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chapter 16 and 17 (concept 16.1: DNA is the genetic material (DNA…
chapter 16 and 17
concept 16.1: DNA is the genetic material
DNA replication is how cells repair their DNA
transformation is a change in genotype and phenotype due to the assimilation of external DNA by a cell
bacertiophages are viruses that infect bacteria and theyre called phages for short
a virus is DNA enclosed by a protective coat
a double helix is a double strand that came together
antiparallel is when subunits run in opposite directions
concept 16.2: many proteins work together in DNA replication and repair
semiconservative model is where two parallel strands come back together
origins of replication are short stretches of DNA that have a specific sequence of nucleotides
a replication for is a Y-shaped region where the parental strands of DNA are being unwound
helicases are enzymes that untwist the double helix at the replication forks
single-strand binding proteins bind to the unpaired DNA strands to keep them from repairing
topiosomerase is an enzyme that helps relieve this strain by breaking, swiveling, and rejoining DNA strands
DNA polymerases catalyze the synthesis of new DNA by adding nucleotides to the 3' end of a preexisting chain
lagging is when the DNA strand elongating in this direction
primase is an enzyme that is a primer thats synthesized
okazaki fragments are the segments that happen when a lagging strand is synthesized discontinuously
a primer is a short stretch of RNA that is produced when DNA is synthesized
DNA ligase is an enzyme is joining the sugar-phosphate backbones of all okazaki fragments into a continuous DNA strand
mismatch repair is other enzymes removed and replace incorrectly paired nucleotides that have resulted from replication errors
a nuclease is a DNA cutting enzyme
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concept 16.3: a chromosome consists of a DNA molecule packed together with proteins
chromatin fits into the nucleus through an elaborate multilevel system of packing
heterochromatin a type of inter4phase chromatin thats visible as irregular clumps with a light microscope
euchromatin is looser packaged and makes its DNA accessibleto gene expression
concept 17.1: genes specify proteins via transcription and translation
gene expression is the process by which DNA directs the synthesis of proteins
messenger RNA (mRNA) carries a genetic message from the DNA to the protein-synthesizing machinery of the cell
translation is the synthesis of a polypeptide using the information in the mRNA
transcription is the synthesis of RNA using information in the DNA
primary transcript is the initial RNA transcript from any gene including those specifying RNA that is not translated into protein
triplet code is the genetic instructions for a polypeptide chain are written in the DNA as a series of nonoverlapping, three-nucleotide words
template strand provides a pattern, or template for the sequence of nucleotides in an RNA transcript
codons are mRNA nucleotide triplets
coding strand is a nontemplate DNA strand
reading frame is the ability to extract the intended message from a written language depends on reading the symbols in the correct groupings
concept 17.2: transcription is the DNA-directed synthesis of RNA: a closer look
RNA polymearse is an enzyme that pries the two strands of DNA apart and joins together RNA nucleotides complementary to the DNA template strand
the promoter is the DNA sequence where RNA polymearse attaches and initiates transcription
terminator is the sequence that signals the end of transcription
the transcription unit is the stretch of DNA downstream from the promoter that is transcribed into an RNA molecule
a start point is the nucleotide where RNA polymearse actually begins synthesis of the mRNA
transcription initiation complex is a promoter
the TATA box is a crucial promoter DNA sequence
transcription factors mediate the binding of RNA polymearse and the initiation of transcription
concept 17.3: eukaryotic cells modify RNA after transcription
RNA processing is where both ends of the primary transcript are altered
5' cap is a modified form of guanine nucleotide added onto the 5' end after transcription of the first 20-40 nucleotides
poly-a tail is 50-250 more adenine nucleotides after an enzyme is added
RNA splicing is the stage of RNA processing in the eukaryotic nucleus
spliceosome is removing introns by a large complex made of proteins and small mRNAs
exons are the other regions
ribozymes are RNA molecules that function as enzymes
alternative RNA splicing is exons during RNA processing
introns is the inbetween regions called interviewing sequences
domains are proteins that often have a modular architecture consisting of discrete structural and functional regions
concept 17.4: translation is the RNA-directed synthesis of a polypeptide: a closer look
transfer RNA (tRNA) a series of codons along an mRNA molecule
anticodon is the particular nucleotide triplet that base-pairs to a specific mRNA codon
aminocyl-tRNA synthesase is where the amino acids and tRNA match up by a family of related enzymes
wobble is the flexible base pairing at this codon position
ribosomal rRNA is large and small subunits that are made of proteins
P site holds the tRNA carrying the growing polypeptide chain
A site holds the tRNA carrying the next amino acid to be added to the next chain
E site is where discharged tRNAs leave the ribosome
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concept 17.5: mutations of one or a few nucleotides can affect protein structure and function
mutations changes to the genetic information in a cell
point mutation small-scale mutations of one or a few nucleotides pairs
silent mutations has no observable effect on the phenotype
a nuceotide-pair substitution is the replacement of one nucleotide and its partner with another pair of nucleotides
missense mutations are substitutions that change one amino acid to another one
nonsense mutation is where a point mutation can also change a codon for an amino acid into a stop codon
insertions are additions of nucleotide pairs in a gene
deletions are the losses of nucleotide pairs in a gene
frameshift mutation is a triplet grouping of nucleotides on the mRNA that is read during translation
mutagens a number of physical and chemical agents