lecture 3 Flashcards
(86 cards)
what is the monomer of nucleic acids? what is the monomer made up of?
the monomer is a nucleotide/nucleoside, the nucleoside is made up of sugar and a base and you add the number of phosphate to the name, the nucleotide includes the phosphate group but doesn’t specify how many phosphate groups there are
what is the main building block for DNA
dNTP or 2’ deoxyribonucleoside triphosphate
when building a nucleic acid, we build on what direction? from what direction? and what kind of bond does it create?
we always build a nucleic acid on the free 3’ end, we always synthesize from 5’ to 3’, DNA is antiparallel and complementary. it creates a phosphodiester bond
what are the pyrimidine bases?
cytosine, thymine, and uracil for RNA
what are the purine bases?
adenine, guanine
what are the base pairings
AT and has 2h bonds , GC and has 3h bonds
prokaryotes have what kind of DNA? how do they protect their DNA and what enzymes help them do this?
they have singular circular DNA, they do METHYLATION: adds ch3 groups to protect from their own RESTRICTION ENZYMES that chop up unknown DNA and SUPER COILING: twisting of DNA to compress it into smaller spaces done by DNA GYRASE
DNA packaging in eukaryotes
sugar phosphate backbone wrapped around HISTONE PROTEINS–>a couple of histones are called NUCLEOSOMES–> a strand of nucleosomes are called CHROMATID–> CHROMATID makes up chromosome that is held within nucleus
what are the the two different types of chromatids?
EUCHROMATIN: unwound active with light staining and HETEROCHROMATIN: tightly wound inactive with dark staining
what is the centromere
region on the chromosome where sister chromatids are held together and where mitotic spindle fibers attach
what are the short arms and long arms on a chromosome called
short arms are P and long arms are Q
what are telomeres
the ends of eukaryotic linear chromosomes, have short sequence repeats and it stabilizes the ends of the chromosomes
what is the central dogma of DNA? why do we use RNA?
DNA (nucleotides) —transcription—> RNA (nucleotides)—translation—>proteins (amino acids), we use RNA to protect DNA to not work with it directly and damage it
codons code for what? what are the codons we must know?
codons have 3 nucleotides and code for 1 amino acid, the START codon is AUG , the three STOP codons are UGA, UAG, UAA
how many chromosomes are there in human genome
46
what are the four sources for mutations
polymerase errors, endogenous damage, exogenous damage, and transposons
what are the two polymerase errors that can occur
point mutation and frameshift mutation
what are the three point mutations that can occur
missense, nonsense, and silent mutations
what occurs in a missense mutation and what is its effect on the protein
in a missense mutation, a codon for an original amino acid turns into a new codon for a new amino acid EFFECT: changes amino acid
what occurs in a nonsense mutation and what is its effect on the protein
in a nonsense mutation, a codon for an amino acid becomes a stop codon EFFECT: shortened protein
what occurs in a silent mutation and what is its effect on the protein
in a silent mutation, a codon for an amino acid becomes a new codon for the same amino acid EFFECT: no effect
what occurs in a frameshift mutation and what is its effect on the protein
in a frameshift mutation, there are insertions and deletions that change the reading frame ex. AUG CCC GAU UGA turns into AUG ACC CGS UUG A when an A has been inserted. EFFECT: addition of the wrong amino acids to the protein and/or the creation of a codon that stops the protein from growing longer.
what is a endogenous mutation? two examples
a mutation that occurs due to a reactive oxygen species or physical damage ex. intrastrand cross link of DNA and interstrand cross link of DNA
what is a intrastrand cross link of DNA
an unwanted link within the same strand of DNA making it not complimentary
