click below
click below
Normal Size Small Size show me how
WGU BIOCHEM Module 1
DNA and RNA
central dogma of molecular biology | the understanding that DNA is used to make RNA and RNA is used to make proteins |
transcription | the process of the cell making an RNA copy of a DNA section |
what 4 nucleotides (monomers) make up DNA | guanine, cytosine, & adenine, thymine |
what 4 nucleotides (monomers) make up RNA | guanine, cytosine, & adenine, uracil |
Each nucleotide includes a ________, a ________, and one or more ____________. | nitrogen-containing base, a five-carbon sugar (pentose), phosphates |
Nucleic acids are read in what direction | 5' -> 3' |
semi-conservative | copies of DNA contain one old strand and one new strand |
what is DNA polymerase | a protein that synthesizes new DNA (makes a polymer of DNA nucleotides) |
how does DNA polymerase work | matches up individual nucleotides to parental sequence to make sure they are a correct pair, then bonds them |
RNA primer | forms a handle on a single-stranded DNA making it double-stranded so DNA polymerase can attach |
DNA ligase | seals the nicks left after RNA primer is removed during DNA replication to create a continuous strand |
The ______ strand of DNA gives the sequence of the RNA to be made, but the ________ strand is the DNA strand used to make the RNA. | coding, template |
the primary enzyme involved in transcription is ____________ | RNA polymerase |
how does RNA polymerase work | reads the template strand of DNA and creates new RNA transcript by bonding together individual RNA nucleotides that are complementary to the DNA template |
________ gene expression = ___________ transcripts made | low, few; high, many |
splicing | process in which introns are cut out, and remaining eons are joined together = making mature RNA ready for translation |
introns | intervening sequences |
exons | expressed sequences |
translation | nucleic acid "language" of nucleotides processes into the protein "language" of amino acids |
codons | 3 base units in the mRNA; the amino acid specified by each set of three bases defines the genetic code |
anticodon | 3 bases on the tRNA that are complementary to the codons |
when codon and anticodon meet and base pair, the amino acid is incorporated into the growing protein chain by a _______________ | peptide bond |
polypeptides | protein products of translation |
mutations that are changes of a single base pair | point mutations |
point mutations that result in no change in amino acid sequence due to some redundancy in the genetic code | silent mutations |
point mutations that change a single base pair in a codon such that the codon now encodes a different amino acid | missense mutations |
point mutations that change a single base pair in a codon to a stop codon that terminates translation | nonsense mutations |
insertions or deletions of one or more base pairs lead to _________________ that disrupt the coding of a protein | frameshift mutations |
base excision repair | repair enzymes removed the damaged nucleotide. gap is filled by DNA polymerase. nick is sealed by DNA ligase |
nucleotide excision repair | repair enzymes remove a section of DNA that contains the damaged nucleotide. gap is filled by DNA polymerase. nick is sealed by DNA ligase |
thymine dimer | mutation caused by uv radiation that fuses two adjacent thymines together. can only be fixed by nucleotide excision repair |
which repair pathway is used for mistakes in replication | mismatch repair |
which repair pathway is used for double-stranded breaks | homologous recombination (and for extreme cases only, non-homologous end-joining) |
genes are located on ______________ and come in pairs in most human cells | chromosomes |
each copy of a gene is known as an _____________ | allele |
DNA is wrapped around proteins called _________________ to prevent tangling | histones |
the combination of DNA and histone proteins creates | nucleosomes |
histones promote coiling of the nucleosomes into a larger ____________ fiber | chromatin |
the chromatin fibers are folded into large loops that eventually form _______________ | chromosomes |
human beings have _______ pairs of chromosomes | 23 (1-22, and either an XX or a XY for the sex chromosome) |
when two alleles are identical, the genotype is ______________ | homozygous |
if two alleles code for two variations of that trait the genotype is ________________ | heterozygous |
pedigree chart: only _________ traits can have carriers | recessive |
pedigree chart: assume that an unaffected/ unrelated mate (does/does not) carry the trait | does not |
incomplete dominance | produces different phenotypes based on the combination of alleles present (red, white, pink) |
codominance | occurs when the effects of both alleles appear in the heterozygote (red, white, red-white) |
x-linked inheritance | the most common form of sex-linked inheritance (ex: red-green color blindness) |
pedigree analysis decision tree: x-linked recessive / are carriers present? | yes (2 parents that are unaffected, but have an affected child) |
pedigree analysis decision tree: x-linked recessive / are only males affected? | yes |
pedigree analysis decision tree: autosomal recessive / are carriers present? | yes (2 unaffected parents with an affected child) |
pedigree analysis decision tree: autosomal recessive / are only males affected? | no |
pedigree analysis decision tree: x-linked dominant / are carriers present? | no |
pedigree analysis decision tree: x-linked dominant / do ALL the daughters of an affected male have the trait | yes |
pedigree analysis decision tree: autosomal dominant / are carriers present? | no |
pedigree analysis decision tree: autosomal dominant / do ALL the daughters of an affected male have the trait | no |
_____________________ is a technique that copies a chosen segment of DNA | polymerase chain reaction |
_____________, ________________, and ___________________ are the steps in the PCR process | denaturation, annealing, and elongation |
explain the similarities/difference in the coding strand from the mRNA sequence | sequence is the same except T bases have been replaced with U bases |
explain the similarities/differences in the template strand from the mRNA sequence | sequence is complementary and 3' to 5' |
when histones pack tightly, (transcription/translation) is decreased | transcription |