Chapter 6: Molecular Genetics Flashcards
genetic material
hereditary information
gamete
sex cells
autosomal cells
body cells
minimal medium
the minimum amount of material needed to grow
spore
an asexual seed
virulent
extremely harmful of toxic
bacteriophage
a virus that infects and destroys bacteria
double helix
a double-stranded spiral that makes up DNA molecular structure
pyrimidine
a nitrogenous base with a characteristic single ring structure (hint: cytosine and thymine)
purine
a nitrogenous base with a two ring characteristic structure (hint: adenine and guanine)
antiparallel
the overall direction of two complementary strands relative to one another such that their 5’ to 3’ orientation run opposite of each other
isotopes
different forms of an element that have the same number of protons and a different number of neutrons and atomic mass
differential centrifugation
a technique that involves the separation of cellular particles according to their mass, size, or density
polymerization
a process by which a large molecule is constructed
phosphodiester linkages
the linkages that hold nucleotides together
DNA polymerase
the enzyme that catalyzes the polymerization of new DNA strands
helicase
an enzyme that unwinds the double-stranded DNA before replication at the site of the replication fork
single strand binding protein
an enzyme that stabilizes the unwound helix during replication
RNA primer
a strand of RNA nucleotides that is required for DNA synthesis
primase
an enzyme that synthesizes RNA primer
okazaki fragments
small pieces of nucleotide that are used to synthesize DNA from the lagging strand
ligase
an enzyme responsible for joining Okazaki fragments into a single DNA strands
DNA polymerase I
an enzyme that assists in removing RNA primers from a DNA strand, replacing them with DNA
leading strand
the strand of DNA of grows continuously in the direction of the replication fork, and can be read easily
lagging strand
the strand of DNA that grows away from the replication fork, and cannot be read easily
excision repair
an incorrect DNA sequence is cut out and replaced with the correct sequence
telomeres
repeating sequences of nucleotide found at the end of DNA strands, which are made up of tandem repeats
telomerase
an enzyme that can polymerize telomere sequences
polypeptide
a chain of amino acids joined by peptide bonds
transcription
the process where information on DNA is coded into a messenger RNA molecule
translation
information on the messenger RNA molecule is converted by a ribosome into a polypeptide strand
codon
3 bases on an mRNA strand that designate a particular amino acid
transcription unit
the sequence on the DNA strand to be coded in mRNA
promoter sequence
a series of DNA nucleotides (15-300 base pairs long) that serves as the site where RNA polymerase binds
transcription factors
a collection of proteins that help RNA polymerase recognize and bind to the promoter
terminator sequence
DNA nucleotides that signal the end of transcription
poly (A) tail
consists of 30-200 adenine nucleotides and is attached to the 3’ end of the mRNA molecule. It protects against degradation and helps export mRNA from the nucleus.
introns
intervening sequences of noncoding nucleotides that occur between coding sequences
exons
expressed sequences of the mRNA transcript
spliceosomes
a composition of proteins and small nuclear Ribonuclear Proteins (hint: snRNPs)
anticodon loop
contains a sequence of 3 nucleotides (anticodon) which are complementary to 3 nucleotides (codon) on the mRNA strand
nucleolus
a site in the nucleus where ribosomal RNA is synthesized and ribosomes are assembled
redundancy/degeneracy
describes the relative unimportance the third nucleotide plays for specifying a given amino acid (hint: ACU and ACC both specify for the amino acid threonine)
charged tRNA
a tRNA molecule bound to an amino acid with a high energy covalent bond (hint: also called aminoacyl tRNA)
ribozymes
enzymes made of RNA that assist in RNA splicing
elongation
the addition of amino acids one by one to form a polypeptide chain
codon recognition
the anticodon of the tRNA binds with the complimentary sequences of the mRNA codon
peptide bond
covalent links that form by dehydration reactions between amino acids
stop codon
1 of 3 sequences of three nucleotides on the mRNA strand, (UAG, UAA, or UGA) which accepts a protein release factor, thus terminating elongation
polyribosomes
several ribosomes attached to an mRNA strand that increase efficiency of translation. They occur in prokaryotes and eukaryotes.
signal peptides
sequences of about 20 amino acids on polypeptides that direct a protein to the ER
lac operon
regulates mRNA transcription of enzymes responsible for digesting lactose
transcriptional controls
control whether or not mRNA is produced
gene expression
transcription and translation to form a polypeptide
repressor protein
a protein that binds to an operator site and blocks RNA polymerase
operator/operator site
the site downstream from the promoter where the repressor protein binds
inducible operon
a regulatory unit that is activated when a small molecule interacts with a regulatory protein
repressible operon
a regulatory unit that is inhibited when a small molecule binds with a regulatory protein
allolactose
an isomer of lactose
operon
a unit of genetic function that consists of regulated sets of genes with related functions
allosteric site
a specific receptor site on an enzyme apart from the active site. Molecules bind here and change the shape of the active site.
genome
the DNA in a complete set of an organism’s chromosomes (both coding for proteins and non-coding DNA)
chromosome
a highly compacted form of DNA and associate proteins
nucleosome
a segment of DNA wrapped around a core of histone proteins
chromatin
a complex of DNA and proteins in eukaryotes
domains
the loops of third level DNA, where chromatin fiber is looped and anchored onto a scaffold protein
denature
the separation of the two strands of the DNA double helix by breaking hydrogen bonds
tandem repeats/satellite DNA
sequences of DNA that repeat one after the other up to several hundred thousand times (ie: GTTAC GTTAC GTTAC, etc.)
interspersed repetitive DNA
sequences of repetitive DNA which are scattered throughout the genome. These sequences are not always identical, but must be similar.
reanneal
the coming-together of DNA strands
centromere
the region of a chromosome that joins two sister chromatids, and is made up of multiple tandem repeat sequences
gene family
long, repeating DNA sequences that can code for genes and are capable of transcribing RNA
pseudogenes
copies of existing genes that lack regulatory sequences that are necessary for gene expression
gene amplification
takes place when many copies of a gene are synthesized in order to increase production of the gene product (hint: salamander eggs and cancer cells)
transposon/jumping genes
a segment of DNA that is able to copy itself and insert this copy elsewhere in a chromosome
retrotransposons
a transposable element that moves within a genome by means of an RNA intermediate
histone
a small protein involved in DNA packing
nucleoid
region where DNA concentrations are found in prokaryotic cells
gene controls
methods used to ensure that certain genes are only expressed when needed
totipotent
containing a full set of hereditary instructions
transformation
transfer of genetic material from one cell to another
complementarity
sets of hydrogen bonds link base pairs together (2 hydrogen bonds between thymine and adenine, and 3 hydrogen bonds between guanine and cytosine)
endonucleases
cut DNA internally
exonucleases
chews away at the end of DNA, helps proofread, and is used by DNA polymerase I to remove the primers after replication
replisome
a replication organelle, made up of an assembly of proteins
primosome
made up of primase/helicase and other proteins
gene
a sequence of nucleotides that determines the amino acid sequence of a protein
triplet code
the 3-nucleotide sequence in each codon
reading frame
part of the genetic code that is read by mRNA
template strand (antisense strand)
the strand of DNA that is copied
coding strand (sense strand)
the strand of DNA that is not copied, and is identical to RNA
-35 sequence
TTGACA, which is 35 nucleotides away from where transcription starts
-10 sequence
TATAAT, which is 10 nucleotides from where transcription starts
transcription bubble
the area containing RNA polymerase, DNA, and the growing mRNA strand
CG hairpin
causes polymerase to pause and let go of DNA
nonsense codons
UAA, UAG, UGA
initiation factors
proteins that position tRNAfMet (in prokaryotes) or methionine (in eukaryotes) at the P site
