcription
- separation of dna at a particular gene
- synthesis of mRNA (using uracil)
- mRNA is sent to cytosol
what is the start codon of transcription
AUG
do the start/stop codon code for amino acids
only the start codon
what are codons
group of three nucleotides that code for one amino acid
what are the characteristics of mRNA
single stranded
synthesized in nucleus with the help of enzymes and dna
has the information of one gene
what is translation
the assembly of the protein’s primary structure according to the codon sequence on the mRNA
what does the tRNA do
decode the codons of mRNA
how does the tRNA work
it has anti codons that complementary bind to the mRNA codons while creating an amino acid chain
how many codons are there
64 (1 start, 3 stop and 61 amino acids)
how many anticodons are there
31 (many codons code for the same amino acid)
what does the rRNA do
links mRNA and tRNA
what is the structure of rRNA
3 tRNA binding sites:
1. A site (aminoacyl-tRNA)
2. P site (peptidyl-tRNA)
3. E site (exit site)
what is the process of translation
tRNA attaches to the start codon at the P site
the next tRNA attaches to the A site
the ribosome moves along the mRNA which makes the tRNA leave through the exit site
this builds the amino acid chain until the stop codon is reached
when the stop codon is reached what happens
a release factor binds to the A site which causes a water molecule to be added to hydrolysis the chain
this releases the polypeptide
what is the range of cell size*
8 to 100 um
why are cells so small*
because as cell size increase the metabolic needs of the cell increases
the surface area is smaller than the volume so it can’t meet the demands
what does having a smaller volume mean for a cell*
less metabolic demands but also less surface area to transport materials in and out