Nucleic acids & protein synthesis
instructs cells how to construct proteins; stored in DNA
segment of DNA that codes for one protein
different versions of a gene
complete set of genes
method used to translate sequence of nucleotides of DNA into a sequence of amino acids
Structure of DNA
•Double helix made of two strands of nucleotides
•Backbone of each strand is a sugar phosphate chain
•Bases of complementary strands hydrogen bond to each other: C-G, A-T
Deoxyribonucleic acid (deoxyribose, phosphate, & nitrogenous base)
adenine, guanine, cytosine & thymine
adenine & guanine
cytosine & thymine
DNA wrapped around ____ form ____.
•Hydrogen bonds break between bases
•Double strands unwind and pull apart
•New nucleotides pair with exposed bases
•What phase of the cell cycle does this happen?
Replication begins at a specific point in the DNA called the ____.
origin of replication
DNA replication step 1
Helicase binds at the origin of replication and begins to unwind and separate DNA strands (unzips)
DNA replication step 2
Single strand binding proteins stabilize the separated strands of DNA
DNA replication step 3
Primase adds an RNA primer at the origin
DNA replication step 4
DNA polymerase adds nucleotides to the RNA primer to form new complementary strand
DNA replication step 5
RNA primer is enzymatically removed & replaced with appropriate sequence of DNA
DNA replication step 6
Because DNA polymerase only works in one direction & the strands are oriented in opposite directions, replication of the leading strand is continuous while replication proceeds discontinuously on the lagging strand forming Okazaki fragments between RNA primers
An enzyme that untwists the double helix of DNA at the replication forks.
Single strand binding proteins
Proteins that bind to and stabilize the signle strands of DNA exposed when helicase unwinds the double helix in preparation for replication.
An enzyme that joins RNA nucleotides to make the primer.
Sequence of RNA primers bound to a region of single-stranded DNA to initiate DNA replication.
enzyme involved in DNA replication that joins individual nucleotides to produce a DNA molecule
the new complementary DNA strand synthesized continuously along the template strand toward the replication fork in the mandatory 5' to 3' direction
A discontinuously synthesized DNA strand that elongates in a direction away from the replication fork.
Short fragments of DNA that are a result of the synthesis of the lagging strand during DNA replication.
Guide to making proteins is encoded in the ____.
Proteins are made in the ____ & DNA is in the ____.
Message needs to get from DNA to ____.
messenger RNA; type of RNA that carries instructions from DNA in the nucleus to the ribosome
Process of copying DNA into mRNA
ribose, phosphate, nitrogenous base
adenine & guanine, cytosine & uracil
adenine & guanine
cytosine & uracil
•RNA polymerase binds to a promoter region on DNA
-Sigma factor recognizes the promoter
•Synthesis of mRNA begins with sequence AUG (DNA: TAC)
•Synthesis of mRNA by RNA polymerase continues until it reaches the transcription terminator sequence (forms a hairpin structure)
•RNA polmerase & mRNA strand dissociate from the DNA
transcription enzyme that links RNA nucleotides together
A regulatory region a short distance upstream from the 5' end of a transcription start site that acts as the binding site for RNA polymerase. A region of DNA to which RNA polymerase binds in order to initiate transcription.
controls the binding of RNA polymerase to the promoter
sequence after a gene that causes RNA polymerase to stop and fall off
mRNA is translated from the nucleic acid sequence to form polypeptide chains
Peptide bond formation during translation requires ___ ATPs.
three-nucleotide sequence of mRNA that codes for a single amino acid
transfer RNA; type of RNA that carries amino acids to the ribosome
group of three bases on a tRNA molecule that are complementary to an mRNA codon
Proteins that function inside the cell are formed on ____.
Proteins that are secreted or become part of membranes are made by ____.
ribosomes docked to ER (RER)
fold amino acid sequence into the proper conformation
How is gene transcription controlled?
DNA structure, DNA methylation, Regulatory proteins
DNA structure transcription control
tightly packed DNA is less accessible to transcription proteins
addition of a methyl group to cytosine
Regulatory proteins transcription factors
can be activated or inactivated by signal molecules like hormones
-Bases are added, deleted, or changed
-May or may not change the protein
-Most mutations that change the protein are deleterious
Agents that induce mutations
-Reactive oxygen species (ROS)
-Metals: iron, mercury, chromium, arsenic, etc.
Reactive oxygen species
toxic oxygen molecules or radicals that are formed by the reaction between oxygen molecules and water during the electron transport chain
DNA repair enzymes
Protection against mutation, detect mismatched base(s) and replace with correct base(s)