CHAPTER 12 Flashcards
(40 cards)
genetic material must be…
able to store information that pertains to the development, structure, and metabolic activities of the cell or organism
stable, so it can be replicated with high accuracy during cell division and be transmitted from generation to generation
able to undergo rare changes, called mutations, that provide the genetic variability required for evolution to occur
DNA contains 4 different types of nucleotides
2 purine bases, adenine and guanine, which have a double ring
2 pyrimidine bases, thymine and cytosine, which have a single ring
chargaff’s rules
the amount of a, t, g, and c in dna varies from species to species
in each species, the amount of a = t and the amount of g = c
double helix
dna is a double helix with sugar-phosphate backbones on the outside and paired bases on the inside
complementary base pairing
means that a purine is always bonded to a pyrimidine
what direction?
dna must always be read in the 5’ to 3’ direction, thus is usually replicated in this direction
dna replication
refers to the process of copying a dna molecule
semiconservative replication
each daughter dna double helix contains an old strand from the parental dna double helix and new strand
what are the pairings
a pairs with t and g pairs with c
dna helicase
separates double stranded dna into single strands
dna primase
synthesizes short rna primers
dna polymerase
synthesizes dna in the leading and lagging strands; removes rna primers, filling the gaps with more dna; and proofreads newly made dna
single stranded binding protein
binds to single stranded dna and prevents it from reforming a double helix
origin of replication
the place where replication begins, a specific site on the bacterial chromosome
dna ligase
covalently attaches adjacent okazaki fragments in the lagging strand
termination region
where replication stops
replication fork
there is a v shape wherever dna is being replicated, this is called the replication fork
rna (ribonucleic acid)
a polymer composed of nucleotides. the nucleotides in rna, however, contain the sugar ribose and the bases adenine, cytosine, guanine and uracil
gene expression
the flow of dna to rna and then on an expressed protein
messenger rna (mrna)
takes a message from the dna in the nucleus to the ribosomes in the cytoplasm
transfer rna (trna)
transfers amino acids to the ribosomes
ribosomal rna (rrna)
along with ribosomal proteins, makes up the ribosomes, where polypeptides are synthesized
transcription
a process by which an rna molecule is produced based on a dna template.
translation
the mrna transcript is read by a ribosome and converted into the sequence of amino acids in a polypeptide
