chap 2- nucleic acids Flashcards
What are nucleic acids
biomacromolecules. They are like proteins and are essential for all forms of life and are found in all cells
what are biomacromolecules
bio- produced by organisms
macro- large
molecules- a group of atoms bonded together
What are the two types of nucleic acids
DNA and RNA
nucleic acids are polymers, what are their monomers?
nucleotides
What are polymers
large molecules made of a chain of monomers that are chemically bonded
What are monomers
the building blocks of polymers
What does a nucleotide consist of
a phosphate group, a 5- carbon pentose sugar, a nitrogen base
What are the nitrogen bases
A,G,C,T,U
Where is uracil found
only in RNA
What does uracil replace in RNA
thymine
What structure are purines
a 2 ring structure. one that is 6 membered the other is 5 membered
what structure are pyrimidines
they have a 6 membered ring
what are the purines
guanine and adenine
what are pyrimidines
cytosine, thymine, uracil
Why is there a base pairing rule
so that a smaller pyrimidine will pair with a larger purine. forming hydrogen bonds between them to ensure they have a fixed distance between them
what is a hydrogen bond
an attraction between a hydrogen atom and an electronegative atom of nitrogen, oxygen and fluorine.
what is the base pairing rule
A-T
C-G
what does condensation polymerization involve
the synthesis of a polymer and releases water as a byproduct
what is condensation polymerization
how nucleotides join to form nucleic acids
how does condensation polymerization work
the hydroxyl (OH) group on the 3’ end of sugar combines with hydrogen from hydroxyl group of the phosphate. creating H2O. holds monomers together
is DNA stable
Yes
What does DNA do
carry and pass on genetic information of organisms through generations
what do DNA molecules consist of
2 strands of nucleotide polymers wound around eachother
what does the order of DNA code determine
which products are synthesized
how do you label 3’ and 5’ carbons on DNA
count clockwise from oxygen at top of pentose sugar
What sugar does DNA have
deoxyribose sugar
What sugar does RNA have
ribose sugar
What is the antiparallel nature of DNA
one strand will run in the 5’ to 3’ direction with the carbon pointing upwards. the other stand will run 3’ to 5’ direction with the 5’ carbon pointing downwards.
what are histones
small proteins that DNA winds around
what are nucleosomes
consist of 8 histone proteins which coil DNA
what do nucleosomes do
fold up to form chromatin fiber which forms loops
what is the chromatin in a chromosome made up of
loops that are compressed folded and tightly coiled
What is the process gene expression for
the process which the info used to direct the assembly of a protein molecule
what is a gene
a small section of DNA that is a basic unit of heredity
what does gene regulation do
conserve energy and materials within a cell
for a gene to be expressed it needs to be:
transcribed, processed in the nucleus, translated in the cytoplasm with ribosomes help
what do upstream and downstream sections of DNA indicate
where transcription should begin and end
what is the structure of a gene
stop/start triplet sequences, promoter regions, exons and introns
what does the start triplet indicate
where transcription will begin
what does a stop triplet indicate
where transcription ends
where are promoter regions of a gene found
before start at the 5’ end of the site where RNA polymerase attaches ready to begin transcription
what are promoter regions
binding regions upstream of the gene where RNA polymerase can bind in order for transcription to occur
what are exons
regions of the gene that code for an amino acid and are usually expressed as proteins or RNA
what do exons make up when joined together
mature mRNA
what are introns
non-coding regions of a gene
when are introns taken out of mRNA
during RNA processing
What is protein synthesis
a smaller single stranded mRNA molecule is created through transcription so that a section of DNA can leave the nucleus
what is RNA structure
single stranded, ribose sugar, uracil,
what are the 3 types of RNA
mRNA, rRNA, tRNA
when/where are mRNA molecules formed
in the nucleus during transcription
what is mRNA responsible for
carrying a copy of the nucleotide sequence of DNA that specifies the amino acid sequence out of the nucleus to a ribosome where the message can be translated
what structure does tRNA have
folded structure
what does tRNA do
match an mRNA codon with the amino acid it codes for
where is rRNA synthesised
in the nucleolous
what does rRNA do
with help of proteins forms organelle ribosome
what do ribosomes do
where info in mRNA is translated into chain of amino acids which can then be folded into a protein
what is the template strand of DNA
RNA polymerase reads template strand during transcription so that mRNA is same as DNA coding strand but it has U instead of T
what does transcription do
make an RNA copy of the DNA code
what are the 3 steps of transcription
initiation, elongation, termination
what happens during initiation (transcription)
RNA polymerase attaches to promoter region and unwinds DNA strand by breaking hydrogen bonds that hold the 2 strands together exposing nitrogenous bases